Low Engagement HC 2-Speed Apex Set Up Info

[VX1R]

In the past few years I've tried the HC Drag 'N Fly's and also the Bender Racing Super Rats. I've had good results running both of them, but wanted to give the the HC 2-Speeds a try this year just to try something different. I did a search and thanks to a lot of fellow TY members who posted their HC 2-Speed set ups I was able to get mine dialed in pretty close right from the get-go.

I've been trying to find a nice and smooth low engagement set up to run since I do a fair amount of off-trail riding, but mainly trail running. My current sled set up is a '06 Apex GT that has a XTX 144" suspension with a 1.5" lug Camoplast Crossover track.

From my previous experience with the Drag 'N Fly and Super Rat weights I knew that any of the HC springs were going to give me a higher and harsher engagement than I wanted. I found a fairly recent posting by TY member Yamahahaapex that mentioned that he found the Yamaha Orange-Pink-Orange spring to give a 3500 engagement speed vs. a 4200 engagement using the HC black spring with the 2-Speed weights.

The O-P-O spring was where I started. Just as Yamahahaapex had found, I was moving out between 3500-3600. In my spring collection I also have some of the old Yamaha short springs that were used on the pre '98 era sleds. I tried the short O-P-O spring next. I figured that the shorter spring should engage lower. This short spring has the same preload and spring rate as the newer style long spring and virtually the same total force (135KG short spring vs. 137KG long spring). The short spring overall length is 74.6mm vs. 82.6mm for the long spring.

Installing either the long or short O-P-O Yamaha springs requires considerably less effort to bolt on the clutch cap compared to any of the HC springs. When installing the shorter spring you hardly need to compress the clutch cap at all to screw in the six bolts.

With the O-P-O short spring I now had the sled moving out at a nice smooth 3200 rpms and did not have to change the weight distribution placement at all on the 2-Speeds compared to my initial set up using the longer O-P-O spring. I ran this set up both on trail and off trail last week. I put on 450 miles and it was very consistent in varying snow conditions.

I just wanted to share my recent tuning experience with the HC 2-Speeds. Not everyone is looking for this type of set up but if you're a Apex rider that wants a smoother take off without breaking the track loose with the strong low end pull that the HC 2-Speeds give you, I'd give this spring a try.

For anyone who's not real familiar with the Yamaha springs, the long springs have the three color coded marks in a horizontal position on the same coil of the spring. The part number for the O-P-O LONG spring is 90501-601L8-00. This spring gives an engagement of approx. 3500-3600rpm with the HC 2-Speed weights.

The short springs have the three color coded marks in a vertical position on three coils of the spring. The part number for the SHORT O-P-O spring is 90501-605J5-00. This spring gives an engagement of 3200 rpm using the HC 2-Speed weights.

The best set up that I found for my liking was using the short O-P-O spring with two washers and one bolt in the shoulder of the weight. I also installed a 3/8" long stainless steel set screw in the center hole of the weight. These set screws do not come from HC with the weights, but you can really fine tune the rpms using them. I picked them up at a hardware store when I was dialing in the HC Drag 'N Fly weights a few years ago. The 3/8" set screws are a 1/4" -28 pitch. When I weighed them on a digital gram scale they came in at 1.2 grams. I used the stock 14.5mm rollers. The secondary was set up using a White-White Yamaha spring set at 3-3, and the stock helix. Like I had mentioned, this set up gave a nice smooth take off at 3200 rpm and a top running rpm of 10,600.

I did not have a chance to try this on a long lake stretch to let the sled really stretch it's legs on top end. All of my running was done on mostly hardpack trails, with some loose, fresh snow from day to day. We were out to have fun riding, and not spend a lot of time changing things. I found the top running rpm to be very consistent from day to day and as conditions changed the rpms stayed the same. I checked the clutch sheave temps whenever we stopped and found them slightly warm to the touch, about the same temps as running the stock weights. My belt wear has been great. I'm hesitant to say what the top speed was on the "dreamometer" since I wasn't testing in controlled conditions, just running on groomed marked trails. All I'm going to say is on a straight stretch of trail that I'm familiar with and had run previously in the day I got up into the triple digits in a hurry and still climbing until I had to throttle down due to running out of straight trail. I was impressed with the acceleration and top speed pushing the 1.5" lug Crossover 144" track on my sled.

I like these HC 2-Speeds.

I'd be interested in hearing from anyone who trys this set up in your Apex and see how it works out. Since I'm running a '06 with a 144" track this set up might need some slight tweaks on a newer Apex or a shorter track sled, but it should give you a good starting point.

Cheers.

 

[80h4thephaze]

Ha in the process of dialing in my 2 speeds. Good to hear that multiple people are having success with the o-p-o spring, sounds like that will be in my future. Did you ever weigh that bolt you have in the center?

 

[VX1R]

Ha in the process of dialing in my 2 speeds. Good to hear that multiple people are having success with the o-p-o spring, sounds like that will be in my future. Did you ever weigh that bolt you have in the center?

It's actually a set screw in the center hole.

1.2 grams.

 

[yamahahaapex]

see ive got a 2.0gram screw in the tip with my pcv to hold me at 10,800 on good conditions. the other weekend i could only get 10,500-10,600 and i know with the '11s and up being closer to 10,800 is where you want to be and im thinking with my belt having 3500kms of hard testing since new that it was sitting a hair low in the secondary so shimmed it up to just above so maybe that contributed to lower rpms that day since it was around -15c,

if i know its going to be an all powder day with the 2g in the tip i replace it with a 1.5g screw to get rpms up to 10,400ish in heavy powder. 2gs and im around 10rpm

 

[yamahahaapex]

its interesting you have your weight in the centre. sure would like to line up with you to see any differences and test for an afternoon

 

[yamahahaapex]

its hard to compare the rate and force of the hc black compared to o-p-o but its damn close. One thing i did notice was the black hc made me spin way to muc off the line but once i hooked up it pulled harder than the o-p-o. Top end rpms were closer to 11k rpms compared to o-p-o so missing 3-400rpms on top is going to hurt for sure

With the -5c to -10c highs were having im going with the 1.5gram in the tip to give me a bit more on top to compensate for warm air, looser trails and heavier snow.

 

[BETHEVIPER]

posting to watch this. thanks for sharing. I have a couple sets of these and havent had time to try them. have a set of dragon flys right now

 

[VX1R]

its interesting you have your weight in the centre. sure would like to line up with you to see any differences and test for an afternoon

It would be nice to get both of our sleds together for some test and tune.

How about you get your butt out of Saskatchewan and down to Minnesota?

Just kidding, but I wish I had someone local that I could test and compare results with.

Thanks again for posting your initial finding using the O-P-O spring. You really helped me getting a initial set up to start with.

I don't think that we'd even be having this conversation without Turk's initial testing and sharing with us of his findings on the 2-Speeds a few years ago. It just feels funny posting and reading about other members talking about clutching without having Turk chime in.

 

[yamahahaapex]

2 speeds are incredibly easy to tune, even on trail since weights are easily accessible. hit hardest out of kits ive used in the past