240-270 MCX clutching and drivebility question

[cscherer]

This is a great thread....thanks to those that have imputed here...

What year is your nytro Dave.

 

[moyiesledhead]

Took three guys to put the belt on too. GAWD!

Stop off at C Tire and pick up one of these. Makes belt changes eezy peezy. Just wrap it around the helix and give it a twist backwards. Clutch opens right up. I've been carrying one in my sled for years.

edit: Actually I've replace it probably 4 times 'cuz it seems to get pilfered every time I bring it out to change someones belt for them!

 

[Nytroman]

Ran the 8BU fully loaded and blue white blue primary spring, green cat secondary and 44 degree worked great at 12lb for 3 seasons. Wanted to run 15 so went to dalton weights and got talked into shockwave. Couldn't sled for a while so haven't got a chance to dial it in but not liking hearing to use the shockwave I just bought as a door stop lol

 

[DaveB]

This is a great thread....thanks to those that have imputed here...

What year is your nytro Dave.

It's an 08. I can report back that the clutching is VASTLY improved. Thanks again Neil! Very snappy, great backshifting.

The only (maybe) issue is a harmonic or buzzing at zero load/slight decel at low speeds 5000rpm. Doesn't do it when you are under any load or clamping on 'er, but just toolin' around kinda downhill in and out of the throttle you can hear a buzzing rattle as the RPM passes through 5000 or so. Maybe I am being picky as it is obvious the Yammy clutch rattles and clanks like no other clutch I've ever heard...I'm told this is normal. I'm going to look into it this week...maybe a roller is toast or something...? I'm not even sure it's in the clutch...might be something else....but I never noticed it before.

 

[DaveB]

Rollers feel OK and don't appear worn. The Bolts that hold the rollers in place all move back and forth about a mm or so....this might be the buzzing?

 

[DRD]

So, like it enough now that it's not an exercise machine it'll stay around for a bit?

 

[NM]

It's an 08. I can report back that the clutching is VASTLY improved. Thanks again Neil! Very snappy, great backshifting.

The only (maybe) issue is a harmonic or buzzing at zero load/slight decel at low speeds 5000rpm. Doesn't do it when you are under any load or clamping on 'er, but just toolin' around kinda downhill in and out of the throttle you can hear a buzzing rattle as the RPM passes through 5000 or so. Maybe I am being picky as it is obvious the Yammy clutch rattles and clanks like no other clutch I've ever heard...I'm told this is normal. I'm going to look into it this week...maybe a roller is toast or something...? I'm not even sure it's in the clutch...might be something else....but I never noticed it before.

There is a chance it is just harmonics. The clutch setup is pretty aggressive and really tends to hold rpm. It promotesbquick throttle response and good backshift though and on/off throttle is very responsive.
One thing you and every yammy guy should check though is the jackshaft and driveshafts bearings. Neither of them have grease nipple so we pull the dust cap off a couple times a season and repack them. It only takes a few minutes and can save a weekend and even a helicopter ride.
I have seen dozens of Yamaha's with these bearings piled up. They are good bearings, but do need a little tlc once in a while.

 

[cscherer]

Not that I have clutching issues, but rather like to try new set ups all the time, would this work on an 2010 nytro alpine kit? 14lbs? Rearmount? Wondering what you set up you had this on Neil.

Cheers.

C

 

[Nytroman]

There is a chance it is just harmonics. The clutch setup is pretty aggressive and really tends to hold rpm. It promotesbquick throttle response and good backshift though and on/off throttle is very responsive.
One thing you and every yammy guy should check though is the jackshaft and driveshafts bearings. Neither of them have grease nipple so we pull the dust cap off a couple times a season and repack them. It only takes a few minutes and can save a weekend and even a helicopter ride.
I have seen dozens of Yamaha's with these bearings piled up. They are good bearings, but do need a little tlc once in a while.

Good call on the Bearings! I pull mine and repack or replace everyfall on both the jack shaft and the drive axle. And find one almost evertime that requires needed attention. Surprisingly the upper chain case bearing even in the oil seems to get moisture through the oring and is not unccommon to find a rusty looking residue in it

 

[Thistledoo]

yup its the 3cyl harmonics. You can shim the spider to make it better but it will never be totally gone. If you put that clutch onto a 4cyl it will be dead quiet. We have tried it and its quiet lol

run 15lbs and dont worry about the rev limiter on the trail, clutch it for deep up top and ride her!!

 

[Tuesday]

yup its the 3cyl harmonics. You can shim the spider to make it better but it will never be totally gone. If you put that clutch onto a 4cyl it will be dead quiet. We have tried it and its quiet lol

run 15lbs and dont worry about the rev limiter on the trail, clutch it for deep up top and ride her!!

Exactly what TD said. Apex is whisper silent in comparison. Clutch it and ride the snot out of it.

 

[Barry Barton]

Check fuel pressure at idle. Should be 44 lbs.
We gap plugs at 22 thou.
Need Dalton DTYA-2 weights with base of 73, blue brown blue or blue white blue prim spring.
Take shockwave off an use for doorstop, order new slides for secondary.
Use 47 degree straight helix an epi cat purple spring.
I have everything in stock if interested. I know of at least 20 Nytros running this setup and all work great. Will save belts too.

do u have any information on a s/c apex stage 1 mpi running stock weights 75 grams pink/blue/ pink spring with a purple secondary with a shockwave any information would be great

 

[NM]

do u have any information on a s/c apex stage 1 mpi running stock weights 75 grams pink/blue/ pink spring with a purple secondary with a shockwave any information would be great

I would clutch it similar to the Nytro, but use a different helix because of how explosive the Apex power comes on. It will help you stay off the rev limiter when hammering the throttle, yet backshifts great.
I have them in stock.

 

[Barry Barton]

I would clutch it similar to the Nytro, but use a different helix because of how explosive the Apex power comes on. It will help you stay off the rev limiter when hammering the throttle, yet backshifts great.
I have them in stock.

whats your phone number so we can talk Barry

 

[Barry Barton]

You're about 1000 rpm low. I'd back the shockwave down and get rpm's up. Weights are heavy, may need to go a bit lighter. The most common setup for 240/270 kits is 8bu's with both rivets, blue/white/blue, cat green in the secondary and a straight 47 or 49 or shockwave.

I had 8bu weights in my apex but why would u bring the weights on the sled down instead of up like they recomend. the 8bu weights are 61 grams and my stock weights in my apex are 71 grams so what I did was added weight to the stock weights and took them to 75 grams with a purple spring on the secondary with a 45degee helix but it would come out of the hole like a rocket and fallon it's face when u hit the deeper snow.

 

[Bigbragg]

Sweet.
Thanks for the link.

Stop off at C Tire and pick up one of these. Makes belt changes eezy peezy. Just wrap it around the helix and give it a twist backwards. Clutch opens right up. I've been carrying one in my sled for years.

edit: Actually I've replace it probably 4 times 'cuz it seems to get pilfered every time I bring it out to change someones belt for them!