The Hodaka Club Forum

Ok,

I was wrong about the torque. But here is the page photo from the Clymer Hodaka manual showing torques and capacities for the 100 MX Super Rat.
Click on it to see and increase size to better view.

Using only generic values for M7 bolts, torque can go from 102 to as high as 132 inch-pounds. Just as Harry suggested using higher values on the Super Combat and similar engines, I can see using the same approach on the 100cc series -- IF -- using the book value does not successfully stop head gasket weepage. On my Webco conversion 93 engine, I have always used the book value, 105 inch pounds, without issues but would note that I was using a beam wrench, which can gives erratic results and at best, estimated values. Depends on degree of pilot error. I would say I was getting values plus or minus 5 pounds, so maybe I was getting a bit more than 105.

For my model 97, I started with 170 inch pounds as stated in the specs, and could not stop blow-by at the gasket. Raising the value to 240 inch pounds stopped the problem. 240 inch pounds is a value that is at the top end of generic torque values for a graded M8 bolt.

For the model 93A, assuming a flat and true mating surface and clean, lubed stud threads, and a new gasket, if the book value doesn't seal the head, try raising the torque five to ten pounds at a time until it doesn't leak, stopping at 132. If it doesn't seal at that value, something else is wrong.

I have a Model 93 carb on my bike. Should be the same as yours. I found it very sticky because the PO let the bike sit for 5 years! I had to clean both the slide and its cylinder with some carb cleaner and 2000 grit sand paper I kept wet with carb cleaner. It worked well and the slide moves smoothly now! 2000 grit will polish it smooth! ; D Victor

When you torque the 100cc I would stay with the hodaka manuals torque specifications 105. If the head gasket doesn't seal, lap the head using fine sandpaper laid on glass. The bolt will take more torque the engine cases will not. The ace 90, ace 100 and the super rat all specified 105 inch pounds. I would not convert 132 inch pounds to foot pounds and try it on the small head bolts.-----Clarence

Clarence,

I agree that the cases may not like higher torque with slim bolts, but am confused about the converting inch pounds to foot pounds warning. Twelve inch pounds is one foot pound. Math doesn't lie, so what is the warning about?

Yeah (what Arizona said) Simple math conversion, what's the problem?

Ed

I think what Clarence is talking about is that some torque wrenches (particularly our ancient ones) are not as accurate at the extreme ends of the scale. Pulling 105 in/lbs on a 150 foot/pounds wrench (8.75 ft/lbs) is not much movement and in the under 10% area of the scale not even counting the difficulty of reading the scale.

If you have the latest digital read-out scale you might be close enough (just because it's digital doesn't mean it's accurate at the extreme ends of the scale) but I prefer using the proper scale for the job. (Even though it's ancient)

Max