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Discussion Starter #1
hi all
i hope you are able to help
i currently race a car in england which is fitted with the rotax 593 twin which i believe is from a 2000 model skidoo. http://norasport.com/news/superlites.php

my problem is with the primary clutch,it is currently fitted with a comet clutch but this seems prone to failure,so i am looking at fitting a TRA clutch which are apparently much more reliable,

i have found some clutches on ebay,which are listed as fitting 600 ,700 and 800 do i have to be carefull or are all the shaft sizes the same.?

i know to get the max from the engine the clutch has to be spot on , so can you reccomend a set up, i feel this may be difficult as it has probably completely different characteristics to a snow mobile, it starts to drive just after tickover then revs all the way to top speed which is around 120mph but the secondry runs through a gear box?

i am a noob at clutch tuning but have been reading various forums and am starting to get the idea,but asking the profesionals has got to be the way forward

many thanks johno
 

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Hello, that 593 twin is what some call "old school 600". The model you have is still made by BRP and comes in skidoo models 500SS.I don't know what secondary clutch you are running, if you are running a 2002 or older secondary then that is the TRA-2 platform and has 1-3/8 belt width.

The 2003~newer primary are TRA-3 clutches and are 1.5" belt width.
You can make a TRA-2 secondary clutch work with a TRA3 primary clutch, as long as you take apart your TRA-2 Secondary and install a 2nd shim....now the secondary will be able to run the correct belt width.

What is "tickover"

Setups are different regardless of snowmoble model per model or Drakarts as you run.
Clutching principles dont change, the parts work a certain way according to physical laws and these principles can be applied to your Drakart easily enough.

I have setup some snowmobile engine powered Sprint and Late model dirt cars to which they are about the same size as your Drakarts.

I would love to ask you some questions of your clutch system.
I would also like to see some pictures of the clutches on your kart.

email me if you can

[email protected]
 

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journeyman sled/motorhead
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you may post pictures of them here as well. I would like to see it. the clutches have to be aligned the way they were intended , to work properly. along with the correct center to center distance for the belt. joe mentioned width and that should be correct along with the deflection. once those are done and or checked then start to tune it . you can bet joe will get it going great. but I would like you to post pics here also. good luck and have fun. :thumbsup:
 

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Discussion Starter #4
thanks for the replies ,
joe certainly does know his stuff i have been looking on his site and trying to soak in some of the info but for a novice like me it takes some reading, but definately the easiest i have found to understand so far.
so joe reserve a copy of your book for me when you get it published

for anyone else interested here are the pictures i sent to joe of my set up ,it was midnight and raining so quality not 100% .
 

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beautiful setup...looks like you have the AC clutch with the 911 roller conversion on it and looks like it has a yellow AC secondary spring...nice unit.

measure your belt width, is it 1-3/8 inch or 1.5 inch?
Really either tra2 or tra3 primary clutch will work with that secondary clutch, you just have to make sure the secondary clutch is shimmed correctly for the belt width.

tra2 is 1-3/8 and come on 1998~2002 skidoo models
tra3 is 1.5" belt width and come on 2003~newer models.

Ok here is another thing, that TRA primary clutch has a different stub for the belt to go around, the TRA is larger diameter and now would require you to change the belt deflection. do these chassis have the capacity for the engine to move back and forth on a slide or something of that nature? What I mean is can the engine be moved closer or farther away from the secondary clutch?..or is the engine fixed?
....I am asking if the center of the clutches can be moved away or closer to each other.

Tell you the truth that comet is a nice unit but the flyweights are expensive and I agree, xpensive to rebuild.

Tell me what you race? rally dirt with lots of corners, slow down speed up....or pavement ovals, or whatnot?
 

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journeyman sled/motorhead
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I would get a tra and drop the comet, the tra is easier to tune. my dad was good with flyweights, I however am not.
 

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Discussion Starter #7
hi joe thanks for the reply and to you dooman
i am pleased you think i have a good set up very encouraging for me but can it be improved?

yes the belt i am running at the moment is 1-3/8" arctic cat 0627-020 are these ok or would a different brand suit me better?

i have just won a tra which i think is the tra 2 you mention on ebay but it is set for 800 so i will need new internals.
is the stub bigger on both models compared to the comet or just the one for the wider belt, i don't think it would be too much trouble to slot the mounts.

the comet has been fine and some drivers seem to have no trouble at all but others me included have had a run of failures in quick succession , and as you say repairs are not cheap. seems the spider ? has failed both times for me ,perhaps it could be driver related?

yes we race at supermoto meetings which generally consist of 80% tarmac 20% dirt so it is more rally dirt with lots of corners, slow down speed up usage.
 

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You will need to make some tools for taking the tra apart - piece-o-cake man! :)

Installation illustrations:
Have a look at these pages...
Joe's online Installation Illustrations....
and
Clicky for more installation illustrations....

Should pick up the Button Holding Forks from the dealer, they are about $12
BRP #529005500

The illustrations show installation of a clutch kit however the bottom line is they are for the purposes of showing you how to take apart your TRA primary clutch. They are a beaut to work on.

When you get the TRA in your hands, let me know what ramps are inside and what primary spring that is installed - this will involve taking the clutch apart to clean.

You'll see what I mean when I mention "stub diameter is larger" when you try to put a belt on, it will more than likely be short and have to move engine back a bit.

Changing flyweight mass is as simple as changing socket head setscrews...they are literally worth only pennies and not a big hole in your wallet.

I'll show you how to setup your belt deflection with that Acat secondary - easy stuff.

ok man, hope that helps
Joey
 

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Discussion Starter #10
once again thanks for your time and help ,well impressed

i will get a tacho as you suggest and when the clutch arrives i will strip it and let you know what we have, and in the meanwhile i will get a tool kit made.

there are no forums i am aware of sorry.

johno
 

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I flew to England this may and got to go test with Johno and Daz and drive both their cars. Daz's car is in this video #20 the green one at 20 seconds, [car behind the blue one]
http://www.youtube.com/watch?v=oXbCZId-vKg
I can't believe how quick these cars go....
Did some tuning to their secondary, change the helix and get the engine to finally run at 8100 instead of the 7600 they were running at.....now these cars go better than they did in the video.
 

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Discussion Starter #12
hi joe
fancy finding footage of me leaving the track ha ha ,as you know from driving my kart lots of work to do on the handling.
i have a arctic cat rear on the way ,so i should be able to try some different helixes and combinations as you have planned for us.
also i am still dialing in the jetting each time out.so improving all the way
any way i hope you both enjoyed your stay with us in the uk because i know we enjoyed your company so your more than welcome any time,and perhaps we can sample some more different english ale's ha ha.

thanks for your help and we will be in touch soon
johno
 

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Anything new with this? I to have a Drakart, Race it here in the states. Also run a tra and a cat driven, Interested in seeing how this turned out...
 
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