400ex locked up today

[atc200m]

i was riding and i stoped to look at something and when i went to go again it went about 3 feet and locked up. i was stunned because it has 8 hours since we put a new crank in it. i took the flywheel cover off and found the fly wheel bolt was loose so i tightend it and turned the motor clockwise. i dont know if the decompressor was hung up or what but it started up. but my friends day said my oil smells like it has gas in it so idk what it could have been

[atc200m]

can anyone help me

[VTredneckgames]

Just my opinion, but

tear it back down. Something is not right. Fix it now before you mess something else up

[jasonwayne222]

its sounds to me like he didnt torque the flywheel bolt properly, I wouldnt tear it back down for that, my friend put a new crank in his yfz and had the same problem, I went over there and torqued it properly and has been good ever since. Also I use some medium or high strength locktite, it will help a lot but I think the torque on that bolt is like 94ftlbs if I remember right which is a lot of torque, if u dont have a torque wrench then get one, this is not a bolt that u want to just guess if its tight enough

[VTredneckgames]

maybe I missed something, but I thought the OP said the engine locked up. How would a loose flywheel lock the motor? Plus if there is gas in the oil, then it could be a broken ring or piston.

[jcs003]

do a compression test. then decide if you want to tear into it. did you go through the proper break in procedure? are your rings put on correctly?

[atc200m]

im pretty sure we did everything rite it runs the same as it always did im not sure if the flywheel might have had somthing to do withit or what but could it have been the decompressor.also i am only running half throttle. im at 9 hours out of my 10

[atc200m]

i drained the oil today and it didnt smell burnt and had no gas soo what now

[jasonwayne222]

Come on guys read between the lines, he said it locked up but he also said that the flywheel bolt backed off, it may not have really locked up like u think it just stopped running. He even said he tightened it back up and it started right up so why dont u read the whole thread before shooting off at the mouth, I know Im a bit rude and I dont care.

[jasonwayne222]

dude if its not smoking and running fine now that u have tightened the flywheel bolt back then stop worrying about it, How much credibility does ur friends dad have, is he a mechanic by trade or hobby, sometimes people who dont know 100percent what they are talkin about can really shoot u in the wrong direction so be careful of anyinformation u get off the internet and in real life,

[VTredneckgames]

If everything is running correctly now, then dont worry much about it. No gas in the oil and since you said its running fine lets me believe that you got lucky and everything is fine.

Jason, I still stand by what I said though. Maybe the OP didnt use the right terminology. When someone tells me that something locked up, it means to me that the motor locked up. Slammed to a stop, will not turn., etc. That means one thing, something is not right.
I agree with you though, from reading the OP's last posts, I think the motor just shut off, it didnt lock up. People shouldnt have to read between the lines, for the most help, clear and concise information is needed.

ATC, dont worry about it. Ride it. You said it yourself, oil looked good and its running good. Go have fun with it!

[atc200m]

thanks alot for the help guys but i found the problem, the nut that goes onto the crankshaft on the clutch side had backed off and dug into the clutch cover. i got it all tight and everything now all i need is to get oil and ride. what oil should i run i ran gn4 for the 10 hour breakin

[jasonwayne222]

well redneck guy ur very right people shouldnt have to read between the lines but its very rare that people on here are very clear with what there problem is, for some reason when we start typing we know what we are trying to say in our head but somehow it doesnt all come out clearly.

[VTredneckgames]

I agree.


atc, If you do a search for "oil" (put "*oil" in the search button) there is a long thread with people talking about what types of oil they are running.

Basically anything that is wet clutch friendly is fine. I have run red top Mobil1 20w-50 before and Ive also ran some Mobil Delvac Diesel oil. You can ask 50 people what oil is best and you will get 20 different answers. If I could get it easier, I would just run Honda oil. Thats what they were designed around. It may be alittle more expensive, but its only 2 qts. If you cant afford the extra $5 to use a proven oil, then why are you out riding in the first place? Thats my take on it.

[atc200m]

i run castrol 10w-40 in bothof my 3 wheelers and i had enough for my 4 wheeler so i put that in it and fired her up. now all i have to do is try to adjust my valves some more because its ticking bad