Need piston expertise ..

hoosierkaw83 wrote: ...what are 29 smooths?....

Here's a link to some carb info furnished on the Z1 Enterprises website:
Click here > www.z1enterprises.com/Z1CarbGuide.aspx

The following is an excerpt from the text with regard to Mikuni 29mm smoothbore carbs:

Once power-hungry riders realized the potential of the Z1 engine, a large array of performance parts appeared on the scene. One of the most important of these was the Mikuni 29mm smoothbore carbs. The stock carbs did not adapt well to the increased fuel demands of high-lift cams and high-compression pistons, nor the back pressure changes of the barely flow restricted 4-1 exhaust systems. The 29mm smoothbore carb was by-and-large a cure for many tuning problems. The top of the carb is identical to the 26mm (and later KZ1000 28mm) carbs. The float bowl went back to using the 17mm drain plug directly under the main jet. Great for racers as it allowed for quick changes of the main jet. None of the VM29's have an overflow pipe fitted in the float bowl.
Note: some very early sets of 29mm smoothbore carbs have a float bowl with a small drain screw angled to the side.

Good Fortune!

I found the 29 smooths very easy to tune on the 750, I really can't say that I lost any bottom end with the combo but gained quite a bit of mid and top. Between the added compression of the pistons, .050 milled head and the cams being really not that agressive but none the less an improvement it worked quited well.

Here's a good read on the modifying of the 750.

members.tripod.com/gpz_rider/technical/FAQ2000.htm

Les

Les, the 82 750 head I have doesn't allow for that much milling - you'd be cutting into the valve seats pretty far at that point. Did the Gpz head have that much extra meat on it? I was under the assumption they were pretty much the same. The 650 head looks like it could be milled more if you left the stock valve sizes, but that puts limits on airflow.

There is a few different heads, I can't tell ya if the 82 to 83 is different, the turbos run what I would concider a 650 head modified, the 750 heads have at least 3 different heads but I can't tell ya what is what anymore. I do remember .050 put me close to the seats but here we are 20 years later and whos is to say what work was done on most of what we find today? I wouldn't have a propblem cutting into the seat provided you don't get the valve sealing area and don't take too much off. I found them to be very durable. I put a ton of spray thru this motor the second year using 2 different bottom ends. They will only take so much but the head always faired out well. That bike holds a soft spot with me and probably will reproduce it some day. I rode it for 3 years after my divorce and was my solice for a lot of pains back then. Stretched 5-7", rode like a lincoln, ran like a vette and looked like a well used, well, it was well used! Inch for Inch I like the 650/750 motor stuff better than the 900/1000 stuff. I believe it has a better head and it really is a durable piece!


Les