2014 viper clutching question

[thunderwolf]

I recently picked up a 2014 137" viper ltx in next to perfect shape physically but with 8500 miles or so on it. First trip it was running right around 9100 rpm at full throttle only on the limiter here and there when spinning. I took out a couple hundred studs and now it revs right up to 9200 and is banging off the limiter constantly.

I'm thinking all I really want to do is drop the rpms 500 or so (probably making the top speed higher I'd assume gearing it up), looking around it seems like stock vipers run well anywhere from 8600-9100 or so? What's my best course of action to load the engine more than it is? It has a blue spring on the secondary that I assume is aftermarket and a black spring on the primary that might be stock. Is it worth it to change anything else while I'm in there?

 

[74Nitro]

You have adjustable weights there.

 

[thunderwolf]

You have adjustable weights there.

Wow if I could change those in the trailer tomorrow morning before the ride that would be awesome. I'm assuming the farther out the weights are the lower it would drop the rpm? Very new to snowmobiles especially clutching I've basically only changed belts before.

 

[74Nitro]

Did it come with extra Allan screws

 

[sxr70001]

What belt is on it. If an 8jp you could just switch to an ultimax and lose a few hundred rpm easily.

 

[mbarryracing]

Looks like a Thunder Products Heavy Hitter kit, I just installed on in my 2015 viper RTX DX.
When is it hitting the rev limiter, off the line or at what speed?

 

[thunderwolf]

Did it come with extra Allan screws

No extra screws or any parts came with it unfortunately.

What belt is on it. If an 8jp you could just switch to an ultimax and lose a few hundred rpm easily.

I have a gates carbon belt on it at the moment, that helped a little bit I just bought it as a spare.

Looks like a Thunder Products Heavy Hitter kit, I just installed on in my 2015 viper RTX DX.
When is it hitting the rev limiter, off the line or at what speed?

Maybe from like 30mph up or so. I've been doing mostly trail riding so from any cruising speed to wot it's on the limiter

 

[74Nitro]

Your quickest fix would be to do as @sxr70001 suggests. Switch to an Ultimax XS if that isn't already on it.
Otherwise, you need to tune the weights.
You could also see what the secondary is set at. You may be able to back it off a setting or two.

 

[thunderwolf]

Your quickest fix would be to do as @sxr70001 suggests. Switch to an Ultimax XS if that isn't already on it.
Otherwise, you need to tune the weights.
You could also see what the secondary is set at. You may be able to back it off a setting or two.

Not sure if this is the setting you mean but it looks like the spring is on 6. I could grab a ultimax xs belt but I already have two more belts in good shape so id like to be able to use them if I can. I could just use them as spares to get back of course if need be. Could I just find some slightly longer Allen bolts at a hardware store to put into the adjustable weight there?

 

[74Nitro]

Not sure if this is the setting you mean but it looks like the spring is on 6. I could grab a ultimax xs belt but I already have two more belts in good shape so id like to be able to use them if I can. I could just use them as spares to get back of course if need be. Could I just find some slightly longer Allen bolts at a hardware store to put into the adjustable weight there?

You could set at 3-3.
But what's going on with the end of that secondary shaft?

 

[mbarryracing]

Don't tune RPM with the secondary. Yes, the primary will grab a different belt with a different rubber compound better and drag your RPM down a bit but it's only temporary and not consistent the more you beat on it and get heat into the belt. You need to add weight to the mid section of the weights, don't dink around and just bite the radish and take the weights out and add weight... The little bolts and washers for bottom side of those Heavy Hitter weights aren't special. The allen bolt in the end of the weight that is exposed is for at clutch engagement, not cruising when the weight is slinging out. Putting a longer allen bolt in the end won't solve your concern.
I ended up moving all the washers and weight to the mid to keep mine off the rev limiter. My RTX is only a shorty 129 so it was a chore to get it clutched where it wouldn't blip the rev limiter during spinning off the line or stabbing the throttle at a medium cruise on the trail even with a 8DN and being lightly studded. Since 99% of the time it's spinning, I over clutched it to compensate. If at 1% it bites hard and hooks, so what if the RPM is down a little there. The torque curve is so flat it is actually quicker that if beaning off the rev limiter.

 

[thunderwolf]

Don't tune RPM with the secondary. Yes, the primary will grab a different belt with a different rubber compound better and drag your RPM down a bit but it's only temporary and not consistent the more you beat on it and get heat into the belt. You need to add weight to the mid section of the weights, don't dink around and just bite the radish and take the weights out and add weight... The little bolts and washers for bottom side of those Heavy Hitter weights aren't special. The allen bolt in the end of the weight that is exposed is for at clutch engagement, not cruising when the weight is slinging out. Putting a longer allen bolt in the end won't solve your concern.
I ended up moving all the washers and weight to the mid to keep mine off the rev limiter. My RTX is only a shorty 129 so it was a chore to get it clutched where it wouldn't blip the rev limiter during spinning off the line or stabbing the throttle at a medium cruise on the trail even with a 8DN and being lightly studded. Since 99% of the time it's spinning, I over clutched it to compensate. If at 1% it bites hard and hooks, so what if the RPM is down a little there. The torque curve is so flat it is actually quicker that if beaning off the rev limiter.

After more testing yesterday with 8inches or so of powder on the trail when I was leading it just barely wasn't on limiter. Seems to hit limiter at 9200 and in 8in it was holding at 9150 or so. It's great in deep snow the way it is now, I got the chance to be in about 3 feet for a few minutes yesterday and luckily it had the power for that no problem.
I also noticed the clutch seems to engage somewhere between 3600-3800 rpm, and cruises at 6000 to 7500 generally. Biggest realization was wherever I whacked the throttle wether it be 10mph or 40mph the speedo would immediately shoot to 50mph then be hitting the limiter climbing slowly. If I stay at abot 3/4-7/8ths throttle I was able to get it up to about 88mph staying off the limiter. So it seems to be completely fine from 0-50mph. I'm assuming 50+mph is the top end adjustment?
Edit: Still the middle bolt needs more weight it sounds like from what you said right? Not the end bolt?

 

[mbarryracing]

When riding in deep snow, the track is loaded way more and therefore pull the RPM's down. You might be good on RPM off trail but will run a higher RPM on the trail. The end "Tip" bolt on the weight will mostly effect RPM at the higher top end speeds where the weight is flung almost all the way out and centrifugal force is pulling on that part of the weight. The mid bolt is for the slower speeds.
My clutch engages around the same RPM and cruises the same as yours.