750 E1 overhaul, tuning?

So the time has come, my bike has provided me so much pleasure, sounding great with her 4 KN pods and stripped 4-1 exhaust.

But she has gotten a major oil leak and a cracked head.
One of the studs that holds the exhaust has come out, by cracking the head, its weldable for sure.

But anyway the gasket between the cylinders and crankcase has given up and have a bad leak.
Also she vibrates so much that there is no use replacing the headlight bulb.

So on my list of stuff to be done.
1, fix the head / replace the head. + Vale job
2, remove the crank, get it checked out, also balanced.
3 new gaskets.

Make sure the engine is fine and dandy

But I am thinking of what i should do while Im in there.
Been thinking of lightening the crank.
If i had money i would make it a 810

But i wonder, about the head.
Is it worth it to get a used gpz750 head?
Whats the difference?

I have a set of mikunis o bought way back, that will fit, think the are of a suzuki, dont remember what they where, but they are similar to the keihins.

If i am not going to go for the 810 kit, thinking about milling the head to raise compression.
But dont know, at this moment.

Trying to formulate a plan.

I guess a lot has been done to this engines already, and would like some tips to whats worth doing and whats not.
Have a great day

You can't mill off more than a few thousands from the head without hitting the valve seats so cross that off the list of things to do.

The 750 engine is a very smooth operator, other than at high rpm's. Balancing will do next to nothing to improve that situation. If your engine is vibrating excessively, something is wrong with it.

Lightening the crank won't do much of anything either, other than lighten your wallet.

A big bore kit will add torque and is a worthy addition. I'd focus there if you want more performance.

Do some searching for 810 kits on 650s and read the drag strip trip on the racing section from start to finish..... tons of info and diff combo's on here...... like said you need to get the vibration thing figured out before you throw a ton of money on it. I always thought about the lightened crank but cheap'd out and got the 700 kit and didn't split the cases. It knocks off 4 and a half lbs and is supose to give you a snappier throttle but it might be a trade off since you lose a little around town on taking off easy...... talk to Jay at APE or Cavanaugh racing about it once you decide how far you wanta go and see if its right for you.

Yeah the vibrations are why I will split the cases.
Its kinda extreme, at WOT forget about seeing anything in the rear view mirror.
Bulbs designed for heavy vibrations lasts mere hours and she is NOT overcharging.

According to a guy i ride with at times, when i pull hard through the gears she lets out a puff of blue smoke on every gear change.
Im thinking rings.

But all will become evident when i pull her apart.
Thinking replacing bearings, chains, hone the cylinders and at least a set of new rings if i dont go down the 810 route.

I think i will just pull her apart and she whats needs to be done, and listen to her

Will of course take a load of pictures and post here

IM BACK!

Life kinda happened and a stormy year landed me broke and back in school.
Since then ive been studying and since i study maritime engineering most money are burnt on beer
And i havent got a workshop here to work on her.

But now i am graduating soon, and i can finaly get back to my babies
Missed my 750 like crazy.,

Life is going to change, already landed myself a job on a small oiltanker and finaly ill have both money and spare time.

So project has been updated.

I got so far that i where able to split the cases, nothing to report so far since i dint have money to buy a micronometer or a source of plastigauge.

But i found out that all the bolts are beaten to shite and the screws are rounded.
Someone has been in my baby before....

So i need to buy a kit of new fasteners, I need to check the non roller bearings with plastiguage, have a feeling that they are fine.
All rollerbearings will be replaced.

I have found one major problem thou but still not the cause since i didnt tear down the head as of yet.

BUT i think this could actually be the main problem, the valve clearance on No.4 intake has gone to 0 and since the others that where adjusted at the same time are okay i guess something has happened there, Guessing burnt valve and seat but i need to tear down the head to be sure.

Since i do suspect that the head probably is more trouble to fix than its worth Im keeping an eye on fleabay for a used one from a gpz.

Now for the fun part and the main reason im back.

Since ill have both a lot more spare time, and a better income once i graduate ill do some more to her .

So im pretty sure what im gonna do now. feel free to help me out with tips on what more I can do "while im in there"

Im going down the 810 route, and probably going for an EFI setup, but i want more
So i guess GPZ head and some better cams are the next step anyway?

Many years ago when in the Navy I lived on a small oiler (YO-179) on Okinawa for 18 months. Ed

Thanks for your service 650ed! Di you stay on board the whole time or did you get off for good behavior now and then.

Rick H.

A gpz head will gain you nothing other than cooling fins that cosmetically don’t match the fins on your kz barrels. 83-86 gpz cams and pistons are what you really need. And then, the gpz cams will shim out better once you get a valve job done on your current kz head as the gpz exhaust cams have a smaller base circle.
Plus, your current kz750e head has a smaller combustion chamber than any of the gpz heads, so you won’t be losing any points in compression.

Food for thought....

Rick H. wrote: Thanks for your service 650ed! Did you stay on board the whole time or did you get off for good behavior now and then.

Rick H.

One or two guys had houses they rented off base, but I lived on the boat. The crew was only 6 guys + or - 1 as folks were assigned elsewhere or were discharged. I did visit much of Okinawa while there, but Okinawa is a pretty small island. Back then (1969-1970) things on Okinawa were very inexpensive, but now everything is much more expensive there since Okinawa reverted back to Japan. I think the Japanese now consider it a vacation spot. Personally I think there may be better places to take vacations since there are deadly poisonous sea snakes in the ocean and poisonous Habu snakes on land. Ed

Well sorry for dropping out again, got into another mess that broke me apart badly, but thank god that nightmare is over.
I will not bore you with the details but, just lets rest at (Never, i say NEVER put your dick in crazy!)

Anyhow, life is finaly going right, and Im saving up to continue my project, She must be ready for summer

If i can salvage my old head (still not taken it apart) i will.
Going for the 810 kit, some mikuni BS34s (already on the shelf)

I think ill undercut the gears as well (well its not exactly the gears but i dont actually know the words for it, help me out )

Running Pod filters already, but i have a vauge recolextion that there was a FIX for getting the mikuni BS34 running good with pod filters, it had something to do with the airjet i think but i cant for the life of me remember where i saw this.

Would love to get some pointers, and a starting point for jetting since they are from a completly different bike.

I am thankfull for all the help btw

And thank you for your service 650Ed.