Primary Clutch Spring

[iasledder]

Likely an old subject, but still looking for an answer. My '06 ER has never reached 10k rpm. 9700 seems to be about max with 800 miles on sled. All stock. So question, is there a slightly stiffer primary spring that would rpm increase the wot rpm without overly raising the engagement speed. I see some suggest removing rivets from the weights, usually the inner most rivet. I have no idea what the rpm gain might be. Have doubts that this would result in 10400-10700 where I would like to run. Tried new belts and have the deflection set so the track just creeps on the stand. Thanks for suggestions.---Jim

 

[Yamaholic22]

How are the clutch temps? Are they real hot after running for awhile or can you at least touch them? Did the sled ever pull correct rpms? You have a problem with a clutch component or you aren't putting out enough power to pull the stock clutching. You can try a new primary spring but I highly doubt that is your issue with that little mileage. You should easily be able to pull correct rpm's with stock clutching with those miles if the engine is solid and nothing in the clutches is binding up. Personally I would tear down those clutches and see if all parts are there and seem to be ok. You could have a loose/missing cover bushing, sliding sheave bushing, helix bushing, or secondary sliding sheave bushing that could all cause binding. You may find that your primary spring is broken or out of free-length spec. Rollers/pins/weights may have a bushing worn or missing which could cause issues. Make sure secondary spring is set at correct twist and twisted in the right direction. How does the sled feel on a full throttle acceleration up to top end?

 

[iasledder]

Thank you. I have been thru all of your scenarios with no faults. The condition I have mentioned has been true since day one. The sled runs great and acceleration up to about 100 speedo is super, then slowly on hard pack gets to 120 (109 GPS). Like you I have thought of engine power or tachometer calibration. Not a real great concern as well as the sled runs. But looking for the best possible, if I'm not already there.

 

[dirkdiggler]

Why do you want to run at 10400 to 10700? That's out of the power. You should run no more then 10400. Trying to gain RPM by increasing the total force of the spring is not the correct way to do it.

 

[trailmarker]

just someting to think about, where does the belt come up to on the primary at full throtle, look at the discolouration on the primary to see ho high the belt goes. mine was over half inch down, but it revved to 10500 and was fast but only got 160kph dealer said it should go 190kph, turns out carb slides did not go all the way up. check carb slides

 

[welterracer]

Thank you. I have been thru all of your scenarios with no faults. The condition I have mentioned has been true since day one. The sled runs great and acceleration up to about 100 speedo is super, then slowly on hard pack gets to 120 (109 GPS). Like you I have thought of engine power or tachometer calibration. Not a real great concern as well as the sled runs. But looking for the best possible, if I'm not already there.

I wouldnt be complaining if i were you... My sled pulls the max rpms (ive even changed the secondary spring and machined the clutches and am running a 23T top gear) and i still havent seen more than 115 on the speedo (about 100 true speed) on a 1 mile run on a railroad bed..

 

[pro116]

welter havbe you evr checked your clutch alignment?

 

[welterracer]

YES.... i have the tool and everything.. my clutches are PERRRRFECT..

 

[RacerDave]

Why do you want to run at 10400 to 10700? That's out of the power. You should run no more then 10400. Trying to gain RPM by increasing the total force of the spring is not the correct way to do it.

I thought peak hp is at 10,700 to 10,900 ????

 

[MrSled]

Brian put the top stock gear back in.... I bet I can get your sled to do over 115 on the speedo

Bring that sucker up to Rib Lake for 1st ice.

 

[Iceman57]

Why do you want to run at 10400 to 10700? That's out of the power. You should run no more then 10400. Trying to gain RPM by increasing the total force of the spring is not the correct way to do it.

The power doesn't start to drop off until after 10700 on a stock engine. Look at the Dyno sheet from Excell for the testing of their pipe vs the stock pipe. The Excell makes power up to 10900 and then drops off.

 

[kviper]

Anything that will bind either of the clutches will result in over rev and or belt slip. If i were you i would get my tack checked and if it is ok i would replace both spring's. Fairly cheap and not a bad thing to do annualy any way. If it is over shifting, Spring's would be the first place to look. Also make sure all tuning component's are proper. Seems as though i recall some earlier Apex's got the wrong tune, Maybe some one else know's more on this. kviper

 

[grader]

install an orange-silver-orange spring in it, available at your dealer. this will raise the rpm to where it should be.