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By Elijah Stone
Hi all new to the forum I have a Yamaha Moto 4 champ (100cc?) (YFM100) so I've been trying to get this thing to start for awhile honestly I'm running out of ideas so I'll start with the things Ive replaced and done first it was not trying at all and then I put a brand new battery then the terminals broke so I bought some nice copper ones fixed that up so now battery is got good voltage and all that I have checked all the plugs cleaned everything off so anyway it still wasn't trying but I couldn't get the crank case off and I didn't think using fire was a good idea lol so I busted the crank case off on the left side(if you are sitting on it) wierdly enough the flywheel started spinning I thought it was odd but went with it then I replaced the spark plug still wasn't getting spark so I replaced the ignition coil then it was getting spark next the carburetor was really gross I cleaned it out still wasn't working so I in turn decided just to replace it with a new one so I did (PS I never figured out how the fuel lines hook up if someone wants to help with that to lol) also for good measure put a new air filter so then I pressing the button Everytime I replace something and nothing so then I think what if it's the stator so I have no idea what a good or bad stator looks like but me being to rough I broke the wires on the thing but still no changes the fly wheel spins gets compression (I think) getting spark from spark plug idk other tidbits that might be useful I don't have a clutch line so idk if that has something to do with it I do have the break zip tied in to bypass the safety feature also the throttle cable is in fact broken and I'm working on buying a new petcock for my gas tank because my current one is broke I have very limited money this is supposed to be a project before I go to school for welding and automotive tech so I don't have any money to get a mechanic lol but I'm pretty confident in my ability to do anything u suggest any suggestions are welcome I'll edit and submit pics
So my latest find is a Moto 4 250. Looked in good shape, started right up but would backfire and die upon acceleration but you
could get it to go if you were good with the throttle. I figured it was the carb. was a brand new Chinese carb, he didn't have original.
I took it apart and cleaned it, only thing I found was some debris in main jet and the main adjustment on bottom was at 41 turns. Cleaned
it out and set at 2 turns, re installed. Starts up, runs better actually drove it but seems really sluggish, once I hit 3rd gear could barely pull
it. Rechecked everything, even ordered a new carb as I had this problem with another atv but still same problem. Now I pull it apart and
decided to check compression, I show only 85 psi. I checked valve adjustment (after aligning up cam gear to mark on case). to make sure not too tight still right at 85 psi.
I assume I need to pull the head and look at the valves, Any ideas I am missing something? motor does not smoke but is super sluggish.
The specs I find are off the downloaded manual of a 94 but figure should be the same. It states compression standard is 128 and Minimum is 114 and Max is 142
Any other Ideas before I tear it down? Thanks in advance Az
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I had the local garage change the oil and filter in my machine and ever since they changed it there has been an oil leak. Taken it back several times and they can't figure out the problem.
Common misconception is that you need to return to the dealer for an exact
oil filter for your ATV. Aftermarket companies actually make filters for
the O.E.M. market. Why go to the dealer when you can get the exact filter you
need at your local auto parts store such as CARQUEST or NAPA. Wix corporation
makes ATV filters that you'll find in most of your popular autopart stores.
In most cases, you'll pay allot less!
WIX is a leader in the filter business. Check out this
ATV FILTER CATALOG. Remember, you can
right down the filter # and have it cross-referenced at your local autopart
store if they don't carry WIX, CARQUEST, or NAPA.
You can also click on the part # for the filter image.
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