gs750 vs gs1100 carbs -how different are they?

[LarsKroghStea]

Hi,

I just bought myself a 1981 gs750e. The guy I bought it off sad the original carbs were "worn out" and that he had bought gs1100 carbs to replace them. He had taken the jets off the original carbs and put them on the 1100 carbs. I have the original carbs also, but they are missing the floatbowls. I'm going to do a carb rebuild. I'm not concerned with originality. Should I just go with the 1100 carbs, or is there any downside to this? I have Kerker 4-1 exhaust on the bike and I'm planning to go with pods ( no flame, please).

-Lars

[Steve]

First of all, the 750 uses BS32 carbs, the 1100 has BS34, so there will be a mis-match of sizes at the boot.

If you can manage to slide the larger carbs into the boots, they will have to be re-jetted for the smaller engine.

Not sure if the spacing on the carbs is different between the two engines.

.

[rudeman]

Pretty sure that 34s will bolt on in place of the 32s. I would give it try and rejet as needed.

[posplayr]

1100e's are routinely fitted with bs36 carbs where the bs34's were stock. There might be some small jetting change required but generally for pods and 4:1 the carb size change doesn't change the jetting to a level that I could speak to.

[JTGS850GL]

There is a small offset on the spacing along with the 2mm difference in the inlet size. They will only fit if the boots are relatively new and very pliable. If you try to use them on hard boots they may split in a short time. Some jetting changes will be required as well. You might also want to consider weather you're using BS34 carbs from a 2 valve 1100 or a 4 valve 1100 as the main air jets are different and will effect your over all jetting. The 4 valve engine carbs will have a 1.2mm main air jet while the 2 valve carbs will have a 1.7mm main air jet. The 1.7mm version will be the same as your BS32 carbs that came with the GS750 and my make it easier to find the correct jetting.

[LarsKroghStea]

Thanks for the info