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Discussion Starter · #1 ·
Hello all, new member first post.

I've done a search within the forums for a similar problem but it revealed no results. I have an '03 SP2 with the PAIR and flapper mods done, full Yosh system, and 4800 KMs (Canadian, sorry metric sysytem). I've put very few miles on the bike this season with the full system (fist season with the exhaust) without a Power Commander, it was running lean but the temps stayed low, but it started burning oil. It smokes under idle only, once it has reached operating temperature. It will smoke slowly under idle, but when you blip the throttle quite a bit of smoke will blow out, if you continue to twist the throttle the smoke dissipates. I've had the bike serviced and the techs are stumped. The problem has been narrowed to the rear cylinder (as theres no residue on the front cylinder),rear exhaust valve guide and seal replaced and machined, rear cylinder piston rings replaced, cylinder honed, and abreviated break in done...and it STILL SMOKES!
I'm mechanically inclined and have ruled out a number of possibilities, as have the technicians who have worked on the bike, but I'm at a complete loss.
If anyone has had a similar experience, I'd very much like to hear from them.
Thanks in advance.
 

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I'm not sure on how the system works on an RC, but I would check into excessive crankcase pressure. Perhaps, there is a crimped hose in the breather? I haven't explored my bike that much, (it functions perfect) but I am a former GM automotive trainer.

Three things will cause excessive oil consumption/smoke: 1) worn, out of round, cylinder/piston, broken ring, 2) worn valve guides or seals, 3) excessive crankcase pressure due to blocked breather

Or out in left field, Cracked rear head?

John
 

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half way reading your post I thought a burned exhaust valve has worn its guide, but then you said it was replaced. A compression leak test would have lead you to replace piston/rings, was it really in need of replacing? Honed the cylinder? It is plated and unless there was a manufacturing fault the original should not even be broken in yet.
If you don;t have a powercommander and you are still running lean possibly it is the front cylinder by now.
Have you checked the intake for oil? Take the filters off and look down the intake with throttle wide open. If you see any oil evidence trace it back as CBXJohn said.
On the fireblades rc51 forum I remember talk of a similar problem and it was on one cylinder. Can't remember whether it was oil or not but there was crud on one intake and not the other.
 

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Usually smoking due to a valve guide seal will occurs on deceleration when the high intake vacuum pulls oil past the seal.
Smoking during idle or increased smoking during open throttle is usually caused by worn rings. However you said those were replaced on the rear cylinder.
A compression check would show wear on the rings.
Have you checked and drained the line for the crankcase breather storage tank?
It may be possible it's full and the engine is sucking oil into the intake.
 

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Hi,
I had a similar problem with my bike after I adjusted my valve clearence. There is a dowl on the rocker cover that the air for the PAIR system passes through when connected. This dowel has a rubber O-ring seal around it to stop the oil from the head running down into the exhaust port. Mine was missing and was causing the bike to smoke its tits off when ticking over, popped in a new one and no more smoke. I believe it only does it at tick over due to the exhaust pressure rising when revving the engine forcing the oil back into the head.
Hope this helps
 

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That's a very plausible explanation.
On another forum, a customer's engine was being rebuilt/performance-prepped and the builder not only removed the PAIR system, but tapped and inserted a grub screw to block off the un-needed passageway.
 

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Hi,
I had a similar problem with my bike after I adjusted my valve clearence. There is a dowl on the rocker cover that the air for the PAIR system passes through when connected. This dowel has a rubber O-ring seal around it to stop the oil from the head running down into the exhaust port. Mine was missing and was causing the bike to smoke its tits off when ticking over, popped in a new one and no more smoke. I believe it only does it at tick over due to the exhaust pressure rising when revving the engine forcing the oil back into the head.
Hope this helps
Thanks for the heads-up! Something to watch for when doing a valve adjustment.

John
 

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It sounds weird, maybe not in excess but oil is meant to go down the valve stems and guide to lube the guide, if it is dry it will not last long. How is this o-ring related to the tube fitting for the PAIR system?
I'm trying to find a fische to see what this is, maybe I'll get back to this note if I discover something.
 

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How is this o-ring related to the tube fitting for the PAIR system?
The air intake for the PAIR sits ontop of the cam cover with the one way valve assembly. The tube runs from the underside of this in a downward (toward the crank) direction. There is also a tube that runs in the head to the exhaust port and where these 2 tubes meet there is a locating dowl to ensure they line up. The O-ring sits round this to stop the ingress of oil into the tube. What happenend in my case was the O-ring remained on the cam cover when it was removed and then decided to drop off when I wasn't looking.
Luckily its on the rear cylinder which is fairly easy to check.
 

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Discussion Starter · #13 ·
Hi,
I had a similar problem with my bike after I adjusted my valve clearence. There is a dowl on the rocker cover that the air for the PAIR system passes through when connected. This dowel has a rubber O-ring seal around it to stop the oil from the head running down into the exhaust port. Mine was missing and was causing the bike to smoke its tits off when ticking over, popped in a new one and no more smoke. I believe it only does it at tick over due to the exhaust pressure rising when revving the engine forcing the oil back into the head.
Hope this helps
This is exactly what has happened, unfortunately it took months of exploratory work, and a decidedly involved process of elimination before the issue was discovered. I had actually decided to ride the bike for the remainder of the season after my initial post, as I was convinced the smoking wasn't due to a major problem. Well, a few weeks ago I decided I would have my local shop take another crack at it, and after another two weeks of investigation they figured it out. I only wish I had checked back with this site more frequently, thanks very much for the interest and suggestions from fellow members.
I'd also like to send out some mad props to Imperial Motorcycle in Burnaby, BC Canada. Ted and Al were very patient with me, were willing to devote considerable time and energy to my smoking habit, and never suggested giving up after a number of failed attempts.

Cheers
 
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