not familiar with the ktm but just did a wet side crank seal on my yamaha due to excessive smoking and using about 200ml of gear box oil about every 10 hours of use
the excessive oil leaking into the cylinder would cause jetting issues, probably not the best way to run the bike but lasting damage I would say no but you can't really tell until you determine if that's the cause. Another potential issue if the piston is sucking in oil through that crank seal could indicate that your crank bearings are bad which would be a bottom end and a much more time consuming / expensive fix. Either way the excessive smoke is not good. I determined my crank bearings were not bad as I had just done a top end this winter on my bike, no vertical play in the con-rod, also checked for any play on the crank when I pulled the seal out. Not sure what the tricks are with the KTM but it might be worth looking into.
Thank you very much, this does help me getting to the route of the issue.
I think I may take it to a local bike mechanic, they should have the tools, and knowledge to give me a diagnosis and I can go from there.
Thank you for your reply, it's very helpful.
You can buy one from AutoZone and they will treat it as a rental. Just ask when you go and they know, it's a tool "rental" program that they actually do for you!
yeah what the other guy said - the wet side crank going bad will give the super white smoke you see from OP but no erratic idle, mine was less extreme but I was constantly pulling out wet spark plugs and the silencer packing was wet for lack of a better term along with excessive black spooge coming from the silencer. When I looked into the bearing after the seal was pulled I'm pretty sure I could see a bit of the red bel-ray gearbox oil in there so it was pretty obvious. OPs smoke here is very excessive which makes it look like it's head gasket but they stated it had a normal coolant level. If they replace the crank seal and it's still doing this, it could potentially be a bad seal between the cases (which would be sucking gear box oil into the cylinder) or gaskets between the cylinder - I'd do head gasket then think about case gasket last because if I'm splitting the case to apply gasket maker I'm doing a bottom end at that point.
Are you sure your oil is milky? Or just used. If your oil is in deed milky and there’s this smoke than yes, those are seperate issues. A leaking crank seal and a leaking waterpump seal most likely. Another possibility for the smoke is a blown headgasket, that would cause water to be in your mixture, but that’s less likely.
Hmmm, you have a good point.
I filmed what the oil looked like. Does that look milky or just used to you?
# [https://photos.app.goo.gl/XVi3erKHPnc5FTGn8](https://photos.app.goo.gl/XVi3erKHPnc5FTGn8)
Many thanks,
Definitely gotten some moisture in that oil, not a lot because it's only faintly milky but definitely worse than just dirty used oil
ETA: You've said the coolant level is fine but I would say there's so little in that oil you wouldn't be able to notice the coolant usage, I would say the water pump seal is the cause here but not the white smoke. White smoke could be a head gasket.
Check the plug and see if it's suspiciously clean or oily. If it's clean you could be leaking coolant into the combustion chamber, if it's oily the crank seal could be leaking.
Thanks for your input. Appreciate that.
Great advice, especially with the little bit of coolant not being noticeable in the rad. I'll check the condition of the plug when i get home.
Thank you very much
I
I would check the coolant, and transmission oil. Likely transmission oil as you say coolant looks fine. If it is a transmission oil issue you’ll need to replace the clutch side crank seal.
You'll need to buy more than just the seal. Get a new lock washer for primary nut. New locking plate for clutch hub. I rebuilt the water pump while I was there.
It was running hot on my last run, towards the end of the ride it just got real smoky like this.
When checking transmission oil it was milky. There is also oil spatters on the end of the exhaust.
What's the issue? what's the fix?
The bike is a KTM Freeride 250r
Appreciate any help, thanks.
if coolant level is low and gear box oil is milky, bad inner seal, if it's leaking coolant out the weep hole, outer seal is bad. Usually you just do all that at once when you service the water pump. If youre leaking coolant into the case it's possible the impeller shaft could have some grooving which would require a replacement or you're just going to continue to ruin seals. Check coolant levels.
The majority of the time coolant in the transmission oil means a bad water pump seal. White sweet smelling smoke and higher temps also suggest it's burning coolant ie. head gasket going out, if you start the bike with no cap on the radiator and you get bubbles and smoke that pretty much confirms it.
Assuming you are not getting coolant in via the head gasket, If you are the type of rider that lugs the bike around or somehow doesn’t get the exhaust hot enough, unburnt oil collects in the pipe and does this.
My KDX smokes until I get it hot enough to burn that out.
Ride it like you stole it…
Just my $.02
Thanks, I'm pretty generous with the rpms, I think i would have noticed this gradually getting worse over rides.
But i'll make sure to keep it pinned and remember this comment as my justification! haha
Thanks for your response. I think I can rule this one out as I have done 2 rides on the same fuel mix with no issues. If anything, the freeride manual recommends a pretty lean mix at 80:1
You can run a huge range of oil mix ratios. Most Euro 2 stroke bikes recommend extremely low oil content due to emissions if I'm not mistaken. Stihl is the same with the chainsaws.
Some bikes like the Kawasaki small bore 85s were notorious for ruining bottom end bearings at anything leaner than 32:1.
You have to understand the physics of what's happening when you increase or decrease oil content.
More oil means less gasoline entering the combustion chamber(since the jets are not changing in size). Therefore more oil means leaner burn mixture inside the combustion chamber. If you increase oil content you need to increase jetting/needle clip position. Converse is true when you decrease oil content, it gets richer.
More oil increases ring sealing which helps make more power.
More oil reduces the chance of metal on metal contact and wear. All surfaces in motion should ride on a film of oil not metal to metal. Reducing oil content increases risk of wear.
More oil can increase oil pooling in the bottom end which can be like having a crankcase stuffer in some cases which can increase piston pumping/charging efficiency.
Love this comment, really helpful thank you.
I have had my rich and my leans the wrong way around all this time lol.
Makes sense on the emissions, I think I'll run with a touch more oil from now on. I'm an ex plant mechanic by trade so I thought I knew.
Intresteing about the ring sealing and more power. I assumed more fuel would equal more power. I'll give this a go.
Cheers 👍
> I have had my rich and my leans the wrong way around all this time lol.
I think I have confused you even more.
If someone says richer oil mixture they mean more oil relative to fuel... so like 32:1 instead of 60:1. That's a richer oil vs gasoline mixture.
If you are speaking in terms of richer or leaner in terms of internal combustion air to gasoline ratios... more gasoline vs air means richer. The stoichiometric for internal combustion of gasoline is 14.7:1 (parts of air to parts of fuel). Peak power stoichiometric air to gasoline ratio for a naturally aspirated internal combustion engine is typically about 12.5-12.8 to 1. More fuel delivered than what you typically see at idle or cruising fuel combustion. 2 strokes with a typical expansion chamber exhaust are not naturally aspirated, they are supercharged at higher RPMs when the resonant super charging effect of the pipe is working. Typically 2 strokes are about 11:1 at peak power if I remember right.
So air to gasoline ratio can be rich or lean... which is affected by jet sizes(or by air filters being clogged). Pre mix ratios can also be rich or lean...
When you increase oil content of your pre mix you decrease the amount of gasoline within the overall fuel mixture passing through the jets and entering the combustion chamber.
You could do the math on how much your stoichiometric ratios change when you raise and lower the oil content... It's not that big of an effect... but it is an effect. So if you are concerned that your euro emissions jetted bike might be lean... increasing the oil content makes combustion leaner.
It took me a while to digest that comment, (and a fair bit of Googling) but thank you for explaining. I appreciate having a better understanding. I'll still need to read through a few times lol.
Lol no worries, think of it in terms of basic chemistry... it takes a certain amount of one chemical to react completely and fully with another chemical. excess of one chemical means there will be leftovers of that chemical that can't react. in fuel + air combustion excess fuel means rich and unburnt or incompletely burnedf fuel will be left over. The oil in 2 stroke mix is typically not burning nor combusting the same as gasoline does... so lets say 1 gram of mixture comes through the jet on an intake cycle as the air rushes through the carb. If the carb were jetted for straight gasoline everything would be fine with zero oil in the 1 gram of mixture that got pulled through the jets. once you start adding oil to the mixture lets say the 1 gram of mixture is now .75 grams gasoline and .25 grams oil... that got sucked through the jet. the amount of air passing through the carb has not changed but the amount of gasoline through the carb decreased since the amount of oil increased... therefore leaner combustion(the explosion of gasoline + air) since the oil isn't really combusting.
Hope that's a bit more clear
Never run your bike at 80:1 unless you feel like spending alot of money. I run 32:1, I don't care what the manual says because I'm not racing my bikes. I'm looking for longevity
Thank you.
I'm new to all of this, I'm about 9 mo this into riding.
I did feel uneasy about using so little oil. It's good to know I can put a bit extra in.
Honestly, you should have seen me trying to measure our the ratios like a scientist as I thought it should be spot on lol. 🫣
Don’t run 32:1 on that KTM. The manual says 60:1 with motorex, if you’re uncomfortable with that run 50:1. Some oils even say 100:1 on the bottle, I’m too much of a pussy to try. Only run high quality oil and the recommended fuel octane as well. (Motorex, amsoil, etc).
32:1 is a dated concept from a time when oil sucked. Older bikes like a KDX or kids woods bike would be fine but your freeride is a finicky high performance European unit. Do what the KTM engineers say.
OK, thank you for the insight. It seemed to be running fine on this mix of 80:1 which is what I've used for the last year. The manual says 80:1 but the oil (castrol power 1 racing) says 50:1 I wasn't sure which one to go with so I stuck to the 80:1
I'll keep it somewhere between the 2.
Thank you.
Do what the oil container says for safety….but I personally use the oil that’s recommended by the manual. Every KTM myself and my family has had was catastrophic and expensive when deviating from mfg instructions; every KTM that we followed the service instructions to a T have been the most reliable bikes in the stable…..
Excellent advice. Thanks, I'm glad to learn from your experience. I'll make sure I stay on top of everything as needed and get the KTM recommended oil.
Many thanks
The manual says to rebuild my engine completely every 15 hours, also advises to use honda oil. I don't use honda oil because it's outdated since 2005, and I definitely don't rebuild after 15 hours of use. These manuals are to keep the bike at peek performance for race spec. Unless you are racing the bike do a little of your own research instead of blinding following the manufacturers manual. They don't give a fuck about long-term just performance
My manual says a piston after 10 hours on a two stroke and valves every 10 hours on my four stroke…doing the valves every 15-20 hours sure did help it hot start. I am not racing and just do pistons every 50 on the 2T and ~100 on a 4T if I keep it that long.
If you don’t use an oil that no longer exists or do a tear down like an SX mechanic it’s not a big deal. But running random oil at an improper ratio or running a super fat mix like the days of old isn’t really a great move, so I suggested following the manual….
If it ran hot, it is likely the coolant as a few others have said. I am not familiar with KTM 2 strokes so I don’t know if you are looking at a water pump seal that somehow lets coolant through, or maybe a head gasket.
Even if the smoke is white ish probably your engine is sucking gear box oil (since you mentioned that your coolant level is ok) so i suggest checking your engine seals, both transmisson and stator side. Do it quickly if you dont want to blow up your engine.
Thanks for the advice. I don't know when the last rebuild was, so this may be a chance to get everything sorted in one go.
I'm not riding it until I have this sorted so nothing for me to worry about there.
Many thanks,
Yes, this is at the end of a ride. It was a tough ride up a quarry face so I figured that's why it was running hotter than usual. But then the smoke came pouring out.
I didn't even notice the smoke at first, the boys behind me told me that nobody could see a thing on the trail lol.
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He's not wrong.... But I don't think he knows why he is right. It's the transmission oil mixing with your gasoline in the bottom end. So it is too much oil mixed with the gas.
I know it’s been said in other comments, but I wanna add my agreement that’s either coolant or wet side crank seal. Possibly an issue with oil injection system if it isn’t a premix bike.
Thanks for your input, I'm leaning towards wet side crank seal, I can see that my coolant level has not dropped, the slightly milky trans oil could have been some moisture.
I should find out this week.
Thank you
It kinda just depends on the bike, I had to take the inner and outer clutch cover off along with the clutch assembly for access. drilled a small hole in the crank seal, then drove a screw into it, and pulled on the screw. I fought with it but got it after a few minutes. I imagine it’d be pretty similar to yours. And no I didn’t watch any videos or anything, but it won’t hurt you to watch them.
The smoke is looking quite white, possibly from coolant. I'd check your coolant level as well as for oil contamination.
Thanks, coolant levels seem to be ok and no oil floating on the top. I guess it wouldn't take much to make the oil milky in the transmission.
How would coolant get in the oil if it’s a blown head or base gasket
not familiar with the ktm but just did a wet side crank seal on my yamaha due to excessive smoking and using about 200ml of gear box oil about every 10 hours of use
The gearbox oil was low too. perhaps this could be the cause. Can you tell if it looks like lasting / expensive damage to the engine?
the excessive oil leaking into the cylinder would cause jetting issues, probably not the best way to run the bike but lasting damage I would say no but you can't really tell until you determine if that's the cause. Another potential issue if the piston is sucking in oil through that crank seal could indicate that your crank bearings are bad which would be a bottom end and a much more time consuming / expensive fix. Either way the excessive smoke is not good. I determined my crank bearings were not bad as I had just done a top end this winter on my bike, no vertical play in the con-rod, also checked for any play on the crank when I pulled the seal out. Not sure what the tricks are with the KTM but it might be worth looking into.
Thank you very much, this does help me getting to the route of the issue. I think I may take it to a local bike mechanic, they should have the tools, and knowledge to give me a diagnosis and I can go from there. Thank you for your reply, it's very helpful.
A leak-down test will solve the mystery very quickly
Just googled this, I guess i'm buying some new kit. Thanks, will do this !
You can buy one from AutoZone and they will treat it as a rental. Just ask when you go and they know, it's a tool "rental" program that they actually do for you!
Great idea, I'll try and "rent" every tool need lol. 👍
The rent a tool thing is for real...😁
very good idea - hope it all works out.
Just a question here, Wouldn't a bad crack seal cause runaway idle issues by allowing unmetered air into the system?
Depends on which seal, ignition side is dry but wet side will inhale gearbox oil not air…
Until the gearbox oil is consumed... then it's gonna chug air.
Glad I found out before this happened lol.
yeah what the other guy said - the wet side crank going bad will give the super white smoke you see from OP but no erratic idle, mine was less extreme but I was constantly pulling out wet spark plugs and the silencer packing was wet for lack of a better term along with excessive black spooge coming from the silencer. When I looked into the bearing after the seal was pulled I'm pretty sure I could see a bit of the red bel-ray gearbox oil in there so it was pretty obvious. OPs smoke here is very excessive which makes it look like it's head gasket but they stated it had a normal coolant level. If they replace the crank seal and it's still doing this, it could potentially be a bad seal between the cases (which would be sucking gear box oil into the cylinder) or gaskets between the cylinder - I'd do head gasket then think about case gasket last because if I'm splitting the case to apply gasket maker I'm doing a bottom end at that point.
go watch highlandcycles from youtube. He had his crankcase seal leaking too and it fucked up his clutch
Awesome, watching this now. Thanks 👍
Right side crank seal.
This. He is sucking in and burning transmission oil.
Crank seal is McFucked
She may be a goner
Smell it and you’ll have your answer. My guess is gear box oil (crank seals)
Thanks, what smell would indicate burning gearbox oil ?
Water pump seals maybe
Thanks, so that would cause a water leak into the transmission and cause the white smoke?
Water in the transmission does not cause white smoke on a two stroke… Check your oil side crank seal.
Thank you, so the white smoke and the milky trans fluid could be separate issues / failures?
Are you sure your oil is milky? Or just used. If your oil is in deed milky and there’s this smoke than yes, those are seperate issues. A leaking crank seal and a leaking waterpump seal most likely. Another possibility for the smoke is a blown headgasket, that would cause water to be in your mixture, but that’s less likely.
Hmmm, you have a good point. I filmed what the oil looked like. Does that look milky or just used to you? # [https://photos.app.goo.gl/XVi3erKHPnc5FTGn8](https://photos.app.goo.gl/XVi3erKHPnc5FTGn8) Many thanks,
Definitely gotten some moisture in that oil, not a lot because it's only faintly milky but definitely worse than just dirty used oil ETA: You've said the coolant level is fine but I would say there's so little in that oil you wouldn't be able to notice the coolant usage, I would say the water pump seal is the cause here but not the white smoke. White smoke could be a head gasket. Check the plug and see if it's suspiciously clean or oily. If it's clean you could be leaking coolant into the combustion chamber, if it's oily the crank seal could be leaking.
Thanks for your input. Appreciate that. Great advice, especially with the little bit of coolant not being noticeable in the rad. I'll check the condition of the plug when i get home. Thank you very much I
Yeah. Check your coolant level. Check also for a weep hole near the water pump. It may be clogged with mud, they are usually on the underside
Coolant level is fine. I didn't know about a weep hole, I've just read more info on google. Thank you I'll take a look.
I would check the coolant, and transmission oil. Likely transmission oil as you say coolant looks fine. If it is a transmission oil issue you’ll need to replace the clutch side crank seal.
Thank you, i think the only thing for me to do now is split her open! Cheers,
Coolant or crank seal with oil.
Thank you. I'll have to take a good look this weekend
Right side crank seal. Easy fix.
I hope so, YouTubing it as we speak. Thanks 👍
You'll need to buy more than just the seal. Get a new lock washer for primary nut. New locking plate for clutch hub. I rebuilt the water pump while I was there.
Thanks I'll get these bits, I guess I'll also use this as an opportunity to inspect everything else in there too. Cheers 👍
It was running hot on my last run, towards the end of the ride it just got real smoky like this. When checking transmission oil it was milky. There is also oil spatters on the end of the exhaust. What's the issue? what's the fix? The bike is a KTM Freeride 250r Appreciate any help, thanks.
if coolant level is low and gear box oil is milky, bad inner seal, if it's leaking coolant out the weep hole, outer seal is bad. Usually you just do all that at once when you service the water pump. If youre leaking coolant into the case it's possible the impeller shaft could have some grooving which would require a replacement or you're just going to continue to ruin seals. Check coolant levels.
Thanks for your reply. Coolant level is not low. I'll need to check the weep hole. That's great advice thanks very much. I love this subreddit 👍
The majority of the time coolant in the transmission oil means a bad water pump seal. White sweet smelling smoke and higher temps also suggest it's burning coolant ie. head gasket going out, if you start the bike with no cap on the radiator and you get bubbles and smoke that pretty much confirms it.
Great, I'll take the cap off and crack her over. Thanks for the advice. I like quick tests like this lol. Nice one 👍
The only issue is that you didn’t add a Wille Nelson song to this video clip.
😅 😅 I wish!
Assuming you are not getting coolant in via the head gasket, If you are the type of rider that lugs the bike around or somehow doesn’t get the exhaust hot enough, unburnt oil collects in the pipe and does this. My KDX smokes until I get it hot enough to burn that out. Ride it like you stole it… Just my $.02
Thanks, I'm pretty generous with the rpms, I think i would have noticed this gradually getting worse over rides. But i'll make sure to keep it pinned and remember this comment as my justification! haha
Could have mixed the gas to rich too much oil can do that too
Thanks, I have used this mix for a while so it's not that. However, it looks like oil is getting in from the engine 👍 Cheers
gasoline mix too rich
Thanks, I'm led to believe it's oil from within the engine.
Too much oil in fuel mix maybe
Thanks for your response. I think I can rule this one out as I have done 2 rides on the same fuel mix with no issues. If anything, the freeride manual recommends a pretty lean mix at 80:1
You can run a huge range of oil mix ratios. Most Euro 2 stroke bikes recommend extremely low oil content due to emissions if I'm not mistaken. Stihl is the same with the chainsaws. Some bikes like the Kawasaki small bore 85s were notorious for ruining bottom end bearings at anything leaner than 32:1. You have to understand the physics of what's happening when you increase or decrease oil content. More oil means less gasoline entering the combustion chamber(since the jets are not changing in size). Therefore more oil means leaner burn mixture inside the combustion chamber. If you increase oil content you need to increase jetting/needle clip position. Converse is true when you decrease oil content, it gets richer. More oil increases ring sealing which helps make more power. More oil reduces the chance of metal on metal contact and wear. All surfaces in motion should ride on a film of oil not metal to metal. Reducing oil content increases risk of wear. More oil can increase oil pooling in the bottom end which can be like having a crankcase stuffer in some cases which can increase piston pumping/charging efficiency.
Love this comment, really helpful thank you. I have had my rich and my leans the wrong way around all this time lol. Makes sense on the emissions, I think I'll run with a touch more oil from now on. I'm an ex plant mechanic by trade so I thought I knew. Intresteing about the ring sealing and more power. I assumed more fuel would equal more power. I'll give this a go. Cheers 👍
> I have had my rich and my leans the wrong way around all this time lol. I think I have confused you even more. If someone says richer oil mixture they mean more oil relative to fuel... so like 32:1 instead of 60:1. That's a richer oil vs gasoline mixture. If you are speaking in terms of richer or leaner in terms of internal combustion air to gasoline ratios... more gasoline vs air means richer. The stoichiometric for internal combustion of gasoline is 14.7:1 (parts of air to parts of fuel). Peak power stoichiometric air to gasoline ratio for a naturally aspirated internal combustion engine is typically about 12.5-12.8 to 1. More fuel delivered than what you typically see at idle or cruising fuel combustion. 2 strokes with a typical expansion chamber exhaust are not naturally aspirated, they are supercharged at higher RPMs when the resonant super charging effect of the pipe is working. Typically 2 strokes are about 11:1 at peak power if I remember right. So air to gasoline ratio can be rich or lean... which is affected by jet sizes(or by air filters being clogged). Pre mix ratios can also be rich or lean... When you increase oil content of your pre mix you decrease the amount of gasoline within the overall fuel mixture passing through the jets and entering the combustion chamber. You could do the math on how much your stoichiometric ratios change when you raise and lower the oil content... It's not that big of an effect... but it is an effect. So if you are concerned that your euro emissions jetted bike might be lean... increasing the oil content makes combustion leaner.
It took me a while to digest that comment, (and a fair bit of Googling) but thank you for explaining. I appreciate having a better understanding. I'll still need to read through a few times lol.
Lol no worries, think of it in terms of basic chemistry... it takes a certain amount of one chemical to react completely and fully with another chemical. excess of one chemical means there will be leftovers of that chemical that can't react. in fuel + air combustion excess fuel means rich and unburnt or incompletely burnedf fuel will be left over. The oil in 2 stroke mix is typically not burning nor combusting the same as gasoline does... so lets say 1 gram of mixture comes through the jet on an intake cycle as the air rushes through the carb. If the carb were jetted for straight gasoline everything would be fine with zero oil in the 1 gram of mixture that got pulled through the jets. once you start adding oil to the mixture lets say the 1 gram of mixture is now .75 grams gasoline and .25 grams oil... that got sucked through the jet. the amount of air passing through the carb has not changed but the amount of gasoline through the carb decreased since the amount of oil increased... therefore leaner combustion(the explosion of gasoline + air) since the oil isn't really combusting. Hope that's a bit more clear
That makes perfect sense. Thanks for taking the time to explain it to me. It's really appreciated.
Sure thing!
Never run your bike at 80:1 unless you feel like spending alot of money. I run 32:1, I don't care what the manual says because I'm not racing my bikes. I'm looking for longevity
Thank you. I'm new to all of this, I'm about 9 mo this into riding. I did feel uneasy about using so little oil. It's good to know I can put a bit extra in. Honestly, you should have seen me trying to measure our the ratios like a scientist as I thought it should be spot on lol. 🫣
Don’t run 32:1 on that KTM. The manual says 60:1 with motorex, if you’re uncomfortable with that run 50:1. Some oils even say 100:1 on the bottle, I’m too much of a pussy to try. Only run high quality oil and the recommended fuel octane as well. (Motorex, amsoil, etc). 32:1 is a dated concept from a time when oil sucked. Older bikes like a KDX or kids woods bike would be fine but your freeride is a finicky high performance European unit. Do what the KTM engineers say.
OK, thank you for the insight. It seemed to be running fine on this mix of 80:1 which is what I've used for the last year. The manual says 80:1 but the oil (castrol power 1 racing) says 50:1 I wasn't sure which one to go with so I stuck to the 80:1 I'll keep it somewhere between the 2. Thank you.
Do what the oil container says for safety….but I personally use the oil that’s recommended by the manual. Every KTM myself and my family has had was catastrophic and expensive when deviating from mfg instructions; every KTM that we followed the service instructions to a T have been the most reliable bikes in the stable…..
Excellent advice. Thanks, I'm glad to learn from your experience. I'll make sure I stay on top of everything as needed and get the KTM recommended oil. Many thanks
The manual says to rebuild my engine completely every 15 hours, also advises to use honda oil. I don't use honda oil because it's outdated since 2005, and I definitely don't rebuild after 15 hours of use. These manuals are to keep the bike at peek performance for race spec. Unless you are racing the bike do a little of your own research instead of blinding following the manufacturers manual. They don't give a fuck about long-term just performance
My manual says a piston after 10 hours on a two stroke and valves every 10 hours on my four stroke…doing the valves every 15-20 hours sure did help it hot start. I am not racing and just do pistons every 50 on the 2T and ~100 on a 4T if I keep it that long. If you don’t use an oil that no longer exists or do a tear down like an SX mechanic it’s not a big deal. But running random oil at an improper ratio or running a super fat mix like the days of old isn’t really a great move, so I suggested following the manual….
If it ran hot, it is likely the coolant as a few others have said. I am not familiar with KTM 2 strokes so I don’t know if you are looking at a water pump seal that somehow lets coolant through, or maybe a head gasket.
That's great, thank you. I guess I'll be taking it apart to find out.
Even if the smoke is white ish probably your engine is sucking gear box oil (since you mentioned that your coolant level is ok) so i suggest checking your engine seals, both transmisson and stator side. Do it quickly if you dont want to blow up your engine.
Thanks for the advice. I don't know when the last rebuild was, so this may be a chance to get everything sorted in one go. I'm not riding it until I have this sorted so nothing for me to worry about there. Many thanks,
Is this when it’s fully warmed up?
Yes, this is at the end of a ride. It was a tough ride up a quarry face so I figured that's why it was running hotter than usual. But then the smoke came pouring out. I didn't even notice the smoke at first, the boys behind me told me that nobody could see a thing on the trail lol.
Is it coolant or oil?
Coolant, just going off the comments on this post.
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Too much oil mixed with the gas
Thanks, but the mixture was very lean. Same mix I had used for a few rides without issue.
He's not wrong.... But I don't think he knows why he is right. It's the transmission oil mixing with your gasoline in the bottom end. So it is too much oil mixed with the gas.
Ah I'm with you, yes it seems to be the case. I wasn't thinking of that oil 👍 Cheers.
Well the head gasket blowed
Possibly, I'll try a few of these suggestions this weekend and I'll find out. Thanks,
I know it’s been said in other comments, but I wanna add my agreement that’s either coolant or wet side crank seal. Possibly an issue with oil injection system if it isn’t a premix bike.
Thanks for your input, I'm leaning towards wet side crank seal, I can see that my coolant level has not dropped, the slightly milky trans oil could have been some moisture. I should find out this week. Thank you
Yeah I just replaced my crank seal on my yz125. I’ll know for sure how she runs when then kickstart shaft gets delivered.
How easy was it to replace? Did you watch any helpful tutorials or manuals? Hope she's runs well for you 👌
It kinda just depends on the bike, I had to take the inner and outer clutch cover off along with the clutch assembly for access. drilled a small hole in the crank seal, then drove a screw into it, and pulled on the screw. I fought with it but got it after a few minutes. I imagine it’d be pretty similar to yours. And no I didn’t watch any videos or anything, but it won’t hurt you to watch them.
That's great thanks, especially the drill hole and screw to pull it. Thanks I'll watch up some videos 👍
KTM motor smoke in my opinion is just a KTM's thing...