Total Motorcycle Community Forums

In case you haven't already....

Simple check: the big idle adjuster screw....wherever it's set, have you turned it a few times either way from there and tried to start it? When I went through the carbs on my '92 NH the first time, I thought everything in the world was wrong with the bike after it wouldn't start...but it was that big idle screw that had gotten way out of adjustment.

Just a suggestion...you have a sweet ride there, I miss my '84 700S...

A trick we use to get superdreams to fire.....Use a hypodermic syringe to inject a drop of fuel into two cylinders ,replace plugs and give it a go.Superdreams were terrible for not sucking fuel through,but after we put a drop of fuel in they started easy.xjrjohn

I ended up buying new carbs on Ebay. After much effort found the carbs had some clogged inner parts (channels) that would not clear. Don't have the expertise to drill them out nor did I want to pay local shop $250 to do it.

Needed a few parts for the Ebay carbs. The choke needed some parts swapped out from original carbs but nothing serious. Total investment in new carbs was $25. Vents all looked clear, needles,jets, and bowls looked clean.

Bike now starts but will die if I either shut off the choke and/or let it idle below 2k (with choke on). Gas is dripping into the air fliter box. I assume because the choke is on full.

Smoke coming from the tail pipe smells like water vapor instead of exhust. Not sure if something else is wrong. Could water be in the bike from sitting for 20 years? Could be water in the fuel? Suggestions welcome.

Turn the fuel petcock to reserve, that should bypass any leaky diaphram issues and supply fuel to the carbs. Air bubbles in the fuel line don't mean much in relation to 'suction' from the carbs, the floatbowls are fed by gravity, turning the petcock to prime should solve any delivery problems to the carb for now. Manifold vacuum opening the petcock can be addressed later if it is a problem.

If it 'almost catches', it is firing, I assume. So you have spark and compression happening at approximately the correct time... that leaves fuel. It really sounds like your carbs are varnished up, your floatbowls aren't filling enough or some other carb problem. Looking at the guts of a carb won't really tell you if it is 'dirty'... it's not dirt your looking for, it is a clear coating of varnish reducing the diameter of the jet openings. A few thou of buildup inside an orifice of several thou will drastically affect fuel delivery. Compressed air won't remove it, neither will most carb cleaners the public can buy. You have to physically get inside the jets and clean it out, without scraping or scratching the jet orifice. Use a material that is softer thatn the brass that the jets are made of. Or find a shop with an ultrasonic cleaner and get the entire bank of carbs cleaned. Or replace the jets with new ones.

A compression test on an engine that hasn't run, especially in years, is useless IMHO, the more P.C. would say 'unreliable'. After you get it to run and put some heat into it, slosh some oil around the internals and loosen up the rings and slap the valves against the seats a bit, then a compression test can tell you something.

I would say you still have carb issues. Give them a proper cleaning and Goodluck, eh.

I'm a little confused about the last post from BuZzz. I am past the "almost catches" and onto getting to run without the choke. Was the post in reference to the original post or the update from today?

Sorry Man, I sorta zoned off on the first post and skimmed the update, so my bad. But I still think you have fuel delivery problems. The low speed or idle circuit is not giving up enough fuel to keep it running with the choke off. Maybe the floats are set too low and there is not enough fuel in the float bowls. Maybe the passages in the carb bodies are blocked, or the jets are wrong or something like that. I don't know what carbs your bike has (and I'm too lazy to look it up ) but they may have idle air screws you can adjust externally.