93 rpm

H

Hammer Down

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Apr 13, 2013
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Rpm at full throttle was 92-9300 and bouncing off the rev limiter. I swapped belts and it came down to 8800-9000. What rpm should I be at? The sled is stock 750 with psi pipes. I have Yammies fast trail clutching with 800 secondary(49-43) and blue spring.
 
Stock 1993 Vmax4 750:
-RPM with 1993 PSI quads = 8250
At 8250 hp peaks at 160 then the hp starts to drop off rapidly only making 155 at 8500 and only 143 @ 8750.
These pipes were quick on the Vmax4s as they built their power at a relatively low rpm.

Further info:
Stock = 140hp @ 8000 rpm
Bender twins = 151 @ 8250
PSI twins = 154 @ 8000
Aaen quads = 160 @ 9000
Bender Quads = 164 @ 9000
 
Ok. So rpm is too high. How do I get it down another 500rpm.? My clutches are to spec as far as offset and center to center. Engages at 4200 rpm. Lots of track spin even with new 3/4" track and new gold diggers(192).
 
Hammer Down said:
Ok. So rpm is too high. How do I get it down another 500rpm.? My clutches are to spec as far as offset and center to center. Engages at 4200 rpm. Lots of track spin even with new 3/4" track and new gold diggers(192).
Click to expand...

Engagement RPM is good.
You are going to have to increase your primary weights by @ 14% each to bring the rpm down from @8900 to no higher then 8300. You can either do this by adding heavier rivets or changing weights. You may also require a primary spring change.
IF the PSI quads are the 93 trail version and your tach is correct your current clutching is quite far off and you have huge potential to increase performance.
 
What is the stock rev limiter set at? If I am hitting the limiter at 92-9300 rpm, does this indicate an accurate tachometer reading? No sense in tuning clutches if the tach is off. I am also fairly certain I have the trail version of the psi quads. I also switched out my worn out primary for a low miles 92 primary that may not be stock.
 
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The stock cdi stopped the engine from reving much above 9000 so I would say 9200 is a reasonable limit.
The 750 cranks needed to be welded for high revs, thats why PSI kept their pipes revs low.
Sounds like you definately need to dial those clutches in for your application.
 
Thanks. Looks like my tach is accurate. I have an extra set of weights off the original primary that are 89A10. Could I swap these to the (new)92 primary an expect the same rpm as with the original primary? Maybe worth a shot since I already have them.
 
try and back secondary twist off slightly. if thats a 800 secondary, drop it to 3-3 also you can try different helix. 45 finish angle would be better. these are only Little help though, your way off. you need to take weights out and add weight to tip. thats a great set-up but tuning always comes into play. 3:16 (YAMMIE TONY)
 
Is there a list of Weights and there corresponding weights.? Also, if I decide to change rivots, do I just drill old ones out? What is the best way to remove and replace rivots? It seems like it may be easier to just swap the actual weights for heavier ones.
 
Does anyone know if the heel clickers off a srx primary will fit(work) on a 92 vmax4 primary.? I've got a set laying on the shelf.
 
The weights are 89A10. They had no rivots in them at all. They weighed 48.8 g. I had an old set off the original primary. They were also 89A10. They had rivots installed and weighed 55.2 g. This brought my rpm down to about 85-8600. Should I still go heavier on the weights or should I try changing the twist on the secondary?
 
YAMMIEGOD3:16 said:
Back secondary twist off slightly. Running those weights emptie with nothing in them caused this over rev lol 3:16 (yammie tony)
Click to expand...

I am no clutching expert but I would concur with Tony's assessment of the weights. I have a 92 here with a complete Bender 880 trail kit in it from back in the day (cylinders, heads, pistons, pipes, DI, clutching, gearing, etc)

It is supposed to run at about 9200. It has 89A10's in it loaded with aluminum rivets in both holes. No rivets on your setup just isn't enough to do the job.

opsled
 
12-18" of snow and rpm will still climb to about 86-8700 rpm. Do I need a surface to hook up on. Track is definitely spinning on top of the snow.
 
Ok i changed it from 6-2 to 6-1. I tries 3-3 first but the belt sat very low in the secondary so I went to 6-1. It brought the rpm down some more 8400. I noticed after the spring was out the movable sheave had a lot of slop/play in the bushing on the jack shaft.About a 1/4". Is this acceptable.?
 
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