Interchangeability of carbs and carb rubbers for oil-cooled engines

[Dezza]

If the carbs are indeed the bst 38s from a 1990 750 (L) and you have the appropriate rubbers, they should go on the engine. A 1987 750 is a slabby, and the bst 38s are a physically large carb but I do not know if this engine, frame, carb combo will work as a bolt on. Something may be fouling preventing the carbs from going on.

Do you have the original carbs and rubbers? You can then check to ensure that the new carbs have the same spacing as the old ones (if not carbs are from a W with different spacing) and/or the rubbers result in an incorrect spacing when mounted on the engine (rubbers from a W???).

Basically, check that you haven't ended up with the bST38s from a 750W. Many breakers fail to describe these carbs properly (I wonder why...) resulting in people ending up with a nice set of big CV carbs that won't fit their oilcooled engine.

Also, check that the rubbers are mounted correctly: 1-4, left to right sitting on the bike.

[Upshotknothole]

23 minutes ago, Dezza said:

If the carbs are indeed the bst 38s from a 1990 750 (L) and you have the appropriate rubbers, they should go on the engine. A 1987 750 is a slabby, and the bst 38s are a physically large carb but I do not know if this engine, frame, carb combo will work as a bolt on. Something may be fouling preventing the carbs from going on.

Do you have the original carbs and rubbers? You can then check to ensure that the new carbs have the same spacing as the old ones (if not carbs are from a W with different spacing) and/or the rubbers result in an incorrect spacing when mounted on the engine (rubbers from a W???).

Basically, check that you haven't ended up with the bST38s from a 750W. Many breakers fail to describe these carbs properly (I wonder why...) resulting in people ending up with a nice set of big CV carbs that won't fit their oilcooled engine.

Also, check that the rubbers are mounted correctly: 1-4, left to right sitting on the bike.

If the intakes are right, it should all work. But, like you said, the BST38s are big carbs, second largest that you could get in an oil cooled engine. The thing that has me wondering is they said they got new intake boots, and Suzuki discontinued them a while ago. Guessing they maybe got some of the Chinese intakes that are all over Eblag and don't include the right parts.

Just had a look on Eblag and they're listing the knockoff GSXR intakes for 89-90 750s now, which doesn't make any sense to me at all. Different engines and different carbs between 89 and 90. BST38s aren't even close to fitting 88-89 intakes either.

[clivegto]

38 and 40 mm carbs use the same intake rubbers, the 89 Chinese dot head rubbers won't fit. 

Edited January 29 by clivegto

[Wagola]

3 hours ago, jmartin said:

im trying to fit some sling shot carbs on an 87 750 is this possible bought new set of intake boots but wont line up donner carbs are from 90 750 

Looks like you've got some reading to do. I bet the info is on here somewhere. Maybe in this post !