Smokes at high rev’s

[JoeMaico]

While waiting for my Piston to show up, I am wondering what else I should look at while the bike is down for repairs. On the last ride, a buddy was riding behind me and stated whenever I got on the pipe, the bike smoked like he was following an old mosquito fogger truck. But, when lugging or pulling mid-range, he didn’t notice any smoke at all. That got me wondering – so I started searching for causes. One search lead me to a Tokyo Offroad video where he said a worn primary drive seal would allow transmission oil into the cylinder and cause excessive smoking. I assume a worn seal on the flywheel side would cause the same issue. He didn’t state if the worn seal would cause smoking at all revs, or just high revs. He also didn’t say if a worn seal would cause any other symptoms (except loss of tranny fluid). Other than worn seals, my search did not reveal any other reason for excessive smoking at upper revs. My bike does spooge a lot, and I wonder if the spooge finally starts to burn out when I am on the pipe – causing the smoke generation observed by my riding buddy. I will keep researching, but if anyone has had similar experiences and found a resolution, I would be interested in hearing them. The bike is a 2016 300 RE with 150 hours (not many for a seal failure), RK head, stock carb and reeds, and stock pipe with FMF Turbine Core.

joe

[Trail Rider]

Excessive spooge indicates that jetting may not be aligned with your riding conditions. That can be easily checked. Incorrect pilot, main jet or needle position could all be an issue. There is good info available from Beta or use a jd kit. Unless you are racing & really revving fast a lot, pilot or needle the most likely issue.

I would also check that your pipe is not leaking spooge at the engine, if it is you might not be getting complete "burning" of the fuel mixture. Check for other air leaks at the carb.

[JoeMaico]

I use the Beta recommended jetting spec's. But, I do run it an elevation richer setting than suggested with the RK head. No spooge from the pipe/head seal. It just oozes out of the rear exhaust and runs down the bottom side of the can. I have seen worse, but I have seen better also. I run 60:1 and Motul 700 usually. An air leak should make it run leaner I would think. Regardless, I have looked for leaks and bad reeds before for other issues, and didn't find any. When I have it apart for the top end, I will will be checking the conditions of the reeds/boot and will replace if necessary.

joe

[aj_mariner]

My vote is for jetting. If it was a bad seal on the clutch side then I’d assume smoke all the time

https://youtu.be/e2xR7DsAirM

[Trail Rider]

I use the Beta recommended jetting spec's. But, I do run it an elevation richer setting than suggested with the RK head. No spooge from the pipe/head seal. It just oozes out of the rear exhaust and runs down the bottom side of the can. I have seen worse, but I have seen better also. I run 60:1 and Motul 700 usually. An air leak should make it run leaner I would think. Regardless, I have looked for leaks and bad reeds before for other issues, and didn't find any. When I have it apart for the top end, I will will be checking the conditions of the reeds/boot and will replace if necessary.

joe

Maybe you mean Motul 800? Another idea is change your 2T oil. I have found certain oils will smoke/spooge more than others. Not my expertise, but I have read that higher flash point oils tend to smoke more due to incomplete combustion if your not racing. For example, the Motul 710 is 190F & the 800 is 495F, thats a big difference.

[JoeMaico]

It is Motul 710. Used my last bottle - so now I will be using Motorex CrossPower until I pick up some more. I do agree that you would think a failed seal should smoke all of the time, not just at high revs. Unless high revs creates more of a vacuum that allows oil to be pulled in from the transmission side easier. I will contact Mark (Tokyo Offroad) and see if he can shed more light on his condition that drove him to replace his seal. I can find nothing that indicates spooge burns off and smokes at high rev's. So, that theory is probably dead.

joe

[mtdirtbag]

I see no mention of having changed the muffler packing, if you have lugged around a lot in the past you may have saturated packing.

[JoeMaico]

It was repacked at around 100 hours (50 hours ago). But, spooge will saturate the packing fairly quick. However, spooged up packing falls into the 'burning of spooge at higher revs' theory. I cannot find any mention of this (at least not yet) as a cause for smoke generation at high revs.

joe