m7 not pulling rpms

[dgreet77]

So I got an 05 m7 that isn't holding the rpms it should be. When i first got it it would hold at about 8020, which is what it should be, due to some port work and rkt head. Well long story short the rollers and weights flat-spotted but even with that it would hold 7800 rpms, well the sheaves were also worn, so ended up just replacing the whole clutch using the same spring and same size weights, and now it only holds at 7740. Seems to engage really high also, a little over 4000. I think the belt deflection may be a bit off as the belt isnt riding above the sheaves on the secondary but is damn near flush, so not off by too much....

Primary spring is orange/white
65g weights
Secondary spring is white with the stock 36 helix.

Any thoughts?

 

[mtn_extreme]

Sounds like maybe it is time for a new belt.

Also keep in mind that springs do wear out and get weak.

 

[dgreet77]

Thats the neat thing. When they replaced the clutch they threw my spare on, which was a brand new AC belt, so i figured maybe it needed to be broke in....put 100 miles on...still no change......

 

[slomo]

what altitude?and have you tried adjusting your secondary spring adjuster a little to gain some rpm's

 

[snoschu]

I had similar problems with my 05 after I put on an RKT head. Wouldn't pull the rpm's like it used too, lost about 250-350 rpm's.
Found out with mine, if I let off of the throttle a little (about 1/8 maybe) my rpm's come back immediately and it runs great. I still don't know why and I'm still working on it. I have talked to RKT about it a little and he gave me a few things to try.
Anyway give that a try. I would be curios to know if you have the same results.

 

[dgreet77]

runnin up in the snowys, so 8-10 i suppose. And to be honest I am not positive how to adjust the secondary spring, so no, did not do that, point me in the right direction?

And I'll have to try the throttle thing, although it was pulling them before, just lost it after the clutch issues, so this is why i doubt it is an engine thing.

 

[dgreet77]

ttt looking for more suggestions?

 

[winter brew]

Adjust the secondary spring tension. That white ring will back out all by itself, needs a set screw through the aluminum cover plate to keep it from rotating ....which cause loss of RPM and backshift.
If I remember correctly it should be about .5" from the outer surface of the cover plate to the flat of the adjuster ring (not the raised ribs)...then adjust from there as needed but not more than .6" or you can get coil bind.

 

[ACMtnCat]

Belt deflection is pretty crucial. If your deflection is off you'll have a number of different problems/symptoms. Get the deflection set so the belt almost squeaks when you stop and idle, then you can start adjusting the secondary spring to gain some rpm's. Maybe a gram less on the weights.???

If that doesn't work/fix the problem, then you need to start looking real close at both clutches for any hang-up, flattened roller, sacked/old springs, dirty belt/sheaves and stuff like that.

 

[Photomaker]

I have a 05 M7 also but all stock (head, pipe, etc.). Does the RPM's go higher then fall back. Watch as you are giving it full throttle, it may peak higher then fall back. It is important to match what rpms the primary will pull (with your engine mods and at the elevation you ride), with what the secondary will allow (by controlling the speed it shifts out). If you are riding in the mountains it is more desirable not to have the midrange shifting out to quickly (this creates a faster acceration for drag racing but makes the sled bog on step hills). Finding the correct amount of upshift that allows backshift and also track speed is the trick and in general you control this with the secondary spring tension. If you shift out to quickly then you tighen the spring tension, to slowly then loosen the tension. So you can control some rpms through the secondary but the real function of the secondary is to control the rate it shifts out. As you increase the tension in the secondary it will slow the shift out and increase the backshift (both favorable to mountain riding) which will increase the rpms if the primary has the power to do so. If the RPM's go higher then fall back your spring tension is too much in the secondary, simple loosen the tension by turning the plastic plate out. But remember now it will also shift out quicker so this may not be what you desire. Your other choice is to decrease the primary clutch weights to bring up your desired RPMs to match your current secondary setting. Sorry for such a long winded explanation but if understand the funtion of the clutches you will be able to fine tune to you riding style, elevation, etc.

I personally ride from 7000 to 9500 feet. Here is what works for me. I started with 68 gram weights and ground them down to 63.5 grams taking most of the weight off the tip area (taking most of the weight from the tip helps the midrange which is great for boondocking and general mountain riding.) The primary spring is the yellow-white (stock spring). The secondary spring is also stock but I have tightened it to slow the shift out. I have also added a shift assist plate in front of the spring so that the secondary spring does not bind from my increasing the tension. I pull 8100 now where as originally from the dealer I was pulling 7600. I have great backshift and midrange performance which M7's are notorious for not having.

Hope this helps.

 

[dgreet77]

Thanks for all the input guys, I will have to fiddle with the secondary next time I go up, the only thing that really gets me is it was holding 8020 like a dream before the rollers flatspotted. Then even with that it would hold 7800 pretty consistently. Now after a new primary clutch I am holding 7740 right on the dot. Seems to me a new clutch with the same setup should have put me right back to 8020, is that wrong?

The RPMs seem to kind of creep along and then bounce a bit before settling on 7740, no real jump above then settling back in that I can tell. Whatever that all means. haha

 

[SnoPro753]

I am having the exact same symptoms as you are. I have been reading up on this for a while now. Everything I have read says to ditch the white secondary spring and go to the orange. Take that for what it is worth. I am thinking I need to replace my rollers.

 

[Photomaker]

As the rollers on the primary clutch wore or flattened they kept the primary clutch weights from fully shifting out -this would cause your rpm's to increase. It should have also decreased your top speed. The new clutch is shifting out properly. I would first try increasing the spring tension in the secondary by screwing in the white plate a full turn (you will need a special wrench to do this). This will slow the shifting out. If this doesn't help then you will need to decrease the primary clutch weight.

 

[SLEDIOT]

Sounds like maybe it is time for a new belt.

Also keep in mind that springs do wear out and get weak.

X@ also check yer spider for cracks, this will cause some issues while under torque. Sometimes you cant see the cracks when its shut down but under torque they will open right up. Been there done that.........

 

[dgreet77]

So I was just out messing with things, checking them out and all, and I thought I'd go ahead and tighten the big white nut/plate for the secondary spring tension; well it was pretty much clear out and all but touching the inner side of the cover plate. So I screwed it in a bit, a turn or two, but its still probably not 1/2" from the outside of the cover yet. I will let you guys know if that helped next time I go up.

Also does anybody know the size of the nut that holds the secondary on just off the top of their heads? Thought I'd go buy a socket and ratchet for next time I go up to mess with deflection a bit. Any other thoughts/tips on getting to the spacers in there to help adjust the deflection?? Thanks and will keep everybody updated.

 

[Photomaker]

I upgraded to the Black Diamond deflection kit. Using this you have infinite adjustment of the belt deflection instead of using the washers. You throw away the stock plastic piece and get a new aluminum one. You also get a new secondary bolt that uses an allen wrench that is included. Here is the link so you can check it out.
http://bd-xtreme.com/search.aspx?find=belt+deflection

You will need the left hand thread for the 05 M7.

 

[superfast]

I upgraded to the Black Diamond deflection kit. Using this you have infinite adjustment of the belt deflection instead of using the washers. You throw away the stock plastic piece and get a new aluminum one. You also get a new secondary bolt that uses an allen wrench that is included. Here is the link so you can check it out.
http://bd-xtreme.com/search.aspx?find=belt+deflection

You will need the left hand thread for the 05 M7.

Well how does that work because I have the bdx belt deflection adjuster and still have to use the washers with it or my clutch will float on the shaft do not ask me why but that is what happened to me