Problem with Downdraft Slingshot Carbs?

[Anonymous]

After having read many posts about the GSXR Slingshot carb mod for GSs, I obtained what I am pretty sure are some '92 Slingshot carbs for my '81 GS1100E. However, upon inspection, they appear to be downdraft carbs, with the bowls at about a 15 degree angle. Does anyone know if this will be problematic in terms of spilling fule into the cylinders, and does anyone have a solution? I would really appreciate some advice, before I wash out my cylinders and blow my engine. Thanks for any help.

Austin

[Carter Turk]

I'm running the 90 GSXR 11's (36mm) on an 1150 with no problems now. I too was concerned about the angle. I had to lean the float height considerably to get it to run right. I bought my carbs used, and I think they may have been fiddled with previously.

The dyno jet kit that came with the carbs had these super blunt looking needles and huge mains. I fouled about 24 plugs, four at a time, until I leaned the floats.

In the meantime, I bought a Factory jet kit and the needles looked totally different, slim and pointy. I tryed these and fouled half the plugs mentioned above. My emulsion tubes, where the needle slides into, may have been fiddled with also so I stuck with the Dynojet kit. I'm using 32 pilots and 147.5 mains with the needle 4 notches down. I had it a 3 for a long while, but was experiencing detonation in the lower rev range. This change solved that..

I would reccomend a jet kit and K&N filters. If the idle adjustment screw is on the bottom it might need to be shortened, but if on the side with the long cable, no worries. The throttle cable needs to be shortened or a GSXR used. I modified my stock throttle housing to accept the GSXR cable, as it has a different end. Carter

[Anonymous]

Carter,

Do you have your carbs tilted somehow (like tied up to the frame) to level out the float bowls, or did you just leave them straight, with the float bowls at an angle? What height did you set the floats at, and are you sure that there's no raw fuel seepage into the cylinders? Have you ever checked the intake boots after riding to make sure that there's no fuel seepage? Are your plugs the right color? I want to use these carbs, but I'm nervous about cylinder washout. Any other information from you or anyone else would be extremely useful. Thanks to all.

Austin

[Carter Turk]

Austin

I dont have them tilted, but I did fabricate a crude aluminum bracket to support the carbs to the frame. I mounted on the top of the inner carbs to the bar that supports the four carbs and connected to the two holes in the frame where the airbox used to mount.

The reason for the brackets is to support the weight without an airbox, but also maybe half a dozen times, I've started the bike and the negative back pressure or whatever its called, blew my carbs right off the boots. I also had three boots burst on startup.

Hopefully this is caused by the backpressure and not seepage.

My plugs tips almost look like they do when new, but inside the threads are darker. I actually think I'm running a little rich, but thats to cure the detonation on the 1229 with a little more compression than stock.

The floats are set at 17-18mm, almost as far as you can go. I had a shop do it as my hand dexterity is clumbsy.

When I've taken my carbs off, I noticed residual fuel on the ends of the boots, but I recall this with stock carbs too.

The power delivery is amazing, the pickup off the bottom, and the lightness of the twistgrip is addicting. Feels like a new engine.

One hot tip is to mount the cable to the carbs before installation, then route the cable through the frame. Try it the other way and you'll cussing and cursing. Carter

[Anonymous]

Thanks, Carter. I'll let you know how mine turn out.

Austin