I am looking for some clutch setups for a highly modded Indy 650 punched out to 693cc for both 660'drag racing and 1000' speed runs. Also, gearing combinations. Sled is lightened, app. 400lbs. Rubber track, wahl rear suspension. Runs between 9600-9800 rpms, 10 tooth drivers, rolled chaincase. Have an idea on some setups, but I know I'm not getting all I can. Should be running low 6's at 105-108 in 660' and 115-120mph in 1000', but I am not there yet.

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two different worlds between 660 drags and 1000' speed runs. for the speed runs you will want something close to a 48-34 or 50-36 or 40-36 helix with a polaris black, silver blue, and red secondary springs to tune with, for drags you will want to tune around a silver blue or blue secondary spring with 52-36,50-38 48-36 50-34, several helixs around that size.
for gearing if your goal is 105 mph in 660 you should be gearing for about 105-120 mph at 1-1 shift.
for speed runs you will want to be geared for about 130-140 mph area possibly a little higher.
for the primary cluch you will want to have engagement up around the 6 grand mark for drags, somewhere around 4500 or lower if you can pull it without to much bog, a little bog off the line for speed runs isnt a bad thing. you will want lighter wieghts for drag with the bigger helix, and heavier wieghts for speed with a little smaller helix.

time out testing will seperate the winners from the whiners. make yourself a track, get 5 nice used helixs 4 nice new secondary springs, 3-4 nice new primary springs, 5-6 sets of real close incremental weights, used are ok as long as they are in good shape. take lots of notes, use a vp race fuel for consistant running as well. get a warm up stand learn to do a good clean out on the line before every run, especially when tunning on your own time. the race track is where you prove what you practice, not to practice.

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Madcow, I read in one of your posts here that you suggest low angle helix's and lighter secondary springs for speed runs, and higher angle helix's and heavier springs for drags. I was just testing with a straight 36 deg helix, polaris blue secondary. At about 750' or so with big gears (124mph at 1:1), the shift just seemed too slow. It held rpm's throughout (9700), so I wasn't getting robbed of HP due to much gear or helix. I was hitting about 102, I would like to get to 110 or so in that distance. So, my first thought was to speed up the shift with a higher angle helix and lighter weights if need be, or try to throw more weight at it with the 36 deg. helix.

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What are you running for carbs htg700? I have a 650/693 that I am going to be running for 660' drags. I am running 38mm mikuni roundslides bored to 39.5mm and need a baseline carb set up to get me started.

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Mine are bored ot 44's to 46.5. My motor is the reed motor, so I am not sure if my setup will work for you. I am running big jets 660, 640,640.

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Yep that setup wont work for me. A reed motor though huh? Nice! I have one too, PSI Genesis II 750 based of the RXL/650 bottom end. Its in my trail/crossover sled.






On another note I missed out on a SLP RZ 707 (reed motor, based off the 650) on ebay about a week ago. I was disappointed I couldnt buy it. There are some old 650 based reed motor floating around out there, damn good motor for their day and still competitive today.

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That is the kind I have (SLP. It has high compression heads (180psi), V-force reeds and some porting work done above and beyond SLP by Lanny Benoit. The guy I bought it from a few years back ran 5.69 at 116mph in 660'

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