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retro rider
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291 Posts
Discussion Starter · #1 ·
My daily rider KZ900 is in need of new rings. It has between 50k and 70k miles on the all origional engine. The compression was low when I bought it 20k miles ago. :mrgreen: Last fall I was adding oil once a week, now with it sitting longer in the winter it smokes bad when you first start it.

From what I have read IF I tear into it I sould do - rings, cam chain + guides, reseat the valves (valve job).

What is the ture minimum cost of this level of rebuild? I know there could be aditional costs if the cylinder is scored for example.
 

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you can probably get the head redone professionally for 350-400....the cam chain would be 45 bucks...the cam chain guides and rollers will put the big hurt on ya...all new would probably run you 300+....with your mileage , they are probably toast.....and then there is the jugs and pistons....cost can depend on how bad they are and what you can do yourself and what you might want to farm out.....
 

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My daily rider KZ900 is in need of new rings. It has between 50k and 70k miles on the all origional engine. The compression was low when I bought it 20k miles ago. :mrgreen: Last fall I was adding oil once a week, now with it sitting longer in the winter it smokes bad when you first start it.

From what I have read IF I tear into it I sould do - rings, cam chain + guides, reseat the valves (valve job).

What is the ture minimum cost of this level of rebuild? I know there could be aditional costs if the cylinder is scored for example.
I did a similar thing to one of my 1977 KZ1000A1's several years ago and was able to do a simple top-end refresh...rephrased, neither the head nor jugs had to go to a machine shop for additional work. I was able to lap the valves/seats myself and hone the cylinders (deglazed). I replaced all those cam chain bits, cam chain, rings, gaskets, etc, and the purchased the odd tool I didn't have...I bought virtually everything from a single vendor (Z1E...I know that is bad form on BKF)...keep in mind there was no cost for labor...I spent US$745.00. So, if there is serious motor work...then it starts adding up.
 

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Eddie Lawson is God!
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5,683 Posts
I may be talking out of my butt, but I'd bet my last buck that Jim wouldn't mind. (3/4 of that stuff has been discontinued by Mother K) He'd rather see that piece of history used and preserved than rotting in the back of someone's garage. ESPECIALLY if you sourced the parts from a real friend of vintage bikes like Jeff Saunders. Most bike shops consider old bikes as these a PITA, as their 17 year old countermen know NOTHING about them. And their 20 year old mechanics. Because you have to PAY the Vintage mechanics.
 

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Obfuscation Engineer
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6,706 Posts
I gave an estimate last year of $1400 give or take for , pistons , rings , valves , springs , keepers , retainers , cam chain and guides , clutch , countershaft bearing , subbing out the bore work and doing the guide and seat work myself . this did not include any of the little bits that you find wrong in the process . Try as I might I couldn't get the customer to send the crank to Falicon while it was out . Oh Well . His bike still to this day needs a real exhaust system , brakes , front fork seals , and steering head bearings .

"But I only paid $750 for it ..."

~kop
 

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retro rider
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291 Posts
Discussion Starter · #8 ·
"But I only paid $750 for it ..." ~kop
That's kind of my line of thought too... I got into Vintage for cheap transoprtation. I'm not the type who enjoys building the "spare no expense" engine. On the flip side, I will not ride it if it's smoking and clearly has issues. I have other bikes to ride.

I am thinking about swapping engines off my $50 parts bike. It has 18k miles on it , no title.

 

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That's kind of my line of thought too... I got into Vintage for cheap transoprtation. I'm not the type who enjoys building the "spare no expense" engine. On the flip side, I will not ride it if it's smoking and clearly has issues. I have other bikes to ride.

I am thinking about swapping engines off my $50 parts bike. It has 18k miles on it , no title.
Why don´t you take the head and cylinders of, hone the cylinders and install new rings, new valveseals and grind the valves? Check so everything looks ok. Even if it isn´t perfect you probably get a few more years out of the engine and it won´t cost you an arm and a leg.
For my GPz 750 new rings costs 30 $ for a set and valve seals costs 20 $ for all of them. A new headgasket is needed.

But if the engine in your partsbike is in good condition it is cheaper and simpler to swap the engine.
But for 200 $ you can change rings and valveseals if you do all the work yourself and have all the tools.
That´s what I plan to do and we then we will se how long the engine vill last.
 

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Biker Chef
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1,026 Posts
Do you know if it is the same thickness as the original? If it is possible to use the turbo headgasket I would be very happy because it is half the price for the turbo gasket compared to the non-turbo.

/Karl
From what I've read over at the GPz forum, a lot of guys use the turbo head gasket because it is more heavy duty than the normal Gpz 750 head gasket, at around the same price. I belive its the same thickness as the original, just beefed up. Makes sense to me, since the turbo makes about 112hp compared to 86 for the stock GPz 750. I'm sure you'll hear more from the guys here that are really in the know, like mfolks or copcicle.
 

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From what I've read over at the GPz forum, a lot of guys use the turbo head gasket because it is more heavy duty than the normal Gpz 750 head gasket, at around the same price. I belive its the same thickness as the original, just beefed up. Makes sense to me, since the turbo makes about 112hp compared to 86 for the stock GPz 750. I'm sure you'll hear more from the guys here that are really in the know, like mfolks or copcicle.
Sounds good to me, the turbo headgaskets are consideradble cheaper than the original in the places I found them. Even if I buy from my local dealer the price for a headgasket for a turbo is 50 $ instead for the 90 $ for the non-turbo Gpz750.
 
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