TC--102

[1650bullet]

Had a look at those cracks. Just a bit of dust or lint. I gave the whole assembly a good clean using degreaser and blow dried it all and had a better look. Well done on picking up on that c-i (I would not of noticed it) Still cant find any marks on the crank lobes to suport those scratches Maybe the flywheel has been removed with the crank at Top dead centre. Gave the cyl a hit with the pressure cleaner after soaking overnight. Gave the bore a hone and its come up trumps.Checked the ring end gaps in the cyl (Just under 1mm) Will give it a coat of black with some clear over the top after i mask everything of. Need to get a base gasket and im tempted to use the original rings because there in tolorence. What do i use to mate the crankcases toghether, I have a tube of loctite superflex high temp RTV (the red stuff) Is that ok to use.

[Charles uk]

End float on the big end on new rods seem to be about 10 thou.

To measure ring wear, push a ring 10mm up from the bottom of the cylinder with the bottom of the piston, the maximum gap at this point the books say should not exceed 15 thou", or you need new rings.

The ring gap on new rings should be 4 to 5 thou per inch of bore so a bore of 2.25" equals a gap of 9 to 11 thou.

If you then do it again but with the ring 10mm over the exhaust port, then gap the same ring again, you will be able to acess how much bore wear you have.

Almost 1mm ring gap sounds quiet a lot, nearly 40 thou".

Where in the cylinder did you measure that & was the ring square in the bore?

[1650bullet]

37 thousands of an inch or 0.94mm. I got the information from Giannos Overhaul manual. Page 13 Vol 3. Big end bearing has 1 Maybe 2 thousands of an inch movment.

[Charles uk]

It might be better if you checked the numbers on the net, there are lots of places where you will find them.

I can't see which type of ring gap your measuring, can you post a clear pic.

As for the big end movement are we talking end float or oil clearance.

[Charles uk]

I've just checked the "Clymer British Seagull Service . Repair Handbook 1.5 to 6 hp Models" all that has to say on the subject is "End gap must be a minimum of 0.004 inch, 0.1mm.

[charlesp]

That gap does sound very big. Is there any possibility you may have mis-read it?

[The Tinker]

I set my ring gaps to 4 thou, over 8 thou and I consider new rings. You may find a lack of compression or back firing thou carb being a few of the problems you will have if ring gaps to big. I would be very wary of the Italians manual has a few mistakes in it. Not all bad.

[Chilli Dog]

God you crack me up Bullet !
"End gap must be a minimum of 0.004 inch, 0.1mm. Also it looks like the bore is very smooth as in has to much shine for one that has just been honed . Should look like the photo below

[Horsley-Anarak]

Seagull say in their service manual "gap to 0.004", personally I have never bothered.

If I rebuild an engine for serious use I normally buy new rings, perhaps now I will start checking the gap, it may make my engines go better.

H-A

[charlesp]

Interesting page here:

http://www.hastingsmfg.com/ServiceTips/ring_gaps.htm

I tend to not bother with much measuring, except for new rings, they get the recommended gap at the bottom of the cylinder.

[1650bullet]

Good thing i brought this to attenion. Thanks for all the help everyone. I should chuck those manuals out i think. I could of ended up rowing back to the boat ramp. New rings it is. There are 2 sets available The genuine seagull or Ex Wd 102. Which ones should i get. And ye" The bore is not all that well finished, I will give it a hone with a different stone.

[Charles uk]

Mr Chilly that cylinder has been honed with a 3 legged hone the type that's normaly used after a cylinder has been bored oversize to bring it up to the exact finished dimension, they leave parrallel score marks unless they are reciprocated rapidly.

The purpose of honing a two-stroke cylinder is only to break the glaze, or shine on a cylinder wall & leave shallow diagonal scratches that will assist the lubricating oil to remain on the cylinder wall, not to increase the bore by removing metal.

How long did you hone it bullet? don't take any more off it.

[Chilli Dog]

I concur Mr Charlie , the glaze doesn't look broken is my point

[1650bullet]

It might be better if you checked the numbers on the net, there are lots of places where you will find them.

I can't see which type of ring gap your measuring, can you post a clear pic.

As for the big end movement are we talking end float or oil clearance.

[Chilli Dog]

that gap looks big bullet , 4 thou is ideal 8 thou okay ~ I measure above the exhaust port where the rings actually run as long as the bore at the bottom allows you to get then in on the piston to that point .
Where you are measuring might not be as worn and there fore not give the "working" reading , but because this is in an area that shows less wear it may be too tight to get them in if the diameter of the bore is greater further up.