ColinD Posted August 6, 2011 Posted August 6, 2011 Bike: 2001 DT230, very low mileage Problem: blows a stupid amount of smoke for maybe a minute or two when starting from cold, then it's OK. This actually starts happening not instantly on start - maybe after 10 or 20 seconds. It happens with or without choke. Very bad look - it's quite embarrassing and unclean. Can't be doing the bike much good either, although so far the plug is not fouled at all. Doesn't seem to have excessive smoke when warm, including starting. Have changed the air filter. It's all bog standard setup. I'm wondering if the oil might be pooling somewhere in the pump or elsewhere? Is the amount of oil feed supposed to change with engine temp? If so, that would be something I could look at.
Moderator Airhead Posted August 6, 2011 Moderator Posted August 6, 2011 yamaha 2 stroke pumps have a spring loaded ball which serves as a check valve to stop the oil tank contents from just free flowing through the pump. Obviously thes can fail from time to time...though i have no experience of it myself. As a check why not remove the thin oil pipe from the inlet manifold (or carb) and secure it over a container overnight to see if you have this problem. If you do ...remember to prime the line when re-fitted.
ColinD Posted August 6, 2011 Author Posted August 6, 2011 That sounds like a really promising line of enquiry - thanks for the suggestion. If the spring is weak, it could easily be letting a few drops of oil through.
yamahait Posted August 6, 2011 Posted August 6, 2011 That sounds like a really promising line of enquiry - thanks for the suggestion. If the spring is weak, it could easily be letting a few drops of oil through. hi want to sell it, chers mark.
2 Wheels Posted August 6, 2011 Posted August 6, 2011 What colour is the smoke? 2 stroke,,,,,,so ya have to clean the exhaust every now and then,,,,,gets oily after a while,,,,,,smoke clears when exhaust is hot. Could also be just smoke from condinsation lyin in pipe, clears when exhaust gets hot,,,,,this be normal. So what colour is the smoke ??
ColinD Posted August 7, 2011 Author Posted August 7, 2011 Still following up the idea about the non-retun valve being stuck, but not as obvious to me as I'd hoped. The small oil feed line from the pump to the carb runs up-hill, so I'm not going to get anything leaking out of it on the carb side (took a pic, but buggerd if I can see any button for upload or attach, even though help say there is such a thing). Anyway there's a thick line leading down to the pump and a thin one leading up from there to the carb. Where would said valve be in this assembly? The smoke is whitish - more white than the bluish colour of normal operation. And it smells bad I's been doing this since I bought it with only 650 km on the clock, so I'm certain it's not about cleaning the exhaust out (not yet anyway). No way going to sell it! Was looking for 6 mnths for one. Only lightweight bike with decent power and wide range 6-speed gearbox (i.e. more than 3:1 range). Planning to make a compact hard-core adventure bike, one that can be easily repaired on-tour and runs off whatever rubbish fuel is available in an Asian village. Beats me why nobody wants to be in that market with a new bike. You'd think just one manufacturer could figure out that not everyboy's idea of an adventure bike is something taht weighs 230kg. Mr Yamaha should do himself a favour and bring it back!
Moderator Airhead Posted August 7, 2011 Moderator Posted August 7, 2011 Still following up the idea about the non-retun valve being stuck, but not as obvious to me as I'd hoped. The small oil feed line from the pump to the carb runs up-hill, so I'm not going to get anything leaking out of it on the carb side (took a pic, but buggerd if I can see any button for upload or attach, even though help say there is such a thing). Anyway there's a thick line leading down to the pump and a thin one leading up from there to the carb. Where would said valve be in this assembly? The smoke is whitish - more white than the bluish colour of normal operation. And it smells bad I's been doing this since I bought it with only 650 km on the clock, so I'm certain it's not about cleaning the exhaust out (not yet anyway). The thick line leading down to the pump is the feed from the tank, the tank is higher than the carb so it matters not that it is uphill from the pump to the carb. The check valve is an integral part of the oil pump. Testing by the method i already said would have proved it good or bad.......However Now you have commented on thick white smelly smoke...that is more likely gearbox oil, Replace the seal on the clutch side of the crank perhaps a minor leak there? Can you smell petrol slightly in the oil filler hole?
ColinD Posted August 7, 2011 Author Posted August 7, 2011 The thick line leading down to the pump is the feed from the tank, the tank is higher than the carb so it matters not that it is uphill from the pump to the carb. The check valve is an integral part of the oil pump. Testing by the method i already said would have proved it good or bad.......However Now you have commented on thick white smelly smoke...that is more likely gearbox oil, Replace the seal on the clutch side of the crank perhaps a minor leak there? Can you smell petrol slightly in the oil filler hole? Yes I see the logic of your test. I did some research on this problem and found a similar reference to 2-stroke marine motors. They have a "popper" valve rather than a non-return valve, the logic being that the oil pump can overcome the spring pressure in the valve, but gravity cannot, hence no downhill draining (I guess it would also work as an NRV). Perhaps it's the same arrangement on the bike? Prefer to try that before replacing a seal. Does the thin tube just pull off the lug? It seems to be clamped on with a "crimp" style collar. How does this sound as a strategy: before starting, I will completely drain the carby through the drain screw, then let it refill again. If it starts without all the smoke, the problem may be the valve. If it still has lots of smoke, the oil could be coming in through the bad seal.
Moderator Airhead Posted August 7, 2011 Moderator Posted August 7, 2011 Yes I see the logic of your test. I did some research on this problem and found a similar reference to 2-stroke marine motors. They have a "popper" valve rather than a non-return valve, the logic being that the oil pump can overcome the spring pressure in the valve, but gravity cannot, hence no downhill draining (I guess it would also work as an NRV). Perhaps it's the same arrangement on the bike? Prefer to try that before replacing a seal. Does the thin tube just pull off the lug? It seems to be clamped on with a "crimp" style collar. How does this sound as a strategy: before starting, I will completely drain the carby through the drain screw, then let it refill again. If it starts without all the smoke, the problem may be the valve. If it still has lots of smoke, the oil could be coming in through the bad seal. That strategy wont work unfortunately because the oil feed is directly into the carb venturi...not into the fuel bowl! I can see why you would want to do this test first...but i am sure you will find it ok/ the crimp has a split in it?? push against the split and chase it round with a small screwdriver and at the same time tease it off the nipple. Do the other easy test...have a sniff of the geabox oil and monitor the level to see if it's falling.
ColinD Posted August 7, 2011 Author Posted August 7, 2011 That strategy wont work unfortunately because the oil feed is directly into the carb venturi...not into the fuel bowl! I can see why you would want to do this test first...but i am sure you will find it ok/ the crimp has a split in it?? push against the split and chase it round with a small screwdriver and at the same time tease it off the nipple. Do the other easy test...have a sniff of the geabox oil and monitor the level to see if it's falling. The gearbox oil smells normal as far as I can tell, although I've always had a weak sense of smell It's dark now and the tube mount is well inside the guts of the bike so it's hard to see. I'm almost certain it's not a split collar type. Maybe it's threaded. Anyway I'm going to have to pull off the brake reservoir to get to that tube. The tube is a lot easier to get to where it mounts onto the pump and it is definitely a split collar in there, so might do that instead.
Moderator Airhead Posted August 7, 2011 Moderator Posted August 7, 2011 The gearbox oil smells normal as far as I can tell, although I've always had a weak sense of smell It's dark now and the tube mount is well inside the guts of the bike so it's hard to see. I'm almost certain it's not a split collar type. Maybe it's threaded. Anyway I'm going to have to pull off the brake reservoir to get to that tube. The tube is a lot easier to get to where it mounts onto the pump and it is definitely a split collar in there, so might do that instead. I'll say for the last time that I would be surprised if it isnt a clutch side crank seal issue...if you want to prove the pump check valve for your own peace of mind fair enough. Dark now...ohh so if we want to buy your bike we have to travel a very long way? Please fill your profile in ! If you do remove the oil pipe, the oil will drain from the pipe to the carb...thats ok let it but upon replacement just hold the pump pulley fully open for 30 secs with the engine idling, this will quickly fill the line.
ColinD Posted August 7, 2011 Author Posted August 7, 2011 I'll say for the last time that I would be surprised if it isnt a clutch side crank seal issue...if you want to prove the pump check valve for your own peace of mind fair enough. Dark now...ohh so if we want to buy your bike we have to travel a very long way? Please fill your profile in ! If you do remove the oil pipe, the oil will drain from the pipe to the carb...thats ok let it but upon replacement just hold the pump pulley fully open for 30 secs with the engine idling, this will quickly fill the line. I'm in denial about the crank seal. Never expected I'd have to do anything like that so soon
ColinD Posted August 14, 2011 Author Posted August 14, 2011 Update to this investigation... Ordered new oil pump o-ring and had to wait a while for it to arrive. Discovered after removing the oi pump the o-ring only seals between the pump and gearbox, i.e. stops 2T oil leaking out of the pump, so actually doesn't have anything to do with my problem. To make matters worse, the slots on one of the pump mounting screws stripped out, so now have to order a new screw before I can put them pump back in place. Everything happens on a one week cycle for me, on account of only being able to get to the Yammie shop on Saturdays. But back to the investigation... Left pump off for the night and not a trace of oil coming from the gearbox. So it now seems that the problem can only be the pump itself, possibly the integral valve. It does seem that the pump can be disassembled to a certain extent, but no telling whether that would expose said valve. May as well give it a go - I have to wait a week to get the new screw, so if I'm gonna stuff the oil pump, may as well do it now so I can order a new one of them too The pump drive shaft seems to be hollow - what's the purpose of that? It would provide potential circuit for oil from gearbox (or more likely the other way, since the pump is under pressure).
Moderator Airhead Posted August 14, 2011 Moderator Posted August 14, 2011 the pumps are sold as a unit and so the integral parts of the pump are not necessarily shown on drawings etc. I cannot for the life of me think why you want to strip down this part of the pump without evidence of a fault there...your efforts would be better served finding the problem and you have said thick white smoke...to me thats gearbox oil. Has your gearbox got a breather tube attached to the top of it? Any screw would gave done given the right length and thread...
Moderator Airhead Posted August 14, 2011 Moderator Posted August 14, 2011 Anyway you must also consider perhaps this is normal for the bike, fact is they all smoke and hesitate when cold and it clears up when hot. If the pump isnt passing as i have said and you are not burning gearbox oil...than all is well
ColinD Posted August 14, 2011 Author Posted August 14, 2011 the pumps are sold as a unit and so the integral parts of the pump are not necessarily shown on drawings etc. I cannot for the life of me think why you want to strip down this part of the pump without evidence of a fault there...your efforts would be better served finding the problem and you have said thick white smoke...to me thats gearbox oil. Has your gearbox got a breather tube attached to the top of it? Any screw would gave done given the right length and thread... Hi there, Can't see any breather tube, though it's such a tight mass of "stuff" in there it's something I'd need to check in good light (not now). Had a squiz at the service manual PDF and can't see anything there either but it's not really that detailed. Took the opportunity to replace the standard pump-to-carb oil feed with clear PVC so now I can see what's going on in there. I haven't primed it so there's no oil in that tube. I'll see if that's still the case tomorrow. Not really a conclusive test until I replace the broken screw and tighten up the pump mount - there's a tiny bit of oil weaping from it just now. cheers
Moderator Airhead Posted August 14, 2011 Moderator Posted August 14, 2011 Hi there, Can't see any breather tube, though it's such a tight mass of "stuff" in there it's something I'd need to check in good light (not now). Had a squiz at the service manual PDF and can't see anything there either but it's not really that detailed. Took the opportunity to replace the standard pump-to-carb oil feed with clear PVC so now I can see what's going on in there. I haven't primed it so there's no oil in that tube. I'll see if that's still the case tomorrow. Not really a conclusive test until I replace the broken screw and tighten up the pump mount - there's a tiny bit of oil weaping from it just now. cheers and my last posting?
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