The Hodaka Club Forum

Victor come tune my piano and I will setup your engine. If you set the cylinder with the top down on your work table and you slide the piston without the ring in, will it freely move through the cylinder on its own? If yes, can you slide a narrow feeler gauge along side the piston without force, if so how many thousands? It still could be a problem with your ring. when you took the head off how hard was it to pull the cylinder off? Would the engine turn over with the head off? Could your piston have hit the head and was stopped. I think there are some things you would want to know before going to the machine shop. If the piston to cylinder clearance is good the machine shop did their job. -------Clarence

Piston is not hitting the head. Piston is not moving in the cylinder. I had to spray lubricant on the piston and let it "leak" around the rings and still had to pry the cylinder off the piston with the rubber covered handle of my 1/2" wrachet!

As I stated earlier in this thread, when trying to get the cylinder over the piston, the cylinder had difficulty dropping over the piston. When I pulled the piston from on the rod, with rings in place, I was able to insert the piston in the bottom of the cylinder. So it seems the base diameter may be greater than the middle and upper diameter. I have never had that much difficulty removing a cylinder from a piston. It is obviously ill fitted.

I can say I am quite unnerved about the possibility of filing the ring gap. The rings were exceedingly difficult to find for a .020 Art piston and I don't want to mess them up!

I would rather have the shop adjust them if needed so it would b their responsibility if the rings get screwed up. Call me chicken but it's not something I feel comfortable doing. I can say the rings were tight against the pin, especially the upper dykes ring and it may be all which is needed. But I'm not at all comfortable doing it. I also do not have a Micrometer for measuring the diameter of things. Victor

Sounds like the cylinder is not cylindrical. Accurate measurement will tell. The machinist might need to check his boring technique...

Victor I have more faith in your ability than you do. If the piston will free fall through the cylinder it is not the immediate problem. If the piston will not free fall through the cylinder it is a immediate problem. You would not need a micrometer but a cheap feeler gauge. Is there anyone of our group close enough to help? -------Clarence

I'll remove the piston & try your drop test. I'll let you know. - Victor

I didn't see one in the index, but is there a past Resonator article on Filing The Ring Gap? Maybe if I had that to read & follow, I would feel more comfortable trying to do it..... Victor

OK. I watched a couple of YouTube videos on how to measure & file ring gaps. Does the Road Toad owner's manual list ring gap specs, and does it matter based on over bore size? Also is it different if you use an Art piston vs. a Wisco/SH piston? Thanks! Victor

I looked up Ring Gap specs on the Hodaka-Parts specs library and it lists Ring Gap from a minimum of .006 to .014.

I'm assuming anything tighter than a .006 ring gap is too small, and, that a gap greater than .014 is too big to maintain reasonable compression on the power stroke.

Is it best to keep the ring gap as close to .006 as possible or is there another specific gap which is highly recommended?

I still need to pull the piston from the rod and check piston clearance with the cylinder. Then I need to insert the top ring and measure the gap. Maybe I can get through this. Thank you Clarence for the vote of confidence. But watching the ring gap videos on YouTube showed me it wasn't that difficult it technical a task to manage! Victor

OK, Clarence. Here's the results of my "drop test." First, the piston binds in the cylinder! It will not free fall through. Second, I checked the ring gap and the dykes ring is completely closed when the ring is inserted into the cylinder & leveled. So the bore is too tight. She goes to the machine shop on Monday.

So I should specify a .004 clearance for the piston and a .006 ring gap, is that correct? Need to make sure before I take the top end tomorrow.

So much for believing the cylinder was shipped at the bore specifications listed. Live & learn. Victor

Sorry you are having this problem but remember you are talking about thousands of an inch. Two people can measure the same cylinder and depending on their equipment and their skill level, come up with different results. Some mechanics will use a spring loaded small hole gauge that is inserted into the cylinder and then allowed to expand to the wall. Its then locked in place, removed and measured with an outside mic. You can imagine how many ways this can go wrong but I've seen many good techs use this technique without issue. I said, "Tech", not machinists.
Both me and my colleague have our own bore gauges. They are what I'd call "mechanic grade" and not what a machinist would use and trust. Before we send a cylinder to the machine shop we both measure independently with our own equipment and then compare results. We are always very close in agreement. But we only use this as a determination of how "bad" the cylinder is. We don't try to tell the machine shop what size to bore the cylinder to. Obviously we can tell what oversize should work and we sometimes supply the piston for them. Often we let them supply the piston for us as this eliminates any issues for certain.
With vintage cylinders we don't have the luxury of that option. Last summer my Hustler caught a ring and wrecked a cylinder and piston. I purchased a standard bore cylinder from E-Bay that took nearly three weeks to get to me. But I couldn't buy a piston until I received the cylinder and measured it. As much as I wanted that bike on the road at the height of our season I had to wait. Once I determined the cylinder was within standard limit I ordered the piston, again waiting for shipping. But there is no other way to know for sure than measuring.

Have you honed the cylinder? Even a few passes with a portable drill powered spring hone might be all it needs.
For sure, other than with a known NOS standard bore cylinder and NOS piston my advice would be never take it for granted that a piston would have the correct clearance.

Ken

I appreciate the advice Ken. I guess I've just been lucky to this point. Everything has fit well & all I've had to do was assemble parts.

But I now understand, having watched a video, and from discussions here, how to check the piston for size to the cylinder & how to measure Ring Gap.

I'll be taking the cylinder, piston and rings to my local machine shop and have them fit everything. If a honing is all that's needed, great. But I'll leave it up to them. That way I can specify what I want. A piston clearance of .004. Ring gap of .006 and bridge relief of .003. Then I can put it together with the knowledge that it will be correct. Victor

That, sir is a solid plan. You'll be ready to smoke after that!
Ken

OK. Just dropped her off at the machine shop. He thinks he can get it there with just a home, but I told him "we'll see!" Gave him all the needed specs. A .004 piston to cylinder clearance, .006 ring gap and an additional .003 relief on the exhaust port bridge and chamfering on all horizontal edges of the cylinder ports. He told me he'd have it ready by Friday at the latest. Fingers crossed.

These guys are good. And the one going the work tells me he has a 1975 Honda 125 (Elsinore?) as well, so he knows what to do with 2 strokes! YEAY! Victor

Redid every single wire connector in the headlight bucket today. All ends have now been replaced on every connection point on the wire harness! Victor

Victor you were at this same place before. Read your post October 27 - 2016. You are right on with the machine shop. We are anxious for you to get this on the road, just like you are and all the grand kids. What will Victor work on next? ----Clarence

Clarence. I think it went together in October because it was getting colder. The metal was contracting and fit together, but it was very tight. It was after that post that I figured out it wouldnt kick over and also ordered a kickstart lever from Bruce. When I mounted the lever I figured, incorrectly, that the problem was in the tranny. Turns out I was wrong. I waited for it to start warm up here to start working again and that's when I concluded it was the piston binding in the cylinder. It's being corrected now with the machine shop and hopefully it will be the last road block! Thanks for the support & encouragement! ; D Victor

Waiting sucks when you are doing it for someone else! Can't complain, just happy it's getting done! But waiting sucks! It's different than when you put things off for your own reasons. But waiting SUCKS! LOL!!! Victor

Talked to shop this afternoon. Said they were almost done with the cylinder. They wanted it to cool off after the work they did before doing a final fit/measurement. So they will have it ready on Monday, mid day.

I know I can't complain, but waiting SUCKS (did I say that before?) LOL! Soon as I get it back I can actually put it back on the bottom end and throw the motor in the frame, add the pipe and some fuel...AND MAKE SOME SMOKE!!??!!

So hang on Clarence, we are almost there! Victor

Got a few more minor things done today. I mounted OEM rear turn signals on the Green Toad, and, I installed a new neutral indicator wire on the shifter case of the Red Toad. Now I can go forward with installing the neutral indicator light on the console of the Red Toad!

All the wiring is now done on the Red Toad, except for connecting the black & blue wires from the motor to the coil & the plug connector on the motor to the ignition switch. Also awaiting the arrival of the turn signal flasher rubber mount. I thought I had one more lying around, but didn't find it anywhere. So I eBayed one because they are sold with the flasher, new & not separate.

Tomorrow I clean up the carb I bought for the Red Toad so it's ready when I get the cylinder back! Also need to get a "T" for the fuel peacock lines and install fuel lines, and an in line filter!

Are you paying attention Clarence! LOL!!! Victor

That is very very good that the shop lets the cylinder temp-stabilize before measurement. Excellent.

I thought so too Bill! It would suck to check for ring gap with a hot cylinder only to find later it was too small again! Victor

Back in the day I had 2 boring machines and I am just wondering what they are doing to the cylinder that would not cool down in an hour.

Finished the Tank Badges on the Green Toad! I really like the 50th Anniversary badges on her! Just that touch of red! Like them better than the silver & black! Victor

Re: ring end gap. Has anyone (else) used an oversize ring and filed the end gap to proper specs?

A 19" on the rear sounds a little as strange. Are you sure it is not an 18"?