67 GT Performance

I live out in LA, CA and I recently bought a 67 GT #VNL2M 55239 W/ a Polini 177 cylinder. I want this thing to haul ass, and Im wondering what kind of mods I can do to increase performance, as an all around bike good accleration and top speed. Ive seen the SIP catalouge and dont know where to begin. If someone could give me some advice on some early upgrades Id appreciate it.

I was also wondering if any parts from another model would fit on my GT

[ Message edited by unleaded91 on 26.03.2002 ]

[ Message edited by unleaded91 on 26.03.2002 ]

All most anything that is made for the PX125 egine will work on the GT especially if it already has the Polini on it. I would have though that the 67 GT would only be a 2 port though as opposed to the later GTR which had 3. I`m not up on the V numbers (why do Americans always know these??) but maybe it has a later model engine in order for the polini to work properly.

The next step would have to be the exhaust. You could try the Polini one which apparently works well with the cylinder kit but it may get in the way off the stand. A side stand may be in order.

From memory there isnt enough metal there to grind it away, but Ive never tried it. Your Polini kit wont be working to its full potential without it though as it`s designed for the 3 port.

Can`t really suggest anything apart from if you did manage to get your hand on a crapped out GTR or Sprint V. engine (or just casings) all the parts will fit the 3 port casing.

What sort size carb have you got? It should have at least a 20mm. (I don`t think that the GT had one of these originally).

Thanks for the info dirk. I looked at the engine and it has two ports is it possible to grind away the metal for the thrird port, if so where would I be able to find the specifications.

Does Sip make a full circle crank that would fit on my GT (is it from the PX)? I have the engine apart and I want to change it to a reed valve.

Im doing some experamenting to my case. For the third port I had the surrounding area built up. I then milled out the port, and then had the surfaces machined. It looks real good and fits tight. My carb is a Dellorto SI-20-17D (Im not sure what size it is or what the numbers stand for.

Sorry to mislead but thinking about it more the PX ignition will also require a PX crank…but I`m sure that Bajaj make an electronic ignition that fits straight on. The Cheetak and the Super have engines based on the Sprint/GT/TS/Super mold.

As far as the carb goes though it sounds like you have the original 17mm. Try to get at least a 20mm (20-20D) or a 24mm from a PX 200 if possible.