A rider ...

[pd]

It does run . I can not start it by kick . Only by power and then it's pretty touchy .

New rings are needed , at least . My end gap is way to wide at about .024" .
I'm not sure a tighter gap will improve the compression enough to make a difference , but , I'm going to give it a shot .

Pete .

[Ricks]

It does run . I can not start it by kick . Only by power and then it's pretty touchy .

New rings are needed , at least . My end gap is way to wide at about .024" .
I'm not sure a tighter gap will improve the compression enough to make a difference , but , I'm going to give it a shot .

Pete .

That ring gap is twice what I would consider acceptable, but Bob Kerr also said do not go too tight!

[pd]

I took a compression test after I put it back together with a reading of about 70 pounds . Not near what it should be , but ...

The fact that it will only start with higher RPMs and then wants to die at lower RPMs tells me that compression is too low .

Pete .

[pd]

Today I tried a 6 hole fuel metering tube . The Carpenter carbs come with 4 hole tubes .
That did seem to help some , but still no kick lever joy .

I have new rings coming .

Pete .

[Ricks]

I can't remember Pete, is this a factory piston or one of Wayne's replacements?  Did you bore the cylinder?  I would at least hone the cylinder before putting in the new rings.

[pd]

Rick ,

 I had Wayne bore it last Summer , to one of his replacement pistons . I also bought one of his connecting rods ( standard length ) .
I have over size rings coming . I'll have to 'dress' the ends to fit the pins and also for proper end gap clearance .

And , honing goes hand in hand with new rings . But , this time I'll only put a decent cross hatch in . They won't seat properly without .
I don't want to take anymore cylinder wall than absolutely necessary . Too much and I'll have to get new piston and rings .

Pete .

[Ricks]

Did you pin the rings?  If so, take a picture when you have it apart.  I know this has been discussed here before, but I don't know if anyone here has done it.  Seems like a good idea to me.

[pd]

Rick ,

Quote from: pd on September 04, 2015, 08:09:10 AM

"In the cool of this morning , I pinned the piston , using 1/4" long x 3/32" wide compression pins .

I drilled the landings above the wrist pin , but toward the rear , to a depth of about 5/32" . The pins had to be driven in , so it's unlikely that much , if any, outward drift will happen . I squared the outer end of the pins and called them 'good for service' .

Then the ring ends needed relieving to fit the pins . I used a jewelers square file to reach that 'end' .

All things considered , I think the project turned out nicely .



Now to ready the piston and cylinder for assembly . Hopefully , for the last time .

Pete . "


End quote .



Ha . I know ... getting old is a bitch .

Through  all the 'testing' and such , the pins have held their position .

Pete .

[Ricks]

You didn't happen to write down the ring gap when you first put it together?

[pd]

Sure did , Rick .

The ring gap at build time after pinning : one was .011" and the other was .014" clearance .

The gap obviously grew with each honing , which I knew it would .
I just didn't expect it to reach .024" so quickly .

Pete .

[Ricks]

Sure did , Rick .

The ring gap at build time after pinning : one was .011" and the other was .014" clearance .

The gap obviously grew with each honing , which I knew it would .
I just didn't expect it to reach .024" so quickly .

Pete .

Tighten that up to .008 and I think your troubles will be gone.

[pd]

Wouldn't that be great ?

I'll hold any celebration until your theory proves itself .
Once bitten ( or in this case - several ) , twice shy kinda thing .

New rings are the next logical step . Hopefully the one that breaks the 3 year streak I've had with this motor .
Good thing we're not talking droughts or I might have another 4 years to look forward to .

Pete .

[pd]

I rec'd. the new rings this afternoon .

They are a simple square cast as opposed to the inner upper beveled rings I originally rec'd. with the new piston .

They should do fine . If I'm not mistaken , the OEM rings were / are square cast . I still have the originals , so I'll check .

I plan to seal the intake holes . Both the screw from the bottom and the drain holes . I'm thinking that at the same time , I'll 'ramp' that section of the intake tube for a smoother transition from the carb to the crank .

Here's the way it was :


Right now , I have the drain hole plugged , but I'm not sure that it's sealed good .

Pete .

[pd]

  Today , before my attention was required elsewhere , I was able to size , shape and fit the new rings to the piston .

The rings were a perfect .008" at the bottom of the bore , but when positioned about mid ring travel area , the gap almost completely disappeared . That proves that the bore is looser at the bottom than the top , which is exactly why rings have to be gaped mid travel or near the top of travel .

I gaped them at .008" at mid travel area and had to shape the ends to accept the pins .  Due to expansion , I didn't dare leave them any tighter .

I got as far as setting the cylinder and piston on the case before I heard my name questioningly called .

Good thing there's usually tomorrow .

Pete .

[pd]

Top end is back on the case .
The compression is up about 10 pounds , but I expect that to increase once the rings find their home .
Initially , I used power to start the motor , which ran a bit more smoothly . It still had a time of settling into idle .
I shut it down and tried the kick start . Dang , it started , once . Not the second time , but almost .

Thinking that the idle passage must have some buildup , I have the carb pulled .
I made sure the intake throat drain hole was packed tight and the bottom screw was snugly in place . I have JB Weld , but I'm very hesitant to use it to fill that step of the intake throat . If it ever came loose ...
I'm not sure just what I'll do there .

Anyway , I've seen some improvement .

Pete .