What pipes do you like for the Viper?

The head mod is to take the viper head and make the center and mag cylinder the same LOWER compression that the PTO cylinder is, this way all 3 have the same compression ratio and lowers the compression ratio some so detonation wont start as easily. The viper has higher compression then a srx does in the center and mag cylinders.
 

Why are the two cylinders designed that way? What exactly has to be done to the head to lower the compression?
 
snow guy said:
Why are the two cylinders designed that way??
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Two? No the two stayed the same, it was the PTO that was re-designed.

My understanding is that on the SRX motor the PTO ran a little hotter than the other two cylinders, think it has to do with close proximity of the primary clutch. To compensate Yamaha jetted the PTO cylinder a little richer then the other two.

When it came time to build the Viper, someone decided it would be more user friendly if all three were jetted the same. Still having the hot PTO cylinder issues to deal with, they lowered the compression on it to compensate for the problem. It's kind of a 6 of 1, 1/2 dozen of the other type thing. To compensate for the hot cylinder you can either upsize the jetting or lower the compression. They did one thing for the SRX and the other for the Viper.

snow guy said:
What exactly has to be done to the head to lower the compression?
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MrViper can explain in more detail, but the volume (cc's) of the Center and Mag domes are increased so they match the larger volume of the PTO dome. Larger volume = lower compression.
 
Your next question is going to be, "Then why do people change it?"

I think with triple pipes the MAG cylinder becomes the hottest (probably close to PTO for that matter) due to close proximity of the pipes. The lower compression helps control pre detonation. It's easier to change jetting then it is to change dome CCs (unless you have a nice set of aftermarket heads $$$).
 
YamerDown said:
Two? No the two stayed the same, it was the PTO that was re-designed.
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Hmmm, re-read what MrViper had posted and it appears this comment is incorrect. Regardless, the rest is still accurate. Lower compression in the PTO was to compensate for the heat.
 
I have a CPR Viper and if I was to start from scratch!
I would go with SLP seems to be ALOT more info on mountain set-ups etc.
and with a guy like Allen to bounce questions off how could a guy go wrong?
my CPR like gas and seem to run rich I really need to just lean it down and go for it!
PS cant beat the sound of a piped triple!!
 
YAMAHOWIE said:
I've set up a SLP triple piped Viper for my son and he's run it 2-years and 3000 miles with no issues. Set it up like they recommend and don't get greedy with the jetting. Makes the Viper a whole new animal !
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I'm just curious what kind of mileage he gets with SLP's setup. I know from experience that SLP's jetting reccomendations at 1300 ft. are WAY too fat on my Pro-X 800 using their single pipe, airbox and flowrites. Their setup says to use 500 main jets. I'm using 460 main jets(4 sizes smaller). I had to lean out the needle as well. I went from 8 MPG to 12 MPG trail riding. :rofl:
 
I have slps. Can't say I'm dissapointed in them, other than one of the pipes sit right against the #3 (or is it #1? The exhaust side cylinder) spark plug cap. I had to add a spring to tweak it over so it wouldn't melt the cap. I tried the hard plastic high heat cap, it would just crack and fall apart over time due to the pipe hitting it when riding the hated trail to get to the meadows and hill climbs (have I mentioned I hate trail riding?). :p Or sometimes it would wallow out the inside of the cap so that it didn't hold on the plug, so when I hit bumps the cap would jump on the plug and cause it to drop that cylinder momentarily. I ended up putting the soft factory cap back on and putting some high heat silicon on the pipe in that spot, along with the added spring. No problems the last couple of seasons with that set-up. My uncle is running Benders on his '02 short track, it has plenty of clearance for the plug and cap. I can't really compare the two power wise, as his is set up more for trails and dragging and mine is set up more for powder and hill climbing. When we drag I pull him out of the hole, but at about 50 he walks by me at a pretty good clip. I don't think there is much difference in loudness, just a different tone. I would probably buy the Benders if I had it to do all over again, just for the clearance.
 
i had benders on my 02 viper and they didnt agree with my sled, burned it down twice due to detonation, had good fuel and had all the mods done to it too run safely so i tried cprs, they worked great put on 2200 trouble free miles but gas mileage was terrible for some reason. I might have had the jetting setup a little fat, i am just in the process of buying another 02 viper and going to stretch it to a 151 and going to try the slp's. I have nothing against the benders i just had bad luck but there are a lot of people that have run them with 0 problems, but the brand that seems to get a lot of praise is slp and thats where my $$ are going this time. jmho
 
I just put the CPRs on my 06 Viper this spring but I was only able to ride with them twice. After the pipes I can overtake my buddy's 900 Cat.They sound good and gave me real good power but were a pain to install. Plus if I would have know how long it was going to take me to get them once I ordered I would have probably went with the SLPs. First I was sent pipes for an sxr, then after I told them that it took another 3 1/2 weeks to get the right pipes. From the time that I ordered to the time I got them on my sled was about 6-7 weeks, which doesn't mean much if there isn't any snow, but this was in Feb. Maybe it's because I'm in Alaska? All in all I'm happy with them, but we'll see how they do for me this winter.
 
I have a 900 stroker and use the slps they seem to work the best for me but their jet spec is way off for 1300 ft. pig rich! witch is what I figured since they do not test alot at sea level better for them to be on the safe side and let you figure it out. I run 152 across the board in my 900 I think there spec for a 700 was 162.5. It would'nt even run past 5000 rpm with that spec. last winter on the lake I was running 127 mph on the radar thats fast enough for now.
 
Yes, the SLP instructions (stock 700) for 0' to 3000' @ 0*F to +20*F call for a 162.5.

Anyone got jetting recomendation for these conditions with a stock motor? I knew their base line was FAT, but it now sounds like it's crazy fat....
 
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