33mm smoothbores work on 79gs1000?

[79gs1000l]

Don you are a genius
WOW!! Major difference, but not yet perfect. the engine still stutors a bit in the mid and high range when cold. When it is warm I can now go through the entire rpm range smoothly and it is smooth at full throttle.(which is a HUGE improvement over the past setup) however if i roll on the throttle too quick it stutors and if i am below 4000 rpm and nail it it will big down, and it still isn't too happy at constant throttle but definately better. I still have one more notch I could raise the needle. should I raise it? should I go with smaller needles? what about my main, should I raise that too? It runs so much better than two days ago. it really pulls well everywhere. when it isn't stuturin.

 

[Don Lobacz]

Try the 135 mains first, then if the stuttering is still there, raise the needle one more notch. If it runs great but starts fouling plugs, go back to the 130 mains. This is just shooting in the dark without plug checks, but it's your time of trial and error, so it's a good way to learn. Synchronization is still needed.

 

[79gs1000l]

I left the needles where I had raised them. the 130 made the plugs so black they stopped working, so I put back in the 115's and it ran very nice. it actually pulled the front wheel up for the first time, which was very fun i must say. a good improvement in power, but they also made the plugs very black. so now i am going to put in 110's to see how they work. Is there anything else besides the main jet that would affect how rich the mixture is. the 115's turned them solid black in 2 days. could it be anything else?

 

[Hap Call]

I run 33mm Mikuni smoothbores on my GS1100E and they work great. I will check my jet sizes to give you some kind of reference.

Hap

 

[79gs1000l]

Thanks Hap, I'd really appreciate it.

 

[saaz]

Just one tghing to remember with big slide carbs on a relatively standard motor..opening the throttle too much at lower revs will bog it down as the air speed drops through the carbs (as opposed to CVs which do the job for you). You can expect some bogging down at lower revs/high throttle applications.

Otherwise, looks like you are on the right track. gets the mains right first, then needles, then idle circuit. The idle circuit/slide cutout/needles do interact a bit to give a smooth transition from idle as you open the throttle. Getting the right idle jet makes a big difference to driveability.

 

[79gs1000l]

Thanks saaz, that makes sense about the bogging problem i have had at lower rpm. Right now I have 110 mains in and i think it is a little lean. when I get on it the engine will stutor, at which time I choke it and the extra fuel helps it out, so I am going to try something in between 110 and 115. Now the 115 was a large head main. the daimeter of the head was over twice the diameter of the threads. the 110 is a small head in that the entire main is the diameter of the threads. Does this difference matter at all?

 

[79gs1000l]

I am a little stumped on this. I had in the 110's and it was running lean for three days. the plugs were white and as i said choking it actually helped. But yesterday I rode with my wife on back. Now when I ride alone i go much faster and accelerate much more rapidly then when she is on back. with her on back, the most throttle it gets is maybe 1/4 tops. and last night the bike ran funny and i pulled out the plugs and sure enough they were black. Is it possible it is getting to much gas at low throttle operation. I have my needles raised almost as high as they will go. I can go 1 notch higher. is this letting in too much gas at low throttle. So with the 110's i am way rich below half throttle, and lean above. Would it be a good idea to lower the needles (raise the clips) and increase main size? or is there another possibility i am not considering?

 

[saaz]

You sure can run too rich on the needles and too lean on the mains. Lifting the needles up (ie putting the clip in a lower groove) richens the mixture.

It sounds like you need to get the mains right first, then the needles. All the mikuni jets I have and have tried are smaller head.

What you are suggeting is right. Richen the main a bit, then get the needles right. make sure you are not getting false readings on the mains, as a bigger main may also lead to slightly richer midrange, blackening the plugs as you go through the midrange. A good hig rev high load run for 30 secs or so should be ok. If the 110s are definitely lean, I would have thought 115s would not be that rich to blacken the plugs, but it could be sensitive. 112.5 should get you close! Lower the needles, and..there you go!

Good luck!!

 

[79gs1000l]

Thanks saaz if it doesn't snow I'll give a shot this weekend.

 

[saaz]

Oh ye, I forgot about that snow thing..it is mid summer here!!!

 

[79gs1000l]

Don't I wish it was here!!

 

[Gilmoses]

Oh ye, I forgot about that snow thing..it is mid summer here!!!

. . . . . . .Please don't rub it in

 

[79gs1000l]

Do I need new spark plugs to get an accurate reading of the mixture or can i just clean the old ones?

 

[Dink]

just clean the old ones.
Dink

 

[Anonymous]

Don is correct when he suggested a 130 to 135 main a #110 is way to small for that size carb with an 8 valve motor you need a small pilot jet like a #15 or 17.5 if you have a #25 or 30 this would turn your plug black to where it would give you a false reading on you plug unles you where to run wide open for about 2 or 3 miles shut it off coast to a stop a check the plug try these settings
135 main needle clip in the middle notch and a #15 pilot with the air screw at 1 1/2 turns out

 

[saaz]

135 main needle clip in the middle notch and a #15 pilot with the air screw at 1 1/2 turns out

That would have been my guess as a starting point. You have to make sure you do a true main jet test as low and mid range jetting may mask the results.

 

[79gs1000l]

Well i cleaned the old plugs and went out and did the high rpm, high throttle load for a few miles. i first did it with the 115's, plugs came out white. did the same with 125's still came out white. today i will try the 135 mains and see what that gives me. I will check the pilot jet to see the size, thanks for the advice on the correct size. now when you say "air screw" turned out 1 1/2 turns, is that the screw that you can adjust on the outside of the carb. very close to the airfilters. and to turn it out 1.5 turns woud I just tighten it all the way and then turn it out 1.5 turns? sorry about my lack of knowledge. this is all new to me. but so fun.

 

[lhanscom]

Yes turn it all the way in, then out 1.5 turns, but be gentle when turning it in so you don't damage it. Good luck.

 

[saaz]

Yes, it can be fun, but feels better when you stop doing it!!!!