The Hodaka Club Forum

Just got my new cylinder back from Hodaka Dave and had it Nicosealed back to original bore. New everything on top.

When I bolt up and torque the head with a new gaskets I get almost 0 compression. I put my Palm over the piston and crank it , the compression will blow my hand off the cylinder. My head has a indent that makes me think the gasket should have a similar indent to match the head but the 2 new gaskets I've ordered are flat . I'm sooo lost on this.

Thanks

Locknut

First thing that jumps to mind is your gauge ok?

And can you post a pic of the indent?

Both the top of the cylinder and the base of the head should be totally flat.

I'm with Thrownchain, the mention of an indent in the cylinder head immediately caused a red flag to pop up. We need more information on this indent.
Ed

This 97 came to me as a real basket case with mixed parts, but I'm so close to finished

Thanks

Locknut

If the indent you are referring to is the ring around the combustion chamber on the cylinder head, no, there is no special head gasket that mates with this ring. All Hodaka 125s use the same aluminum gasket.

Have you checked for leakage around the head gasket and spark plug? Some soapy water sprayed around suspect areas may help.

Someone (Ed I think) reported an instance where the head bolt bottomed out before it clamped down on the head. It may be worth checking.

Sometimes a fresh dry bore may not produce the greatest compression. After running and allowing parts to "bed in", the compression will increase.

Brian

I never run on a dry bore, lube it well as it goes together. ------------------Clarence

taber hodaka wrote:I never run on a dry bore, lube it well as it goes together. ------------------Clarence

Same here Clarence, I like lots of lube when putting the engine together, but I remember back in the 80's some racers were installing the piston dry claiming it would break in faster.

Brian

Ok, I painted the head gasket area with a marker and set it on some 600 sand paper on a piece of glass. Polished the head and it came out as good as it can get I think. Then I doubled up on the head bolt washers already in case the studs bottomed out. I'll try the soapy trick.

Thx

Locknut

Make up, or borrow a rig to do a pressure test, only takes 6psi to check things out.

Two thoughts for you:
1. Spraying soapy water on the edges of the head gasket while kicking it over probably will establish that you have a leak there - but it will also suck soapy water into the engine. It would be better (I think) to not do that. Doing a standard pressure test would be better.
2. With the cylinder head off, install the cylinder head nuts on the studs and run them down finger tight till they stop turning due to bottoming out on the thread ends on the studs - now "eyeball" them for even-ness. You may find that one of the cylinder head nuts simply won't go down as far as the other three. If so, tap that nut to achieve full, normal depth threads . . . and the head sealing problem should go away. I know about this because I have experienced it first hand.
Ed

I'm working on a Wombat motor at the moment that had a head sealing issue. Turns out someone milled the top of the cylinder, and didn't do a good job, so if you set the head on the top of the cylinder you can actually rock it side to side. Obviously not good. So we're in the process of sourcing a non milled cylinder to replace the bad one. There were other issues with the motor (missing parts) but nothing that can't be repaired.

I'm cornfused Captain (that's what happens to us in Iowa). Are you suggesting dressing the threads on the nut with a tap or extending the threads deeper onto the stud with a die?

I'd say just chase the threads to make sure they're clean. I do the same and run a tap into the holes to make sure they do what they're supposed to do. ( the case and cover screws)

The word "tap" was purposefully chosen. In the case I described, the cylinder head nut was not tapped deeply enough to allow it to come down far enough to tighten on the cylinder head. The stud could have been made of "all-thread" and that nut would not have come down tight on the cylinder head.
Ed

My apologies, should have read with more cognition. I went right over "tap", but at the same time it wouldn't hurt to run a tap thru the nuts and a die down the threads. And make sure the studs are installed correctly. There is an up and down to them.

Thank you for the clarification, Captain. I'm with you now.

I don't run a die on the stud threads unless a visual inspection shows such an effort to be needed . . . and the threads on the bottom of studs are unfinished/over-size to provide a tighter than normal "fit" in the cases to help assure that they don't come out when removing the cylinder head nuts. Running a die down on those threads would "erase" that factory/engineered feature.
Ed

I was referring to studs that were already installed, just to clean up the threads.

97 No Compression FIXED !!!!!!!!!!

I bow my head in SHAME .!!!!

Also along the line KISS. Keep it simple stupid.

The Cylinder had full compression all along. !!!!!

After the top end rebuild I did not think the clutch had any issues, as the piston approached TDC the clutch would slip very slightly and the piston just kept on going giving me the impression of major problems that did not exist. UGH.

Sorry for wasted time.

Locknut