Barn find

[jdbornagain]

Agreed. This is so great!

[perogie]

Great before and after Glen, did you get that seat fitted on there ok ? Brent

[340sracer]

John's upholstery did a real nice job on the seat as he found a pattern for the foam and made the complete seat. We had to cut a little bit of the foam to fit over the toolbox.
Haven't fastened on the seat yet because having trouble finding the hardback Velcro like original that is fastened to the tunnel. What is everyone else using to replace the worn Velcro?
Also need the hinges for the door on the toolbox any ideas where I can obtain them?

[400brian]

The simple solution is to eliminate the Velcro. The original plastic strips were brittle, and the Velcro hooks were tearing off, so I removed it all from both the seat and the dash. I riveted snaps in all the holes ( and don't think I drilled any new holes ), and I installed satin finish black snaps in the seat and tank cover to match the vinyl . The racing tips sheets even mentioned this fix. I think Don Amber had mentioned that by the time they were ready to race, the seat had been on and off so many times that the Velcro was already shot.

Matt has the hinges in New Bred Parts. Go here: http://www.newbreedparts.com/newbreed/i ... uct_id=252

[340sracer]

340s ... Plan on moving the timing from.022th to .090th BTDC .I'm wondering how much I have to move the timing ring to achieve this ? The engine turns clockwise so I assume I will need to turn the timing ring counterclockwise .
Any suggestions would be greatly appreciated. Thanks Glen

[400brian]

Why the timing change?

[340sracer]

If you go back about 13 post January 14, 2015 I put a post on there wondering if I should go to the bother of changing the timing and I gathered from Troy that it would be a good idea to get it right on the mark of 90 th BTDC. But if the consensus is that it won't make that much difference I would gladly leave it the way it is as this could be a very finicky job to get it right on the money . I am a little concerned though because when I was racing the 1978 cross-country I did burn down the engine and the only thing that we could find that could be the problem was that the timing was out. Can't remember which way and how much .

[400brian]

OK, thanks for the refresher, it has been long enough since I have done this that I had forgot what the 340 RS/2 was supposed to be set at. The 440/21 I did last night is timed at .023 BTDC.

What I do remember is that getting the timing set on these is a pain. A lot of trial and error, a lot of taking apart and putting back together.

If it were mine I would probably want it closer to where it is supposed to be. I really don't know what the correct answer is considering todays fuel.

[HoosierDeereMan]

Glen,

I set my 340/S timing just as the manual suggested. I had to pull my flywheel twice to get the timing set correct. It was retarded. If I have to tear into it again, I'll scribe a line on the case end and the timing ring so I know where to set it without having to go through it all over again. In my opinion, I think you would be much happier with the sled with the timing set correct. The RS/2 is rated at 47hp at 8,000RPM. By having the timing backed off you are in a sense detuning the engine and robbing it of power. How much??? You want that advance in the timing to give the ignition enough time to fully burn the gas air charge to make maximum power and take advantage of the tuned pipe. I think the timing change would aid in starting, eliminate bog and increase throttle response and crispness throughout the power band. Fuel mileage will increase and it will reduce the risk of the dreaded oil goo leaking from the manifold exhaust joint. It will really wake up the sled. The first step in tuning carbs is to verify the timing is correct.

I have a '73 400 JD that when I got it ran pretty crappy. Hard to start,fuel fouled plugs, boggy and very lazy acting. The issue was timing. Once set correct and carb tuned the problems went away.

As for burning down due to detonation? My 340/S service information bulletin from 11-21-74 states that 30,000-JDX-8,800,295/S, and 340/S require premium grade gasoline. "Premium grade gasoline is required on these sleds to prevent detonation engine damage. They have higher output engines resulting in additional heat. The higher octane rating prevents detonation at the increased temperature operating range." Also keep in mind you aren't racing. Even with some aggressive trail riding detonation should not be an issue. If I'm in a long straightaway, once I'm at full speed, I lift the throttle from pinned to 7/8 or even 3/4. It will breathe without losing speed. I'm running a Hewtech cdi box and rewound stator. My original Prestolite quit. The book calls for Champion N-19V surface gap plugs which are not available. NGK makes a BUE surface gap plug. I can't read surface gap plugs for carb tuning so I run NGK BR9ES electrode style plugs in mine. Once you get the main carb jets selected to your liking you could always increase them once size for added fuel cooling to help prevent detonation if you are that concerned about it.

Troy

[340sracer]

Thanks for the information.I have put in all new electrical except the timing ring ( trigger ), I was thinking if it is available I would like to put it in new also when I go to all that trouble of taking it apart to time it
When I took it for a ride on a warm day last spring it went down on one cylinder so I hauled it home, after cooled off it ran OK so I'm not quite sure what was going on there . It is spitting out the y pipe but I thought that was because I am running about 20 to 1 oil until it is broken in . Does anyone know if a new timing ring is available ?
Glen

[400brian]

In the experience of myself and others, i think it is safe to say your problem was jetting. The 340/S is very sensitive to temp changes. On a long ride, just the under hood heat soak can cause issues.

[340sracer]

Went for a 10 mile run on the 340 S and then tried timing it and this is what I came up with .
At 40 mph 65 to 7000 RPM and at 45 mph just over 7000 RPM and on take off it was just under 8000 RPM running in about 2 inches of snow . Is that reasonable?
Found unwanted surprise when I took off the recoil to pull of flywheel the new belt that I put on last year and only going 50 miles on the fan belt Kimpex 289900 is coming apart. I'm glad I decided to time the engine today or I probably would've blew up the engine before too many more miles!!! Is there a better belt available?
The fellow set the timing last year said he put it where he usually sets it but he can't of put it anywhere near the marks because there at least an inch away and there is absolutely no way a person can use those marks as it will not turn enough on the screws so I made my own Mark and moved it about half an inch that only brought it A bout 45° before top dead center so then I pulled the flywheel again and moved it right to the end of the screw slot.
Then a mishap happened when I set the flywheel on the bench it picked up one of the recoil screws and I never noticed it so now I have wrecked the flywheel and the stater.
I was planning on putting on some pictures but they have to be resized first.

[JDT]

Oh no!!

[WinnipegStPaul9]

Sorry to hear Glen :-(
DA

[HoosierDeereMan]

Glen,

The speed and RPM you are describing sounds about right. Now that you mention it, I think I had my trigger ring turned to the very end of the cap screw slots as well. Don Amber was able to cross reference a Napa belt that is a replacement. Hopefully he will post the belt number. On your flywheel, I'm wondering if any Kioritz CDI flywheel would work? They show them as a different part number but it may only be due to the starter ring gear? It may be possible the Cyclone or Liquifire flywheel might work. You would have to remove the starter ring gear to fit. The stators should be the same.

Troy