excessive oil blow back

My last ride my bike suddenly started spuddering badly from 1/4 to 3/4 throttle. Just running horribly! Did alright full throttle. I was thinking the carb was messed up some how. Before all this it was stalling easily.

I removed the air filter (it was quite dirty) and found an alarming amound of frothy spudge that came out of the crank vent. It was all over the inside of the filter and the throat going into the carb.

I changed the oil before the ride so I know oil level was correct.

Have you experiance this? Whats the problem?

going riding in the morning, need to fix!!!


I was worried about that but its not the problem. Oil level is normal

I dont recall laying the bike on its side or upside down either

I'm going through the carb and I discovered the slow jet is partially blocked

Dang, I rode today and its still running bad. I thought the clog was the problem. Had an unbelievable ride anyway.

I will tear my bike apart again and give it another go.

I'll try a post in jetting

Do you have a bad guide seal?

Bad guide seal? I'm not sure. I checked the valves tonight and I'm disappointed left intake is at 0.04

I just notice its been 100 hrs since top end job. Stock piston and Kibblewhite ss valves.

Do my problems sound like they could be low compression? Might need piston and rings? More than likely.

Heres a list

erratic idol

spudder off idol to 3/4

oil foam coming into airbox from crankcase vent

hard to start sometimes

Hauls butt 3/4 to full throttle

Man it sucks having a sick bike!!

I'll probably pull the cylinder tomorrow

Any more thoughts appreciated!

Sorry, I misread your post thinking the foam was coming out of the cover vent. So, you're on track with a new piston and rings. Just out of curiosity have you shimmed the valves since the last rebuild?

no Cubera I have not.

I've check them acouple of times.

Last time I checked the bike was warm. They were out alittle. Something did'nt seem right but I re-shimmed anyway. I checked again after it cooled down completely and it changed. I ended up putting it back where it was. I learn something new all the time. Its not a big deal when you have a shim kit though.

Cubera, Do you think my valves are going? My gut tells me they are. I can lap the SS valves. Right?

Cubera, Do you think my valves are going? My gut tells me they are. I can lap the SS valves. Right?

You probably don't have any valve worries. Take them out of the head and look at them them when you have the head off. If they are cupped then replace them. If they look good put it back together and shim them on the loose side of spec (intakes) and the exhausts on the tight side of spec. After you run it for 15-20 hours check them again. The KW valves will hold a shim for a long time....to a point.:confused:

ya my gut was right. left intake was hammered. Seats look ok though.

No big deal my machinist said he can clean them up.

I will be replacing the piston with an R piston for a slight increase in compression.

Why does it always rain when I have my bike torn apart?

Good to go, troyss! Is the R piston higher compression?

I just noticed my spark plug how white it was. On my last ride before I opened up my engine I was racing my friend down a long wash all the way to my truck where we loaded up.

I havent touched the jetting since my last valve job so apparently I've been running very lean on the top end for the last year.

I'm was running JD red needle middle position. 162 main. Air box mod - snorkel removed, vents opened on sides. twin air filter backfire screen in place. Unmodified stock exhaust.

Conditions - 2800' 55 degrees

Does that setup sound lean? Does that hammer the valves?

Unbelievable, the crankcase breather has a plug at the end. I thought it was a drain so I've never removed the plug before. I removed it and a lot of crap (water, oil, foam) came out of it. I hope that is what was causing the sputtering. Am I the only one who didnt know this?

Another thing I noticed is I think my timing was off a tooth for the past year. Last valve job I couldn't line up the marks. This time I did so I must have screwed up last time. Its ran fine but has been hard to start the whole time. I even burnt up a starter.

Wrenching your own bike is such a blast:bonk:

Cant wait to get her back out to see how she runs!

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