may have figured out my rpm problems

[sledneck_03]

bought my 08 700 rmk back in fall 08, had the black/white 140/320 spring in it and am running 64 gram weights and a ultimax belt. would only see 7900 rpm. guys i know same sled are running 66s....

I put a 160/320 in it to have some fun and thought a fresh spring should wake up the rpms. NO

just checked my sled is suppose to have a 140/330!

not a huge difference but im going to put a 140/330 and see what happens.

i adjusted my clutches and got my 8100 back but still running 64s....

So im guessing the grippyer belt the 10 less lbs on top is accounting for the rpm drop and the reasoning why im running 64s.

whats the difference in running say a 140/310 spring with 64s and a 140/330 with 66g weights???

 

[shmuckaluck]

Hey guys,
I have a 08 700 dragon 163, ported, slp pipe muffler, reeds, head, 62 weights. I can't get it run over 7800 rpm's. I figured after the porting I would need to go heavier on the clutch weights but it's just not pulling over 7800, would like to see 8100 or 8200?

 

[sledneck_03]

What elevation?

 

[sledneck_03]

Well everything was all well until I just looked at my spare weights and realized I have 60s in my sled at 1200 ft reving 8100 rpm? Wtf I'm suppose t be running 66s. I had 165/320 primary spring, stock everything else, and 18/43 gearing.

I just changed my spring to a stock 140/330 and my gearing to 19/41.

I'm going to try it out Saturday but all I can say is what the hell? Seriously why is this happening?

 

[chunkysoup]

I would stick the weights in there that you should be running for your elevation then play with springs to get your rpms. may need a different helix or spring in the secondary too. Give that a try and report back so we can get a better idea of whats happening.

 

[sledneck_03]

Well ill try my new spring. And see how it runs. I can go to the slp blue pink.

 

[sledneck_03]

I compression tested it and its 120 warm both sides so I don't think I need to freshen the top end. What about fuel filter? Haven't changed it for a while? Can't see it under powering motor.

 

[chunkysoup]

May want to change the fuel filter and check the lines in the tank. I just put all new lines in mine cuz they were crumbled on the bottom of the tank.

 

[diamonddave]

Hey guys,
I have a 08 700 dragon 163, ported, slp pipe muffler, reeds, head, 62 weights. I can't get it run over 7800 rpm's. I figured after the porting I would need to go heavier on the clutch weights but it's just not pulling over 7800, would like to see 8100 or 8200?

Who's porting and head package did you go with?

Are you running a fuel controller?

Depending on the answer to the above questions, a fuel controller may help, in fact, if you don't have the Carls porting/head package, a fuel controller would definately help. Carls reflashes the ECM (used to a couple of years ago anyway) with their package.

What gearing ?? what helix?

Recovering Lost/low RPM's can sometimes be difficult. I would install new springs in the drive and driven. Keep the stock spring rates. Sometimes we found not having enough weight (load) on the clutches will cause low RPM's. Or if your gearing is too low, same thing.....not enough R's.

We also found low R's caused by full throttle mapping being too fat. A power commander is a must have on ALL CFI's from 07-10 IMO.

We have also found if all of these things have been addressed and still fighting low R's......loose piston to cylinder clearances have been culprits. Yes, it happens in 700's also.

 

[sledneck_03]

May want to change the fuel filter and check the lines in the tank. I just put all new lines in mine cuz they were crumbled on the bottom of the tank.

I just bit the bullet and bout a 115 belt for $200. I was running ultimaxes, friend of mine was running them in his xps and had rpm trouble too, hope in some weird way this fixes the issue.

 

[TheBCSledder]

I compression tested it and its 120 warm both sides so I don't think I need to freshen the top end. What about fuel filter? Haven't changed it for a while? Can't see it under powering motor.

Remember, the compression doesn't always mean the engine is good. I was testing at 120 on my 08 800 dragon, and my sled was under powered and not sounding and acting like it should. After changing the fuel filter without success, I pulled it apart, and I caught it just in time. I almost had to re plate mag cylinder, and potently worse!

 

[MARV1]

1115 belts are worth it, 1122 if you have to which is a bit softer. And yes, time for a rebuild, 120 is low.