We have to remember that by raising the rpm on the sled from stock 8500 to @ 9600 is not unlike gearing the sled up over 10%.
The mph you posted in the 1/4 mile was very respectable for a 700 SRX on snow so I think the 23/40 gears you are running should be kept for further testing.
At 9600rpm , 2.52 x 9 drivers, with 23/40 gears is good for @ 119 mph at 1 : 1 ratio.
I would think exceeding 119 mph in the 1/4 mile on snow is unlikely.
JM.02c
JB.SRX700
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Okay that does make sense, I will get a strip plowed off the lake and do some runs and see what I can come up with I do my testing with a draggy when I am alone I under stand it may not be the best form but I figure it is fairly consistent and it’s somthing I can go back to to compare when changing thing. As for the 23/40 gears when I was stock I was getting 118mph in half mile. In the 1/4 I was running average of 108 in 1/4. That was 8bu-00 weights at 56g, www prim, green secondary, 51/45 helix at 60.
Running weights empty at a stock rpm isn't comparable to the rpm of 9800.
The higher rpm naturally generates more force.
The higher rpm naturally generates more force.
JB.SRX700
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Yeah I didn’t explain well reading it again, when I was stock I wasn’t running empty weights I was running 8bu-00 at 56g at 8400 in a half mile I was getting 118 on the 23/40 gearing which on a gearing calculator it should only go 104.95 lol. Now with built engine it running same gears now I have empty heel clickers running 9800 rpm. Wasn’t trying to compare was thinking I can likley gear up now that’s all
You were well into overdrive to get 118 with 23/40 at stock RPM.
At 9800 RPM you prob will want to gear the sled down, if anything, like 22/40 which works out to 1.82:1 or maybe even lower.
For now though I would get the sled dialed in with the current gearing and get a good baseline before starting to change gears to attempt to gain performance as doing too many changes at one time is hard to determine what worked or didn't.
As a side note I always liked @ 1.83:1 gear ratio on my 2 stroke Yamahas....even my Vmax 4s.
JB.SRX700
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I’m not even sure what overdrive on a is or how it works / happens. I will do a couple passes on a plowed strip and I will get back to you with what my speed was and how I make out with my rpm. I called bender today and was talking with a gentleman who said he use to do all the clutching and testing for Yamaha. He has told me he will throw a package together for me if I want. He was mentioning I need to use some parts from a 4 stroke primary. And we suggest i get rid of my 45/39 helix said I need to go a bit steeper?
Are you in Canada? Gerry Prosser used to be Bender Canada. He was a successful racer especially on Yamaha 2 strokes....very knowledgeable and helpful and well worth consulting. Make sure he is aware of make of secondary you have that it is not Yamaha OEM.
I dealt with him a lot back in the day with my SRX, SXs, and Vmax 4 mod.
On the SRX and piped/ported SXs we used to run @ a 53/47 with a Yamaha secondary....bear cat secondary is a different animal and helix angles are apples and oranges.
It is very difficult to top properly tuned Yamaha OEM clutches for performance.
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JB.SRX700
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Yeah I am in Ontario, yeah it was Gerry I was talking to. Sounds like he really knew his stuff! He got very impressive numbers out of the srx’s by the way he was talking. By the way he was talking I was getting the idea that he really knows his way around an engine as well. I’m going to emailing him tomorrow and get him to send me the list of things he would like to set me up with.
Oh ya, raced against Gerry for years when we ran these SRX's. I won the high points in B stock stock 2 years in a row, and high points in A stock one year followed by runner up the next year. Only was runner up due to missing two races.