H50/60 Ring End Gap????? WTH????

[Dr. Shop Teacher]

I was doing some reassembly on the H60 for the Trail Bike and had swapped the "new" piston onto the rod and I went to check the ring end gap before installing the piston. I followed the L-Head manual instructions and pushed the oiler down to the center of the bore with the piston and got an End Gap Reading of 0.043". The gap is supposed to be 0.20".

So, I had another set of rings that came on the "new' piston, so I inserted the oiler in and got a new reading of 0.038" !!!! WTH???? So, then I put one of the compression rings in and got a reading of 0.028". Alright, getting closer, let's try on of the "new" piston rings----0.025" Still not right.

As near as I could tell, the block was never cracked open and the "original" piston is stock. I did hone the bore but only enough to restore the crosshatch and it measured right around 2.625" like it's supposed to be. There was a modest amount of carbon buildup on the piston and head but the engine looked like it never smoked.

My question: Anyone ever see a ring gap this big on a big block? What are the chances of two different sets of used rings being so far out of spec? I know I need a new set of rings unless the L-head manual is wrong (not likely). I don't even know how the gap could open up that much.

Thoughts?????

 

[Ajf]

Are you checking bore size with a bore gage or are you using telescope gages. Sometimes the telescope gages are hard to use and get an accurate reading

 

[creia]

Are you checking bore size with a bore gage or are you using telescope gages. Sometimes the telescope gages are hard to use and get an accurate reading

That was my question as well. Lots of room for error (It does not take much!) when measuring cylinder bores. Also, are you taking NUMEROUS measurements at different locations- top, middle, bottom, and also at right angles?
Michael

 

[125ccCrazy]

yep I have had the same issues on the BB Tec engines..end gaps all over the map... if you can find a set of .010 rings they can be file fit to get a good gap..I like to keep mine tighter than factory specs..

 

[Dr. Shop Teacher]

Thanks for replies...I used a caliper for bore (wrong but what I had). Will grab something tomorrow. 010 over sounds like a good fix. I did check gap in multiple places--glad to know I'm not totally nuts.


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[OND]

Yep I would do the.010 over to and then file fit'em...good catch Pete !

 

[Ajf]

Thanks for replies...I used a caliper for bore (wrong but what I had). Will grab something tomorrow. 010 over sounds like a good fix. I did check gap in multiple places--glad to know I'm not totally nuts.


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Usually a Tecumseh engine will always measure to new size and round with a pair of calipers because the very top of the cylinder doesn't get worn because the rings don't travel that high. You can get a cheap bore gage that used a travel indicator for fairly cheap and get accurate results but you have to be gentle with them. I've seen a lot of the Tecumseh bores go out of round and have taper really bad and checking them with a bore gage or telescoping gages (if you know how to use telescoping gages) is the only way to go. Going by the ring gap your getting it sounds like the cylinder needs to be bored and honed oversize.

 

[Dr. Shop Teacher]

Thanks all for your advice. I took 125cc's advice and found a set of 0.010 rings on e-bay for a good price. Had to cross match numbers a bunch of times, but I found them in Rhode Island. Need to pick up a dial indicator today, so I'll look at other "toys" to measure the bore properly.

 

[creia]

AJF is right on. I would advise measuring the bore THOROUGHLY and ACCURATELY before you go to the time and expense of fitting the .010 oversize rings. If your bore is tapered or out of round (very common conditions on a worn engine) installing those rings will not accomplish anything.
Michael

 

[Dr. Shop Teacher]

Checking Bore

AJF is right on. I would advise measuring the bore THOROUGHLY and ACCURATELY before you go to the time and expense of fitting the .010 oversize rings. If your bore is tapered or out of round (very common conditions on a worn engine) installing those rings will not accomplish anything.<br>
Michael

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Got the gages to do that today, too. Given that this was a snow blower engine, I doubt it's been rode too hard (aside from the gunk in the crankcase). Below is a pic of what the cylinder and rings looked like: