Now What..

[Anonymous]

Any time I read about an engine that performs differently under different external conditions -- temp, atmospheric pressure, humidity, etc -- I wonder about an intake leak. Especially when the idle isn't stable.

You say that you have CV's so there aren't any intake boot O-rings. I don't see any connection between the two. Most GS's with CV carbs use the same intake boot style -- with O-rings.

You also mention much earlier that you have tightened the 'induction boot clamps' adequately. That means you HAVE induction / intake boots to worry about.

Read this:

http://www.cycleorings.com/intake.html

This is my standard sermon. Humor me. If your 'induction boots' (good enough term as any) are shaped like this where they meet the cylinder head, then there are O-rings between them and the head, and they're almost guaranteed to leak & cause grief.

I don't sell these, and I'm not trying to be argumentative, but it would be a shame to exert this much effort (and $$$) while overlooking a really fundamental possible cause.

[KEITH KRAUSE]

Just to help you with the names of parts. The "needle jet" with a screen and clip as you describe, is actually called the float needle valve.
The plastic spacer(s) I mentioned go on the jet needle, a long tapered needle that goes up and down in the needle jet.

[Scud]

Hello Robert,

The intake manifold is a solid piece that sticks out from the engine, there is no seam it was molded righ tinto the engine so I know that there are no o-rings in that area, I lloked at your link and my engine does not have a part that bolts on that could be hiding the o-rings. The rubber boots simply attach the carbs to the engine and the airbox to the carbs. I wish I had those it would be the very thing I would replace!

Keith,

Thanks for the the vocabulary lesson, I did not mess with the spacers in the jet needle, in fact I did not even remove the needle from the housing at all, just pulled out the whole assembly before the dip.

My mechanic friend stopped by yesterday and spent at least three hours with the bike, his conclusion was that the idle circuit is not working properly or possibly at all. He thinks that the only thing keeping it running at all is the main jet and he ruled out the choke system, he was scratching his head (he is a car mechanic and small engine repair guy, he is used to working with single carb engines, but knows about multiple carb units). He wanted me to ask if the timing was to advanced would it be possible to get the carbs to run correctly?

We had the sychronizer attached and would start the engine, he would adjust the air screw and the engine would speed up and he would back it off so that it would maintain a 1,200 RPM idle, then move to number two carb and do the same thing. As soon as he got done with the number two carb the engine would race to 3,500 and then he had to back off on the idle adjuster so it would be back at 1,200, but then he had to recheck number one and number two carbs. Does this information help to possibly point to a potential problem?

It still will return to 1,200 RPM when revved to 3,000 but it will stay high when revved to 4,500-5,000, returning to 1,200, it stays at 4,500-5,000 for eight seconds then drops fast to 1,200.

Hmmmm..............

:-({|=

Scud

[KEITH KRAUSE]

You should always set the ignition timing correctly before carb tuning.
I'm not familiar with your ignition except I know it's electronic. Set the timing as your manual tells you to and check everything for correct operation.
This brings back an experience I once had with an old "Martek" ignition. I'm not saying yours is doing this, it's just an idea. The collar (with the magnet) that fits over the end of the crankshaft, had a set screw that came loose and my motor acted similar to yours. At times, it was spinning freely, seperate from the crankshaft. Obvious delay in the rpm's returning to normal after revving it. So as I said, check everything and set the timing if it's off.

[KEITH KRAUSE]

Oh, and about your carb screw question. You're talking about the mixture screw on each carb, correct? I hope the CV carb experts will correct me if I'm wrong, but I think they should be set for the highest idle you can achieve and then re-set the idle using the idle screwknob.
If so, with the motor warmed up, adjust 2 screws at a time (if this makes it easier to hear the rpm's), adjust all 4 for the highest idle possible and then set the idle with the idle screwknob.
You did do a good carb sinc', correct?

[Scud]

Keith,

I went out and checked the nut and it was secure, the one on the end of the crankshaft. I am not sure of the type of ignition but it has two springs behind a cover and two magnets opposite of each other, the srpings are intact and when I grip the spinner it turns slightly and the springs expand and return normally. Hope this makes sense???

I had the carbs synched yesterday and they are pulling 6 in. of mercury at 1,200 RPM, is this low? I could not remember what Earl said with regards to how much it should pull, at 1,200 RPM something between 8 and 10?? 6 inches is what my friends synchronizer measured, it is a good one!!! The carbtune II I purchased would not read at all at 1,200 RPM, when blipped it would read but once returned to idle no measurement.

Scud

[Scud]

One more thing, last night I took her for short (5 mile) ride, it pulled good and returned somewhat to idle quicker then she has, then this morning I went out to go for a lengthy ride and she would not start at all, gas was not reaching the combustion chamber, I had good spark but no fuel, plugs were dry. Then later this afternoon I thought I would 'try her again' and as soon as I hit the starter she fired up....your tellin me...huh??? I revved her to 4,000 RPM and she returned to normal idle of 1,200. I turned her off after trying this twice for a total running time of about 1 minute...did'nt want to push my luck. So I am feeling pretty good right now but am afraid to go and try again until tomorrow....I could use a good nights rest. Does this turn on a light bulb for anyone??

Sincerely

Confused

[KEITH KRAUSE]

I think you're OK with the sinc' levels, as long as you got them fairly level with each other. If you cranked the motor and did'nt get fuel in the cylinders, you may have a petcock problem or faulty vacuum line. You said the carbs are clean inside. This would'nt cause the sooty plugs and hanging idle though.
The 1980 petcocks are strange. They only have prime and on positions and no thumb lever. The factory manual says the motor must be cranked to initiate fuel flow, even in the prime position. Most other petcocks will flow just by turning their lever to prime and no motor cranking. If you continue to have a problem with it, you may have to re-build it. I would replace the vacuum line first unless you know it's new. Some cracks can be hard to see and a new piece of line is cheap.

[Scud]

I will look at the petcock today sometime, it appeared to be leaking slightly and this is a recent development. It has a sheen of wetness that has an oily appearance near the screw that turns it from prime to on.

Consider a new vacuum line purchased this morning, it appears fine but new has to be better.

Scud