75' JDX8

jdsledwheelman · Post by **jdsledwheelman** » Fri Jan 23, 2009 12:35 am

Have a problem I can't sort out. My 75' X8 is blowing light bulbs out and the tach is freak'n out

.[reads 5500 RPM at idle and tachs out to the end of the gage at 1/4 throttle] Today I just put on a new voltage regulator and nothing is any better than before

. Hence why I can't figure it out

. What else could be wrong? What do I need to look for?

Thanks nick

Attachments:

_75_X_8.jpg (2.07 KB)

400brian · Post by **400brian** » Fri Jan 23, 2009 4:06 am

Assuming the voltage regulator you put on is good, the only thing that comes to mind is the condition of your grounds.

The V-reg needs a well grounded mounting location.

There is the ground on the engine at the connector plug near the recoil, and one of the connections inside the plug.

It sure sounds like you are seeing unregulated voltage.

JDT · Post by **JDT** » Sat Jan 24, 2009 1:45 am

Is this an electric start sled?

jdsledwheelman · Post by **jdsledwheelman** » Sat Jan 24, 2009 1:57 am

JDT wrote:Is this an electric start sled?

No electric start. I don't think it was an option in 75' because the expantion chamber exits out the same spot where the battery box goes on the 73-74 models.

nick

JDT · Post by **JDT** » Sat Jan 24, 2009 2:14 am

The battery box is located deadcenter behind the gas tank on the 75 JDX8. Mine has the ES option.

JDT · Post by **JDT** » Sat Jan 24, 2009 2:23 am

Does your voltage regulator have the small aluminum block installed between the heat sink and the frame?

If so check that for corrosion. Dissimliar metals, brass, alum and steel, set up some type of electralysis and I have seen a loss of ground caused by this. A sanding or file wil fix that.

Test for good ground connection between engine, chassis(frame) and the wiring harness. Any reading over 1 ohm needs attention.

Test the regulator with your ohm meter. Should be around 125 ohms.

jdsledwheelman · Post by **jdsledwheelman** » Sat Jan 24, 2009 2:24 am

JDT wrote:The battery box is located deadcenter behind the gas tank on the 75 JDX8. Mine has the ES option.

I didn't know that

, but that's what I love about this site and the wonderful people on here. I learn new things here all the time. Thanks.

nick

jdsledwheelman · Post by **jdsledwheelman** » Sat Jan 24, 2009 2:27 am

JDT wrote:Does your voltage regulator have the small aluminum block installed between the heat sink and the frame?

If so check that for corrosion. Dissimliar metals, brass, alum and steel, set up some type of electralysis and I have seen a loss of ground caused by this. A sanding or file wil fix that.

Test for good ground connection between engine, chassis(frame) and the wiring harness. Any reading over 1 ohm needs attention.

Test the regulator with your ohm meter. Should be around 125 ohms.

Hey thanks, I'll check that out. :idea:

nick

JDT · Post by **JDT** » Sat Jan 24, 2009 2:29 am

Hey how do you get the quote to show up on your posts?

jdsledwheelman · Post by **jdsledwheelman** » Sat Jan 24, 2009 2:35 am

JDT wrote:Hey how do you get the quote to show up on your posts?

I just hit the quote button at the bottom right corner of the post that I want to show in my post. I do it so everyone knows who I'm responding to.

nick

JDT · Post by **JDT** » Sat Jan 24, 2009 2:38 am

jdsledwheelman wrote:
JDT wrote:Hey how do you get the quote to show up on your posts?
I just hit the quote button at the bottom right corner of the post that I want to show in my post. I do it so everyone knows who I'm responding to.

nick

testing quote

JDT · Post by **JDT** » Sat Jan 24, 2009 2:38 am

Cool! Never knew that. Thanks!

jdsledwheelman · Post by **jdsledwheelman** » Sat Jan 24, 2009 2:44 am

I also can't get this sled to run more than about 2 min. at a time. It acts like it runs out of gas. Starts up runs good then bogs.Then runs on one cylinder for maybe 30 sec. and dies. Any thoughts?

p.s. Ran real good when parked, but had the voltage problem when I bought last spring.

nick

jdsledwheelman · Post by **jdsledwheelman** » Sat Jan 24, 2009 2:46 am

JDT wrote:Cool! Never knew that. Thanks!

No problem you guys are helping me, it's the least I could do.

nick

JDT · Post by **JDT** » Sat Jan 24, 2009 3:01 am

If it is a fuel starvation problem it could be the carb/pump.

But if it stops hitting on one side than I would think it is not fuel related.

Test compresssion cold and then again warm right after it dies. Could be it looses compression when it warms up from a head gasket for example.

Also test the coils cold and again warm right after it dies. Bad coils can test good cold and bad when they heat up. Same goes for spark plugs.

Stators and Cdi boxes are also temp senstive if they are on the way out. These Prestolite Systems have a lot of history in this area.

Another form member just posted about a bad stator on his JDX8.

And of course crank seals.
A seal can be good cold and then when it heats up from friction it opens up and leaks. If the bad seal is on the same side as your impulse line the fuel pump output will drop way down and it can sputter out. This would also explain why it stops hitting on one side as you will loose full fuel transfer with a bad seal.