Carb tuning

[Simonak3000]

Soo last spring I got my 1982 GS650GL working good and I used it all summer. Now that its winterised im looking to fix little problem. When I got it, the last owner put one air filter per carb instead if the original airbox and single filter. Because the bike was now drowning with too much air the owner gave up and sold it to me. On my part I solved the problem by upjetting my main and pilot jets 2 sizes. That fixed the problem on mid to high RPM and I was ok for the season. Now I want it running good without putting the original airbox in. I know I have to play with 2 things: 1) Idle mixture and 2) needle height. Thats where I need help.

By how much should I raise my needles and how to I precicely set my idle mixture? Thanks for the help again!

(pic of the new single filter per carb)
air filter.jpg

L.Leblanc
1982 GS650GL

[tom203]

Sadly, the stock needle was designed/shaped to run nicely with the 110 main and stock air box setup ...this gave a nice transition in the idle to mid range area while keeping the epa folks sorta happy.
Consider a dynojet kit if you want to keep the individual pods....this comes with differently shaped needles designed for your setup - might save you some tuning grief.

[Tom R]

Check that those pods don’t block any of the air passages on the carbs. If you must stick with the pods, people in the know will tell you to avoid those cheap ones and go with K&N or Ape pods. Then they might tell you that you should by a Dynojet kit.... and a 4-1 exhaust. I personally believe the stock air box and jetting is what I’d want for that bike.

http://factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

The first step is to make sure they’re clean so your not working with a clogged pilot circuit port, which is common.
There’s a cleaning/ rebuild tutorial on here somewhere.
If the carb holders are original, they’re probably hard and prone to vacuum leaks.

[Simonak3000]

But the kit expect me to drill my carbs, I don't think im ready to do that, no way I can just buy some new needles or raise the one I already have? If its too much trouble ill put the stock airbox back in, Im not looking for super extra power anyway

[Tom R]

It’d be hard to find the needles outside the kit.... you can raise the needle you have. You just have to remove the spacer on top of the needle clip, and replace it with a thinner stack of washers. Unless you’ve done other performance mods, you’re unlikely to see much, if any benefit switching to pods. It’s a look, and it makes taking the carbs on and off easier, but you’ll have to take them off several times before you get the jetting right, if ever. It’s hard without a dyno.

[Simonak3000]

Ok, Ive taken the decision to put back the original main and pilots jets. Only thing, I need the air filter support, the plastic thing inside the airbox to put the filter on. For some reason, I dont have it. Also I need the metal rings for the 4 rubber air tubes but thats ok they aren't expensive. Do you know somewhere I can get the filter plastic support?