I ordered a new primary spring for my Apex mountain from the local dealer it was supposed to have more preload but it is shorter that the original yellow-pink-yellow and after installing it I didn't notice any differance in rpms at take off and the sled was would start missing at take off sometimes so I put the old spring back in and stretched it a little I gained about 500 rpms by doing that but what I am wondering is what spring does the Apex use, the dealer doesn't know and I dont think a shorter spring is going to give me more preload I would like to find a good gearing and clutching setup for climbing. Any help would be awesome,
Wakegod
Pro
Talk to MPI, they have a good assortment of Yamaha clutching parts.
I bought a spring there last year and it was shorter than the one I had. I bought some spacers to to make up the difference.
I bought a spring there last year and it was shorter than the one I had. I bought some spacers to to make up the difference.
BlgsRX-1mtn
TY 4 Stroke God
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Your stock spring has a pre-load of 30 a 2.50 rate with a total force of 113. For more pre-load (35) with the same rate and a total force of 118; you will want the Yel-Sil-Yel primary spring. This will give you some more RPMs. Stock gearing looks to be 20-40 for a 1.89 ratio (according to MPI). Maybe go to a 19-40 ratio for a 1.99 ratio to keep the revs up.
I'm not sure what your seeing now and what you want to achieve.
Edit; By the way, here is a thread with the APEX clutch chart where I got the info from. It gives you the stock clutch settings from Yamaha for different elevations. http://www.ty4stroke.com/viewtopic.php?t=32179
Jim
I'm not sure what your seeing now and what you want to achieve.
Edit; By the way, here is a thread with the APEX clutch chart where I got the info from. It gives you the stock clutch settings from Yamaha for different elevations. http://www.ty4stroke.com/viewtopic.php?t=32179
Jim
I am looking to get more bottom end for harder launches and better climbing performance especially when I am climbing in trees and I have to vary my speed and I need to get power to the ground quikly.
rideblue
Expert
try 19 - 42 gearing, 70 link chain and a preload shim or two in the clutch.
I ordered 18-42 gears so I could keep my stock 68 chain and a spring with a preload of 35 I will try this out and see how it works if I have to I will go back to the stock spring and use shims. Just depends on how she launches, and pulls while climbing.
Frostbite
TY 4 Stroke God
I think Jim is right. A yellow/silver/yellow is probably what I'd put in too.
BUT.......................
I may be a bit out of my realm of expertise over here on the Apex side but here's my basic theory on clutching.
I was told by a very wise (hill climber and boondocker) to throw as much weight at the clutches as possible to LOAD the motor and make it work for peak RPM. From what I have seen, if I don't really load the weights the sled will still pull the proper RPM but it just doesn't seem to PULL as hard.
I have tried many Yamaha and Dalton primary springs on my RX-1M. It make power very comparible to the Apex and I can say without a doubt that my sled likes the 142 total force Orange/Silver/ Oranage Yamaha primary spring the best. It's got a slightly higher preload of 35 for a little stronger take off and 3.25 spring rate whxih won't allow the clutches to shift up quite as quickly.
I think the reason why is simple. The higher the total force the more wieight you can throw at the primary before the spring compresses completely. By employing this method it sure feels like my midrange is stronger too.
Heck, I even use three Yamaha spring shims to get a little more out of the spring.
You might want to give it a try. It just might cure what ails you.
Best of luck
Frosty
BUT.......................
I may be a bit out of my realm of expertise over here on the Apex side but here's my basic theory on clutching.
I was told by a very wise (hill climber and boondocker) to throw as much weight at the clutches as possible to LOAD the motor and make it work for peak RPM. From what I have seen, if I don't really load the weights the sled will still pull the proper RPM but it just doesn't seem to PULL as hard.
I have tried many Yamaha and Dalton primary springs on my RX-1M. It make power very comparible to the Apex and I can say without a doubt that my sled likes the 142 total force Orange/Silver/ Oranage Yamaha primary spring the best. It's got a slightly higher preload of 35 for a little stronger take off and 3.25 spring rate whxih won't allow the clutches to shift up quite as quickly.
I think the reason why is simple. The higher the total force the more wieight you can throw at the primary before the spring compresses completely. By employing this method it sure feels like my midrange is stronger too.
Heck, I even use three Yamaha spring shims to get a little more out of the spring.
You might want to give it a try. It just might cure what ails you.
Best of luck
Frosty
I have noticed that rider weight also plays a big role in rpms. A friend on my sled gets 3-400 more rpms than I do on my sled.
I finally got the right length spring but I cant seem to find the gearing I want, I tried a 19/42 setup and the chain wont fit, will an 18/42 work with the stock chain. Ulmers website says that the 19/42 should fit with a 68 chain ( I think thats stock) but it didn't fit on mine I really dont want to have to buy a longer chain. I have ordered gears three times and will be ordering again tomorrow. What about a Team Hyvo sprocket that is 18 t will that work on my Apex.
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