PSI Twins and a '95 V-max 600 Jetting/Clutching Suggestions

I have a 1995 Yamaha V-max 600 with PSI Twins.

Last season when I got the specs from PSI, they were for the 94-95 V-max. Only problem was that the 95 Max changed to the VX clutching system, and they are different clutches altogether. The specs are for the 94 sled with different clutches.

Does anyone have a recommendation as to what I should be running on this sled for clutching and jetting at 6500+ elevation? Also, the airbox is gutted, and I have V-Force II Aftermarket reeds on the sled. It is the long-track model with a 136" track, and I'm curious what gearing I should be using.

If anyone can help, I'd sure appreciate it.

Thanks for your help.

You can call PSI, I have heard they are very helpful

I called them, and they said they "couldn't find anything in their notes" about the 95 settings...

Right now I'm using the settings recommended from Yamaha on their GYT twins, which I heard are the same pipes as the SLP twins???

Ok, I think we will need some more info, since these are the new style clutches most of us should be able to help you set this up.

We need to know what you have in there now for parts, springs, weights, rivets, helix and secondary spring preload. Also what is your engagement rpm, shift rpm, and how do you feel it is backshifting in different conditions, hardpack and powder or when climbing.

Once we know what it is has and how it is running, it should be easy to tell you which way to go with the settings

But before any clutching make sure your jetting is right and that should be pretty easy by reading plugs and piston wash. Normally with pipes I will go up 2 sizes on the main and raise the needle one position and then run it and adjust accordingly.

The stock jetting for your sled at 6500ft is a 148.8 main jet and the needle in the #2 position, air screw at 1 1/8 turns out and a 52.5 pilot jet.


Gearing should be 19/39 or 18/39


Also my sister has a 96 Vmax ST 136" with twin pipes and I will be up her way later this week, so I will check what they have for clutching on that sled for you, her carb settings may not be much use for you since the 96 ST has the smart carbs.

WOW! That is awesome. Thanks KGMZ. I have all of the settings written down at home, and will post them tonight. This will really help a ton. Thanks.

OK, here's what I'm running...

Keep in mind, these settings are based on the GYT Twins, and I am running PSI Twin pipes.

Main Jets: 142.5 - 1 1/2 Turn Air Screw
Pilot Jet: 52.5
Jet neeedle Clip: 1.5?
Prim Spring: OR/PINK/OR
Weights: 8AB
Rivets: Aluminum Inner/Outer (10.3mm)
Rollers 15.6mm
Sec Spring: Red
Spring Twist: 70 Degrees
Torque Cam (Helix): 39 Degrees
Gearing??? 18/39

It shifts at about 81-8300 RPM Engagement is about 3900 RPM

The problem I am having with it is when I throttle from a stand still on Hardpack, or let off the throttle then apply the throttle again, I'm getting a major bog on the low end. It's slow to accelerate, but once RPM's get up to about 4000, it seems to run okay. Hill climbs are scary because I start to lose power at the top of the hill when I lose momentum and the sled will not backshift to reaccelerate enough to get the sled turned around.
In powder it does okay as I usually keep it floored. I haven't noticed much difference in powder.

Those settings again are for the GYT pipes, but the recommended PSI specs for the pipes I am running are as follows: (Keeping in mind that these settings are for the '94 sled with what I am told are different clutches...)

Weights: 8AY-40
Rivet: Aluminum
Primary Spring: PNK/PNK/PNK
Spring Shims: 3
Helix: 39 Degree
Sec Spring: Pink
Sec Setting: B-2 60 Degrees
RPM should be between 81-8200
Main Jet: 156.5
Jet Needle: 9FLZ4 3rd Pos?
Pilot Jet: 52.5
Airscrew: 1 1/4 Turn

So which of the above settings should I try to shoot for?

Should I switch to PSI's settings (even though the clutches are a little different) and make adjustments from there, or keep the GYT settings and make adjustments from where I'm at?

The problem I am having with it is when I throttle from a stand still on Hardpack, or let off the throttle then apply the throttle again, I'm getting a major bog on the low end. same problem i am having with my 1995 vmax 600 ,slp pipes

Hmmm... I hope it can be fixed.

jetting prob

could it be a rich or lean conditions with the pilot jet?? b/c by the sounds of thing u got it geared and clutched to climb mountains, lots of twist on helix with low angle = more revvs plus 18/39 gearing. its a tough call

i ride my sled at sea leval no mountians. when i let of the throttle then apply the throttle again, I'm getting a major bog on the low end,takes along time to get going again "getting revs back up" MAJOR bog. getting ported and poilished now at bender hope this will work.slp pipes ,vforce reeds,the right jetting for the pipes ,and a bender clutch kit ?cant under stand it

The bog is from the secondary not backshifting fast enough. Common on those Vmax's and Vmax 4's... It's not jetting

Check out this thread. I'm very close with this setup. I'm not even sure I can get anymore out of her. I'm at about 1,000 feet.

sounds to me like the seconday spring is wound a hair tight.