smoking bird on overrun

[gerryc]

Righto mate as yours is an import I'll bet its got the PAIR system, i.e rebreather hoses back to the air box from the valve cover, where unburnt gasses go back through the air box into the combustion cycle again.

Now the fact that the mechanic head the rocker cover off (figure of spreach I know theres no rockers in there, so valve cover for the pedants) I'd also be willing to bet they've missed one of the O-rings that go round the the hole, tract, port call it what you will that goes to the exhaust port.

Hence when on the overrun your sookin oil direct from the cylinder head into the zorst port.

Trust me I know this from experience, simply pull off the valve cover and make sure all 4 O-rings are in place, if not replace them and bingo one sorted engine again.

let us know how you get on budp0pc0rn41

 

[rhubarbray]

Righto mate as yours is an import I'll bet its got the PAIR system, i.e rebreather hoses back to the air box from the valve cover, where unburnt gasses go back through the air box into the combustion cycle again.

Now the fact that the mechanic head the rocker cover off (figure of spreach I know theres no rockers in there, so valve cover for the pedants) I'd also be willing to bet they've missed one of the O-rings that go round the the hole, tract, port call it what you will that goes to the exhaust port.

Hence when on the overrun your sookin oil direct from the cylinder head into the zorst port.

Trust me I know this from experience, simply pull off the valve cover and make sure all 4 O-rings are in place, if not replace them and bingo one sorted engine again.

let us know how you get on budp0pc0rn41

Beat me to it! I was thinking that on a steep downhill run the oil is pooling at the front of the engine and getting sucked into the PAIR system then on the flat the oil was moving away from it. Definite possibility.

Don`t pull the engine yet!!

 

[bishbosh]

Haven't read all the posts so don't know if the plume is coming out of the pipes. Have had two issues with smoking oil on my bird.

1. Numbnuts mechanic (me) didn't remove the o'ring from an old oil filter when doing a service. The new oil filter then had two o'rings but this meant that they blew after 20 miles with huge oil plume as oil gushed onto pipes.

So it could be possible that on the overrun you have a bit more pressure and blowing the seal, albeit temporarily, at the oil filter, a lot of oil could be lossed in no short order.

2. Oil cooler pipes could have corroded and you have a small hole, but again under higher pressure this leaks the oil directly onto the pipes and hence a sudden plume of oil.


I'd check for corrosion around the bottom of both oil cooler pipes and put some clean rags around them and also wrap a rag around the oil filter. Then take on short run to produce you oil plume and check the rags for oil.

 

[Oldbull]

remove the P.A.I.R valve altogether and blank it off, blanking plates are readily available for most bikes (imports)

Well spotted Gerry :bow:

;-0))

 

[loosedougie]

Smoke is most certainly coming out of the end of the cans. Enough oil was inside them to make the Exon Valdez look like a slight mishap.

I like the o-ring idea. need to read up a bit on that as to what I do and where I look. Cars I'm good with - bikes no clue really.

Next weekend I'm not working will break out some tools.

Keep you posted on progress.

 

[keith inglis]

I think before I did anything I would change the oil and see what happened, you do not know what oil is in there? it might be the wrong type, re the compression test, I do not think any engine holds the top compression pressure when it is worn a bit, but if all else fails and like someone else has said have a good look at the breathers and the valve stem seals.

 

[loosedougie]

It's taken a while for me to come back, but gerryc may of found the problem (pairs valve), pulled the valve cover off in the weekend and found one of the pipes missing an o-ring. Don't think it pulled off when I removed the cover. The o-ring was sitting in a corner beside one of the cams. All the pipes seemed to be filled with a black carbon deposit. Reed valves good and clean.Tried to carefully clean inside of pipes. refitted o-ring and reassembled.
Also redone compression test with a hot engine open throttle. This time reading were between 167 and 175 psi. Think this means rings and valves are ok then. Hopefully now problem sorted. Just need time now to go for a decent ride to check. Thanks all.