1999 Honda Foreman 450s oil leak

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Ive got a 99 450s the top end was rebuilt about 2-3 years ago and ive had a slight oil leak for a while, but its gotten worse. I cleaned the motor up lastnight to see if I could tell where it was comin from, topped it off and went to do some food plot work on my hunting lease. all seemed fine untill it got hot enuff for the fan to kick on I ran it for about 10-15min after that and stopped to take a break and to let it cool off. I checked the oil again before gettin back to work and there was barely any on the stick, toped it back off and done it again, let it cool down a 2nd time and ran it about 2miles back home...

any chance stop leak may help or atlast slow things down untill I get my plots done and then replace the gasket? what all am I lookin at as far as changing it out? Is it as simple as pull the top end off, clean the old off, replace and put back together or is it more involved? Ive never done any atv motor work thats why I ask....sorry for the dumb questions but thanks for the help!

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I take it you took pics of the bottom of the cylinder because that is where you determined the oil to be leaking from? I don't think any additives are going to be of any help, from the sounds of it, it is leaking pretty fast. You may be able to buy some time by re-torquing the bolts at the base of the cylinder, and popping the valve cover off and re-torquing the nuts on the cylinder studs. You will need the torque specs and sequence for those nuts and bolts and you will likely need a new valve cover gasket. I don't think I would waste my time with that option though because it might not work, it will likely cost you around $20 if you need to replace the gasket and you will probably have to buy it again when you go to fix it properly. If the gasket is just blown out, this will not help and replacement is really your only option. To replace it is as simple as pulling the top end off and replacing the gasket. Since this is not an OHC engine, there is no timing chain to mess with, so it is relatively simple compared to other machines. The old gasket is most likely going to be ruined when you remove the cylinder, so cleaning it off will not be an option, I wouldn't try to re use it even if it did come off in one piece. You will need to replace the head gasket as well and likely the valve cover gasket too. Once again, you will need to have all of the torque specs and sequences to properly re-assemble. If you don't have a repair manual, I would order one. Ebay has decent prices on repair manuals and you can probably find a top end gasket set there too. If it were me, I would just tear the cylinder off and replace that gasket first thing. Good luck.

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