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Too much Clearance?

Old 08-19-2011, 06:28 AM
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skip1320
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Default Too much Clearance?

http://www.youtube.com/watch?v=TST414hPC-U Como S .61
Old 08-19-2011, 12:28 PM
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pe reivers
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Default RE: Too much Clearance?

Two strokes have a connecting rod load that is always directed to the crankpin, unless at extremely high rpm. So any play will not make itself noticed in engine running.
When the play becomes so excessive as to alter the engine timing much, power output will change (for better or worse)
Old 08-19-2011, 12:45 PM
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skip1320
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Default RE: Too much Clearance?

Yea I understand that,just dont know how long it will last,looks pretty sloppy,gonna try to get liner out and inspect more,or just put it back and see,really no fun cause it was so easy,maybe look for cheap replacment,like to try smaller .40 or up,thanks
Old 08-19-2011, 03:52 PM
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Default RE: Too much Clearance?

that looks normal to me.
my Jett 56LX has everybit that much, and it's design like that.

when we first ran the K&B elephants back in the 70's, they broke many rods from being too little play.............that and of course the taper was too tight.
Old 08-19-2011, 04:38 PM
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Default RE: Too much Clearance?

lol is it moving, is it moving i have never operated a.................... then video quits.

Wives can be so funny sometimes cant they.




Ok to question that really doesnt look like a lot to me it may heat up some and close that gap even more.
Old 08-19-2011, 05:33 PM
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Default RE: Too much Clearance?

You are OK, that doesn't look bad at all. There has to be a little gap to help allow oil to get in there and also as the engine heats up the metal expands.
The actual power thrust is down on the crankpin at a angle as it rotates, so it is OK.

Old 08-19-2011, 08:36 PM
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skip1320
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Default RE: Too much Clearance?

Thanks all,I quess I should mention I have ran abot 16oz of [email protected] 32/1 on spark through it,quess I will put back together and see,thanks again.
Old 08-19-2011, 09:38 PM
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Default RE: Too much Clearance?

This is normal. When the engine is running, there is no sloppery bearing in whole time due pressure by compression/combustion in two stroke engine.
Old 08-20-2011, 01:25 AM
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Default RE: Too much Clearance?


ORIGINAL: skip1320

Thanks all,I quess I should mention I have ran abot 16oz of [email protected] 32/1 on spark through it,quess I will put back together and see,thanks again.

That is a good mix if you are running a needle bearing rod, otherwise you are running much too little oil for the bushing type rod you have.
Old 08-20-2011, 04:26 AM
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Default RE: Too much Clearance?

As he stated, you need 20% oil in the fuel for the engines with a bushed connected rod.

Old 08-20-2011, 04:58 AM
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skip1320
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Default RE: Too much Clearance?

So go a head and Run ar 20%,she should hold together?hate to break it,it,s old someone mite want it,thanks guys
Old 08-20-2011, 05:13 AM
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Default RE: Too much Clearance?

ORIGINAL: skip1320

So go a head and Run ar 20%,she should hold together?hate to break it,it,s old someone mite want it,thanks guys

Not anyone that is following your videos.


I thought you are trying to kill this engine.


It is remarkable that this engine is taking this without letting the rod go. I would like to see what happens to a OS .61 under the same torture test.
Old 08-20-2011, 05:19 AM
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Default RE: Too much Clearance?


ORIGINAL: rcdude7

ORIGINAL: skip1320

So go a head and Run ar 20%,she should hold together?hate to break it,it,s old someone mite want it,thanks guys

Not anyone that is following your videos.


I thought you are trying to kill this engine.


It is remarkable that this engine is taking this without letting the rod go. I would like to see what happens to a OS .61 under the same torture test.
Ditto, but i'm a bit confused..............is there some advantage to running an engine deigned for glo fuel on gas?
Old 08-20-2011, 05:37 AM
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skip1320
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Default RE: Too much Clearance?

I did drag engines for 18 yrs,if ya cant make it last, ya cant make it fast! If I get the liner out I will look into putting needle bearing,Yea,no slime,less fuel consumtion,hand start
Old 08-20-2011, 06:53 AM
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Default RE: Too much Clearance?

Well to convert to a needle bearing rod, you'll have to make a all steel rod so the rod can serve as the outer race and the crankpin becomes the inner race. The steel rod allows you to keep the overall size of the rod down so it can fit in the crankcase. Now on many engines with bushed rods, they don't harden the surface of the crankpin all that much, so it may or may not last a long time. You would want to use a caged needle bearing setup too. Using a steel rod allows you to make it more thin so it has less drag when the engine is running.

Some model engine companies did this way back in the 1960's Like Fox for example on their .60 and .74 engines at the time. But it was more expensive though, so eventually they quit doing it. As glow fuel with 16% to 20% oil content worked fine with the engines and bushed rods.





Old 08-20-2011, 08:49 AM
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summerwind
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Default RE: Too much Clearance?


ORIGINAL: skip1320

I did drag engines for 18 yrs,if ya cant make it last, ya cant make it fast! If I get the liner out I will look into putting needle bearing,Yea,no slime,less fuel consumtion,hand start
ok i see your point.........we all have our desires with these little monsters eh?

are you picking up more power on gas with this one?
Old 08-23-2011, 06:38 PM
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skip1320
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Default RE: Too much Clearance?

http://www.youtube.com/watch?v=jT7Ctrrptt0,still goin!
Old 08-23-2011, 07:16 PM
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summerwind
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Default RE: Too much Clearance?

great, but i would have liked an answer to my question.............have fun

watching the video tho says you lost power from using gas, so what's the point?
Old 08-24-2011, 03:52 AM
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Default RE: Too much Clearance?

To run an engine with a plain bearing rod on gas the mix should be a minimum of 24:1. An engine run at high speed a total low end rod clearance should be 1.5-2 thou. The oil in the fuel will cushion the rod journal against crank pin contact provided that the mix is adequate ie: 24:1. the oil should have high shear strength.
Old 08-24-2011, 04:32 AM
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skip1320
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Default RE: Too much Clearance?

No slime,less fuel consumtion,hand start.

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