JDX8 carb/ignition problem

[JDX8]

Hi,

I've got a 1975 JDX8 and for the life of me I can't figure out what's wrong with it.

The first problem was/is that it surges at idle. ~1500 RPM idling quite nicely then waaaaaam! it's revving ~4000 then slowly (10 seconds?) returns to idle.

I got a diaphragm/gasket kit and installed it thinking that would help, but it didn't.

BTW, it's the stock walbro carb.

Now, not only has it continued to surge at idle, it has a problem quite suspiciously similar to this guy's:http://www.jdsleds.com/community/viewto ... =11&t=6899


When I first start it up and let it warm up a little, get on it and it'll damn near throw you off the seat it's so quick.

after about 3 runs around the yard, it heasitates, sputters, and can hardly get moving. I tried, as the other guy, taking off the plug wires one at a time. #2 seems to not change anything, #1 kills it almost immediately.

Both plugs have spark.

Can anybody help me?!

Thanks from Montana

[400brian]

Does the sled have CDI or points ignition?

Spray some starting fluid on the crank seal behind the clutch and see what happens.

[JDX8]

CDI ignition I think. It has the box on the 'firewall' thing...

[400brian]

It's possible that your stator is crapping out once it warms up, or the CDI box.
The diagnostic instructions are in the FAQs. They are not a sure indicator, but it's a start.

Your crank seals should be replaced just because of their age.

[JDFanPa]

Like Brian stated cdi is a possibility aswell as the crank seals. Im inclined to think crank seals more with the flare up on the idel problem specialy with the number 2cyl giving no results when you pull the plug wire. Do as you were told and spray starting fluid on the seal behind the clutch and see if it revs up on its own. Crank seals should be done in any sled this old but the clutch side is even more prone to failure do to it being esposed.

[JDX8]

Problems solved, and I owe stuoid tax on both...

1. The clutch side crank seal is bad. I thought the problem seemed like a air leak, I was spraying ether around the intake manifold, impulse line, etc. but forgot all about the crank seal.

2. I guess you could say the CDI box was the problem. The plug going to it has a loose wire. Fixed that and it runs great again.


Thanks for the help guys!