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What should I go from here?

8213 Views 57 Replies 8 Participants Last post by  Helmut
Where should I go from here?

Hey guys,

I bought a 98 300ex off a guy that ran pretty good but it was knocking from the top end like a tink-tink knock didn't bog or anything when I was test driving it. It needed new clutch plates and he had some that came with the quad that were brand new EBC Dirt Racer brand... also had the clutch cover gasket.

Took it out riding that weekend all was great ran fine just the knocking was still going and the clutch needed some new plates but wasn't bad.

So a couple days later I drained the oil changed and took the cover off and found quite a bit of metal shavings down under the oil screen so I checked all the bearings and they were all in good shape and went ahead and changed out the clutch plates and put it all back together and as I was putting the nuetral switch on it sheared off and I had to get it out and get a new one so I finally got it all back together. and it started up and ran good and the clutch was now fixed.

Anyways I took it out riding that weekend and was doing some trails and I pulled in the clutch to check my battery to see if it had fallen out because it's only held in by zip ties and the engine just died on me. So I tried to start it back up again and it wouldn't start... the starter motor was turning but the engine was not.

So I got home and checked all the fuel lines and such and it was all clean no obstructions checked the spark plug and it looked ok nice blue spark... put my fingers over the plug hole and checked the compression and it blew by fingers back so now I'm stuck... Any ideas?
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Was it smoking at all out the exhaust? Cuz if you dont have any smoke i wouldnt change the piston or rings either. I just took mine apart and it looks pretty much like yours my cylander walls are smooth but deffinitly check the rod for up and down play mine moved like an inch up and down. Oh and another thing i know this isnt a common problem but make sure you check your oil pump because i put mine all the way back togeather and the oil pump failed causing my rod bearings to go that bad. So while your there check it. It will save you headaches down the road.
Take it off and check the oem specs do you have a chiltons or clymers book for your quad? And yes if the rod moves your rod bearings are going. Prolly not but better to check while your right there then find out later. And if you dont have a book ill scan my page for checking the oil pump. Mine was pretty easy to figure out tho the main gear right on the front of it moved a bunch in and out. It should move like a couple millimeters at most. Mine moved like 1/4 to a 1/2 inch.

Oh and those marks in the side of your block look like either your cam chain was really loose or it came off at one point in that quads life. Not a big deal tho.

Oh and another thing you should probably check the cam chain tensioner. Its prolly bad and that would be why your chain is loose or your chain could be stretched? Tensioners are cheap and a good insurance policy.
Go to the other side of the motor and take off the two allen wrench covers ones big and the others small. Turn the bolt in the bottom hole and shine a light in the top one and turn it to the second T mark make sure your at top dead with the piston and make sure your on the compression stroke. Then match the marks on the timing chain gear there should be 3 marks one goes up and the other matches up with the top of the motor. If you have any other questions feel free to ask i am currently rebuilding my whole motor so i will be glad to help you out. Oh and welcome to the forums! you will be glad to know that lots of ppl here can help you with any problem you may b having. Welcome to the family!
Yep no problem bro!
Sweet Sounds Like its gunna look good. I dont really worry about the cosmetics all that much i just like to make mine go fast lol
The 400ex ones are a +2 wider if you have stock rims on the front. I have douglas rims with a 0 offset and they are like a +1 1/2 or so. And if you buy the kit from diamond j customs you can put 400ex shocks on and get way better suspension travel. When you put the 400ex a-arms on with the 300ex shocks its like a lowering kit for the front which is kinda gay. And you literaly have no suspension at all. That should clear things up for yah bro!
Yes the front +2 makes you handle alot better way harder to flip and you can throw the back end around corners alot more. The ones you have on it look like 300ex ones but its really hard to tell. As for the back shock. They are fine stock if you ask me i mean i jump some pretty gnarly gaps on mine and have never had a problem with it bottoming out in the back. But thats up to you! And yes the kit from diamond j customs is very strong and easily capable of jumping and stuff. I hit a 30 foot double with my quad and its never had a bend or crack in there kit.
I would double check your cam chain wheel bolts. They backed out on mine the first time i started it after the rebuild. Your probably gunna have to rejet with the filter and pipe. The stock main isnt gunna be right. Your gunna run it lean when you ride so it may seem hotter than normal. Other than that i wish i had the time to pull mine down and pain the frame black! That looks SICK!
Oh and give those new exhaust valves a good break-in period. Just dont romp on it for a little while.
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