clutching a 835

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spainman61

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I have a 2001 Yamaha Srx 835 big bore with big bore pipes..... I am thinking about running some 500' grass drags. The motor was built as a trail verison big bore.... I was wondering if you guys had any advise.. I have some experience with jetting, but do not have much clutching experience.. This is what I thought about running and what I have.... Stock clutches, orange primary ??bender?? spring, yamaha green secondary with a 51/43 helix, stock carbs. It has a 1 inch track with 240 studs.... I think 21/40 gearing, Pod filters...
 

Buffalo Bob gave me a setup, do a search for 500 grass drags. Also, I don't know how well your setup will work.. Maybe someone will help, but it does not seem like to many people are willing to give out the bug bore setups...
 
If your making any power you would be around 6 grams in the heel and 7 or greater grams in the tip and or middle, total you should be around 68 grams for a big bore making good power. 51/43 helix would be ok... but not great, something with a little bit shallower finish would be more beneficial. 50/40 is great for h/c in a srx and drag racing.

For drag racing only, I will use mostly all heel weight and a small amount in the middle hole, not much on tip, becuase in 500ft your not concerned with topspeed tip weight, you want low et, and clamping the belt from the start is what you have to focus on.
 
with h/c red primary spring, and on thesecondary, for grass youll need a silver yamaha, snow and or lake racing a green yamaha. The reason you need silver in grass is usually the traction will cause it to overshift if you dont run the silver
 
you wont be able to use the bender orange with h/c weights unless they would possibly be totally empty and then even doubtfull, its not a strong enuff spring
 
I just took my clutches off for cleaning and checkout.I forgot what i have in there and they are over at my buddies garage.I believe the set up had yamaha 8bu weights.It worked very well on my hauck big bore.I will check all parts tomarrow and post if you want to give it a shot.I will be going to boneyard tomarrow as i found broken powervalve cable on middle cylinder.Found problem!!!Wakeup call to my buds F7,and his F3800!!I hope they got tissues!!HAHA.
 
50/36

Would a 51/36 be better then the 51/43 or is it 2 shallow of a finish angle?
 
with h/c's the shallower the finish the better, you can still use it for drag and then change the set up around in weights and trailride and lake race it, thats whats nice about h/c's you can make them do what you want to by moving the weight around on them for differnt terrain types.
 
Thanks, I put in 6.0 heel, 7.0 mid, and 5.0 tip, for a total of 68 grams, with the red heel clicker primary, 51-36 helix with silver secondary, wrapped at 80 degrees.// I have not gotten to try it yet. What do you think?
 
youll have to try it! watch rpm's in your distance run, it all comes down to how hard the sled hooks and applies load to the motor.
 
silver secondary spring is tooo weak - it will suck the belt if you hook up hard.
below are specs that will get you close.
bob

gearing - 20/40
plugs - .020
mains - 160 - all
pilots - 60
needles - #4
fuel screw - 2 out
v-force 2 - soft
oil cable - 20 mm
h.c. - 60.4 grams ( tip - 3.3, inner 4.9. heel 3.1 )
h.c. spring - red
15.6 mm rollers
helix - bender 9870c
sec. spring - bender white/blue @ 80*
 
Why do the weight setups change so much for Mr. Vipers setup, it is 8 grams per arm difference.. Is it because of the spring and helix???
 
I have never had any problems with the silver on grass even with a 6800rpm engagement on a pro stock 700. A 9870c isnt that big of a helix, a silver would be more then enuff to control it. Theres tons of ways to clutch a sled, youll have to pick one and fine tune it from there.
 
I ran the setup you gave me Mr. Viper, with the exception of a green spring, I could not come up with a silver.. It ran 5.9 or so but the track was muddy with some standing water, that slowed me down a lot.. MY engagement is only around 4000. Can I run a engagement shim with the red spring? What sled or sleds use a silver spring?
 
yamaha part number is 90508-556A7-00 for the silver secondary spring.

What were your rpms going down the track?

you can remove a gram from the heel to help your engagement speed or notch the weights is the preferred method, this will get ya a good 5500rpm launch.The drawback is you cant trail ride with the weights anymore. Dont shim the h/c red spring or youll end up with coil bind.
 
the setup i posted should engage around 4500. that's plenty for that motor. it makes a bunch of torque & the pipes have a broad power band. full shift as you cross the line should be around 8500. if you put a bunch of heat in the pipes @ the line then full shift may be a bit higher.
if you want to trail ride the sled after racing the only thing you will have to do is change the mains to 170's & loosen the secondary to 40*.
with the track & studs you have 5.6's would be about right.
bob
 
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