Srx improver help

t-rav

New member
Joined
Aug 27, 2008
Messages
179
Age
35
Location
hanmer,ontario
Hey guys I have 2002 srx improver motor is Ian tomassi built full improver porting and cases were port matched it has 36mm bored srx carbs with 2000 srx race box and harness it's running bender high rpm pipes around 9800-10 000 i think with 23-42 gearing and I just cant seem to get over that 120 mark in 1320ft it's lowered on a speed track also what is everyone's suggestion for gearing and clutching wich is 50/42 helix with green spring set at 110 special cut 8bu-10 to be able to Rev that high and g-g-g primary spring
 

Well, I think if you want more speed gear up for it, you might be running out of gear. A nicely tuned stock srx should do 115-118 (tops maybe not in 1320 on ice) with 23-38 and spinning 8500. You have a few extra's and spinning Maybe if 10 tooth drivers could fit, which I doubt but maybe since you are running a speed track, probably have to tune clutches after that since it would change your gearing exponentially, might be able to achieve a little more by decreasing the tension in your secondary...A few thoughts...cutting weight wont do a thing....Try the 38 tooth.
 
I have a similar set up on asphalt. I think your gearing is to low I run 21-40 with 10 tooth drivers. I would try that and may be a shallower finish on the helix.
 
Hey 383stroker have any idea what the equivalent gearing would be to your 21-40 with 10 tooth drivers, if t-rav left the stock drivers in. Alot less work to replace drivers than to replace upper or lower gear... or possibly point in the right direction to figure out the equivalent overall gear ratio. What speeds you running anyway
 
23-40 or 23-39 or 24 -42 with a 9 tooth driver very close to a 21-40 with a 10 tooth driver. I have used 8bu-10 will mph very well with the right helix.
 
Your current gearing, assuming a 9 tooth 2.52 pitch driver, calculates out to 115.25 mph at 9800 rpm or 117.6 mph at 10000 rpm. Going to 23/40 would get you to 121 mph at 9800 rpm or 123.5 mph at 10000 rpm. Just going up to a 10 tooth driver would take you to 128 mph & 130.7 mph which I would imagine would be too high so you would need to drop the gearing some and change the driver as well if it would fit. These numbers are assuming a 1 to 1 shift out. It is hard to get much past that.

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found with my improver it will pull well up to about 5% overdrive in the clutching. Anymore it will start work to hard and wont mph the same. I would run a 21-40, 21-39 or a 22-41 for a 1320ft
 
would work the clutchs more, 110 degree twist on the sec spring is eating up mph. if you drop that twist say 20 degrees its likely easy 5+mph more on topspeed. If your running it at that twist to sustain your peak rpm, then you need to go to the front clutch and work either on weights or change primary spring. A tight secondary is a very non efficient one and eats up mph!
 


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