Only runs on three cylinders

[jwpatryn]

I have an '87 with only 10'000 miles on it! Over its lifespan there have been several multiyear periods when it's sat idle due to persistent maintenance issues. Here is the latest. I drove it in June for approx. 10 miles and it ran fine. A few days later it "got sick"! It always starts, but when I tried to accelerate, it was exhibiting symptoms of only running on three cylinders. When I removed the air cleaner, only 3 of the sliders were moving. I've heard a lot about bad diaphragms, as well as other issues so here's what I've done (over the past 8 months). I thought that it may be a case of old gas so I initially gave it the Sea Foam treatment. No improvement. Although I couldn’t see any holes in the diaphragms, I didn’t want to leave any stone unturned so I have purchased several new diaphragms as well as slider/diaphragm kits. Just in case there was a problem with an old needle, I found a source and bought 3 new ones.($$$$$) Throughout the past 8 months I have turned it into a frustrating pastime of routinely mixing and matching sliders, diaphragms and needles to try to find a combination that would work. Here I have to emphasize that all through this process all I’ve managed to do is move the problem! The bike always starts with no hesitation but (even after it’s warmed up) it won’t respond to any acceleration. Incidentally, in order to try to minimize my efforts, I have just been juggling parts on the right two carbs only. In essence, I can get either the right front carburetor to act normal OR the right rear, but not both simultaneously. Here it is December and not only is it past riding season in New England but it’s also too cold to pursue this problem anymore in an unheated garage until Spring. Meanwhile, if anyone has any suggestions about something I haven’t tried yet, I’d sure like to hear it and I’ll take it into consideration when I resume trying to fix this problem in the Spring. It sure eats my heart out to own a bike that is mint physically but sick mechanically.

[Squidley]

Make sure all the carb bowls are getting fuel. Open the drains and drain the bowls completely, then turn the key on and let them fill back up. This will insure your getting fuel inside all the bowls. If you haven't changed the wires and caps out, do that, spark plugs too.

 

You can tell if your diaphragms have holes in them by watching the speed at which your slide go back to the closed position with the air cleaner cover off. Holes in them, it will be noticeably faster to close. You may need to take the carbs off and go through them as Seafoam will only work if there is an opening in the jets, if they are completely clogged shut, it wont do any good as it needs to flow through to clean properly.

[billmac]

been a few months, did you find the problem?

[jeeper0202]

been a few months, did you find the problem?

mine did that and i found out that one of the coils was bad:322: