VM carbs on a 76 Gt750

[elbert]

Iæm a bit disapointed with the trottle response on my GT750, so I've been thinking about replacing the CV carbs with VM carbs from an early model. Anyone have any experience with this "mod" I'm planning to keep the rest of the engine stock.

[oldjapanesebikes]

There will be several folks who have done this conversion jumping in with good information, but first - if you have a stock exhaust system then have you given thought to cleaning it out well ? And that you are sure everything else is set up correctly ? The amount of crud and deposit in 30+ year old original Buffalo pipes can be amazing and it will impact performance.

[tz375]

Ian makes a good point. Slide carbs generally respond faster than CV types if they are set up correctly and flat slides are even better.

But stock exhausts are sluggish and clogged exhausts are worse and an engine with poor seals or low compression will be even more sluggish.

If the rest of the motor is in great condition and the pipes are clean, then it might be time for a change.

I think that Lane changed his pipes for jemcos and kept stock carbs and later on swapped to VM34s, so he's probably the best guy to talk to.

[elbert]

The engine should be in good condition, starts very easily and pull like a train. But compared to my 350 the trottle respose is very slow.
I will have a look at the exhausts though just in case...

[Wayne Meuir]

Elbert, what kind of bike is yur 350? If it is a twin cylinder or even as S2 Kawasaki Triple, they are going to rev much faster than a GT750 because of the weight of the rotating mass of the crank.

My GT with CV carbs does not seem to lack throttle response, and it pulls hard from idle, it just does not have the snappy performance of lighter, shorter stroke engines.

Wayne

[rngdng]

With VM carbs, a GT750 can do power wheelies. With the CVs, fugetaboutit.


Lane

[Buffalo-guy]

Elbert:
If you are retaining the rest of the bike as stock, then you would do well to just acquire a set if the earlier 32 mm VM carbs from either a 72 or 73 model buffalo. They do work better than the CVs. A little fiddling is involved, but nothing too complicated. The early spigot mount rubber manifolds is required, as well as the appropriate throttle cable, and choke cable w/ lever. You will need to fabricate a mount for the oil pump actuating cable, and acquire an early pump lever to make the two work together. All the stock jetting from the early carbs works just fine on the later engines, and you may even notice an improvement in fuel economy, and definitely an improvement in response and a bit of power. The specs may say that the CV's are 40 mm, but if you look closely down their throat, you will see something much less, and more restrictive. Even the stock airbox can be retained with some appropriate automotive hose as connectors. Everything comes out looking very stock to the untrained eye, and I suspect you will be pleased with the results. Good luck, and cheers.
Fred

[Wayne Meuir]

Lane, didn't you mean to say a Buffalo with 38mm VM's, a bunch of port work, 3into3 chambers, and a plate under the cylinders to raise the ports, and about 50 lbs of accessory stuff removed, and a 145 lb rider will power wheelie?

Wayne

[rngdng]

Lane, didn't you mean to say a Buffalo with 38mm VM's, a bunch of port work, 3into3 chambers, and a plate under the cylinders to raise the ports, and about 50 lbs of accessory stuff removed, and a 145 lb rider will power wheelie?

Wayne

Not at all. First of all, Blueboy only has 34s! I rode Ed Zunz's 72 model which happens to have a 75 engine on it, but the original 72 carbs and pipes. It power-wheelies very easily in first gear.

Besides, I weigh 160 right now....I'm really fat.


Lane