79 Spitfire Troubles

Hawkeye · Post by **Hawkeye** » Tue Jan 13, 2009 6:55 pm

Ok, I was following the "A real conundrum!" thread over in the General Forum, even described some of the issues over there (also my first encounter in the thread "79 Spit not making power, below). Thanks RP for the advice so far, I am slowly eliminating things off your list. For all others here is the background.

HISTORY:Picked up this sled, ran good, brought it home, ran good, cleaned it up, painted exhaust, new windshield and new seat. Christmas day it ran great, day after Christmas very, very humid, it wouldn't make power - found leaking fuel line and replaced, also cleaned carb (Mikuni Butterfly - this is an odd ball carb!). Made good power til about half to 2/3 throttle then would not advance. Suspected Fuel pump (due to large air bubbles between fuel pump and carb so rebuilt fuel pump and replaced impulse line (due to large hole found near engine after rebuild of fuel pump), also pulled the carb and cleaned it again (it didn't need it, but wanted to make sure). Now it again won't make power past idle. Sounds like it is only hitting on one cylinder (as it did when the problem 1st presented itself day after Christmas) but if I pull the plug wire on either cylinder it runs the same.

Following RP's advice, I have disconnected belt, exhaust, impulse line, no change. All seals seem to be good when checked. I have new plugs in (and more standing buy) Now I'm into the electical stuff, RP said disconnect Limiter (I didn't know it had one) but what is this, could it be the Voltage Regulator (but earlier he referenced "rev limiter)? Also does anyone in SE WI have a known good working CDI, so I could test that, if not how does one go about testing a CDI to find if it is good. Finally, or at least for the moment what resistance should I look for across the Stator?

I am trying to avoid similar mistakes I made with my 125th anniversary John Deere 180 lawn tractor (original owner!) that is spending a lot of money replacing parts that in the end didn't need replacing... Also hoping to get this running for the Horicon show and most importantly my girls, seeing all the snow pilling up in the backyard keep asking, "Dad can we ride the Deere???" Thanks in advance for any help anyone might be able to provide.

400brian · Post by **400brian** » Wed Jan 14, 2009 3:01 am

There is a topic in the FAQs dealing with CDI diagnosis.

79spitfire#100340 · Post by **79spitfire#100340** » Wed Jan 14, 2009 10:57 am

It is the cdi.This is common on the denso units.Next ,it will only idle.I have replaced 3 of these on my sleds.You can buy a used one if you check around as these were also used on quite a few arctic cats.If you would like to purchase a brand new unit.I live close the company that bought Kohler and they had a run of the cdi 's made in 2007.Let me know and I will give you their number.They are $93.00 ---MIKE

Hawkeye · Post by **Hawkeye** » Wed Jan 14, 2009 1:29 pm

Thanks guys, I never thought to look in the FAQ. Will go there first going forward. I'll update this post with what I find. I sure hope its the CDI, thats a pretty easy fix...

Thanks,
Steve