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Post by midniterupper on Oct 12, 2019 20:05:06 GMT -6
I'm looking to beat the Yammie's at the grass drags here in Michigan. Any helpful tips for setting up a 1976 Nitro are Greatly appreciated, hope to Ruppture the competition!
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Post by mrrupp1 on Oct 14, 2019 19:10:33 GMT -6
Do you have to run stock clutches, or can you use anything ? The stock stuff is a little tricky to make work. There are guys out there that can do it, but it takes some doing. I race a 76 Nitro, but its on an oval track. I changed the drive clutch to a Comet 102C and changed the driven to a later Artic Cat reverse driven. They made it a hole new sled. It takes a little time figuring out what spring a weights that work best for your sled, but once you do you'll give them yammies a run for there money.
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Post by midniterupper on Oct 16, 2019 7:01:17 GMT -6
Thank you for your reply! Your advise is greatly appreciated, not many folks around racing these sleds anymore. I will go to a salvage yard today to pick up a '96-99 Arctic Jag 440 secondary and get a belt to match up. I wasn't sure if there is any tricks for the chassis, maybe make some shims to lighten up ski pressure? Head squish clearance is .072" wasn't sure if we could tighten up to .050"? What do you recommend for fuel & oil? Thanks again for sharing your wisdom!
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Post by mrrupp1 on Oct 16, 2019 18:14:53 GMT -6
The Xenoahs have a pretty thin power band they like to be on the pipe. I run VP 110 leaded in my nitro. I run a yellow green spring in the drive clutch and a white or yellow in the secondary. For cam arms in the drive clutch I start with C and ground them to what is best. The Xenoah master is kevin hasse at Pipestone small engines, his number is 269-461-6421. The biggest problem with the Rupp liquid is they are heavy, so loose as much weight off the sled as you can.
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Post by mrrupp1 on Oct 16, 2019 18:15:14 GMT -6
The Xenoahs have a pretty thin power band they like to be on the pipe. I run VP 110 leaded in my nitro. I run a yellow green spring in the drive clutch and a white or yellow in the secondary. For cam arms in the drive clutch I start with C and ground them to what is best. The Xenoah master is kevin hasse at Pipestone small engines, his number is 269-461-6421. The biggest problem with the Rupp liquid is they are heavy, so loose as much weight off the sled as you can.
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Post by mrrupp1 on Oct 16, 2019 18:16:13 GMT -6
The Xenoahs have a pretty thin power band they like to be on the pipe. I run VP 110 leaded in my nitro. I run a yellow green spring in the drive clutch and a white or yellow in the secondary. For cam arms in the drive clutch I start with C and ground them to what is best. The Xenoah master is kevin hasse at Pipestone small engines, his number is 269-461-6421. The biggest problem with the Rupp liquid is they are heavy, so loose as much weight off the sled as you can.
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Post by mrrupp1 on Oct 16, 2019 18:16:39 GMT -6
The Xenoahs have a pretty thin power band they like to be on the pipe. I run VP 110 leaded in my nitro. I run a yellow green spring in the drive clutch and a white or yellow in the secondary. For cam arms in the drive clutch I start with C and ground them to what is best. The Xenoah master is kevin hasse at Pipestone small engines, his number is 269-461-6421. The biggest problem with the Rupp liquid is they are heavy, so loose as much weight off the sled as you can.
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Post by mrrupp1 on Oct 16, 2019 18:20:43 GMT -6
The Xenoahs have a pretty thin power band they like to be on the pipe. I run VP 110 leaded in my nitro. I run a yellow green spring in the drive clutch and a white or yellow in the secondary. For cam arms in the drive clutch I start with C and ground them to what is best. The Xenoah master is kevin hasse at Pipestone small engines, his number is 269-461-6421. The biggest problem with the Rupp liquid is they are heavy, so loose as much weight off the sled as you can.
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Post by midniterupper on Oct 16, 2019 19:03:30 GMT -6
Thanks for the helpful tips! I did some research on the Xenoah 440 motor, it sound like 8300rpm is the target. I like the idea of running VP 110 for fuel, do you have a favorite oil and ratio that you use? I picked up a Arctic reverse secondary today but am running into a clearance problem between the factory Rupp jack shaft bearing support and the Arctic helix. They interfere with each other by about 1/2". It sounds like a common upgrade for the secondary, just not sure how to install it to align the clutches?
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Post by midniterupper on Oct 19, 2019 17:27:17 GMT -6
Ok, so now after examining my comet primary and finding it cracked, I replaced it with a P-85 primary using my Comet yellow/green spring and A-2 arms. I am still engaging at 4800 rpm and spinning at 7400 rpm. Any suggestions for raising both RPM's?
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Post by Ruppsforever on Oct 20, 2019 17:39:38 GMT -6
Polaris 10MR weights should be good weights for you. How stiff is that spring you are using ?? I'm not familiar with that one.
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Post by Ruppsforever on Oct 20, 2019 17:45:27 GMT -6
A2 weights are 48 grams according to my book. That is pretty damn heavy.
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Post by midniterupper on Oct 21, 2019 8:38:26 GMT -6
A2 weights are 48 grams according to my book. That is pretty damn heavy. |
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Post by midniterupper on Oct 21, 2019 8:55:12 GMT -6
Yep, I agree as my rpms will not climb above 7400 with those (A2 = 48.8 Gr.) arms. I found a formula for calculating weights from Alav Aaen, very helpful! Sounds like a basic rule of thumb is 1 gram of weight change equals out to about 200 rpm, I need to gain about 1000 more rpm so I'm thinking I need approximately 5 grams of less weight. I am going to try out a few different weights starting with A3 arms @44.9 grams, then try A10 arms @ 41.3 grams. The yellow/green spring is something new to me also, not exactly sure the rates yet, more research to do. I was reading through all the posts on the boards here and someone said they were using it and liked it so I thought I would give it a try also. I was using the comet gold spring before trying this one. I have to replace my track drivers now, I can't eliminate the racheting on take off by adjusting the track tension. The drivers look pretty egg shaped right now. I also want to see if I can come up with a 4 wheel rear axle set up like we used on the skidoo's for drag racing. They seem to help out reducing rolling resistance, what do you think about that idea? I guess I'd better get at it eh?  |
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Post by midniterupper on Oct 21, 2019 13:45:48 GMT -6
I will give the Pol 10MR arms a try also as they may have a more aggressive profile. Do you know how many grams they weigh?
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Post by Ruppsforever on Oct 22, 2019 18:08:24 GMT -6
10MR weigh about 44 grams. They spin 8300 with the Almond Gold Polaris spring. I always used the stock secondary with a comet 102-C though. What you have going on with the secondary you are using might change some things. You will just have to experiment. I have only raced ice and snow. Been a few years since I've raced now.
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Post by Ruppsforever on Oct 22, 2019 18:15:28 GMT -6
I forgot to mention that all of my experience with drag racing a stock Xenoah 440. The quickest times in 500 feet my motor spun 7900- 8000 rpms. 10MW weights I liked to use too. And I noticed you said you have the Aaen clutch tuning book. Try taking the 10MR and 10MW weights and Tuck them under. In the book it shows how to do this. Comet and Polaris weights you have to grind them different from each other. That really helps the engagement. I think it gains about 1000 rpm. I was never a fan of notching weights.
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Post by midniterupper on Oct 23, 2019 6:40:06 GMT -6
Thanks for your input, your ideas are greatly appreciated and very helpful! I will read up on the tucking procedure in Olav's book, the man is certainly a guru with sleds. I'm looking forward to testing the clutching suggestions, so far we have improved the top speed by 10 mph (61mph) - not the greatest yet but considering it was a basket case when I bought it at A-1 in 2009. We will dedicate the sled to just doing 500' grass.
Right now I have the suspension, track and drive axle out of the sled to replace the drive cogs. It ratchets terribly on take off. I'll look at everything on the suspension/drivetrain to see what can be done to help reduce rotational friction too. True up drive sprockets, idlers, alignments, ect. Keep you posted on the progress, thanks again for your time and help!
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Post by Ruppsforever on Oct 26, 2019 6:29:56 GMT -6
Sure !! Good luck !!
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Post by midniterupper on Oct 27, 2019 18:54:14 GMT -6
Well, upon further investigation I found the drive chain had begun to fracture and disintegrate taking the 19 tooth top sprocket with it. Both upper and lower chaincase bearings were not the best also and the lower drive shaft seal was leaking. This along with the drive sprockets being badly worn causing the ratcheting on take off. Thanks to Kevin Haase for having the parts available. Now the drive sprockets and all idlers have been trued, even have a 4 wheel rear axle to reduce rolling resistance. Had to install thicker tunnel protectors due to stud damage evidence, perfect opportunity! Installed 1 extra shim plate for the forward mount on the rear suspension hoping to decrease ski pressure and lighten the front end with weight transfer. Hopefully will button everything back up tomorrow, well worth going through the entire drive train making it good as new. Let the testing begin! Going to try to engage at 5800 rpm and attain 8100-8300 rpm during the run. First starting with the comet yellow/green spring with 1 shim using my comet A-10 arm @ 41.3 grams (P-85 primary) and the reverse arctic secondary using their yellow spring and a 53 degree helix. I already had these arms laying around so I thought I'd give them a try. Also want to try the A-3 arms @ 44.9 grams since they're here too. I will look for the Polaris 10 MR arms @ 44.0 grams to see how they shift out. Pretty cool, exciting to see it coming together! Should make quite an impact, keep you posted...
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