should my 800 be faster ?

[Mac67]

hey guys this is my first older jd sled , it is a 75 800 with the 440 ccw in it , i mean it moves nothing super quick , should it really get up and scoot or is it more of a trail sled slow goin lots of torque kinda sled ? i also rode a 440 skidoo citation thisevening with the 377 rotax and a 440 scorpion whip with the cuyuna in it and they both really moved , the 340 trail fire will out perform this 800 easy i belive , is there something i should look for or is this just how they are , its got an 80mph speedo and i just dont see it doing it ,

[JDFanPa]

Its really not meant to be fast the X series sleds were more performance minded. The 340 trail is a different breed altogether and should be faster. I wouldnt expect anything more than about 45mph personaly. Most old sleds have speedos that go that high and most dont do it not to mention I dont beleive they are all that accurate. You have to look at the condition of your motor aswell as wear and tear on the sled not to mention if a previous owner changed anything around like in the gearing etc.

[JoeRainville]

Hi Guys,

Something is up with your 800. You have a 46 hp 440cc motor with a tuned pipe. You have way more motor than chassis! Basically, it's the same motor the 75 JDX-8 used.

I would suggest checking out the basics, like compression and spark. Then clean the carb and reassemble it with a new diaphram kit. If your motor is running fine, I would go after the clutches. Take them both apart and completely service them. The drive is a Comet 101-C, and it not a bad unit. Trash the dust cover however.

Even with the older boggie chassis, that 800 should smoke a 340 Trailfire with its 30 hp motor on the flat. In the bumps and corners the Trailfire has a way better chassis and a much lower center of gravity.

Good luck with your sled!
-Joe Rainville
"Tech-Ed"

[JDGuy]

Joe is right. I owned a 75 800 new and it would run with the best of them at that time. A few were faster, but not by much. They had one initial "out of the crate" problem besides handling, severe spark plug fouling at slow trail speeds. Lake racing, no problem. Deere had a no cost update to fix the fouling problem but I cannot remember what that was. I do remember it was a dealer only installation, they wouldn't let you pick up the parts and install them. Take the engine cover off, go full speed, wide open throttle, and lean the adjustable main jet for max speed and then quickly richen it a bit. It will take a couple of seconds to evaluate your new setting as the crankcase has to burn out the previous setting. The amount you richen it is proportional to your tolerance for a burn down. Don't leave it lean. If you optimize the setting at 28 degrees above zero, it will be way too lean at 20 below, etc.

My 800 would smoke my heavy as a military tank 440 Cyclone every time in a lake race. The 800 was a good performer in its day. Hope you find the problem.

[JDFanPa]

No kidding I stand corrected I had no idea these were such a hot sled. I think I need one bad. I have a tuned exhaust from one of these and thats it. I was thinking of trying to use this pipe on a 73 x8 any thoughts on this. Actually was thinking of using the pipe and a twin carb intake off a lf motor.

[Matt]

Andy, you'd need the right exaust manifold to do that, which is hard to find. I've been looking for one too because the one on my '75 X8 is chewed up and leaking at the flange. The CDI is part of the improvements too.

[JDFanPa]

Yeah I hear that Matt was cgoing to probably fab up a manifold. Now that you mention the cdi I wonder this can a complete cdi setup from the lf motor be bolted in an old fan motor since from what I gather the bottom ends are very similar. This is just one of my many down the road projects I just want to gather peices as I find them.

[Mac67]

ok guys , talk about stupid , sorry ive been away for a while , all i got to say is WOW !!! , ok first off i did a kit in the walbro , ,, ohh by the way this is my first year for working on sleds so its comin along pretty good , anywho , i noticed one cylinder had very week spark , maybe a quarter of what the other had , i started tracing wires and one for the 2nd cylinder was almost completley cut in half due to a rattleing head cover , cut it , crimped it and wow what a difference , with a little tug on the bars this thing is carrying skis , not very high but itll pull em , and it took the skidoo 4500 citation , and a john deere 500 , and the trail fire , the closest race to it so far is my 80 or so scorpion 440 whip , the scorpian will pull away after so far , and then there is my brothers yamaha phazer , good lord that ones fun , but the funny part about this sled is i got it for parts only , they didnt have the ground strap hooked and couldnt get spark , so across my hood in big white letters it says for parts only ha ha ha , and im gonna leave it there , !! thanks for the info fellas , ill try to check back more often