Yamaha Starbike Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
i think my piston rings may be going bad....slight blue smoke when first starting, then it clears up and then runs smooth... any ideas of ball park price ranges for repair by certified repair shops? I hope this isn't the case though. This issue didn't start until I installed an oil filter relocation kit and accidentally over filed the oil a bit. I have since drained it and started from scratch with the install and oil fill, I am hoping it may just be blowing out some oil that was unable to drain!
 

·
Registered
Joined
·
124 Posts
i think my piston rings may be going bad....slight blue smoke when first starting, then it clears up and then runs smooth... any ideas of ball park price ranges for repair by certified repair shops? I hope this isn't the case though. This issue didn't start until I installed an oil filter relocation kit and accidentally over filed the oil a bit. I have since drained it and started from scratch with the install and oil fill, I am hoping it may just be blowing out some oil that was unable to drain!
That is a typical sign of valve seals leaking. When the engine off, a little oil seeps down the valve stem and then causes smokes when the engine is started. Since the seepage is small it takes a while (like overnight) for enough oil to accumulate to cause smoke. Running there is usually no sign of smoke (unless the seals are really gone).

Worn piston rings will cause smoke while running. Get on the throttle hard then coast (high engine vacuum), then get on the throttle again, if you see smoke now then maybe the rings are worn. Also worn rings will allow combustion gases into the crankcase. Remove the crankcase breathe or pull the oil fill cap and see if any smoke comes out. If no, then your rings are probably good.
 

·
Registered
Joined
·
909 Posts
Usually if oil gets past the rings it'll be constant and won't clear up. If the motor smokes on startup but then clears that's usually an indication of bad valve seals. I'd first do a compression test and if one of the cylinders is 'weak', put about a teaspoon of oil in that cylinder and test the compression again. If the compression in that cylinder doesn't increase then there's most likely a leak past the valve seal and along the valve guide. Oil getting past a valve can cause carbon deposits on the valve face and seat causing a slight leak and poor compression.

***UPDATE - Looks like CountryB beat me to it
***
 

·
Registered
Joined
·
23 Posts
Discussion Starter #5
Thanks for all the info! Y'all rule! I will give this a try today... it will have to be an idle and rev test as that its 32 degrees here is ohio! Hopefully that will be enough to determine rings or valve seal. I am using yamalube SAE 20w/50 and the bike has 35k miles on it. Would y'all recommend a different weight?
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
okay... I just started it up and no smoke come out of exhaust then after it warmed up I revved it up and kept it there for several seconds and after releasing the throttle there was smoke. I did this several times and every time there was smoke...however when I opened the oil fill, there was no smoke coming out of there.
 

·
Registered
Joined
·
386 Posts
Thanks for all the info! Y'all rule! I will give this a try today... it will have to be an idle and rev test as that its 32 degrees here is ohio! Hopefully that will be enough to determine rings or valve seal. I am using yamalube SAE 20w/50 and the bike has 35k miles on it. Would y'all recommend a different weight?
That's a good quality oil. I personally use 10-40 because our weather stays colder longer.
Pehaps you are still burning off the residual oil. Maybe check all your crankcase breather lines too.
Pull the plugs and see what they look like.
Ride it around for a couple hundred miles and see if it clears up.
 

·
Registered
Joined
·
909 Posts
I prefer to stick with the factory recommended weight for normal operating temps, that being a 40 weight. As for the cold starting 'weight' I opt for the lightest I can get so that the oil, which is thicker when cold, can get pumped through the motor quicker and easier. That's why I run 5W-40 instead of 10w-40, it flows easier like a straight 5 when cold instead of a thicker straight 10 but once at operating temps flows just like a straight 40 would.
 

·
Registered
Joined
·
386 Posts
I prefer to stick with the factory recommended weight for normal operating temps, that being a 40 weight. As for the cold starting 'weight' I opt for the lightest I can get so that the oil, which is thicker when cold, can get pumped through the motor quicker and easier. That's why I run 5W-40 instead of 10w-40, it flows easier like a straight 5 when cold instead of a thicker straight 10 but once at operating temps flows just like a straight 40 would.
I went with valvoline 10w\40 full synthetic motorcycle oil. Cost 5 bucks a quart at the wallyworld. Cranks just as fast at 24 degrees as it would at 80 degrees.
 
1 - 9 of 9 Posts
Top