ATC200S Engine Problem

[Tuckeredsoul]

I am new to three wheelers as of tonight. I bought a 1984 ATC200S for 150 bucks. The person I purchased the trike from told me he bought it from a guy that supposedly put a new top end on it. For some reason the air that is supposed to be going into the carb is blowing out the carb towards the air box. He seemed to think the person that rebuilt the engine didn't set the timing right? I have never messed with timing an engine before although I am mechanically inclined and am sure I have the tools necessary besides a timing gun.. Any help would be greatly appreciated. Really nice machine for 150 I though! I will try to add some pictures asap. Thanks in advance!

[350for350]

I always tell people that you need to do three things when you pick up a new toy. Buy a manual, buy a manual, buy a manual. Now the "timing" that could be off is the cam timing. Possibly the cam wasn't lined up right during the rebuild. The cam chain and/or guides could be worn allowing the cam to be retarded in time compared to the crank. When I personally ran into the same thing on the same model, after a "rebuild", the problem was that the intake valve didn't have any clearance so it was being held open the whole time, no matter the cam position, allowing the air/fuel mixture to be pushed back out of the cylinder on the compression stroke. It could be any of these things. Sorry I couldn't be more specific. Just trying to give you some starting points.

[cap]

Pull the cover, pulse rotor and pulse base off so you can see the cam sprocket.
Line up the flywheel "T" mark in the inspection hole.
The "O" mark on the cam sprocket should now be lined up on the mark in head cover at 12:00 position. Very important now to see the dowel pin on the cam shaft at the 11:00 position because this is what index's the pulse rotor. Now install the pulse rotor base and the rotor should line up just before the generator, move the crankshaft to the "F" mark and the generator/rotor should line up, if not adjust the generator position slightly.

It's easy to screw up the first couple steps when doing a top re-assembly and be 180 deg. out, then you need to pull the cam and make it right.

You can find the manual to download here somewhere.

[Tuckeredsoul]

Well believe it or not I made it to the cam sprocket. After adjusting the valves to .002 thousands of an inch (with no allowed tolerance in the valve clearance) unbelievable! and cleaning the carb out I am still not getting gas to the sparkplug. I then pretty much assumed the cam was off. I did get down to the cam sprocket and when the flywheel is lined up with T and valves closed, the O on the cam sprocket is at roughly the 2 or 3oClock position. Luckily a service manual came with the machine or I would have not made it this far. It really doesn't describe what to do if someone installed the cam wrong because your not supposed to do that! Help! Thanks! I do not know what to do from this point. Also I have to hold the T line in place with a wrench on the end of the cam sprocket shaft or it will skip past the T mark by about a 1/4 of an inch. The cam sprocket is held on with two bolts, I have the chain loose too..

[cap]

Great job, you found the problem.
Now fix it and make it right.
Line up the T mark
Remove the two bolts holding the sprocket, don't drop them or you will be pulling the engine.
Pull the sprocket/chain off and rest it on the shaft. You can now turn the cam shaft and line up the bolt holes 12 & 6 O'clock with the little index pin on the shaft at the 11 O'clock position.
Re-position the sprocket in the chain so it bolts up with the cam and the little 'O' on the sprocket is at 12 O'clock lined up withe notch in the rocker cover.
Re-assembly and check the timing again like I posted in the above, adjust the timing chain and get back to us on how it runs.

[Tuckeredsoul]

Everything your saying is making sense. Although I'm hesitant on doing it because I'm worried the other end of the chain may fall off from whatever its connected to down at the bottom for one.. and also concerned about the fact that the engine wont stay on the T mark without holding a wrench on the end of the sprocket shaft. When you take the two bolts out of the sprocket what happens? What does this allow? Why can I not just rotate the shaft and sprocket (with chain off) with the bolts left if?

[cap]

The chain may fall off the bottom sprocket, not the end of the world as you can manuvouer it back on with out to much difficulty.
You really have no option but pulling the bolts, reposition the can shaft and then reposition the sprocket so the (o) is lined up.
Take out the spark plug and the crank should stay on the T mark.
You can use a piece of wire to keep upwards pressure on the chain while repositioning the sprockette, or just hold the chain up.

[Tuckeredsoul]

Alright! Thanks a lot! I ended up pulling the recoil off and holding the T-mark there. Repositioned the sprocket, put everything back together and it still didn't fire! Someone had the float way off and it wasn't allowing gas to go through the carb.. Readjusted the float and she's alive! I am going to need a new gasket for the float bowl, got a lot of gas coming out around but still road it around for a while. Every once and a while it would run funny, guessing that has something to do with the leaking carb. I heard these things are really tuned to the air box/ stock intake system. Hope I can work that last little kink out of it. Thanks again. Any suggestions on the way it runs let me know.

[Dirty200]

I just got one of the cheap china carbs off eBay for 25 bucks and it works great. I'd love to see some pictures man I've been rebuilding a 200s recently my self. Awesome little trike

[cap]

Yea, China carb is about the same as a rebuild kit and come with a inline filter.

[Tuckeredsoul]

Yeah, I got on eBay a while ago and noticed those china carbs. I have always been taught to stick with stock carbs if you can but this carb on this particular 200 has been through the wringer. Missing the stock screw with spring for the idle speed adjustment, the choke lever is missing some parts (rigged with a spring) and leaking gas profusely... Any idea what size the two ends of the carb need to be? Does the china carb come with a slide and needle or do you reuse yours?

[cap]

They come with a new side and needle, just hook up the throttle cable.

[DohcBikes]

Good thread. The moral of the story here is that just because you feel a push of air from the carb, doesn't mean the cam timing is off.

I wonder how many good keihin carbs get thrown away every day because people just give up and buy a chinese carb. Nothing against them, I use chinese everything on my bikes, but cmon guys. Carburetors generally do not wear out. Sure the slide can wear (this site is obsessed with the idea lol) but its not as critical as many make it sound. So the carb is leaking, so what. That means it needs maintenance. My .04. (inflation)

[cap]

I have to disagree, if you have air pushing out the carb when you pull it over the cam timing is off or the intake valve is not closing. This was confirmed by the sprocket (O) and the flywheel (T) not lining up.
In Tuckeredsouls case he also had a stuck float needle, probably from sitting too long.

[DohcBikes]

I missed the part where he had to reposition the sprocket, my mistake. Without seeing that I assumed his intake valve had no lash and needed adjusted. Thanks for pointing that out, what I said is still 100% true.

[Tuckeredsoul]

Well I'm getting ready to take the 18 dollar plunge on the Chinese carb on eBay. I would have rather bought a rebuild kit for the stock carb but pieces of the body are snapped off and having problems with the choke lever. One thing I noticed while looking at it today is the valve cover is leaking. It has a blue liquid gasket material for a gasket on the cover. Should I make a paper gasket for it or try to seal it with a perma-gasket material? If so what specific brand have you guys had good luck with? Its wet down to the bottom of the head from about a 20-30min ride. Hoping its not a head gasket leak also.. Thanks guys for all the info!