650 crank treatments

750 turbos are a special case as they have a secondary oiling circuit for the turbo. This puts an additional strain on a system which isn't that great to start with, and there is no difference between the 650 oil pump and the one on the turbo. They do have crank (and turbocharger) oiling problems, in fact my current streetbike was bought with the crank gone at just 23,000 miles. MrTurbo identified low oil pressure on individual bikes and issued a tech bulletin with some improvements which could be made.

When Harris raced a GPz750 in F1 they used a rev limit of 11,750, and a soft limit of 11,500. I have spun shells in my drag 750 revving it to 12,000 so I try to stay well below that. When we raced a 650/750 hybrid we also broke shims and buckets from overrevving it. I wouldn't attempt running one to 13,000rpm.

The other thing to consider with a dragbike is the oil pickup. My drag 750 ran 1.3 sixty foot times. This is in the zone (1.4 and quicker) for causing oil starvation from the oil surging to the back of the sump. People have used baffles, windows, gates etc to try to alleviate this problem over the years but the modern solution is a swinging pickup. No-one that I am aware of makes on for the 650/750 but it's something to keep an eye on, with a datalogger if possible (a wideband commander can do this as well as record the fuelling for the run).

I'm not aware of any material differences between the 650 and 750 cranks. My advice would be to keep the revs below 12K and use a good 20/50 mineral oil, like Kendall GT1. If you still have a problem, try to determine firstly if it is oil pressure related and if not then maybe crank treatment would be the way to go.

I have also been thinking of doing something like this with my bike next spring, for street and strip. I burned a piston, and was going to go to the 700cc kit until I found out about using the KZ750 jugs on the KZ650 base, and going with the 810 kit. (This is my first bike and all this stuff is new to me...) A turbo on top of the 810 kit sounds even better, but I have no idea of how to do it, and any help would be greatly appreciated. I have been reading a lot of posts, but I still dont know where to start, and have a lot of questions. Do I try and get a turbo from a GPz750 turbo? or just try and build my own setup with Mr Turbo (or similar brand) stuff? What about carbs? Do I use my 650 head/cams or something else? thx,
Scott

I built a KZ650 motor four years ago for road racing. It has custom pistons from JE 12:1. I would have to get the cam grind from notes for the web cams, but they were the biggest cam they suggested for road racing and the valve springs they recommended, good for up to 5000 revs over stock or 14,000 with hopefully no valve float. Tech services at Kawasaki put me in tough with a brit who worked on the factory race bikes. He told me to have the oiling holes on the crank opened up and elongated and micro polished. The bearings he had me cut a groove at 11:00 and 5:00 o'clock. I also shimmed the oil relief valve. I use Motul oil 20w-50w. I also ported the head and added 29mm smoothbores with a dyna 2000 with the limiter set at 13,000, and routinely go there. It has amazed everyone. It doesn't start to run until 9000.

I don't road race, just drag. but I will admitt, I've spun these little buggers whay up there in the past. This was back when extras was plentiful and could swap a bad bottom end for a good one out faster than one might think on a saturday night. Not talking just crank, took my jugs and head and swapped to unbroken lowers. As for cutting grooves in bearings, I'm just a little shy, no puns intended, but I remember the days of a full grove in small chevy cranks to keep them together and it wasn't the correct way. Tell me more, prepped crank, dead on clearences, ballanced to go 14,000, anything else. Those things alone would do wonders, I'm sure. Just don't want to be in this thing anymore than I have too. It doe's cost $ and time which is getting more valuable all the time.
Lorcan, I gaurentee I have more questions for you. Tearing off 1.3 60's, is this in street trim:blink: or drag settings:evil: ,either way, BAD TO GO!!!

Les if you decide to go the turbo route then you would be much better off starting with a GPz750 turbo engine (ZX750E1 or E2). Kawasaki reworked the whole engine for a turbo application, almost no part of the original 750 engine is unmodified in some way, from the head to the sump, so it's a better unit to start with.

My drag 750 had wheelie bars and a 7" slick to run 1.3s, my street one at stock length has only run 1.6s so far. The drag one was 760cc, ran on alcohol and ran 8.69 @ 162mph in June 2000.

My dad had a 650 back when they were new and used to drag it all the time. His used to automatically down shift from first to second at like 8500 if it wasn't shifted hard enough. when ever this happened it cracked shim buckets and fouled the spark plugs. funny thing is my lil 250 does the same thing, only it burns the points when that happens.

Hey gang-Here's my 2 cents worth on the 650 revving issue. I put a 700 Wiseco kit into my 650 last year. The motor had only 12,000 miles on it. I didn't touch the bottom end or cam chain but cleaned up the valve seats and ported the head. Put a pipe, pods and jetted the 24Mikunis.

The bike ran strong and really perked up from 5-10K rpm. I did spin it higher to 11K which buried the tach. I don't doubt the motor would have revved higher but I didn't want to risk grenading. I also found that the power levelled off at redline of 10k.

Higher revs equate to more power up to a certain limit then motors tend to taper off on the hp generating. If you don't believe me then Google some graphs of engine dynomometer testing and you will see that motor's power doesn't continue to climb at the same linear rate...forever. There is a limit.

Because of this I don't see the risk reward ratio of rying to wring maximum rpm out of a motor. Put the bike on a dyno and you might find that the extra 1-2000 rpm you are trying to attain is nothing but a higher risk, without higher power.

I'm sure my new 810 kit with the 750 top end 650 bottom end will pull strong enough at 10K rpm to keep me smiling. Anything past this level is territory I am not willing to explore with my wallet.

Cheers-Colin Firth-Ontario Canada

About the bearings: The babbit bearings have less drag on the rotating assemblies, because of the material it is made of. They are soft. So if you happen to spin one chances are it wont hurt the crank. Babbit bearings do not last long either. The tri metal are harder and can withstand heavy loads for extended periods. The down fall is that it has more drag on the crank and weight more. If you happen to spin a bearing it will scare the crank. Hope this helps.

To start off with, here is a definition of Babbitt:
www.answers.com/topic/babbitt-metal

I have just examined a GPz750 main bearing, and I can assure you it is not a pure babbit bearing, it is a layer of babitt over a shell appearing to be steel. I can't tell if it is a tri-metal bearing, and I'm not going to scratch the surface to find out (I intend to use the bearing).

I will take a look at a rod bearing later, but I am unaware of any pure babbitt bearings in use as a rod or main bearing shell in automotive use, I believe all are of bi-metal or tri-metal construction.

IIRC, the Model A Ford used pure babbitt bearings, but they were poured bearings and not bearing shells.

Rod and main bearings are not supposed to contact the crank directly, they are supposed to ride on a film of oil, so if the rod bearing is contacting the crank surface then there is a problem somewhere, and I'm still trying to figure out where the problem is.

It gets more complicated from here on, and my two typing fingers are tired (plus I have things to do).

many motors used babbit"poured" bearings right up to the 50s,babbit beaters they were called lots of chevy 6 cylinders 216s and olde used them.havent seen any newer motors that use a true babbit bearing,they use inserts or roller bearings. :whistle: