The Hodaka Club Forum

OK. I took this cylinder & I placed a top ring in it. The ring is a 50mm .020 oversize. When I place the ring in the top of the cylinder, the ring gap closes to smaller than .010. I don’t have a thinner gauge but it appears there is ZERO ring gap.

Is there any way to compute the diameter of this cylinder with just this information? Just asking because I don’t have the tools to measure the cylinder diameter. I’ll have to take it to a shop to be mic’d. Victor

Nope. (not with enough accuracy to make decisions)
Ed

How does the piston fit ? You do need a feeler gauge that goes lower, why mick it if the piston feels good and is within tolerance. Just check it with the feeler gauge. ----Clarence

Let`s play Guess This Bore Size! I say it`s a Standard. The winner gets a Candy Bar. Joe

Hodaka Archeology. Some wild guesses.

Could be a overly worn 10 over cylinder that has been honed too many times, making room for a tight fit +20 ring.

Could have been bored to 20 over using a very worn piston. Parts got scarce in the past and most shops use the actual piston to fit the new bore, not the manufactures recommended bore size. An old piston might have been all that was available, making a new ring too tight for the bore.

Your ring not what is says on the box. A lot of shops had open boxes of pistons and rings from different manufacturers. Once the ring was out of the box or the box was water ruined, or just plain roached out, they would get tossed on a shelf. Someone may have taken a best guess as to what ring it was. There were a lot of 50mm bore 100s manufactured in the seventies. Multiply that by 8 over sizes available for many models, and you have hundreds of rings that look a lot alike.

You can file fit a ring with no end gap. I find it most often with single ring Hodaka dykes rings. Take your time and make sure the ends are square. Be sure to also enlarge the area where the ring ends surround the locater pin. Many guys forget this step. If the ring has no room to expand, it will pinch or break, seizure problems will be on the menu.

I would guess Joe is right but lets push the ring down 3.5 inches and look at the gap. I would guess the ring gap as shown is .003. I already owe Joe a candy bar. I just read Joe's last update and he is spot on. ------------Clarence

I bought a Ace 100 engine from some guy near me really cheap. The engine was locked up but was complete. COMPLETELY REBUILT ! BUT whoever bored that cylinder was BRILLIANT!!! The Cylinder had been bored and the Piston was +.020. The top ring was .020 over and the lower ring was .010. At the top of the cylinder where the top ring didn`t make contact (Model 92 Piston) I measured it.That piston was set up with .001 clearance. So, it seized. The Factory calls for .004 and I go by that number. Now that Cylinder needs to go to .040. It gets better!!! My brother gave me a 72 Wombat engine. Tore it down. Another Einstein rebuilt the Crank in it. The Rod still has the Hone pattern on the small end BUT is missing one of the Thrust Washers on the big end! It never ends! Joe.

Unless it's measured, it's just a guess.

No piston. That’s the problem. I wish I had a piston I could stick in it and measure clearances. However, none are currently available.

The rings were in the box, which is still in very good condition. The tape had to be broken open to open the box, so I’m pretty sure the rings match what the box says.

Ring in at 3.5” leaves a ring gap less than .010, estimating between .004 & .005 but the smallest gauge I have is .005 and that one is a bit tight. Victor

I’m inclined to agree with Joe, that it’s likely a Std bore size. Just no piston to insert & measure clearances.

Talked with Terry’s wife. He’s awaiting a bid for a purchase of new pistons to be made, but has not received the quote yet.

Can someone provide me the number for California Hodaka? Thanks! Victor

Well, I spoke with Greg at California Jodaka. Greg advises he has 1, and only 1, .030 piston & rings for an Ace 100. I told him I want it, but, I have to consider if I want to take what appears to be a relatively pristeen std. bore cylinder to .030, or to wait 8 weeks for Terry to get them in stock. What would you do?

I can continue to work on the Combat, and when my nephew gets out of school, we can work on everything else but the top end. What would you do....... Victor

I would get that cylinder measured and if it`s +.010, take it to .030 because it probably won`t clean up at .020 if it is. Joe

I would bore it exactly as much as it takes to clean it up completely, measure, and see where you are. Hopefully you will be within tolerance of the next overbore. Otherwise, you will need to go to the next overbore. In reality, I would ship it to Hodaka Dave. He will bore-match it to the proper piston so as to conserve as much of the bore as possible for the future.

Well, I contacted the guy from whom I bought both Toads & both Aces. He told me, “Victor, I have 2 std. Ace pistons & 1 .020 Ace piston. All of them new. I’ve already made quite a bit of money from you, so I’m just going to mail them to you tomorrow, along with a couple extra fork seal nuts that you need.”

Did I just luck out or what???!?!?!! Victor

We never had Hodaka Dave in the 60's, and 70's or any of the fine professional engine builders. Most kids had their own apart. I would stay with the smallest piston that is within spec. The Hodaka engine is one of the the easiest to rebuild. wipe the cylinder down, oil it lightly, slide the ring down 1&3/4 inches, making sure the ring gap is not over a port, Measure the ring end gap and if it is close to tolerances you would be good to go or you would know what you need to do . You could buy the 30 over and trade it for one you need. ----------Clarence PS You can buy a digital caliper at Harbor Freight for under $20.00 I think it would measure the cylinder and piston it works up to 5&1/2 inches the item number 62569 You just made a great deal victor, may we call you Mr Piston?

Wow! The stars have aligned, Victor. Sweet!!

Clarence. I looked at the Harbor Freight calipers but they only guarantee them to be within .020. So that means you could have a std bore and the gauge could still show it as being .020 over. Not close enough measurement needed for cylinder & piston sizing. Victor

Well go the cheap proven route and use a feeler gauge guaranteed to be right on. used by the most of us?---------------Clarence

Just looked it up, item 62569 measures acuratly to within .001or .03mm that is along way from .020 Clarence

OK. I’ll go see if I find that one at my local HF! Victor