Having heck of a time with my spitfire

[just_some_dude]

For it's age (1978) a couple weeks ago I was on the trail and it ran great. A couple days later I took the sled back to the trail, had my wife with me, so two on the sled, and the sled had no power. It couldn't get up hills, couldn't handle full throttle, and would not go fast at all. I could jog as fast as it could move.

I recently cleaned the heck out of the carbs, so I'd be surprised if that was the issue. And I cleaned the carb before I went on my initial single run. So, nothing should have changed.

Ever since the last ride, it performs the same. Has no power, and cuts out if you give it too much gas. It has trouble even moving at all. I've posted on other forums, but I'm simply not getting enough response. I'm hoping since this is a JD forum, most people have a better idea with what's going on.

One additional thing I did to the sled was I, by accident, put in 87 fuel when I should have used 89. After playing with the carbs a bunch and finally checking my spark plugs, they were black and sludgy. I can't say they were always like that before I started really messing with the carb, but maybe? I'm in the process of picking up some new plugs, but I need to start ruling out possibilities. I'd like to get this thing back on the snow by this weekend.

I guess I have another... . Normally, smoke comes out of the right side exhaust. When I hit the throttle and the sled is stationary or struggles to move, smoke starts pouring out from both sides of the sled. I haven't really had the opportunity to see it that's all from the exhaust or something else.

[kreechur]

Is it the round slide, or the butterfly carb? Spark plugs that are black and sludgy, and excessive smoke sounds like the carb mixture is set too rich to me. One of the plugs could be fouled out causing your poor performance. Try the new plugs if it runs good again with the new plugs check the plugs after a short ride. If the insulator is black again carb is set rich, and you should lean it out a bit. You want a light tan color on the insulator of both plugs.

[just_some_dude]

I believe it's a round slide carb... Do you know the air/fuel mixture screw directions? For example, in for more fuel, out for less fuel, etc...

[mikehjd]

If you have a slide carb its 2 1/2 turns out and 1 turn on the butterfly carb, these are the settings you should start with and then go from there. You just have to play with the mixture screw a bit to get it set right. Turning it in should lean it out and turning it out should richen it. Warm it up and adjust it and just keep at it until you get an nice smooth idle.

[HoosierDeereMan]

J.S.D.,

I remember some others posting Spitfire issues much like what your are describing. It was a bad CDI box. If I remember correctly the sled would start and idle fine. It might even allow you to rev the engine slightly. Then once it got into the higher RPM range it would lose spark or have intermitant spark. Maybe one of the guys who had CDI problems with these will chime in.

Troy

[just_some_dude]

I don't know anything about the CDI, but a lot of what I've read elsewhere people always say the CDI works entirely, or not at all. Again, I really have never had to mess with them, so I have no idea how true that is.

[kreechur]

My 79 lost the CDI, it acted like i lost the cylinder. If i remember right the service manual has a way to ohm it out, which i did and it seemed to be within specs, but it never would run right. I bought a new one, and it instantly ran very nice. Depending on the motor, start on page 79 for the kohler: http://www.vintagesnow.com/John_Deere_f ... July79.pdf

This manual will also help you with the carb if you need it.

[just_some_dude]

kreechur, were there other things you did before you suspected the CDI? Or did you know immediately?

[just_some_dude]

... and regarding the carb... the large screw, idle, starts from a fully suppressed spring, then turn out 2 1/2 turns? The small screw, air/fuel, is screwed all the way in, until it's can't be screwed in any further, without force?

Right?

[mikehjd]

No the small one is the one that is turned out 2 1/2 turns. The large one you shouldn't have to touch if it was running fine before.

[just_some_dude]

I recently took the carb apart and cleaned it. I didn't pay attention to where it was supposed to be. I imagine all I have to do is make sure the sled idles okay. Educate me !

[just_some_dude]

I think I got it. On the service manual it says turn in until there is slight resistance, then turn out.

[just_some_dude]

Okay. I just made some carb adjustments and put in the new spark plugs. The Deere is running better, but still not ideal. It still lacks power. Before the sucker would barely budge. Now, I'm getting places . Just slowly. If I hit the throttle it cuts out.

I checked the plugs and both tips are just about the same brown, but moving towards the black side of brown, mainly because they are wet and oily. I kinda have a feeling like there might be too much oil in the fuel. Any thoughts?

[JDT]

A CDI box CAN fail as RPMs increase.

Fought this one a couple of years ago.

New box and problem gone.

[just_some_dude]

It's looking like I'm going to have to go the CDI route... I didn't want to because I don't want to toss another $100 into the sled, right now. I can't seem to find anything around me with a spitfire parts sled either.