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RON LAX
Joined: 22 Apr 2006
Posts: 77
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 Posted: Mon Oct 22, 2012 4:33 pm Post subject: Stock appearing TT75 question/HELP |
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Can amyone give me specs on port timing/heights on stock appearing TT75????
Will going below 9 cc work well?
ideas on squish???
Any solid info will be greatly appreciated!!!
karter9907@yahoo.com thanks!!!!! |
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Oscar Aguilera
Joined: 18 Jul 2001
Posts: 1614
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| Posted: Mon Oct 22, 2012 9:03 pm Post subject: |
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| sounds like you need a good motor builder? dont know where you are so cant help you much to send you in the right direction. |
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RON LAX
Joined: 22 Apr 2006
Posts: 77
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| Posted: Mon Oct 22, 2012 9:15 pm Post subject: |
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I have two motors that are different...so i am looking for what might be average settings.Roadrace...gas...S4...hr191 carbs...  |
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RON LAX
Joined: 22 Apr 2006
Posts: 77
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| Posted: Mon Oct 22, 2012 9:16 pm Post subject: |
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| I have two motors that are different...so i am looking for what might be average settings.Roadrace...gas...S4...hr191 carbs... |
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al nunley
Joined: 13 Nov 2006
Posts: 3030
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| Posted: Tue Oct 23, 2012 3:56 am Post subject: |
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Going bigger/higher, on the ports, is always worth more HP. The higher, the bigger, (same thing) the higher the clutch slip RPM.
Compression increases are always good, if you can control the detonatio. The EGT will help with that.
With gas, you’re limited by octane. The higher the compression, the more octane you need.
I found, with the K78, that less ignition timing was good.
_________________
If the data does not support the theory, get a new theory. (Al Nunley)
All else being equal; Compression is the Holy Grail.
45 years, in and around karting |
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Walt Gifford
Joined: 19 Jul 2002
Posts: 4290
Location: United States, South Jerrrsey,
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| Posted: Tue Oct 30, 2012 10:48 am Post subject: |
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VPC12, RLV DS1 pipe, 9cc head, 15 degree squish .032 clearance, .090" btdc ignition, 16K, piston skirt clearance .005". The only porting you could do is to widen the boost port, very labor intensive for small gain, you need to pull the liner out twice and make sure you leave enough cylinder wall for the piston ring gap/pin. 191 carb needs lots of work but one thing is file a small groove in the throttle plate where the low jet is to help draw fuel when off throttle. Pumper stack on top not side or bottom.
Hope that helps,
Gif 
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FAA certified jet engine and aircraft technician
Nicholson Speedway class champion 2001
Yamaha KT100 Service Center
40 years karting experience |
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Mark Horne
Joined: 02 Aug 2001
Posts: 86
Location: United States, Missouri, DeSoto
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| Posted: Fri Nov 02, 2012 4:36 am Post subject: |
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Ron, I sent you a PM.
_________________
SLK PowerLab
2 Cycle Dyno Tuning
"Racing is life,.....everything else is just waiting"
Steve McQueen - LeMans
"There are only two things that make feel alive, racing is one of them."  |
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al nunley
Joined: 13 Nov 2006
Posts: 3030
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| Posted: Fri Nov 02, 2012 8:35 am Post subject: |
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| Walt Gifford wrote: | | VPC12, RLV DS1 pipe, 9cc head, |
Steve, I raced stock foreign back in 1977 and we used high octane pump gas, but there was no race gas that I know of in those days. I also ran less timing, .060” BTDC. I won the Championship that year and got 2nd at the Atwater Nationals. Ran direct drive.
I still think I should have gotten first place. Culver did the winning engine and the transfer passages were really worked over. And this was a “stock” class.
_________________
If the data does not support the theory, get a new theory. (Al Nunley)
All else being equal; Compression is the Holy Grail.
45 years, in and around karting |
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