670 clutching

[prairieguy]

i have a 670 with a revers secondary i just installed a 50 deg helix and i am having problems hiting top RPM also backshifting. i have a yellow spring and have tried it tight as it goes and half way and it takes off good but does not pull hard mid range. its geared 21- 39, i have a 136 inch track. i was wondering if i have the wrong spring? primary is on 3

what are you guys runing in your 670's?

i'm 2500ft

thanks
joe

 

[winter brew]

Gear down to a 19t on top, clutching a 200/320 294 ramps, 47*helix with either Doo beige or Goodwin blue at 14-16lbs of pull, as much weight as it will pull...I ran 19g at 3-6000ft on a SummitX.

 

[prairieguy]

what about a EPI maroon spring anyone try one?

 

[prairieguy]

i got a new maroon spring and put it in today and could not get my 79-80 rpm i don't know what to do i even turned the clutch up to number 6 possion and tightened the secondary to over 22lbs and all i can get is 7400rpm. this is all what i've done so far, i have a 21-39 gears and 50 deg helix and a EPI maroon spring. the secondary i'm running is a rer of a 500 fan thats what was in the chassi when i put my 670 into it. could it be a problem with my belt? the belt looks good and still sits nice. when i was running the 500 gearing it was 17-44(only 11 wide tho) with a yellow spring and stock helix and i could pull over 8000 rpms easily. with the changes that i've made maybe do i have to changes the ramps in my primary now?

anyone have a clue?
thanks
joe

 

[skidoome]

Brew gave you a good starting point and his set up will work well with your sled. 19-39 with stock drivers is 1.85 assuming you will reach full shift out with the tra primary you could see 102.11 mph.... Do you really want to go 102 mph?

19-43 gearing is a better choice for keeping belt temps down and will still let you go "fast". 92.61 mph.

How much primary weight do you have? At that low elevation you should be able to pull 16-19 grams pretty easy.
I have 16 grams in and ride at 9000 feet but the sled is not stock.

 

[prairieguy]

hey skidoome
your saying my problem could be with my gearing running 21-39 1.86
stock 99 summit x is 21-43 2.05 8000rpm @ 83.9 mph
98 summit 23-43 (i was told not good to run two odd numers) 1.87
97 summit 23-44 1.91
brew's 19-43 2.26 8000rpm @ 74.2mph

i only have a 136 track next year i might go bigger but do you think with running such a high top sprocket and low bottom sprocket is giving me my problem finding the rpm

do you thin brew's 19-43 is still a good ratio to go with?

 

[skidoome]

I don't think the gearing will be a fix for all the rpm's but it will help. brew's suggestion of 19-43 is a good one and if your only running a 136 then your should be fine with the 19-43.

Without knowing what you have in the primary it is hard to tell you one fix for the rpm issue. Once you get the primary apart let us know what you have and we can give you some good advise.

I like the

200-320 primary spring
lightened arms ( i made them )
14-16 grams of weight ( will be different from sled to sled )
294 ramps. ( stock 287's weren't bad just not as good as 294's )
clicker 3 at 9000 feet but I ride from 5000 to 9000 so I can go down to clicker 2 or 1 when I ride at a lower elevation.

secondary
44 straight in the secondary with the beige skidoo spring set at 14-16 lbs. personal preference.

hope this helps

jon