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Discussion Starter · #1 ·
I have a 95 mojave ksf250. I've replaced the rings, 2 springs on the intake valves, reseated the valves, new gaskets and valve seals. When i kick it, i only get around 40lbs of compression, but it doesn't hold it, it leaks off. I'm new to atvs, but i have done mechanics most of my life. Am i missing something. Possible crack in the head, or otherwise. I've redone the timing and its dead on. So, right now i'm kinda lost. Any help is much appreciated....
 

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Well..it has a compression release so the normal range would be about 35-66psi being cranked at or under 300 rpms. A service manual would confirm this. As for leakage it will through the ring gaps if nothing else quite quickly. Does it not run?
 

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Discussion Starter · #5 ·
OK thanks. I don't have a way to do a leak down test. How can I chk the compression release to make sure it's working right. What I mean is. If it is working at cranking lbs, could it be stuck while it's running. ? And not let the compression build. Just asking. Idk know how the compression release is supposed to work.
 

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Discussion Starter · #8 ·
So I got my carb and still trying to get it running. No luck. It fires but it's short lived. I bought a new spark plug. No change. But my issue is I the k timing. As soon as it hits compression stroke I get compression, but right after, I get blowout thru the carb. It used to run decent, but I had to fluctuate with the choke to keep it running. But now it's hard to even get it running.
 

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Discussion Starter · #10 ·
What can I use to do a leakdown test. I'm going back thru the timing and recheck everything g again. I put new rings in. I'm getting 40 kicking, it doesn't hold. Just leaks off. Starting back at square1. New rings, valve lash at 008. New carb. New spark plug. Like I say. Before I replaced tines etc. It would run but had to let it run on choke till it warmed up. But after that, it would idle for a short time, then due. Could restart easily with choke on. Ran good with choke off. But now idk.
 

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Discussion Starter · #13 ·
Thx. Im gonna build one. So I decided to recheck the timing to see where it was at, I noticed that the spring was missing off the compression release. So I ordered that. But my exhaust was off by 1 tooth and my intake by 2. Crazy. The exhaust valve weren't fully closed when the intakes started to open. Now I'm just waiting on my spring.
 

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Thx. Im gonna build one. So I decided to recheck the timing to see where it was at, I noticed that the spring was missing off the compression release. So I ordered that. But my exhaust was off by 1 tooth and my intake by 2. Crazy. The exhaust valve weren't fully closed when the intakes started to open. Now I'm just waiting on my spring.
That's normal on the transition from the exhaust stroke and intake stroke...it's called "overlap" and it will be at TDC of the exhaust stroke. 180 out from TDC of the compression stroke. Still think there's a valve timing problem though.
 

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Discussion Starter · #15 ·
So I made a spring that I think will work. Put it all back together and tried to fire it up, but nothing. It acts like it wants to start but doesn't. I rechecked timing and it all looks good. I have spark. New carb. If I cover the intake on carb I get good suction. I'm lost. Lol.
 

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Ok, what else...let's see, got compression, got fuel, valve timing is fine, got spark...but is it firing at the right time or is there any reason for it to be weak enough not to jump under compression. First, is there any reason that the flywheel may have sheared it's key...as in anyone been in there lately? Might check. And, is there at least 12 volts to the coil when cranking? Might check that too. Is there a battery or charging issue?
 

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Discussion Starter · #19 ·
ummm..ok. so if timing is right with the t in the hole, when does it actually fire. nobodys been in there.. hmmm.. not sure on the 12v to coil. like i said. it used to run before i put new rings, carb etc.. you might be right.. still a timing issue,, but not sure how to go back to square 1. umm..new timing chain and guides were put in. tensioner is still good. can you give me a rundown on starting over.? this way i can be sure.. again, it did run before i decided to put rings etc in it.
 
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