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Discussion Starter · #1 ·
So I got this 02 400ex with a trashed top end. When I took it apart I found the piston rubbing against the cylinder wall. I figured it had a bent rod maybe, but it still ran good but just smoked alot. I put it back together and it still ran just the same.
I decided to see what a 440 kit would do so got a new piston and cylinder ( rings and gaskets and the works ) Now all I did wasput the new stuff on there and it won't start. I have fire, which seems about every other cycle though. I've tried changing the timing 1,2,and3 teeth advance and retard, and 180 degrees the same way, still no start.
I put the trashed topend back on ( which I knew worked ) and it's doing the same. The valves are set right also because I thought one might be tight and sticking open.
I've been over to exriders.com and got nothing from them.

Just wondering if someone here might have an idea and be more willing to help since I'm not as much of a stranger in this site as that one.

Thanks
 

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i had that same problem with my yfz450 mine would backfire and stuff but wouldnt ever start. i sold that one broke because no one could figure out the problem
 

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there is a pin and spring in the head for the cam. if it falls out it wont start.look a the parts diagram u will see it. it is very small. i did that on one i built and drove me nuts til i found it.
 

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I looked for it on exriders and couldnt find it. If it was me, this is the process I would go through.... First off, put the timing back how it should be. How long has it been since the last time it ran? Are you sure the gas is turned on, and it has gas in it, enough to fill the carb bowl. How did you check for spark? Is the spark plug sparking or did you use a spark checker? Do a compression test. What is the compression?
 

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But quadboss is exactly right about the cam set plunger. Have to make sure thats in there!!
 

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Discussion Starter · #6 ·
I have a spark checker light that goes between the plug and plug wire... Definately good spark. I've tried dr7ea and dr8ea plugs.

Around100 psi by my compression guage.

I think I remember that pin and spring the first time I took it apart. Is it right under the cam in the head, near the sprocket? I'll look at it tonight and make sure it's there. I remember the first time I put it back together it "clicked" a little. It ran then. I haven't payed attention to see if it's still there the last 100 times when it doesn't run.

Hope that's it.
Updates to come.

Edit: it ran 2 days ago, before the 440 came in.
 

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100 psi is aweful low, especially for a 440, double check valve clearances. Might be in your best interest to remove the auto decompression mechanism, along with that eency spring and plunger. Are your spark plugs new?
 

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You know with that cam 180 out, you may have already damaged the valves.
 

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Discussion Starter · #10 ·
Valves are still good, well, were. I always turn it over by hand before I fire it up.......so ......I found the pin and spring in my tray that I forgot to put in and it fired right up. Woo Hoo:D....Thanks a bunch to Quadboss and chucked for showing me the little things.

I went and rode it around the little track next to the shop. I was dissappointed in the 440 vs. the trashed stock bore. Guess thats what ya get for an air cooled engine. Or maybe I was expecting the night and day difference like ya get with the twin cylinder motors. It was like going from stock intakes to crossovers. but not quite as snappy.

Ran good though the first 10 or so laps then I almost put the head through my nuts...It lost a bunch of power a few seconds before that and I just thought I blew a gasket. The sleeved cylinder that I bought, the sleeve let loose. What a POS!!!!:mad:...I have another sleeve that should be heading my way tomorrow that I'm gonna have pressed in myself from the shop I use here locally. Hopefully, with that and some new bolts and studs, I might have something that is reliable enough to sell...I'm just glad I didnt sell it to someone before it let loose, and them blame me for the shitty work.:cool:
 

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Discussion Starter · #11 ·
Got new parts installed today. Other than the cold weather it was fun to ride. I like it now. Instant throttle response and it will keep right up withone of our z400's with me riding the 440. The 400 will pull a bike length out of the hole but can't pull me anymore than that with my 260lb ass riding the Honda. It's a hell of a lot better than I expected!

Just thought I would give yall an update. Maybe I'll have it sold by February now.
 

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Did you install the HD head studs with your 440? If not you will be blowing head gaskets left and right. The OEM head studs will literally pull themselves out of the cylinder. been there done that :lol:
 
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