PDA

View Full Version : Need '84 200ES Big Red, Veteran Advice - Possible Compression or Air Leak Issues



G_Nuts
07-23-2012, 03:03 PM
A little background first to establish the baseline:

Recently purchased '84 200ES, changed all fluids, new spark plug, reset cam chain tension, new carb and new air filter. Carb needle clip in second slot from the top per '84 Big Red manual. Mixture screw backed out 2 turns from fully closed. Idles very good/smooth and great throttle response when stabbed and through all gears. The issue is twofold:

Issue 1: Every time I let off the throttle it sounds as though the engine is misfiring, almost like it's trying to backfire. The sound is hard to explain, it's a fast paced clicky/wheezy sound that lasts for half second or less. This happens in every gear, even neutral, every time I back off of the throttle.

Issue 2: While accelerating, just prior to reaching the top end of any gear there is all of a sudden a wheezy, breathy sound coming from the engine. It almost sounds as if its coming from under the gas tank or the gas tank itself. As soon as I switch to the next gear it stops but it will happen again right before you would normally shift to the next gear, right at the top of the power band of any gear.

I have gone through any and every combination of carb tweaks you can think of with the exception of changing the position of the needle clip. At this point I really think I have an air leak somewhere as both sounds have a wheezy, airy sound to them.

If this were your ATC, where would you start? Does this sound like a compression or air leak issue to you?

Thanks

G_Nuts

PS - Two other things to note, both hoses coming from the crankcase breather are shot to hell. I haven't been able to change them out yet. And no matter what I do, even with brand new oil and ultra "lean" settings on the carb, my spark plugs keep coming out black and covered with carbon but not wet.

kb0nly
07-23-2012, 10:17 PM
Two things...

Replace the crankcase vent hoses, thats a possible source of noise as well as other problems if they are plugged and the crankcase isn't venting correctly.

Check your exhaust. On my 84 200ES i went through the same crap when it comes to the carb and mixture settings and it running rich and fouling plugs. The exhaust was partially blocked because it was rotted apart inside and the baffling all moved around. I put a new DG exhaust on mine from Dennis Kirk, then it was running a bit lean, adjusted the mixture screw again following manual instructions and watching the plug after every use, got it to a nice color on the plug and she runs good and strong now.

Also check and adjust your valve settings as well.