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TB 88RH and piston w/ 50mm crank

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zwieblekopf

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Discussion starter · #1 ·
I have a TB 88RH kit one one motor, and a kitaco head/piston with takegawa 50mm stroker crank on another motor. I want to put the TB top end on my tak bottom end but I know the TB stroker cranks are 51mm.



Do I need to get a thinner base gasket to get the right squeeze out of this setup? And how far in the hole should the piston be from the deck, I know the TB head gaskets are pretty thick so I'm thinking I could get away with 0-1mm?
 
#2 ·
If you are using the TB head gasket, bolt it up and see if the deck height is correct. I'm going to assume that Takegawa used a 0.5mm longer rod to compensate for the 1.0mm shorter stroke so basically it will be the same as the TB crank.
 
Discussion starter · #3 ·
wouldn't a longer rod mean more stroke?

I guess i was thinking that they used a taller piston to make up the extra 1.0mm

maybe that's why my motor isn't making as much power as I think it should since I'm using a kitaco head/piston now and the kitaco crank is also 51mm



and what is the correct deck height? I'm planning on measuring it before doing anything but I don't know what number I'm looking for or what kind of clearances are needed to prevent the piston from hitting the head/valves
 
#5 ·
All of the Tak 50mm cranks I've seen have an 88mm rod, and leave a TB/Honda-height piston about 1.75mm in the hole. We shorten them up on the lathe. TB now has a 54mm thin head gasket, too, and Tak/Kitaco should have 52mm thin versions for more money. If you swap to 54mm, the import 114cc piston is 2mm taller and will let you use the thick TB gasket and still have .75mm piston-to-head clearance.
 
Discussion starter · #8 ·
what would happen if I used rtv instead of a traditional gasket to try to take up some of the extra space instead of putting the cylinder on a lathe? As long as I clay it up to make sure I have enough space would that work or are their other problems associated with that like the oil passages and cam chain timing?



maybe I should just find someone willing to trade me a tb or kitaco 51mm crank for my taky 50mm one.
 
#10 ·
Yup, silicone is awful stuff. You can use Yamabond, but you'll only gain .5mm, the base gasket thickness. A single-layer steel head gasket is .25mm vs the 1mm TB and some others.



If you decide you want to swap for a different crank, hit me up.
 
Discussion starter · #11 ·
suppose I did yamabond for the base gasket AND head gasket, would there be any problem with that?

that would put me 1.25mm in the hole, but with nothing above it where ideally I'd be flush with the cylinder deck and have a 1mm tb headgasket compressed down to about .9mm Granted I'd still be a little low on compression but much easier than paying a machine shop to turn it down.



I guess my question is would yamabond be a suitable replacement for a head gasket too, or just a base gasket?
 
#13 ·
Look Yamabond isnt going to work as a base gasket or a head gasket.. Wont last at all as a head gasket.. Takegawa 106cc kits 52mm piston 50mm crank.. The kitaco 108cc kits are 52mm pixton and 51mm crank.. You can run a Kitaco piston with a TB crank but NOT on a Takegawa crank. The compression would be real low.. And I think thats what you have now.. Yes Takegawa makes there pistons a little taller than the Kitaco ones to make up for the shorter crank. A takegawa piston on a Kitaco crank comes up and out of the cylinder.. You can have a cylinder milled for 25 dollars.. Thats it mill it to whatever height.. IF you are going to run the 50mm crank you need to run a Takegawa piston only. Or get a 51mm crank for cheap.. TB makes 51mm cranks and you can find them on the forum all day used.. Firepower might even have one. But you have to use a head gasket and a base gasket. I order my gaskets from Cometic Gasket when I need a special thickness gasket made.. They have the CRF info already loaded lol... BUT milling a cylinder 1mm or more starts to change cam timeing for less power. You can fix this with a sloted cam sprocket and degree wheel but to each his own.. Just get the right crank it it would be even a little bit faster than a 106.. Or like Firepower said keep the crank and order the Import 114cc piston from TB and run the thick TB head gasket I think that would work as well...
 
#15 ·
Head gasket, NO. Yikes.



Base gasket doesn't see much different loads than the case centers, and tons of engines are gasket-less there:confused:



1mm at the base of the jug is only about 1 degree of retard on cam timing, and since almost nobody has a clue where theirs is at anyway...lol



Tak 106 Superhead kit pistons are not taller than Honda's, they just sit down in the hole. We cut several jugs, and have had zero issues. Make sure to use a new, good cam chain. We converted a couple camchain adjusters to manual, and notched tensioner arms, but neither is really needed at -1 to -1.5mm overall.
 
Discussion starter · #18 ·
that's a good price for a cam chain, I'll be ordering one from you in the next couple days.



how do you mount the cylinder in the lathe when you are shaving them down? I just remembered a friend has a brother that runs a machine shop so I could probably just do it myself if I can figure out the best way to hold it in the chuck
 
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zwieblekopf
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