SRX/Viper Big Bore Kits

Mac said:
Griz - That is truly a one off build from what I can see in the pics. I have never heard of RDZ. When it comes to snowmobile pipe manufactures the guys on this site know the target RPM of each pipe builder for sleds. I doubt anyone here could help recommend what RPM as every pipe builder has a different RPM where max HP is achieved. You would need to contact RDZ and inquire about these pipes and what RPM they make max power. What RPM are you turning when 3/4 down the track?
I notice a cover over the power valves. This engine had factory variable power valves. I would guess the previous owner could not incorporate the electronics to operate the servo.
The head is the stock Yamaha head. You won't know if has been modified until you take it apart. When I say modified I'm referring to the chamber size in cc. You can raise and lower the compression by machining the head. What fuel are you using?
Also I can see a Polaris primary clutch and a roller secondary. You will have to learn how to tune this setup to obtain maximum performance and RPM control.
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I put a phone call into RDZ Thursday after reading this. They could not give me an exact answer until I sent them pictures with dimensions of the pipes, which I did Thursday night.

What RPM are you turning when 3/4 down the track? I was running 11,000 the whole way. I do have some new weights for the primary, hopefully will get to the track next week for some T&T.

What fuel are you using? I was told to use a minimum of C12 or equivalent mixed with Klotz Benol only.

I started on a different forum about the clutch setup. After some good advice I've been in touch with Goodwin's Performance in Zion, I'm looking to get there Tuesday (clutch school 101) starts at 8am lol.
 

extremelyfastmax4 said:
the best way 2 find out pipe performance is a dyno all of ur internal parts and how they are conformed will change those stats as 2 what rpms 2 run, don,t waist ur time every body has a answer the only right one i can give u is dyno then clutch 2 that and u will be at maximum run ability my 2 cents, the dyno is not expensive if ur a serious runner AL
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Agree with you Al, if someone wants a 100% setup right away, use a dyno. But this takes all the fun out of test and tune days, learning how to adjust things, break stuff, buy more stuff only to break it again or find out it's the wrong part, I would really miss the aggrevation and pulling the last few hairs out of my head. When I'm bald, dyno here I come.
 
tippmannator said:
griz, i dont know much about engines, but i can assure you that there are more then enough guys here that will make your head spin with the wealth of knowladge they have to offer. on this site there is no stupid question (trust me)
good luck with it
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Sounds like I'm in the right place. Been reading some of the past builds, comments on builders work good or bad.
 
ha buddy i,m allready bald from pulling all my hairs off lmao , ya u,ll be ok and u have a very fast unit for sure and lookin at those pipes from what i can see they should make u good numbers. i build and race vmax4s so i don,t have a lot of time 2 waist so i like 2 know what my rpms are 2 be right from the start then i can clutch 2 that and make maxium power, that way i can take most of my time on suspention set up. AL
 
GR1ZZLY said:
I put a phone call into RDZ Thursday after reading this. They could not give me an exact answer until I sent them pictures with dimensions of the pipes, which I did Thursday night.

What RPM are you turning when 3/4 down the track? I was running 11,000 the whole way. I do have some new weights for the primary, hopefully will get to the track next week for some T&T.

What fuel are you using? I was told to use a minimum of C12 or equivalent mixed with Klotz Benol only.

I started on a different forum about the clutch setup. After some good advice I've been in touch with Goodwin's Performance in Zion, I'm looking to get there Tuesday (clutch school 101) starts at 8am lol.
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The rpm in which youll make power will be dictated by 2 basic things, the pipe length and the exh. port height. You kinda need to know some specs on the engine to be able to have a "idea", and know the pipe dimensions to even remotely give it a stab in the dark. The stock viper engine makes power at 85-8700rpm with the stock single pipe. If you add triple pipes as produced for a sled, most pipe guys will run them up at 9000ish rpm,because the stock cdi has alot of timing below 8800rpm, but the exh port will make good power in this range as well. I would see maybe if you can find out some engine dimensions or at least if its stock. Then youll be armed with that information already as the stock port specs are here on the site, then all you need is to get your pipe length. Any changes in pipe length are critical to rpm, as little as 3/8" differance in the head pipes makes a big change in rpm
 
Back pressure.. (tuned)........to desired rpm............ with many other things factored in........ hehe,
 
GR1ZZLY said:
Why does small increments of pipe length make a difference in rpm (within the powerband)?
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It's my understanding that the length of the stinger dictates the timing of the sonic wave within the expansion chamber that helps scavange the combustion chamber of exhaust gases. Kinda like a supercharger except instead of pushing a/f into the intake the e/c acts like a vacuum drawing exhaust out and drawing in a larger volume of fresh a/f charge.

Of course the timing of the wave changes with rpm.

Anyhow, that's how I understand it.
 
That's some really interesting information. I thought snowmofo was joking when he mentioned sonic waves, sounded like a Star Trek episode. I don't plan on taking the motor apart until I need to, so I guess I'm relying on what the original builder did for now.

I've read a lot on here about different companies putting big bores kits on, good and bad, a lot of different opinions on here.
 
how did you do with the quad ever find out what if any port mods were done?

interesting clutch set up polaris prim, arctic belt and roller secondary... you ever get this thing going good? sounds like you may have been over revving you ever get it set up?
 
Hey its been a year since I made a comment here.

And nope! I haven't made a successful pass yet. I'm ready to sell it, anybody looking for a asphalt quad pm me.
 
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