GS1000GT behaviour a result of over rich low speed circuit?

[bobasoozoo]

GS1000GT behaviour a result of over rich low speed circuit?

I'm new to this so don't have any experience for comparison.

She starts good.
She idles nicely.
If not fully warm she stumbles when throttle is opened and closed quickly the exhaust pops a little. Open = about 1/4 throttle.

Once warm she doesn't stumble if I open the throttle slowly with no load. In first gear she stumbles just a little. She still pops but not as much.

If I open the throttle all the way, quickly, she stumbles for a split second and if in first the front end lifts up and she's off like a rocket. Same when shifting to second.

Before I got her, she hadn't been on the road since about 1993. Here's what I did:

Went through the carbs and cleaned all passages.
and replaced nasty jets and float valves.

In the low speed circuit the pilot jet is 200 and the pilot air jet is 40. The manual calls for 180-40. The main jet is 115 as per the manual. These are stamped, not measured numbers.

Floats are all set to 22.5mm within about 0.2mm

Carb boots are not leaking. Airbox may leak a tad but not much. One start boot is a little cracked but problem seems to be across all four jugs.

I made a new air filter element out of open cell foam with about the same cell size as the OEM which was gmmed up. This saved $26 and a weeks wait.

I replaced the rat chewed high tension ignition wires and the boots.

The two pilot screws that were not glued in place are set at 2 1/2 turns out.

I'm thinking she might be running a little rich at low speed settings. Spark is good so probably carbs. I do smell a faint odor of unburned fuel in the exhaust at idle and low speed and it's about the same from both pipes.

What I don't know is whether over rich low speed setting would account for the symptoms? I would really like to know in order to decide where to go next.

If it does, then I wonder if I should just get some pods and larger main jets rather than dealing with glued pilot screws and swapping around pilot air and pilot jets. I'm pretty patient and rather enjoy fixing things, but the airbox seems real good at sucking the fun out, everytime it has to go back in.

Would rich mixture alone be enough to cause the exhaust popping? The only other thing I can think of to account is that the exhaust valves not seating well or a good bit of crap in the combustion chamers that's coming out and setting off the unburned fuel.

[Rock]

Re: GS1000GT behaviour a result of over rich low speed circu

I made a new air filter element out of open cell foam with about the same cell size as the OEM which was gmmed up. This saved $26 and a weeks wait.

Just a thought, but the foam may look the same but may not let air flow any where near the same rate as a stock filter. Which would definitely affect the mix. All foam is not the same even it it looks to be.

[bobasoozoo]

Thanks but thought of this. The new foam breathes as well as or better than the old. Besides, she is only running rich at idle and low speed settings. I'll try to find some time to write this up with photos and foam source-adhesive info once I've got thre bike running the way she should.

It jsut dawned on me that this thing has a mechanical advance governor for the ignition timing and that the weights may be sticking. This would contribute significantly to the crappy acceleration up to 4000-5000 RPM range.

So, I may have two things going on.

Should have time to spend a day in the shop toward weeks end. Will check advance, observe change, and then pursue over-rich problem.

[KEITH KRAUSE]

I'm also skeptical of the home made filter. I can only suggest you order a replacement. These home fix its generally cause more trouble than they save. You simply can't look at the foam and say it's close enough. The jetting may be very difficult to set with this mod'. Some mod's have a greater effect on a certain jetting circuit and you may not be able to tell.
I'm not sure about the two mixture screws you say that weren't "glued"? You mean the factory sealant was missing? If so, that's no problem.
I do believe 2 1/2 turns out is too rich for a stock intake (filter lid on too).
Try 2 turns out.
If the pilot jets are larger than stock, there has to be a reason for it. If no apparent reason, re-install the stock ones.
Be sure the two float bowl vent lines are clear and open.
After checking the timing/advance action, then I'd vacuum synch the carbs. Test.