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Kawboy's restoration/conversion of a 1980 KZ13 6 years 6 months ago #17489

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StanG wrote:

The company who supplied your intake valves in Germany also offered a complete set of valves for $263 U.S.


Yes, I know. Kind of regretting not getting the whole set instead of getting just those two Vesrah exhaust valves separate. Basically 5 of my exhaust valves are fine, so I was just trying to save funds for endless list of other things... Will see how they look and what happens. Good thing is those German sourced valves are available.

Are original seats still available? The valve guides are, just in case.

Probably all of my seats need some light machining. I feel a bit scared now, haha One shop specializes in motorcycles here and has a great reputation but big dollars. Another also very good reputation, cheaper, but majority of their work is all sorts of car and truck engines. I'd do it by hand if I could source the right set of valve seat cutters.

It seems like you have a real big custom job on your hands, to custom fit each valve.. I wish you success and hope to see a couple of photos!


Replacement seats are easy enough to source aftermarket. any machine shop has access to them.

Neway make a great set of seat cutters. They can be driven with a hand tool or a power driver. If you're just cleaning up a set of seats, doing them by hand is the way to go. Just make sure you use a cutting fluid to keep the carbide cutters clear of swarf. I had a set of cutters but they went a stray. Will have to buy another set. You can tool up to do the KZ heads for around $300 with the Neway cutters. Readily available on Ebay. The 1-1/4" series of cutters should do both the 29.5mm and the 34mm seats. I would buy a 30deg 45 deg multi cutter and a single 60 deg cutter

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Kawboy's restoration/conversion of a 1980 KZ13 6 years 6 months ago #17490

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Thank you for the info! The technical details are so important - choosing the right tool. I will look around on the internet for the right elements.
The price of the tool set which you mentioned would be the same as the price of the tools, but I would get to keep the tools! :) Perhaps worth a try. The shop will still need to resurface the cylinder head.

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Kawboy's restoration/conversion of a 1980 KZ13 6 years 6 months ago #17491

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Just a quick follow up, before it will look like I am hijacking your thread, haha
They say in manual you need four cutters: a 45, 30, and two 75 degree cutters - one for intake and one for exhaust. I am still not sure what will I do.

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Kawboy's restoration/conversion of a 1980 KZ13 6 years 6 months ago #17492

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Yes , if you go with the 75 deg cutter you will need 2 different diameters. It's because the angle is so steep that the inner diameter and outer diameter are so close to the same that they won't cover both diameters of the intake and exhaust. Going with the 60 degree and you can get one cutter to do both sizes. One could alway just blend in the last corner down below with a grindstone (minor porting)

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Kawboy's restoration/conversion of a 1980 KZ13 6 years 6 months ago #17493

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I see. All this makes me want to buy all sorts of tools and do everything myself! It's like a domino effect on the other hand. One purchase triggers other two needed... I just bead blasted the exhaust collectors. A 50 km trip one way to another town to DIY, plus of course the rental cost. Very happy with the result. Went to purchase high heat resistant paint and voila, you need to bake them after spraying, or within a few days install them on a running bike. Brake calipers tougher - after bead blasting the fine print on the paint says I need to bake them. So I need to look now for a used tabletop grilled sandwich toaster.
The cutters will also need a couple of guides and a handle. Also just got a couple of valve guides to be replaced. Then will need the reamer.. It goes on!
I feel like being stuck between a hard place and a rock. Much too often things don't get done properly unless you do it yourself, on the other hand diy requires quite a bit investment to have the tools, and of course space.

I am definitely bookmarking the Neway website. Not sure yet which way I will go at the moment. I will ask them for a quote including shipping and taxes/customs.

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Kawboy's restoration/conversion of a 1980 KZ13 6 years 5 months ago #17623

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The SAGA continues.......
The new Valves arrived from Germany a acouple of days ago. They look sweet !! Definately some structural differences on the tulips of the valve heads which makes them lighter than the stock valves. I weighed the old intakes at 52.9 - 54 grams each. the new ones are 46.6 - 46.7 grams each. The old exhaust valves are 47.1 - 48.1 grams and the new exhaust valves are 44.5 - 44.6 grams. That's significant. The intakes are 12% lighter and the exhausts are 6% lighter. Getting the weight off of the intakes really helps at high revs since the intake is trying to close near piston top dead center. I hate hearing the piston tapping the valves. Stronger springs definately help if you're running up near redline.
But what's interesting is the tulip on the back of the valve head. The new valve have a much lower tulip than the stock valves. Weight savings and a radical change to the flow characteristics i would imagine. It would have been nice to have the heads flow tested with the stock and the new valves for comparison. At this point i don't know which would flow better.
The sad part is I was hoping to gain some clearance in the shim set up since at this point, even a 2.00 mm shim is too thick. My original thought was the valve and the valve seats had been overcut at the machine shop and let's face it, the shims we have to work with are 2.00 - 3.20 mm. That's a .048" window. I'm looking at 1.95mm shim right now to fit and it's not available. I could grind the top of the valves to get a 2.10mm shim to work, but then the next time the valve clearance would need to be done, I'd have to pull the head. All I gained with the new valves over the old reground valves was .003". So I sit here and think "What the hell happened?" I measured the margins on the old valves at .024" and the minimum spec is .028" so "What the Hell happened?" I pulled out the old valves from my stash of spare parts and had another look at them. Well I'll be damned, there's a chamfer cut on the bottom corner of the head of the valve and when I didn't have my reading glasses on, I missed it so I was actually measuring only part of the margin and condemming the valves. My real problem lies with the valve seats cut too deep.
so I pulled out my spare head and tried some test fitting in it. Damned if the spare head has seats cut just as deep.

Lesson to be taught here-
The shims available for use are 2.00mm - 3.20mm which means you have a 1.2mm window within to cut the valve seats and grind the valve faces. That's a .047" window
when the valves wear, the valve clearance tightens up and you constantly need to reshim with smaller shims so if you are planning on machining the valves and seats, you need to aim to achieve tolerances that cause you to install thick shims up in the 2.80mm or thicker so as the valves wear, you've got lots of shims to choose from. That typically means tell the machine shop to take off the least amount possible from the seats and valve faces and have them top the valve stems to get you to the thick shims. There's only .3mm or .012" which can be removed from the valve stems if required.
Most engine machine shops deal with cylinder heads that use pushrods and rocker arms. There's so much room for error in the tolerances in those heads. There are some high performance machine shops that understand the geometry of the valve trains and work to much higher standards and these are the guys that need to advise you when you're looking having the KZ1300 heads done. In my case, had I done the homework first, I would have realized that the valve seats even on a brand new head were machined to a rough window that fit any shim within the 2.00mm - 3.20mm with little thought for the poor guy down the road when he needed to reset the valve tolerances.
So I've always planned on grinding the camshafts and now I have a plan to fix the tolerances I have to deal with in the valves and cylinder heads. I need to recoup around .6mm or .024" so the plan will be to regrind the camshafts and take that .024" of of the base circle which in effect will give me probably .020" extra lift in the valves. We'll see how this all goes once I start to tool up the lathe with a "profile grinder" (patent pending) HAH !! and then make a master pattern to grind the camshafts to.
There might be some Stellite 6 tig welding to come, we'll see.



exhaust valves stock valve on the left


Stock intake on the left
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