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Discussion Starter · #1 ·
Or at least I think that is what it is called... anyways... This is my Buddy's sled engine (replacing the seals) it has been sitting for around 9 years and has 110 & 112 PSI in the cylinders. We took the engine outta the sled and brought it to my house (after 2 1/2 hours of fighting) Now me and him have to take the whole thing apart tomorrow. We need to know if it is the seals, the spark, or something else... plus what are the torque specs of the engine?
 

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Over 100lbs in a early 80's engine is good. They did not have high comp like the engines of today have. They had very loose tolerances.
 

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I thought the John Deere JDX were built in 1973-1975 and most of them had a # behind the name.
JDX4, JDX6 and JDX8 all ranged from 300 - 800cc
Like SnowAttitude said "Need more information"
Before I tear into the block I would check the fuel pump, carbs, plugs and all the rubber hoses for signs of deterioration.
 

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Originally posted by xcr440
[br]Over 100lbs in a early 80's engine is good. They did not have high comp like the engines of today have. They had very loose tolerances.
Those sleds had higher "compression ratios" because good quality leaded gasoline was available. "Regular" was 91 octane!

In regards to the engine question. It could be from a 1973 JDX4 and be a Kohler, all others would be a CCW. I would do a pressure test (low pressure with intake/exhaust ports closed off) to determine the condition of the seals and crank case sealant before disassembly (unless you simply want to put new seals in so that you do not have that concern).

Let us know which engine.
 

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Discussion Starter · #6 ·
Its a 340cc engine... the heads are off now and it doesn't look to bad. I have no clue what the year is. And the problem is that the engine doesn't like to keep running, and when it is running it only runs on one cylinder till I hit around 20 MPH then it kicks in and then it just dies if its idling there.
I have no clue what could be causing this problem, but many say it could be the seals, they are cheap so I'm gunna do that for my buddy. Oh and one more thing... I think hid carb could be fu^%ed even though him and his father rebuilt it last winter.
 

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Discussion Starter · #7 ·
I have another question as well, is it okay to use 120 grit sand paper to take some carbon build up off?
 

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Discussion Starter · #8 ·
Engine tuned out to be a POS and now it is just going to be sold as a parts sled now.
 

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so why is the engine a POS?
 

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IF it is a JDX and IF it has a 340cc and IF it is the original engine...it would be the a 1975 JDX4 with slide rail suspension and reed valve KEC340. This is a rare sled. If you sell it, sell it with the engine so that someone can rebuild it and keep it original!
 

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Discussion Starter · #11 ·
it is a 1973 JDX
 

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our jdx4 was a ccw 292 and the x8 was a ccw 440. but they were right around 70 models. good running sleds. the x4 could keep up with other 340's.
 

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1973
JDX4 Kohler K295-2AX Piston Port Boggie Suspension
JDX8 CCW KEC-440/21 Reed Valve Boggie Suspension

1974
JDX4 Special CCW KEC-340/5 Piston Port Slide Suspension
JDX6 CCW KEC-400/22 Reed Valve Slide Suspension
JDX8 CCW KEC-440/22 Reed Valve Slide Suspension

1975
JDX4 CCW KEC-340/22A Reed Valve Slide Suspension
JDX6 CCW KEC-400/22 Reed Valve Slide Suspension
JDX8 CCW KEC-440/22A Reed Valve Slide Suspension

THIS IS HOW THEY CAME OUT OF THE HORICON FACTORY...
KEEP IN MIND THIS WAS OVER 30 YEARS AGO AND THINGS GET SWAPPED
 

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Originally posted by TakeItToTheLimit
[br]
Originally posted by xcr440
[br]Over 100lbs in a early 80's engine is good. They did not have high comp like the engines of today have. They had very loose tolerances.
Those sleds had higher "compression ratios" because good quality leaded gasoline was available. "Regular" was 91 octane!

In regards to the engine question. It could be from a 1973 JDX4 and be a Kohler, all others would be a CCW. I would do a pressure test (low pressure with intake/exhaust ports closed off) to determine the condition of the seals and crank case sealant before disassembly (unless you simply want to put new seals in so that you do not have that concern).

Let us know which engine.
I was always told that leaded fuel was phased out before the 80's.

All of the cars (pre 70's mustangs) that I had, under the hood said reqular 89 not 91.
 

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Originally posted by xcr440
[br]
Originally posted by TakeItToTheLimit
[br]
Originally posted by xcr440
[br]Over 100lbs in a early 80's engine is good. They did not have high comp like the engines of today have. They had very loose tolerances.
Those sleds had higher "compression ratios" because good quality leaded gasoline was available. "Regular" was 91 octane!

In regards to the engine question. It could be from a 1973 JDX4 and be a Kohler, all others would be a CCW. I would do a pressure test (low pressure with intake/exhaust ports closed off) to determine the condition of the seals and crank case sealant before disassembly (unless you simply want to put new seals in so that you do not have that concern).

Let us know which engine.
I was always told that leaded fuel was phased out before the 80's.

All of the cars (pre 70's mustangs) that I had, under the hood said reqular 89 not 91.
You are correct about unleaded being phased out in the 70's. Deere detuned the engines in 1977 for lower octane. I was specificly addressing the engines used in the JDX models which were 1973-75. For example the 1973-75 JDX8 440 had a compression ratio of 7.9:1...by comparison, a 1980 Trailfire 440 had a compression ratio of 6.5:1. This significantly changed the octane requirements.

Deere commonly refered to "quality regular grade gasoline of 90 (or 91) octane". They recommended "Premium Grade gasoline, of at least 95 octane, is required for the JD295/S, JD340/S, 800 & JDX8 (30,001 - ), to prevent detonation damage."

It is not my intent to discuss topics outside of the initial post nor is it my intent to claim knowledge outside of that which I have documented. If Ford stated that 89 octane was the miinimum octane required...that is all the compression on that engine needed to prevent detonation. That is key even today...follow the O.M. recommendations in terms of octane recommendations.
 

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Discussion Starter · #17 ·
Originally posted by TakeItToTheLimit
[br]1973
JDX4 Kohler K295-2AX Piston Port Boggie Suspension
JDX8 CCW KEC-440/21 Reed Valve Boggie Suspension

1974
JDX4 Special CCW KEC-340/5 Piston Port Slide Suspension
JDX6 CCW KEC-400/22 Reed Valve Slide Suspension
JDX8 CCW KEC-440/22 Reed Valve Slide Suspension

1975
JDX4 CCW KEC-340/22A Reed Valve Slide Suspension
JDX6 CCW KEC-400/22 Reed Valve Slide Suspension
JDX8 CCW KEC-440/22A Reed Valve Slide Suspension

THIS IS HOW THEY CAME OUT OF THE HORICON FACTORY...
KEEP IN MIND THIS WAS OVER 30 YEARS AGO AND THINGS GET SWAPPED
The engine has reeds, and it is a 1973 deere (or that is what I am told)
 

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I had a 1975 JDX4 340. Motor was Kioritz, 34 or 36 hp, I don't recall. Reed valve. Fairly high rev'ing motor. Intake manifold turned 90 degrees so carb (Tillotson butterfly) faced vertical. Fastest I had it up to was 72 mph on a hard pack snow covered road. MPH reading was by the speedometer. Also, I weighed 130 lbs so pretty light. Loved that machine, very well made and very reliable. It's demise: while running, a screw came loose from the air cleaner and fell down into the intake manifold, got pulled in below the piston, and destroyed the motor. Replaced it with a 440 Kohler. lower rev'ing motor, but really good torque. It now topped out at 58 mph, but with those Deere's, the motor was mounted a bit further back, would pull the skis up off the snow on fast starts.
 
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