clutch adjusing

jdjason · Post by **jdjason** » Tue Dec 11, 2007 12:36 am

new to this site looking for a liitle help. i have a73 jd400.
runs great very smooth, but will only go 40 mph is there any clutch adjustment,or is this all it will do?

jdjason · Post by **jdjason** » Tue Dec 11, 2007 7:49 pm

the sled was saved for me as agift from my gradfathers jd dealership in his will.
It has just over 150 miles on it. the suspension, belt, everything is in showroon condition. I am the only person to ride the sled except my grandfather who preped it before storing since 1974. I will look at the clutch and spring who knows what happens after thirty years. the carb is rebuilt . crank seals fuel lines and tank have been replaced or cleaned . it cant compete with my cyclone or jdx8 but it shouldnt be that far off.

JDFanPa · Post by **JDFanPa** » Tue Dec 11, 2007 10:50 pm

It really wont compete with an x8 or cyclone they are both reed valve motors which in this case run much faster than the 400 motor. Thats quite an impressive story about the sled and how you got it in such sweet condition. If I had a sled like this I wouldnt worry about top speed as much as keeping it like new.

400brian · Post by **400brian** » Wed Dec 12, 2007 5:13 am

Your 400 needs a bit of tuning. It should hit 50 without much problem, closer to 60 under the right conditions.

S_Kyle · Post by **S_Kyle** » Wed Dec 12, 2007 9:58 am

We clocked my buddies 7?' JD 400 @ 65 MPH last winter, so yours should go a little faster than 40 MPH

HoosierDeereMan · Post by **HoosierDeereMan** » Wed Dec 12, 2007 11:17 am

I would look at the condition of the drive belt. Most of the guys here that dealt with the original belts will tell you that they didn't last long. The belt width for a '73 400 new is 1 3/16"wide. It may just be worn. Also you said the carb was rebuilt? When you are running at 40 MPH does the engine sound like it is laboring? It may be something as simple as adjusting the high speed mixture needle.

My '73 400 ran 62 MPH in a nice long flat stretch of road last winter. It was nicely packed and ideal conditions. Also keep in mind that there is a margin of error with the speedometers. I'd guess and say mine is reads 4 to 5 MPH faster than actual speed.

jdjason · Post by **jdjason** » Wed Dec 12, 2007 10:37 pm

adjusted carb settings as advertised under engine cover and jdsleds.com even on the brink of detonation sled wont go over 40 drive belt is new.premium fuel and oil used. guess its time to take apart the clutch and inspect. my uncle has been the sled mecanic at the dealership so I'll ask him to help with project. thank you all for the info. this is my favorite sled and its the first won i run to when the snow flies. any other ideas would be appreciated.
also cant find a drive belt for x8 havent evn had luck at own napa store ?

400brian · Post by **400brian** » Thu Dec 13, 2007 5:21 am

The X8 belt should not be a problem.
MN Vintage Snowmobile has them, as should Central snowmobile or Dennis Kirk.
That belt was used on several JD models.