yet another thread

lol just wanted to say thanks to everyone that has helped me out. got my engine back together and fired up today for the first time. all in all cost is about 300 for the bike and every part including a new top end. now for one more question what are the stock(ish) settings for the pilot jet needle? as in how many turns out from fully closed?

Usually 1 1/2 to 1 3/4 turns out should get you in the ball park.

Well I just tried to ride it and when you pit it in gear it just bogs down and dies not will it rev out the way it should

Check your float level, you can find plenty of threads here, and online showing you the procedure.

I don't recall what model you have. When you put the engine back together, did you use new seals and gaskets? What premix ratio are you using? Do you see a lot of smoke once the bike is at operating temp? Also, is your jetting set to stock specs or something else?

Best chance of getting the jetting right is to start with it at stock and adjust from there.

Its a 93 yz250 the jetting is stock, and yes all new gaskets also the case was sealed with yamabond. The ratio im running is 40:1 with yamalube 2r. Heres whats throwing me off with the jets though my main is 350 pilot is I think 76 which seems too big but i am still a noob as well. The only other thing I can think of is the powervalve is not functioning properly, but I do not know how exactly to diagnose these problems, or symptoms correctly.

Anyone have suggestions as to test the power valve?

define bog down, is that a kind of sputtering?

what i mean by bogging is that instead of hitting a higher rev it simply acts as if the engine is starving for either fuel or air causing the rpm's to drop instead of increase correctly.

i've tried to search and only luck ive found was many different resolutions from power valve replacement, re-ring, air filter clogged things like that. so i have been through all that no luck pv is way to expensive to replace so i want to be able to test it if there is a way to do so.

sorry for being a little extra winded lol

I used a different needle and my normal setting went way to high. I had sputtering from 75% throttle onwards.

Changed the needle and all sweet right now. Still a tad rich but no sputtering at all.

So should I go with a more rich jetting if so about how much should I start with

So with these symptoms should I jump my jetting by one needle set or two in your opinion?

Well I just tried to ride it and when you pit it in gear it just bogs down and dies not will it rev out the way it should

It is too hard to tell just what is happening without seeing and hearing the bike in person.

But, normally if a bike is lean it will still rev out. It is when they are stupid rich that they blubber and load up. If your powervalve is not working properly, then it won't run right either, but it should still rev out - it will just be flat on top.

Have you pulled the plug to see what it looks like?

Does the bike rev out normally in neutral? There should be almost no hesitation for revving in neutral.

When you put it in gear, the bike just dies? Or can you get it moving and it won't pick up revs? If it just dies, then you might need to adjust the clutch.

I would first ensure that the jetting is indeed stock for that year (carb stock also). Then I would do a leak down test to make sure that I don't have a bad crank seal. Set the needle position in the middle and that with stock jetting and carb should be in the ballpark.

If it still won't run after you have verified the carb settings, then you have something wrong internally. Could be the PV, could be a bad crank seal, etc, etc.

Evening folks-Hope you don't mind if I jump in.I have my 94 YZ-250 that i have been wrenching on here with you folks for alittle over a year.

The Power-valve has the stop on the left side to regulate the open/close-At TDC-Take the right PV cover.There is a Factory hole in the Cylinder and a slot in the Spring cover plate bracket. Loosen the center nut--use a small Phillips screwdriver to line upBikeproblems006-2.jpg

I hope this helps.I have several Bikes that try to keep going.Kids/Wife My Yz is the Flipp'en Baddist of them all,but I am constantly having fuel/plug/smoke/hard-starting after a ride---issues. What kind of pipe do you have ? And were is your height position on your needle ?


The plug comes out with black suit on it so it should be a rich. It does not rev out the way it should and putting it in gear and it will try to pull but just falls out flat and dies clutch can be in need of adjusting im just trying to get this rev problem corrected first. I went to the dealer to check the std jetting needle sizes and they are stock jets crank seals were replaced also. So I can only think power valve timing and grounding issues so I plan to disconnect the kill switch sand the coil mount and all other connections.

also its a stock pipe and what do you mean with what my "height position on your needle?"

Are you sure your mainjet is clean? Does gas drip out of the overflow tube on the carb? I don't see how the powervalve would prevent you from launching in first gear. If it were stuck open, I guess, but that would be pretty easy to check.

Will the bike rev out correctly when it's in neutral?

Also, put the bike on a stand and make sure you can roll the tire while it's in neutral and while it's in gear as well.

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