Hello!!!
I have a 97 MachZ *It has a 925 kit and goes like heck!!

My problem is that I will thump ported and modded t-cats and even most 1050's out there. The sled *will pull 2-5 lenghts ahead and then it just stops at 100mph. I mean it will not go over 100mph. The RPM stay's at 8900 at all times. I have tried 26/44, 26/43 and 26/42. Still 100mph top end with all three gears. I have 286, 250/380 spring, mag arms w/18.5 grams.
56/48 helix,goodwin blue spring @18lbs.

Any suggestions would be great.

Thanks.

hey machzer; how many studs are u running? or how deep of a track? if studs and r somewhere around 198+ that would most likely be it.

Machzer, I agree with machz69, how heavy is your track ? I would also try something like a 52-46 or 52-44 cam to allow the clutches to keep on creeping open as a 44 finish angle has more side pressure and shifts slower. Also, if you have a heavy track (deep lug or lots of studs), I would try gearing down a little more to give more h.p. and torque to track at high speeds (@8900 rpm, 25-44 gearing will still shift to 109mph in 1:1 ratio). Check center to center of clutches, too close, and you won't shift out, too far apart, still won't shift out, but with your power, would probably blow the belt.
Things you could try !

MACHZER: What pipes are you using,at what rpm doo they peak at? Dino

Thanks for the help!!

I am running no studs and use a 1" track. The sled hooks up real good on the lake and the skis will not touch at all the whole lenght. Use to be about 2 feet of the ground,got it to 6 inches now and we do not ice race. The funny thing is the sled feels like its pulling and rpm stays at 8900 at all times.
Its like the secondary is stuck yet there is enought belt slippage to compensate. The pipes are for 8900. I my try lower gearing but you would think that the sled would easliy pull 26/44 gears into the 0ne-teens?/

The sled is a real bear and almost scary

If your running mag arms you should add wieght. 23 gram pins 185-410 spring 50/44 26-44. What do you wiegh? How much heat in the clutches?

Well, I don't know if this will help you, but here is my setup, and I have tried a ton of different setups trying to achieve acceleration and topend. *I run a 99 MachZ with a Crankshop 1025. The 1025 does have alot to do with it, but I know your 925 will be very similar.
Clutch/gear:
25/43 gearing
286 ramps click 3
stock arms w/24.6g pins
Goodwin 215/375 primary spring
Goodwin Blue secondary spring on 25lbs
straight 52 helix

Rear Susp
SC10II, Camoplast .52 Speed track w/240 1" studs

This has been by far the fastest setup that I have had in that Chassis. My last trip to the U.P., I found a nice long back road to test on, and I had the sled up to 125mph, and I kid you not....it was still pulling. I'd say I probably had it pinned for about 1/2 to 3/4 of a mile. Maybe it was just perfect conditions, but I'd say that is pretty darn good with 240 studs. Granted this is not as quick as my drag setup, which is 280 ramps, mag arms, 24.6g pins and a 52/46 helix, but it is faster and much more trail friendly.

Sounds like a puzzling problem! *I think that your sled should run over 100 no matter what gears you have in there. *I have no experience with this, but I have heard of people having their cranks out of balance (over 4 deg) and having the same problems. *This sticks in my mind because I have recently talked to people who were blowing belts on their 800 twins. *After putting on new belt the sled ran fine but lacked top end.
Just a thought...may be a good summer project/test if you don't find anything the rest of the winter.
Good luck

MACH 1025,,, I wonder how close our HP is. What rpm are you pulling?? On your drag setup what primary spring, secondary spring and pressure, and what gearing are you using??

ZR800MAN ,,, good suggestion,I have checked the static timming before but will revist.

I just know it's going to be something stupid!!!!

AGAIN THANKS FOR THE HELP!!!!

Give it pin wieght or soften the front spring. You don't need a huge spring to get big r's. In my 670 race motor that spins at 9200 I use mags 22 grams and a 160-270 spring on clicker 2. Try it!

I bet our HP is not to far off. I am supposed to be around 200hp at 86-8700. On my race setup I was using Cudney springs. Primary 240-400 and secondary was a red cudney spring set at 20lbs. Gearing was still 25/43. I also could not use a hard compound belt with my drag setup. I tried both a Gates Xtreme and a Skidoo Gold and they would both slip bad at lower gear ratio's, I think mainly due to the mag arms. So I had to run a Dayco Ultimax. *With my trail topend setup, I am able to run a the harder compound with good success.

I am going to do some testing this weekend. I will be racing a highly modded 900 t-cat,, ported and piped zrt 800 and a 1000t-cat.

Going to try some of your suggestions. I wil let you know the results

If it was me i'd be taking the sled to a dyno to see what kind of power you really have there and what rpm it occurs at. In theory if it pulls well at your indicated rpm at 50 to 100 then just stops id say your clutching is close enough to at least go 100 (heck a stock 800 mach can go past 100 with ease) Id bet you have a chassis problem , bad bearing in one of the shafts or your track is too tight, something of that nature.Either that or you just happen to be the size of a sheet of plywood in which case youll have to tuck more.

Check your clutchs for heat after a pull if they are hot your problem is belt slipage.

Add weight and or softer finish rate spring in the primary for those mag arms.