The Hodaka Club Forum

this is in relation to my patina build . so i go to start it and no compression . what the ##$%*&^ !. so back in the beginning i accepted a very generous offer from dirty rat for a 03 piston , bought rings , had it bored , every thing was going great , but ran into this when the no compression showed up. the ring groove in the piston is wide so the ring moves up and down in the groove the groove in the old piston is 1.48 mm and the one i have is 2.10 mm the rings measure about 1.46 mm . so what gives . 1 have 3 , 03 pistons they all have hodaka on them , they all look the same but the standard and 2nd over pistons have the same groove measurements but the .030 one i installed has a way wider groove . so were they different for different types of cylinder material or did somebody have a set of wide rings and find a lathe and widen the groove any thought would be welcome . so some of you might say i should of just sent the cylinder to hodaka dave and be done with it and maybe i should of in retrospect he does great work and it comes back in excellent shape its a no brainer , but as this is my 4th hodaka i wanted to have a more hands on experience to learn more about the process and well im getting educated please any thoughts .....albert

Wow! That’s a significantly wider ring groove in the piston. Where did you get the piston? I would try to get rings which match the groove.

I don’t recognize the piston being darker like that either. Could it be it is a 56.75 piston for a different make? Do the wrist pin holes line up identically on the 2 pistons? As I recall the 03 wrist pin hole is in a different location on the piston compared to the other Hodaka 125’s. Someone sent me this hand drawn representation of the wrist pin position differences. Victor

the groove is much wider and im trying to determine if that is a hodaka thing . can i find wider rings to fit the groove ? do i have to hunt down rings from some source that fit the groove? do i scrap it all and start over , new piston , bore , rings ? i got the piston from a fellow hodaka forum member . the darker color is a ceramic coating the guy who bored the cylinder put on cause, if i remember correctly ,he wanted to clean it up . and the piston is a 03 piston .030 . i have 3 03 pistons , .000 , .020 , .030 and they are all the same except for this one has wider grooves ......albert

Well, either it’s not an 03 piston, or someone manipulated the ring grooves. You will need to find thicker rings. Don’t know what’s available. Maybe 94 Wombat rings? I think they are thicker? I would try a set of .030 Wombat rings if you have a set on hand….Maybe….

i have an 94 wombat piston and when you put it side to side with my piston its just like your diagram ,so it is a 03 piston but when i measured the rings and grooves on the piston i have its ... rings 1.48 mm and the groove is 2.11 this is thickness , and the 94 rings and grooves are rings 1.95 mm and the groove is 2.02 mm. so your idea of using 94 rings might be the answer will have to investigate further.....albert

On your hand drawing could it be that the 03 piston wrist pin is lower from the top than the 94/95/97 wrist pin that's how it looks and measures from the pistons I have....albert

The 03 piston / crank is in the right. Pin is higher and rod is longer. Victor

Albert,

The piston I sent you definitely came out of an 03 Wombat. In looking at photos I have, the ring gap looks very close to the same as the 94 Wombat piston ring gap. Are the other pistons you have NOS Hodaka pistons or are they Wiseco?

Hey , the piston you sent matches exactly the two others I have. And they all say hodaka on the inside. Apart from the ring groove that is. Both of my old ones came out of the 2 03 engines I have .I'm still perplexed about the difference in the ring groove, how, why, what the heck..

.albert

Any progress on the piston and rings issue?

yes there is . i ordered some .030 rings from terry for a 94 wombat and they fit in this 03 piston grooves very nicely , compression now up to 125 . i still don't know why this piston ring groove is bigger then the other 03 pistons i have i guess in the long run it doesn't mater. so i have it all back together and for some reason the carb is leaking now which it wasn't doing when it was together before when i went to start it and sorry but im throwing my grandson/ helper under the bus ,he stripped a screw on the battery cover and that took some time to remedy , chalk it up to a learning experience. so in the next couple of days i should , hope fully , find some time to get the carb problem fixed and give it another go. time sure fly's when your having fun.... albert

Good to hear. I wonder if some time in the past, a dealer was having trouble getting 03 rings, so they machined the ring grooves to accept 94 rings, as they were available. Just a thought.

Albert, Regarding your leaking carburetor, I will share that I recently encountered one that would overflow horribly as soon as the petcock was opened. I went the usual route of cleaning and then replacing the float valve. Neither effort fixed the situation. I then took just the bowl with the two plastic floats in place and filled it with gas. Neither float would rise completely. I could not detect any fluid in either of them, but they would not float. Replaced them and cured the issue. First time I had encountered this...

Hmmm...I wonder if if the material the float was made out of was effected by oxygenated gasoline. At the time of manufacture, contact with ethanol would have not been anticipated.

matt glascock wrote: ↑Sun Sep 18, 2022 3:25 pm Hmmm...I wonder if if the material the float was made out of was effected by oxygenated gasoline. At the time of manufacture, contact with ethanol would have not been anticipated.

Matt,
Your theory has some merit. Both floats failed the same and neither had any signs of damage or deterioration. Just weird!

this morning found time to take the carb off and check it out . it seems i didn't have the floats set right put it together than remembered what dale said about the floats so apart again and checked the floats and they are fine . it took some coaxing but it fired up . wont idle , smokes like a demon , found the brakes need adjusting , need to really check out the oil pump , head light and the indicator light works now , that's a plus. put it through a heat cycle and will mess with it tomorrow. about the ethanol when this bike was set off to the side to rot away not sure how much ethanol played apart in gas ...albert