225dx wont stay running

[85burbanator]

no, it was closed. i wondering one of the valves isnt closing all the way or somethine because when it was running it seemed fine. i dont have tire on it so seeing how it acted under a load isnt gunna happen.

[MonroeMike]

Hold the throttle wide open, when you do the compression test.

[85burbanator]

so hold the throttle wide open then. and if it still reads low like that what do you think it could be? rings or valves not closing? it did sit for a while.

[MonroeMike]

Don't forget to check that the compression release isn't holding the exhaust valve open.

If it still has low compression, squirt some oil into the cylinder, do the test again, if you have a higher reading, rings are bad.

If the reading stays the same, it's either valves or a head gasket.

[85burbanator]

right on. ill check it in the morning and let you know how it goes.

thanks
mike

[85burbanator]

i did as you said and it read 60psi at the highest. it was hard to turn over but i got it lol. so the rings are prolly bad then huh

[Lukeatc185]

if you want to see if the valves are seating, remove the rocker cover and head. flip it over you will be able to see if it is seating or not. i use oil. pour it on the valves while its upside down and check to see if its leaking through. if not then its valves. or it could be a worn down cylinder wall.

[85burbanator]

I'll check the head when I get home. So if the valves are properly seated they won't leak correct

[MonroeMike]

If the compression went up after you put oil in the cylinder, the rings are bad.

You can test valves on the bike (and more), if you have a air compressor. Put the piston at TDC, compression stoke. Brace it from rotating or have someone help.

Pressurize the cylinder with air, you'll have to take the one way valve out of the compression tester hose, if you use that.

If air comes out the muffler, the exhaust valve is not seating.

If air comes out the carb, the intake valve is not seating.

If air comes out the breather, rings are bad.

If air (oil bubbles) comes out around the head gasket, bad head gasket.

I'd say, you will have air coming out the breather. If you plug the breather hole, you can then check for other air leaks.

[85burbanator]

yea I don't have a compressor unfortunatly. I've got the head off and just looking at the piston and cylender they don't look bad at all. Think I could hone the cylender and replace the rings? I might take it to a shop to get measured up and see what they think. I'm getting ready to test the valves by dumping oil on em or whatever her in a little bit and well see how that goes

[85burbanator]

i just got back from checking the valves and they seem to be fine. oil sat in the head for about an hour and it hardly moved so im thinking rings or head gasket. the head gasket is kinda bowed up by were the chain goes through for the cam gear. not sure what that means really.

mike

[MonroeMike]

My local motorsport shop mics my stuff for free. Maybe there is one around there that will check that cylinder for you.

Edit - My shop does all brands, not like a Yamaha only dealer. I went to the "dealer" once and mentioned "three wheeler" and they went back to eating their lunch. They are expensive too.

[85burbanator]

yea ive got a reputabl shop close by that is friendly. im gunna swing in there and see what they say. just wondering if everything checks out if i can just replace the rings or if i need a new piston and ring set. there is zero play in the piston when i tried to move it around in the cylinder.

just trying to keep costs down

mike

[code200k]

if all looks good you can just replace the gasket and rings

[85burbanator]

awesome. I hope thats the case then.

Mike