Low compression, whats next?

[countryboy9799]

I knew this was going to be a project but its getting to be more than what I wanted. Oh well riding for me is still 2 months away. I tested my compression on a somewhat warm engine and it tested out to 110psi. The spark plug was wet but it may have something to do with the carb that randomly overflows. I think the float is hanging up on something in there because it will seal and then later it will overflow.

So should my next step be to get look into new reeds or just do a tear down and see what I have?

Part of me just wants to go with a top end kit from ESR or what do you guys recommend?

I should also add that my main is a stock 152 and it has a FMF Fatty gold series. It really should be running lean according to everything I have read, keep in mind the temps have been 10 to 30F. On a positive note it started on the second kick the other day and normally starts quickly. I have only started it maybe 8 times since I got it.

[countryboy9799]

I should also add that I want to keep it as close to stock as possible. What I do is mainly trail riding with my family and I want it to be reliable.

Thanks

[Skeans1]

I'd start with a leak down even before I'd tear into the motor just in case the crank seal or cases have leaks, and probably rebuild the top end.

[countryboy9799]

I will start with a leak down test. I took the pipe off and was able to see the piston on the exhaust side and the cylinder in the intake side looking in from the exhaust. It actually didnt look to bad from what I could tell. I couldnt see any scoring or anything so maybe just do a leak down test, if that checks out good take the top end off and put a new piston and/or rings in it. I will have to get one of those this week.

On a side note I dropped my carb and bent the idle speed/choke assembly, I tried to straighten it out and broke it in half. I am not sure if I should find a replacement or just replace the carb as I am having trouble with the float. Anyone have some links for new ones?

There is an exhaust leak where the pipe connects to the engine and where that spacer piece connects to the pipe. I noticed it when it was running and there is oil leaking out pretty good.

Would that cause low compression?

Thanks

[Skeans1]

Excessive piston and ring clearance between a the bore, that compression test was done at wot and you kept kicking till the gauge quit rising correct?

[countryboy9799]

It was wide open and I kicked until it quit rising.

What is the lowest you want it to go before rebuilding?

[thesmith87250r]

i think its below 160psi. and you can get a choke / idle adjuster on e bay last time i seen there about 40$ new

[Tbone07]

If you're at 110 psi tear that top-end apart and check it out. No sense in beating around the bush, 110 is extremely low

[countryboy9799]

Well I got my pressure tester rigged up and it lost pressure quickly, maybe went from 7 lbs to 2 in 30 seconds. I didn't test for other leaks since I can't use soapy water at the temps here are too cold.

I did plug the transmission breather with my thumb and kept pumping it up and when I released my thumb there was a lot of pressure in the transmission so that would mean my crank seals and/or case gasket is shot right?

Anything else I need to do before I start tearing it apart? I have taken a 250r motor apart 25 years ago when I had my first 2 but this will be my first time taking the transmission apart.

[thesmith87250r]

can pull the mag cover and see if there is air on that side and or oil. if the right side seal is leaking bad should have gear oil in the crank case. you can change the seals with out splittin the motor.you will have to remove some stuff but not a bad job.

[countryboy9799]

Here is what I found on the Mag side. Some antifreeze in the bottom and when I lift up and down on the flywheel there is noticeable play. I then pressurized it again and it leaked down but when I lifted up and down on the flywheel you could hear very clearly the air coming out. I didn't notice any oil in there though. I guess a complete tear down is inevitable now. Do you guys think the bearings are bad or could the cases be bad?

Here are some pics.

[thesmith87250r]

i would just go for a  rebuild at this point. there is a coolant leak somewhere head gasket /base gasket . from the looks of that mag either the cover gasket was bad and alot of water got in there to rust it up so bad or there has been a coolant leak for a bit.

[countryboy9799]

So how does the coolant get from the head/base gasket to the Mag cover? I have never had the lower case apart so I am just trying to understand how it would. It would leak down past the crank bearing and seal? If that's the case the antifreeze would more than likely take the bearing out.

Any tricks to getting the flywheel off? I cant get the nut off because I cant hold the flywheel. I am not sure if oriellys or advanced auto has a flywheel holder for this.

[thesmith87250r]

well to make your life easy with out air tools get a 1\2 electric impact gun i will save you headaches in the long run. you will need a mag puller that threads into the mag once the nut is off i suggest putting some p b blaster on that nut first before breaking it free. if this nut is giving you trouble wait till ya try and remove the clutch basket nut by hand lol.

[countryboy9799]

The clutch basket was the first thing I did, that was easy except for pressing the gear in the basket lol.