Will not start when warm

[Snowslider]

Hello Guys,

I have a 1975 300cc JD sled it was my grandpa's and we have owned it since new.

The machine has always run fine but now I am having issues with it starting when warm. It starts no problem when cold but once it's warm if you turn it off it will not start.

It has gas and spark.

After it has run if you turn it off and go to start it you will just pull and pull and pull till your arm falls off! If you let it sit for about an hour and come back to it it will start!

If anyone could help it would be greatly appreciated.

thx

[400brian]

Have the crank seals been replaced?

[Snowslider]

No they have not.

[Snowslider]

Can this cause the warm starting issue?

[400brian]

It can cause lots of issues, and is the first thing we advocate doing when first trying to run a vintage sled. They are not expensive, but you will have to pull the clutch and flywheel to do it. I have never worked on Kohlers, which I assume is what you are talking about, so I would have to review the manual for anything more specific on the topic. We replace the seals on the Kioritz engines as a matter of maintenance. Seals would be a good place to start, you need to do them anyway just because of age.

[AirborneX4Special]

Change the crank seals before you do anything else. After that, we can get into carb vapor lock fun and games and/or coil issues if the situation persists

[Steven Rempel]

I deal with alot of these mid mounts and had one last year do this to me. It would start ok when cold and run fairly good, felt like it had ok power and response, but if you shut it off and wanted to restart it. you were s o l. Until it was stone cold. I replace many things like condensers, coils, plugs, wires, rerouted the fuel lines, different carb, ect on and on this went. Final I changed the point with new ones as it was the only thing I had not yet tried. and as luck would have it that was it. After inspecting the old point with a magnifying glass you could see that they were pited. Yet thy had enough surface to make good contact when cold, so when checking the timing things were good, spark look good, but when hot spark was gone, or weak, or intermittent. so I added new points to my list of must refresh.

Yes crank seal are very important and it the frist thing I change if you can prove when they had last been change out. but have a really good look at the point, and for the cost, new ones are worth it, at least its on the list of must change when picking up new to me sleds.

for me in this order of importance as it relates to the motor before the frist test run.
crank seals
fuel filter
fuel pick up (intank)
carb kit
fuel lines
plugs
plug wires
points
timing
and a leak down test
compression test
degrease engine


just my though hope it helps.

[AirborneX4Special]

It's so much fun to operate old junk.....but at least you can wrench on it without using a computer!

[Snowslider]

Great thanks guys appreciate the help,

Yes it’s a Koehler.

Here is the list of things I have done over the past couple years.

Done:
Fuel filter
Fuel pick up (intake)
Carb kit
Fuel lines
Plugs
Compression test about 105 psi per cylinder if I remember correctly was a year ago
Degreased engine


To do:
Crank seals
Plug wires
Points
Timing
Leak down test

I will start with the crank seals and try replacing the point.

That being said can I please ask fir some help and guideance in how to replace the crank seals? Is there a guide or has anyone done up a step by step for this engine?

I’m a very mechanical guy and have done a lot of work on engines and cars but never a complete tear down and rebuild. So some guidance in this would be great.

[Snowslider]

Sorry hit post by accident was not done.

As well dies anyone have guidance on the points and how replace/ replace.

I’m not super farmiluar with thus engine but would like to learn.

And lastly when it comes to parts where does a guy get crank seals and a new point?

Thanks guys

[Snowslider]

Was doing some searching on the forum and found these documents are these the best to use and are there others I should be consulting?

JD Service Manual SM-2100
JD Operator's Manual
Kohler two-cycle engine service Manual


Thanks

[400brian]

SM 2100 is what I am most familiar with, I consult that all the time.

Seals are available here on the site. Go to : New Breed Parts at the portal page.

[Snowslider]

Hey guys any tricks to removing the Sheave?

I don't have a drive sheave holding tool.

Can this be done any other way?

Thanks

[400brian]

You need 2 tools to work on these engines: a clutch puller, and a flywheel puller. No substitutes. Matt has them here at New Breed Parts.

[Curlymurt]

This isn't a "correct" way to remove the sheave, but I used an old leather belt wrapped around and folded over top of itself... Like a universal size oil filter wrench. To hold it while I cranked on the bolt, I pinched it with two sticks of whatever I could find and rolled it around a couple of times. Then I propped one end of the stick on the frame and held the other. That probably doesn't make much sense, but it held tight and helped with leverage.

To actually pop it loose, I did use some "soft" blows with a rubber mallet while prying with a hammer handle between the sheave and engine to keep constant, light pressure on the sheave ... In the direction I wanted it to go.

It's a good idea to just buy the tools from New breed. It'll make life easier, less stressful, and you won't ruin a leather belt.