79 trailfire 440

mcmullenx4 · Post by **mcmullenx4** » Sat Mar 25, 2006 9:06 pm

Hello everyone, I just got a 79 440 trailfire for a trade and it runs but of course, with all great things in life there are isues. first of all, I was suprised to see a starting system on the sled and after some electrical troubleshooting I was able to get the system working with my lawnmower battery, but it did not have enough power to turn the engine over. So question number one- what battery is right for the sled? Ok, next on the list. It starts using the pull but dies very soon after starting, do this about 8-10 times and it will run at idle however when I apply throtle (before the sled runs for a long time) it boggs down and dies. I read the fourum before this and it sounds very similer to my problem, solution- crank seal, and carb rebuild kit. question number 2- How hard is the seal to replace and how hard is it to rebuild the carb? ive rebuilt a jeep carb a couple of years back, but never a 2 stroke carb. question number 3- where can i find a manual to do the work so when my wife starts yelling at me that she cant get her car in the garage becouse I have all these snowmobile parts all over my garage in a huge mess I will know how assemble them into a fine tuned, functioning snowmobile worthy of the John Deere embalem on the side. and the final question, there is a 3-way switch on the right side of the handlebars, its red. what dose this do? sorry its such a long post, any input would be greatly appreciated.
thanks, Jeremy in Fremont Ohio

Octane · Post by **Octane** » Sun Mar 26, 2006 12:31 am

I believe the red switch on the right handlebar is the kill switch.

Danzig · Post by **Danzig** » Sun Mar 26, 2006 12:37 am

Octane wrote: I believe the red switch on the right handlebar is the kill switch.

Correct!!

mcmullenx4 · Post by **mcmullenx4** » Sun Mar 26, 2006 12:51 am

thanks, I dident know becouse the previous owner put a hose clamp around it just to hold it on becouse the bottom half is cracked. I just use the ignition key to kill the engine.

400brian · Post by **400brian** » Sun Mar 26, 2006 2:41 am

The number one problem on all these vintage sleds seem to be fuel issues. We have talked and talked about this. Read the "Trouble shooting" FAQ ( frequently asked question ) for a broad overview of what you are looking at. The FAQ was written with the 00/JDX sleds in mind, but much is applicable.

You need to inspect, clean, or replace components of your fuel system, starting at the tank, and working back to the carb. That is the most likely cause of your problem. Even if it isn't, it doesn't matter, it all needs to be done anyway.

The FAQ section also has a link that will direct you to the source of new Service Manuals.

The Mikuni carb has few moving parts, it is very simple. Making it work correctly is not as simple.

I mentioned once before today, you might as well get real familiar with your Mikuni, cause your gonna be messin with it alot. Not to repair it, but to clean it, they just don't tolerate any crud. Also, you should write down all the numbers on the installed jets and the needle, to compare what is installed, to what it should have.
With a bit of information, and a little experience, you'll be answering Mikuni questions yourself in a few months.

Crankshaft seals are a little bigger deal. Both the clutch and flywheel will have to be removed, if not splitting of the case. Others on the list know vastly more about Kaws than I do.

Good luck

JDFanPa · Post by **JDFanPa** » Sun Mar 26, 2006 2:48 am

Yes its the kill switch and the center position is the run position.

From your symptoms lets not jump the gun yet on replacing crankseals it wouldnt hurt but might not have to be done right off the start. Have you tried new plugs? Is there fresh fuel in the sled? Does it have good compresion? Most of the time these mikuni carbs really just need a good cleaning and not new parts. So give us some info on what you have done.

Also there is alot of good info on getting a sled running again in the FAQ section

JDFanPa · Post by **JDFanPa** » Sun Mar 26, 2006 2:49 am

HAHA ya beat me Brian lol

mcmullenx4 · Post by **mcmullenx4** » Sun Mar 26, 2006 1:43 pm

so far, I replaced the plugs, added a fuel stabalizer (there was only about 2 gal of gas in the sled) and I injected some 2-stroke intake cleaner. I think my next step will be pulling the carb and clean it, and clean it. and when im done, Ill clean it some more. Is there a carurator rebuild kit that they sell? should I get it? or will just cleaning it really well resolve my carburator issues? then I will replace the fuel lines between the carb and tank. we dident get alot of snow in Ohio this winter so I only rode it a few times, but something it did one time while I was riding it makes me think that the crank seal might be bad. I first got it started and let it warm up then I rode it for about 5 min then went up a steep hill then it leveled out and about 15 sec after when I hammered the throtle the sled died (although it could have just been fuel starved from the climb). but it still takes a while to get it started and warmed up, it will start, then imediatly die, no mater what kind of throtle-choke combination. and I have to use starting fluid to get it runing. I was messing with it yesterday, I just tinkered and got it running and let it run for about an hour. any sugestions guys? I relly apreceate all the help, you guys relly know your JD sleds.

mcmullenx4 · Post by **mcmullenx4** » Sun Mar 26, 2006 1:46 pm

also, the compresion is good

JDFanPa · Post by **JDFanPa** » Sun Mar 26, 2006 6:53 pm

Your first post says you just got it,now you say you rode it a few times this winter

:blink: its hard to say if its still got old fuel or not alot of your symptoms are related to old crappy fuel and the crud that builds up in these tanks even having to use starting fluid

400brian · Post by **400brian** » Sun Mar 26, 2006 8:31 pm

A Mikuni rebuild kit doesn't amount to much.

A bowl gasket, needle and seat, and a few other small bits, and the last one I bought didn't even come with the correct needle and seat!

If your bowl gasket is intact, you probably don't need a kit, but it wouldn't be a bad idea to have one "just in case", they're less than $10. Fire series sleds will leak fuel into the crankcase while sitting, if the needle and seat aren't sealing 100%.

Clean your tank, ( plastic tanks need a different proceedure than the steel ones ) replace the lines, consider rebuilding the pump, clean the carb, and you have a good start.