2 stroke ring gap question

**gottcha3232** · 03-01-2015, 08:42 PM

When setting ring gaps do you measure the part of the ring that goes around the pin in the piston ring groove that keeps the rings from turning, or do you measure the smaller tips of the rings which are actually closer together and come in contact with the cylinder. I'm looking at a seloc book and it looks like you measure the part that goes around the pin. If so is there a minimum that you want the tips?

**eli** · 03-01-2015, 08:46 PM

ring gap at cylinder 14 to 16 thou ,file fit rings you may have to clearance for pin also

**Carter Powell** · 03-02-2015, 05:51 PM

14 to 16 mm seems like you would have NO compression! Maybe only just a little loss.

Carter Powell

**Scott in MN** · 03-02-2015, 06:39 PM

If I remember right there are 25.4 mm per inch so 14-16 mm is more than half an inch....maybe there is a mixup between mm and thous...

**FMP** · 03-02-2015, 07:01 PM

.004-.005inch / inch of bore. The ends of the ring. Check the bore in three or four places by stuffing a ring in the bore at different depths and check the end space , the end space not the space where the pin would be, then adjust if needed. Check near the top , between the ports and the top , just above and below the ports. If you get much more than .002 differnce in the end gap measurements at the differnent spots , refinish the bore. Check with the book for the spec. and the piston manufacture if replacing.

**powerabout** · 03-02-2015, 07:02 PM

the spark plug thread is 14mm so you would need a bore of about 4' to have a ring gap that big. lol
ring gap and how to measure is in the manual
ps
https://www.outboardbooks.com/ if you cant buy an original

**FMP** · 03-02-2015, 07:07 PM

funny

**tlwjkw** · 03-03-2015, 12:03 AM

14mm ta 16mm? what is that in A'marecan?

what is it? might be a little bitty Suz or a stroked out monster..................

**TEXAS20225** · 03-03-2015, 09:34 AM

i dont member reading nothing like that in all my merc books seems like its was thousandths

**FMP** · 03-03-2015, 10:14 AM

1mm = 0.03937 inch.
Measure the bore with a dial, if the taper or difference between measurements is greater than .002 inch (.05mm) rebore, or if out of round.

**racervboat** · 03-03-2015, 03:11 PM

maybe he ment 1.4-1.6 mm but that's still to much?

**powerabout** · 03-03-2015, 04:39 PM

Originally Posted by racervboat

maybe he ment 1.4-1.6 mm but that's still to much?

sure is
golden rule I use, all metric measuring tools on a metric engine and all imperial on an imperial
and a hacksaw blade is 025" for pinion height..lol

**tlwjkw** · 03-03-2015, 05:13 PM

Originally Posted by gottcha3232

When setting ring gaps do you measure the part of the ring that goes around the pin in the piston ring groove that keeps the rings from turning, or do you measure the smaller tips of the rings which are actually closer together and come in contact with the cylinder. I'm looking at a seloc book and it looks like you measure the part that goes around the pin. If so is there a minimum that you want the tips?

ta answer your question.....its at tha ends (tips as ya call 'em) with tha feeler gauge against tha cylinder wall....gap is whatever tolerance tha manufacture calls for no mater what its measured in.....seloc sucks...go straight to tha manufacture...that's why I asked what kinda motor ya talkin' 'bout...and yes, ya may/may not need ta work on pin clearance also.

**olboatman** · 03-03-2015, 05:30 PM

If I remember correctly a folded matchbook was 16-17 thousands.... was great for points in a pinch. But didn't use it for rings as couldn't "lite em up" after they got covered with oil!!!!

Gary

**afr** · 03-03-2015, 05:38 PM

this is why i dont build outboards lol and then those big ole front half rings OMG

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