74 JDX8 runs but doesnt move

400brian · Post by **400brian** » Sun May 14, 2006 12:55 am

My personal opinion is that if the seals aren't bad on a 30 year old sled now....they will be shortly after you start riding it. The seals are cheap, the installation is the bigger problem. The PTO side can definitely be replaced by just removing the clutch and installing the new one. The mag side is less clear, no one seems to know for sure if it can be replaced without splitting the case or not.

It seems bad seals can manifest themselves in different ways. Sometimes the engine will not idle, other times guys will have the mixture needle screwed out a huge amount to get enough fuel to make it run decent, other times the first indication is when the engine seizes going across a lake at WOT.

If you replace the seals now, you can eliminate them as a potential problem. Other than that, you can shoot a little starting fluid at the PTO end seal and see if the engine responds, the mag end is tougher to get at.

I'm wondering what would happen if you shot a bit of premix into the carb while it was running at the engagement speed you talk about, ( hold the throttle open and spray ). I'm thinking you are not getting enough fuel due to possible seal leakage, or fuel system problem.

The other thing that comes to mind, would be a problem in the ignition system. You could possibly have a bad coil, that's why folks are asking you if you're sure its running on both cylinders. Another possibility might be a mechanical issue, like a scored cylinder, that of course is why we asked about a compression test.

BTW, If the sled is a '74, it has a points ignition system, not CDI.

jhecht · Post by **jhecht** » Thu Aug 10, 2006 11:36 pm

ok i fixed one sled- I was able to fix the 1986 yamaha-I know its no deere but wait till I explain. it was having the same problem as my 74 JDX8 so i thought they would have the same fix, now ive been a mechanic for a few years now and i got my diploma and everything, but i guess i forgot what they taught you-no two problems are the same but i was hoping anyways the sled that i was thinking it was the CDI box was the 86 Yamaha- I know the JDX8 has points- i had to reset them to get it running. The yamaha had a broken bushing that wasn't allowing the clutch to close- but its fixed, well i have the parts just gotta put them on. the JDX8 is a different story- I thought it could be the same problem but I double and triple checked the clutches and they are fine-lubed greased and working. I never thought of the seals, its just weird because my trailfire had a bad PTO seal and it had perfect compression, so i guess it should of crossed my mind but for right now the JDX8 is sitting on the lift waiting to get fixed as i got a couple of customer bikes to get fixed right now. Again I THANK YOU FOR YOUR HELP!!!! i greatly appreciate it. two heads are better than one.
Thanks again

Rodimus Prime · Post by **Rodimus Prime** » Thu Aug 17, 2006 3:50 am

bogs out and wont move or barely moves means its running on one cylinder you have some checking seals gaskets etc..

word of note sometimes the simple things get overlooked like a bad spark plug or dirty points.

i should add that lifting track in air WITHOUT engine running and checking for easy track movement is also a good idea. usually track or clutch problems smoke a belt though so they are different.