GS650 carb fun

[Guest]

Yo team!

Got an 82 gs650, pair of KN filters, and a non standard exhaust (4 into 2)

It starts, idles ok, but only with the choke, won't do much on the standard needles yet, and climbs down the revs very slowly, and has a few pops in the exhaust now and again.

Idle jets are 2 turns out right now.
Going to fit a stage 3 dyno jet kit
Will be checking the gas seal between the manifold (call these boots?) and the engine.
Floats were set with a vernier when the carbs were cleaned and reassembled.

Any other recommendations?
Why would the revs climb down slowly, any ideas?
What do the back fires indicate (too rich?)
Why do you guys think it only idles well with the choke?

Cheers dudes

[BigD_83]

Curious...you say a PAIR of KN filters....what does that look like?

It sounds like an air leak, based on the hanging idle and popping, so yes, check those o-rings at the head, as well as the seal on the filters.

2 turns out, although more than the 1 1/2 set at factory, is probably still not enough to enrichen the circuit at idle, so you need to use the enrichener. You might also find that if you can baby it through the low rpms, that it will run fine in the mid-high range, as it comes on to the needle.

Another possibility lies in the cleaning procedure used. If the choke passages are still blocked up, that might present as the problem described.

The backfiring, is it through the carbs and airbox, or in the exhaust? Backfiring could be caused by valve issues (not fully sealing) or unburnt fuel making it through to the exhaust pipe (poor/weak spark, low compression, etc)

[Steve]

The answer to basically ALL of your questions is " LEAN ".

Your mixture screws probably need to be out just a bit more.

Your intake boot o-rings are probably shot, needing replacement.
You should have gotten those along with a full set of o-rings for the carbs from cycleorings.com.

Good call on the DJ kit. You will likely need Stage 3.

Did you set the floats from the BOTTOM of the step?
And did you set them to 22.4mm?

.

[tom203]

Why would the revs climb down slowly, any ideas?
--airleak at carb boot /head interface
What do the back fires indicate (too rich?)
-- idle circuit plugged-causing lean out,especially on closed throttle
Why do you guys think it only idles well with the choke?
-- idle circuits plugged- not enough mixture to keep things going,

[Oliverstrother]

So far so good.

A few questions so here's a couple of answers.

Carbs cleaned good a proper. All galleries and passages clear etc.

A pair of KNs .. Google RC-2383. One filter fits over 2 carb intakes. They're sweet. (I also have a spare pair going at a reasonable price!)

Pops heard are in the exhaust, I always thought this was in unburnt fuel. I hope the stage 3 dyno helps cure this one.

Yes 22.4mm rings a bell. I followed a guide. And yet it was to to the bottom of the step. (The step at the split between carb and bowl)


General consensus is to:
Richen the mix (turn the idle screws out)
Check the 'O' rings
Fit the jet kit

I'm keen to hear any more tips.

What size 'O' rings go in? Anyone know of the top of their head?

Ollie.

[Oliverstrother]

I mean RC-2382!!!

[tom203]

For o-rings go here and look for boot o-rings

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

Interesting filters- good luck, good thing you're getting stage3 kit

Popping in exhaust could also be one cylinder fouled and not firing- unburned stuff meets up with hot gas. Check #2 plug if you got a vacuum petcock still -mine did this at idle when the petcock failed

[Oliverstrother]

Will do,

How can the petcock affect cylinder 2? Does the diaphragm inside the pet cock fail and you pull in gasoline?

[tom203]

Yeah, the diaphragm fails and leaks fuel down vacuum line into #2 - in my case it was a small leak.

[Oliverstrother]

Pilots out 3.5 turns now. Idles smoothly once warm.

Also driveable on the needles.

Jet kits arrive tomo.
Not checks the O rings yet.