1980 Trailfire 440

[Hoffmanuno]

I bought a rough looking JD 1980Trailfire off craigslist for $75 4 weeks ago. The guy had bought it as a project sled, but The engine was seized and he said "he didn't know how to work on them". Good for me! Three days later I got the engine broke loose after a soak with a little bit of tranny fluid and kerosene. Cleaned off the spark plugs put them back in and got it to fire over. Great consistent spark on plugs, even dirty ones I uses to test it. Lol. Check the compression and it had 150 psi on both cylinders. Cleaned off the corroded brass from inside the carburetor, cleaned/drained fuel tank, new fuel lines, filter, and shutoff valve installed, cleaned air box, and got it started. That's when I noticed it had a blown head gasket in the front. Instead of doing a complete rebuild right now I just ordered a seal kit and put the head gasket on so I could maybe drive down the road in test ride it this winter. I looked at the cylinders closely and noticed the mag side was perfect but there were two or three deep scratches in the lower part of the cylinder on the PTO side. Still has great compression but that may be a problem to address this summer when I do a proper reseal and rebuild . Got it idling fairly well and adjusted the carb and choke cable . Motor revved solidly. That's when I noticed that the clutch was rusted/frozen. Got that off pull the part cleaned up and put back on . That's when I realize the secondary clutch was seized/rusted. It came right off the shaft it was just rusted together. Got that all torn apart and cleaned . Are use starting fluid to test the seals on both sides of the crank which had looked very good and there was no racing of the engine and or leaks around the carburetor. Big moment. Got it started and took it 2/3 of the way around the house before it just slowly died. My friend didn't think there was much gas in the line and so I bought a new pump kit . The old one didn't look bad at all but you never know . That seemed to fix the problem and I got the idol tuned down pretty low. I took it up and down the road real quick for a test and it ran fine with a bit of hesitation at the low end, but I had the secondary spring in the number three position and thought maybe that was part of the problem for though weird take off . Went to take it out yesterday and had it running great in the garage on stands but when I flipped the gauge cluster box over on top of the engine I noticed that the idle would stutter and die . Did it again same thing happened . Started flipping the box bass back-and-forth while it was running and it would start to die then come back . Wth? Said the hell with it and just got it running and then killed it and drag it out of the garage to face down the driveway . Couldn't get it started again . The choke cable is a little rough but seems to be working fine and the choke tip still has a fair amount of rubber on it . Am I correct in assuming this is a carb/choke issue? I've got a bit of experience rebuilding old 60s era outboards but none on snowmobile engines so I'm out of my depth here. Also this sled seems to not have a cleated track but a segmented rubber track. I thought all these trail fires had cleated tracks ? This one is wearher checked but in decent shape.

[Hec In Omaha]

Sure sounds like the choke is not adjusted correctly. To adjust correctly you should have at least 1/8" of free play at the choke lever on the dash with the lever in the half choke position. With the dash lid closed, adjust the choke while simultaneously trying to tug on the choke lever on the dash. You will notice if you adjust the choke one way you will not have any free play at the choke lever. If you adjust the other way, you will be able to tug the choke lever out some. Adjust it till you can tug on the choke lever and pull it out 1/8” or so.
If there is no free play then you may be engaging the choke a little when you close the lid because it too tight. Hope this makes sense. Good luck!

Hec

[Hoffmanuno]

Thanks! I had a feeling that was the problem. I'll try doing that tomorrow. Right now it's in the driveway encrusted and ice and snow from that massive rain/ice blizzard that came through here this weekend. I just want to get it running so I can Road test it now I know what I need to do it this summer do you have it completely ready next year.

[Hec In Omaha]

I just noticed you are in Pacific Junction, IA. I’m just on the other side of the river at Beaver Lake! That was some storm! I spent 5 hrs digging me and some neighbors out. After that, I tried riding my TF 440 on the lake today but there was 6” of wet slush under the 8-10” of snow. All on top of the ice. I couldn’t get any traction.

Hec

[Hoffmanuno]

Small world! Yep, that storm was a doozy! I was trying to start it in the driveway to run it down the icy road quick but after an hour I was soaked and left it there with the track off the ground. It's still there covered in ice and snow. Lol.

[Hoffmanuno]

I just of the choke and it started in the idled easily and revved up perfectly. I thought I had it licked and took it up and down the road a few times getting her up to 50 miles an hour. Let her sit for an hour and a half and then went outside and rolled it up and down the road again and noticed the idle was climbing again. Then it started to idle much higher and when I stopped and shut it off to turn around I couldn't get it started unless I pulled the choke open a little again. I had to keep one hand on that choke lifting it just a little bit in order to get it back home. Maybe I need to take apart the carb again and see if there's some blockage. I don't see how though because I put all new fuel lines and new feel filter on it, but maybe the carb needs a good soak.

[Hec In Omaha]

A few things to check.
* Make sure you don't have a sticky or frozen throttle cable.
* Make sure the threaded cap, where the throttle cable connects, didn't loosen up. This would raise the slide valve and needle causing increased RPM's. Happened to me once.
* Make sure the air screw is set to 1-1/2 turns open.
* Set the idle stop screw by doing the following: Turn screw in until it just makes contact with the slide valve. Then hold the throttle wide open and turn the idle stop screw in two more turns. Idle speed should be 1,800 to 2,300 RPM. Do you have a tach on dash? If it still won't idle you will need to open up the carb and make sure all the jets are clear.

Keep us posted

[JDT]

Your dried up 30 year old crank seal cracked on your test drive.

Change them now or you will never ride it again as the engine will be junk.

[Hoffmanuno]

I readjusted the choke, still has the problem. Noticed jet needle was silverish on lower part. Suspected wear and moved clip up one from middle to #2 position to counteract. Friend helped me and said my throttle linkage was too tight. Loosened it a lot, and it helped, had a very low steady idle. Took it around tge house a few times, ran great. When I stopped to turn the ass end around it idled real low, sputtered and died. Played with choke lever and got it started and up driveway. I'm thinking carb needs a better cleaning and adjustment. Tach doesnt work, so tuning idle so secondary doesn't engage/idles steady.

Crank seals are fine, for now, as I visually inspected them and continuously teat tgem with ether for air leaks. I know I need to replace them, but I'm not doing it until this summer when I do the complete tear down, inspection, and rebuild. I researched all the crank seal horror stories already and am aware. I just need to road test it now to figure out what's good, bad, and ugly on tgis tgibg while snow is still on the ground. Lol

[Hec In Omaha]

Have you checked the float level? It may be off since you picked up the rear end and it died. Do you have the technical manual? The float adjustment procedure is in there. While holding the carb upside down the float arm should be parallel with the carb body. Make sure the floats actually float in fuel too!

Float Adjustment

Link to the Technical Service Manual

http://www.vintagesnow.com/John_Deere_f ... ilfire.pdf

Hec

[Hoffmanuno]

When I took the car part and cleaned it I checked the floats and made sure they were adjusted correctly according to the specs I saw online. I found the choke cable adjusting not had come loose. I also decided to move the needle back into the middle position which is number three I believe . Finally got it started and adjust the choke cable night and once I was satisfied it was running OK I adjusted the slide carb idle screw . There is a bit of a Divet in the slide card from that screw being adjusted to tight I believe. When I got it and was checking out the car but I found that that slide car adjusting screw had been turned all the way in. I'm trying to decide whether or not to rebuild the carb this summer or buy a new one . I've looked at the fine-tuning manual and a technical manual and they list to say different carburetors for my engine /model/year. The fine tune manual says I have a vm-34/232 and the other lists it as a vm-34/193. Which one is correct ? I finally ordered an owners manual for my year so I don't have to keep looking at PDF copies. It's only 42 pages long though which doesn't seem right, but it's the JD oem manual.

So now it seems to be running great but if I shut it off I have a hard time starting it again when it's warm. I got a kind of lift the choke open a little bit and open the throttle to get it going . After that it idles fine . Had it running for about an hour today in the field and front yard. Got the front end off the ground a few times and even got the entire sled in the air jump in a snowdrift. Lol

And I sprayed some ether on my crank seal again just to make sure and it's fine. I'm being very careful about that . Lol

[Hec In Omaha]

Well at least you got it running and got to ride it. Make sure the rubber carb mounting flange is good. Check the two bolts for tightness and the rubber clamp too. Check with ether to rule out a vacuum leak.

By the way if you don't have the factory air box get one! Running without it will result in a lean running condition. Unless your carb is a total wreck I would rebuild it. They are very simple. The trick is making sure that all the right jets, needle, slide valve etc.. is in there. You also want to make sure the choke bore is clean so the choke plunger doesn't hang up. When you take your carb apart take note of the pilot jet number, main jet number, slide valve number, needle jet number, and needle number. When I rebuilt my Carb I had replaced all the jets per the manual only to find that I couldn't get it to idle right on the #25 pilot jet. I reinstalled the #42.5 jet that came with the carb I bought and its been running great ever since. I have purchased a #35 pilot jet and may try it to lean it out a bit on the idle circuit. Take a look at your slide valve and make sure it's a #3.5. Pay attention to the anodized metal. If you see bright silver color this indicates that it's been modified. My old slide opening had been machined to make the engine run leaner. The edge that got machined was shiny silver in color.

My carb is a VM-34-193 and its on a 1981 TF440. The VM-34-232 is for the LX which has oil injection
I am running - #230 main jet, #42.5 pilot jet, 166-Q-2 Needle jet, 6F27 Jet Needle with the clip in the 3rd position.

This summer I would replace all the drive bearings on the drive shaft and replace the bearings in the jack shaft. Check the conditions of the plastic hyfax on the bottom of the suspension skids. Especially towards the front of the skid. You don't want the ride it if they are worn out or you will damage the suspension slides. Remove the entire suspension and check all the wheels and shafts to make sure they are free.
I have the required clutch puller and clutch alignment tool and could come out to help with the removal and installation of the engine. Having the right tools makes it a snap!

Good luck!

[Hoffmanuno]

Thanks! I have the airbox on. I took it off and cleaned it out good too. Now I know wbat carb it is and jet sizes. I'll do your recommended rebuild. Also plan on replacing all those bearings this summer. I'll need to borrow the alignment tool too. Lol.

[Hoffmanuno]

It's running quite well now. Plugs are finally not covered in oil/soot and are burnong clean. Sled has great mid to high throttle response. I had it flying up and down my dad's pasture the other day and jumping drifts in my front yard. Haven't got it over 55 yet, but she could easily do that on a more flat surface. I think a carb rebuild, engine overhaul, new bearings, and a primer installed on the intake will have it ready for trail riding with friends in WI next winter.