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Post by shiftless on Dec 7, 2009 15:19:59 GMT -5
The longer end of the mount should be on the flywheel side  . I forgot to note that when i took my motor apart and stood scratching my head for a min. lol  .... Thank you sir |
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Post by shiftless on Dec 13, 2009 13:59:19 GMT -5
Well I had a clearance issue..... The piston was touching the head at tdc  Resolved it with a .4mm aluminum base gasket and a standard paper gasket on each side of it and a new head gasket Its all tourqued and rotates freely with 1.4mm of squish on the solder  Put the cvt together with some NCY 4g rollers Painted the cover & removed the filter  Exhaust is in the mail  It'll be ready to put in the scoot soon |
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Post by 90GTVert on Dec 13, 2009 14:27:40 GMT -5
Did you check the ports at BDC to help you choose where to add gaskets, or just put gaskets in to make clearance?
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Post by shiftless on Dec 13, 2009 18:45:50 GMT -5
Actually, that never crossed my mind
I know the ports matched good before with the holes a tad bigger on the jug
I was focusing on the piston clearance
I'm used to building thumpers
Do you think that little of raise is critical ?
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Post by 90GTVert on Dec 13, 2009 21:45:11 GMT -5
If you added the .4mm aluminum gasket and then an extra paper gasket you probably moved up .7-.8mm. That can make a difference, but it should run fine. It could improve upper RPM power, although it will likely degrade low RPM power, because adding base gaskets retards port timing. I think it would also increase port duration since the piston will leave the ports uncovered longer. Might decrease fuel economy? Stepthrutuner would probably have better advice than I would on this one. I will say that 1.4mm of squish shouldn't really be necessary on a 70cc. I'd think you could cut it back to 1mm and still do alright for a street motor if you do decide to make any changes. It's never a bad idea to take a look at what you've got when you are assembling.
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Post by shiftless on Dec 13, 2009 22:35:18 GMT -5
Thanks for the advice
I typoed the squish it was 1.2 not 1.4
My research told me that .9 is ideal for max compression
I'm gonna hang it as is, fire it... then go from there
We'll see what it'll do
I'm about out of gaskets and hafta play Santa b4 I put any more $ in it
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Post by 2strokd on Dec 14, 2009 8:47:20 GMT -5
You should be fine to start with, you can always pull the top-end back off to adjust the timing later with the motor hung. I have done it many times . If you havent already, read into a good 2t tuners book. Check out Bells book, great stuff on port timing and squish settings. www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdfAre you planning on entering it in Twist and go? If not, at least bring it if you can ;D. A extra ride is never a bad idea  . |
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Post by 90GTVert on Dec 14, 2009 8:49:28 GMT -5
.6 - .8 is quoted by A. G. Bell (Two Stroke Performance Tuning) as ideal for 50-70cc. Realistically, .8 - 1.0 seems to be needed for many 70ccs without working the combustion chamber. I had 1.4mm squish on my 99cc to push to the limits of pump gas without changing timing. I then had the combustion chamber recessed to create 2 more cc of CCV and allow me to run the quoted ideal spec of .9mm. The difference was minimal and not worth the time waiting for the machine work or the added cost. If you get it running and want to experiment, you might wanna see what you can do by just using gaskets to change port timing and/or squish.
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Post by shiftless on Dec 14, 2009 22:05:44 GMT -5
Just got everything together and ready to hang the engine   I'm gonna jet and put the carb back together tonite and remove some plastic so I'll be ready to put the engine in 2moro I wanted some Amsoil and looked all around local, but nobody has any The guy at the local MC store said this is the best for premix  Has anyone used it ? Any reccomendations on break in ratio would be appreciated Thanx again to all for answering my many questions Im gonna try to get it all together 2moro, I need a battery... all the ones I have dont fit in the box on this scoot, hopefully I can find 1 without having to wait on shipping |
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Post by stepthrutuner on Dec 14, 2009 22:40:53 GMT -5
Those squish figures are for high performance race prepped motors. That figure of 1.2mm should do fine for you. If you try to get the squish down to that 0.6 to 0.8 range chances are your compression ratio will be too high for sustained high speed cruising (engine will heat up and go into detonation). As he said, Brent has gone through this process of having his combustion chamber recessed to get his squish down with minimal results for the money. For your engine to live and be reliable it is best to err on the low side as far as the compression ratio is concerned. Two strokes don't tolerate high compression ratios near as well as four strokes do due to having only half the time to cool down between power strokes.
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Post by stepthrutuner on Dec 14, 2009 22:57:54 GMT -5
I'm sure that is quality oil. I just don't want to know what you had to pay for it. Break-in mix should probably be 32-40:1. Post break-in 45-50:1.
Cheapskate me runs Havoline tc-w3 @ 32:1 for $2.99/qt. at the local Fred's Dollar store. Been working good for about 2/3 year now.
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Post by shiftless on Dec 15, 2009 10:35:03 GMT -5
Thanks stepthru I feel better about the squish now I paid 11.99 for liter the oil Got some more done last nite  |
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Post by 90GTVert on Dec 15, 2009 11:18:52 GMT -5
Almost there. ;D
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Post by shiftless on Dec 17, 2009 21:54:01 GMT -5
Tried to get some fire 2nite... Everything connected, hot battery, new coil & plug Start button............. nuthin Pulled the plug and used the kiker........... no spark Gonna hafta ring out some wires & check pickup clearance I just love electrical gremlins  |
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Post by 2strokd on Dec 18, 2009 8:04:37 GMT -5
Been there bud  . Check the simple stuff first. I bet your controls(kill switch, turn etc) are the same as mine. If so, check your kill switch on the bars. Early last spring mine started cutting out and dying on me for no apparent reason and it ended up being a bad connection in the kill switch. I just took the plastic thumb piece out with the contacts and have been using my key to shut it off. No problems w/that since. |
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