If you want to program a ignition curve...there is a ignition that has that feature. Send a PM to mpascual. He can give you more details. Capt,n

If you want to see and read about gapless piston rings,go here.
http://www.precisionrings.com/rings....FYtX7AodqAj-mAPrimary Sealing:In the case of an expanding ring, primary sealing is established at the ring outside diameter (OD) surface and the cylinder bore. For contracting rings, the primary sealing is formed by the inside diameter (ID) making contact with the shaft/rod. This contact is maintained by the inherent tension built into the ring until pressure differential is sustained across the ring. Pressure differential keeps the ring "seated", forming an effective seal.Secondary Sealing:This is established at the ring side face in contact with the groove wall. The desired clearance between the ring and its groove forms a flow channel that carries fluid to the back of the ring to establish pressure differential. Once pressure differential is attained, the unbalanced reacting forces at the ring sides cause the ring to form an effective seal. Both primary and secondary sealing produce the desired sealing action for the application. The same factors that contribute to seat the piston ring also cause drag forces. Axial Drag Forces are a result of the high pressure fluid acting on the I.D. surface of the ring and the coefficient of friction between mating surfaces. In addition to this force, one must consider the drag forces due to the ring's inherent tension. On very high pressure applications, these drag forces become almost negligible by comparison. For low pressure applications, rings must be carefully designed with drag forces in consideration. Another type of drag force is caused by friction between the ring side face and the groove's side surface. If this Side Drag Force is too large, the ring will not achieve primary sealing contact. Again, for low pressure applications, this drag force must be carefully balanced

Ring gaps http://www.precisionrings.com/ringgaps.html

The timing curve of the old original syncro spark ignition was just right..4 BTDC fpr starting, linear advance to 28 or 30 at 4000 rpm... .It was designed by Ed Vollmer and sold by C&H....No one has so far been able to clone it..
RC EXL got close, then screwed it up when DLE wanted it changed...
There is no real need for an advance curve on our toy gassers anyway..28 total works just fine except for starting...And then no retard is needed if you use an electric starter.I bet 99.9% of all model airplane pilots couldn't tell the difference between different timing "curves"

Looking over the DLE last night. the ring is very thick. A new thinner ring would help in the power part but would require a new piston.
Yes the gap less rings would require special setup to run in a two stroke. I remember reading somewhere about someone making a special ring pack to be gap less just cant find it again. This was early on when the DLE came out with the V1 30. On this size of engine I now dont think it would be that much of an improvement. The thinner ring correctly gapped would be better. I was looking for a programable ignition for running three spark plugs in the the engine. there is room in the cmabe for them but untill i am racing on this engine it isnt worth the trouble right now. for the extra weight of the two extra ignition units i could just instal the 55. I will look at a larger carb of clean up the stock one. work on the porting some. the exhaust is very narrow. I didnt measure the ports yet though. I will order some bowman rings today.

Man oh man, everything all over, just smarter, why not just leave them alone and run them, have 2 20's, run on 55 ignitions, hauling a, 2 30's stock (STOCK) ample power, no Drag Race needed with them, they never ever failed or gave me trouble, come on Guys, give it a + here as they are, no changes needed, these Puppy's work just great, sorry but had to say this. [>:]

... subtitles please ...

ran the bone stock engine last night on 30-1 Stihl HP. With the Bisson wrap around muffler and XOAR 18x8 recoreded 7,050 rpm. I ordered two regular Bowman rings and had him also make two special "thin" rings. once they get here i will get some more numbers.

How do you make thin rings work in the stock ring grooves ?

Antique

Was wondering the same thing. Must be some new Technology????????

Some chainsaws and other gassers use just 1 ring...Leave the bottom one off for a test....Our 12,000 rpm GT80 race engines use only 1 ring...190+ mph ain't too bad..

Antique 12,000 on the Gt80 must sound awesome.
I asked him to machine the top of the ring down by .010-.015 and about the same in depth. This will also raise the timing just a little. dont know if will work or not but we will see. I have 30 mins on the engine today and recoreded 7,100 with the bisson muffler. Once i get the Bowman rings I am debating on if i should get a new cylinder for the new ring and rerun or just use the old one. I would like to see how much better the stock Bowman rings are then do another test with the modded rings.


Antique since your are in the know on the Racing circuit I would like your opinion for a great speed engine for my Dominator 1500. I have been thinking the lightest option that would some good speed would be the EVO 58 on a pipe. What are your thoughts?

I have a Husqvarna 372 chainsaw (72 cc single cylinder) that revs up to 14000 when not in the wood. I set the mixture rich so it would not go faster.

It has been ported and the muffler opened up. I like to run it around 9500 in the wood.

The USA versions have a two ring piston but I just have the top ring in the two ring piston.

If there is room above the wide ring groove ....you cut a narrow new groove above where the wide ring went. Capt,n

The old cylinder should be good for the test..
If the ring is thinner it will be too loose in the groove, what happens then ?

We raced Dominators for a few years using mostly Moki 30s....If the airplane will hold together it should be a rocket ship....A Dominator with a piped Evolution 58 and the right prop should be good for somewhere around 140..Stock unmuffled G62 powered 26lb AT6s go about 125....It should be interesting, the Dominator is kinda draggy..You mignt want to try one of our APC T6 race props. our G62s unload to 9000 in the air...

We used to use a metal shim( Called a GI insert) under the top ring after we cut the ring groove wider to accept it, this was a fix for worn out ring gooves back in the day.
I think a step ring would get you where you want to be, from the sounds of it I think that is what your having Mr Bowman make for you, Or did I missread it?

Yes it is a stepped ring. the ring is the stock thickness. It just has a corner cut into the top section. The top section already has a notch for the pin in the piston.

I also measure the ports last night and the transfers and boost port are to high in this engine compared to the exhaust. I like to see .050 for every 10mm of bore which would be around .175 the DLE is at .216. I will order a couple of cylinders and see what can be done to fix it.

Hi That amount could be possibly faced off the bottom of the cylinder flanges, then reach inside of the cylinder with a boreing bar and lengthen the depth of the edge of the squish area the same amount and blend it back into the proper configuration. I am sure the piston would hit if this was not done. It will also raise the compression ratio somewhat, without doing some math I can't say just how much but some is a given.
If done correctly it should kill 2 birds with one stone in help of more performace.

yes cyberwolf that is my plan. I was thinking that or a verticle mill. Either way will same results. I dont know how strong the rod is though I would like to raise the compression up some. There are some good "Race gas's" that are in the 94-96 range. Heck Sunco sells 96 pump gas in some places. more to follow.

Airraptor, Why is your wot rpm only ~7100. Seems low compared to the 'prop' data on this site. My dle30 ran 7600rpms out of the box, dino 32:1, Xoar 18x8. Am I missing something?

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Good point ,mine ran 7700 on an 18 * 12 APC prop from new .
I find it hard to understand why anyone would want to try and get more power out of this motor as it is not far behind a CRRC 50 cc motor for power .
in fact my one powers an identical model faster than my mates fitted with one of those .
DA50 is a different story .

Graeme

I havent put the stock muffler on it to see what rpm it is. it has less than one hour on stock ring. i was going to mess with it and fly some on sunday but was raining all day and the games were on.
I will run it on wed. at the field. I will run the stock muffler over the Bisson wrap around muffler to see the difference. I also got my Bowman rings on sat. I ordered them on friday. i will also test the two Bowman rings on same day.

I find the stock muff turns the most wood. Mine turns a xoar 19x8 beechwood at 7500.

Well I guess mine is still to new or a week one. I havent changed a thing on it except the muffler.

Today I ran it with the Bisson again and pulled 7,100 with it. I installed the stock muffler and pulled 7,300.
I then installed the stock bowman ring and got a quick 7,700 and then settled to 7,600. a good 300 rpm just with a ring change and no time on it. Tomorrow i will change from the stock bowman to my modded Bowman ring.

Interesting, sounds as if the stock ring was not sealing near as well as the new not run in bowman ring. 300 PRM's is a nice gain anyway you look at it.

Shows that the cylinder is not quite as round and straight as it could be, and/or the stock piston ring is too hard...