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I have a GS that I feel sould have better performance.Some timing advice,and piston ring experience would be helpfull.
Bike specs. -conversion big tire,button start 1394cc
1150 head with 31/27 valves,RS40 carbs, .348 cams@107.5/108
8.70s at 148mph with 1.25-1.28 60ft.
Do you have any total seal ring experience
Cam timing and total timing shifting at 9750 rpm
Thanks
Put the intake cam at 110 and the EX at 112
Start IGN timing at 35 deg.
With Totalseal rings leakdown should be 1-3 %
The bike doesnt sound that far off to me. Its in the ballpark
There is probably a little left in it.
That 1150 31/27 head would probably like a little more rpm.
Edited by: Fasthouse
have had good luck with total seal
why is the shift point so low
Also those cams a very small for a 1400+cc IMO.
I agree with bump the shift point. My small tire 1260 with the same valve sizes and about 14-1 compression ran 8.70 @ 150 with .348's @ 110 - 108 (I think). With .370's it went 8.56 @ 154 with a 1.26 60' at about 600#. All shifting at 10,500 rpm. 34-36 degrees on the timing. I was often short shifting and adding weight trying to run it in the old 9.20 P/G class. It sure was fun being the smallest motor and fastest bike in the class!
Scott
Thanks for the information so far.
Rpm was based on seeing many GS cranks break on fellow racers bikes,even with billet parts and stright cuts.
I had .418 / 385" in for a few races and saw no increases,I asumed this is because of the low rpm.The small cams seem to make the clutch tuning window much more flexible as well.
Bike/rider 650#
i spin my GS 1500cc over 11'000 rpm and have yet to launch a crank, no billet pieces either just a good welded falicon crank. you probly needed to screw with the timing on the other cams to take advantage of them. your timing numbers seem a little low at 107, many people run up in the 110-113 range, however they shift higher to take advantage of the bigger timing numbers. what kind of a clutch do you use 650lbs is also a fair amount of weight to move, mines more in the 615-620 range. personally i would use lectrons instead of RS 40's you will probly see a gain there, maybe you can borrow a set off somebodyto see if it picks up also being a cartire i would expect to see quicker 60' times, mines in the 1.16-1.17 range, for comparison my small tire GSXR streched 8" will 60' 1.25 on a 1216cc motor and run 8.70's. i think you have some time to gain in the 60', cause your 148mph is really good for a cartire running 8.7 at 650lbs. honestly i think with some tuning on the clutch to get down to 1.20 60' and a higher shift point you would probly hit low 8.60's not to shabby! with those changes and lectrons i'm really sure you would hit low 8.60's
good luck!
My clutch is a MRE lock up.
And yes your right tuning is everything!
1.17 60' is very impressive IMO
I will try again next year,and see what happens.
bummer, your in Canada, i thought you still might be racing for the year, never looked at your location!!!!!!! Dont feel bad i'm right across the lake from toronto and its snowing here and all my bikes are parked for the winter too......[img]smileys/smiley19.gif[/img]
good luck!
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