Engine help

[84atc200es]

Im in need of some help, my three wheeler was running good last weekend but seemed like it needed a bigger jet. This is the first time I've ridden it hard it was sitting outside for year previously according to the po. I removed the carb and put in a bigger jet(100 from an 88), and it wouldn't start(yes the carb is very clean). Changed the jets back, still would start. Then I realized I have no compression and air blowing out of the carb. Where do I need to start to free the intake valve? Soak it in PB blaster? Pull the head? Check timing chain? I would prefer not to pull the head in the middle of deer season I don't understand how the intake valve got stuck open just turning it over any input would be appreciated.

[fabiodriven]

I'm sure there are ways to free it up without head removal, but you really don't have the full gist of what's going on in there unless you take the head off. IMO the head has to come off or you risk more damage.

[84atc200es]

More damage is okay with me i just need to get it through deer season then it's getting a complete rebuild so any ideas or should I slap a head from eBay on it for now?

[fabiodriven]

If you've got time to slap another head on there then do it. Valve train and piston damage isn't something you limp by on and "try to get the season out of". If you're going to get a new head anyways then get on the stick and rip the old one off so you can see what you're working with.

[Flossyb20]

Sounds like you have a stuck valve...or your timing is off...either way you can just pull off the cam cover, remove the cam, and inspect your valves...they should be shut...if not, then try a little PB, and lightly tap the valve with a rubber mallet until you're sure the valve is seating correctly. Then reassemble making sure your timing is correct...this should get you through deer season, but if your valves are sticking, then you'll eventually need to take the head off and clean out/replace your valve guides.

[sammiefish]

do you think it is possible that your change in fuel mix may have deposited extra carbon
under your valves causing the problem??... or even if it was too rich, washing some carbon
loose to find a spot under your valve seat?

if thats the case then a quick cleaning and going back to the stock carb may help....

either way, you'll get a look at the valves

[kb0nly]

Does the exhaust valve open and close? Take off the valve adjustment caps, turn it over, do you see the rocker going up and down and moving the exhaust valve, what about the intake valve is the rocker just loose? If the valve is stuck open i agree with the other guys, it can only be a bad guide, bent valve, or maybe carbon deposits. But since this happened suddenly i would think its something more catastrophic but it doesn't have to be.

First step i would think is remove pulse gen cover so you can see that the cam is turning by the rotor turning in there, then look in the valve adjustment caps and see if the exhaust valve is moving, and then the intake, if the cam is turning and the other valve moving then its just a stuck valve. Since its a 200ES with a decomp lever if you flip the lever up and crank it over does the lever drop back down? I have had them stick before that gives the appearance that something else is wrong and it was just the lever, this will also tell you without opening it up if the exhaust valve is moving to disengage the decomp lever after turning over.

If your really lucky you can pull the intake off and look down in and see if its got crud stuck in there and spray some PB blaster around the valve guide and then tap it through the adjustment hole. Spraying anything from the top won't do any good as the valve stem seal will keep it from seeping down into the guide anyway. Did you hear any noises when this happened? If you were really out of time due to bad timing you could have had the piston smack the valve, again you have to pull the CDI cover off and check the cam for rotation and timing.

[84atc200es]

Thanks for the replys I just got off work and I'm about to PB it. Tomorrow when I'm done hunting I'll take the head off if I can't free it up with PB. And yes I understand valve train and piston damage isn't something I can limp by on I may be new to atv motors but I've been turning wrenches for a long time, I understand if I get it free and it's not just carbon build up I'll have a catastrophic melt down soon but I'm trying to get it as far through hunting season as I can without borrowing my old mans rancher