Snowmobile Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
146 Posts
Discussion Starter · #1 ·
Took my '79 JD Spitfire on the trail today and it totally failed. It was struggling to get up small hills, etc. I had to totally get off and push it sometimes. By the end of the trail the sucker wouldn't barely move forward on flat land. A couple days before the thing was moving without issue. In addition, on the trail if I hit the accelerator the engine would cut out. Again, couple days before, no issue. Was just a really crappy experience.

Trail fail.
 

·
ride till your broke
Joined
·
2,560 Posts
so how much snow was on the trail??:D
 

·
Registered
Joined
·
146 Posts
Discussion Starter · #5 ·
Enough that the sled should be running without issue. A thin, but very supportive layer. No fluffy stuff. I imagine I need a new drive belt. But that whole engine thing cutting out when hitting the gas has me a little thrown...
 

·
Registered
Joined
·
228 Posts
Freaknyea,

Have you done a plug reading on the sled just after it acts like that? RJ Gleason, BCDan, or Smallengine Guy can give you better guidance, but it sounds to me like it's either running really lean, or short on lubrication.

Not sure if you're familiar with plug checks. So here goes- if it's running lean, the tip of the insulator will be either very pale tan, or white. It might be blistered, or shiny. Too rich will be black or dark gray, either sooty/fluffy or wet and slimy. Normal is dry, tan to dark brown.

Those Kohler free-airs are usually bulletproof. Especially the model run on the Spitfire, it was conservatively tuned with an eye on light weight and reliability.

Your engine might also have a bad carb boot or a leaky crankshaft seal.

You might want to run a compression check on your engine. If it comes out low, or uneven, you definitely have a problem.

Sorry I couldn't help more, but hopefully this will be some use to you.

-Strato-
 

·
Registered
Joined
·
146 Posts
Discussion Starter · #7 ·
It's been about 24 hours since it was last run, but I just pulled the plugs out and they are black and almost sludgy...

Should I just add a bunch of straight gas to the tank without oil?
 

·
Registered
Joined
·
146 Posts
Discussion Starter · #8 ·
I just started the sucker again and noticed it spiting smoke out the head. Just for giggles I tightened a few of the bolts on the head, but I think one of the screws actually broke entirely. I've never taken a head off of one of the engines. Is it possible to replace those screws? I imagine I need a new gasket as well.
 

·
Registered
Joined
·
228 Posts
I just started the sucker again and noticed it spiting smoke out the head. Just for giggles I tightened a few of the bolts on the head, but I think one of the screws actually broke entirely. I've never taken a head off of one of the engines. Is it possible to replace those screws? I imagine I need a new gasket as well.
Not sure if your engine has replaceable studs; if the stud is broken or stripped it'll have to go.

The problem you're experiencing is just the opposite of what I expected; I'm kind of stumped. Sounds like your engine is running REALLY rich.

Pulling cylinder heads and replacing is no big deal on a 2-stroke engine; you just need to replace the head gaskets.

I will refer to the sled "bible" and see if the info is there re: head attachment on your engine. Should show hardware used, torques, and patterns.

TTYS,

-Strato-
 

·
Registered
Joined
·
146 Posts
Discussion Starter · #10 ·
I just went to the JDparts website and they list the stud as a part that you could have purchased. I'm sure you can't anymore, so I'll have to find something. I've never replaced a stud before, so I have no idea what I need to do.



I'm a little confused on the options of purchasing the gaskets. There are two kits on the following site, and I'm confused if one is any different from the other.
710006X - Kohler 295,340 Pro-Formance Gasket Set.
711006X - Kohler Professional Engine Gasket Set

I've been messing with the carb a lot recently. It's entirely possible I've been sending tons of fuel into the engine. I'm confused on if when you screw in you get more fuel or more air...
 

·
Registered
Joined
·
146 Posts
Discussion Starter · #13 ·
I pulled off the head and everything was fine. The gasket looked new. The stud was coming out of the engine, though. I have no idea, yet, if it's stripped. The screw looks fine, which scares me.

I'm having a lot of stupid moments with this sled recently. I realized I put regular gas in and it takes premium. I imagine with a 2 cycle engine that will decrease the performance.
 
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top