BST34SS on a 1000

[Fjbj40]

These carbs are off a 86 GSXR1100, just finished rebuilding, with stock jetting. The mains are 130, the same size as the mains in the VM33's I was running. I opened the idle mixture screw out 2.5 turns. Float height set at factory of 14mm's. Running K&N pods.

First she starts way better and idles off choke in about 30-40 seconds at 1000 rpm! Impressive as it would take 3-4 minutes with the 33 smoothbores and idle had to be about 1200-1300 for smoothness!

The engine at no load accelerates very smoothly and quickly, throttle action is very light compared to the 33's.

Took it out for a burn, pulls hard to about 4500 then stumbles and then pulls hard until I stop asking her too!

So I did a plug chop, should have put new plugs in as they were black from rich life with the 33's. Anyways from my reading of the 2 outboard plugs she is lean. The electrodes were no longer black but light grey with very minor frosting, so I suspect lean. This would explain the hard pulling plus the mid range lean stumble? Running BR8ES NGK's

I am going to need a Dynojet kit as there is no adjustments for the jet needle with the stock setup.

I am really surprised that it is lean as these are off an 86 gsxr1100 which makes something like 130 hp and I suspect my engine is only making 105-110, typical for the 1000 8 valve engine with my mods.

Any thoughts or suggestions?

Cheers,
Daryl

[blowerbike]

a friend had a set on his 79 GS1000.
st.3 jet kit and changed the head boots.
ran great all through the RPM range.
i do not remember of him changing it much if any from the instructions.
the needle is the secret.

oh,
in the states the 86 GSXR1100 made under 100hp at the rear wheel from the factory.

[Fjbj40]

Thanks for the reply. Theses are USA market carbs. I am running KZ1000-1100 boots.

You say 100hp at the wheel eh? Was the GS1000 hp back then stated at the wheel or crank? I suspect crank, so I think I am still making less hp? Maybe not as with the 33's this thing once above 5000 rpm is pretty impressive. It will lift the front under hard acceleration. It's just all the other 33's faults that make them not a great street carb. I think this bike had a racing life before.

Yes I think the needle adjustability will fix the lean situation I am encountering.

a friend had a set on his 79 GS1000.
st.3 jet kit and changed the head boots.
ran great all through the RPM range.
i do not remember of him changing it much if any from the instructions.
the needle is the secret.

oh,
in the states the 86 GSXR1100 made under 100hp at the rear wheel from the factory.

[blowerbike]

yes the adjustability but mostly the shape of the new needles do the trick.
the 86-88 US GSXR1100's was low weight low HP.
but...
just a full system and jet kit/advancer added 30HP give or take.
the exhaust was the killer.
i bet just that added 15HP.
i bought one new and the above changes made huge differences at the strip with the best of a 10.32@135..just what i mentioned...nothing else engine or chassis wise.