79 spitfire

AZspitfire · Post by **AZspitfire** » Thu Feb 12, 2009 12:46 am

back in nov. had problem with bad cdi box picked one up from patssmallengine put it in the new box it ran great after about 15 hours of riding it backfired 3 times out the carb now there is no power it idles great revs up when i pick up the track off the ground and rev it up it seams all to be working good then put it on the ground and give it the gas it goes about 30 feet then no power no throtle it stays running but wont go any were after a couple min at idle it another 30 feet does anybody have any ideas could the cdi box have failed we just got 2 feet new snow can't wait to get back out there any help

79spitfire#100340 · Post by **79spitfire#100340** » Thu Feb 12, 2009 1:40 am

Sounds like its only running on 1 cyl.replace plugs?Check coil next.A spitfire running on one is never a carb issue.The cdi going bad will usually cause the engine to only idle but will quit when throttle is advanced,or a total lack of spark.Check out your spark situation and let us know.Good luck ----MIKE

JDT · Post by **JDT** » Thu Feb 12, 2009 1:43 am

Check compression. Maybe burned down a piston an it is running on one cylinder.

Crank seals, head gasket or similar failure.

JDFanPa · Post by **JDFanPa** » Thu Feb 12, 2009 2:35 am

Check compresion as Todd stated. If you got 15hrs on it and the plugs are good sounds like you burnt a piston.

AZspitfire · Post by **AZspitfire** » Fri Feb 13, 2009 1:52 pm

thanks mike&todd
checked spark it looked good felt strong when it got me pulled plug wires one at time big difference running on one cylinder i don't have compresion gage so i held my finger over plug hole it had good pressure so i thought lets give it a try same thing 30 feet as soon as i went up small grade it lost power but kept running i noticed the headlight was getting real dim then would get bright next i pulled the coil cleaned the contacts with steel wool took for another try went up the hill around yard then it stalled and limped it back so i think it might be the coil won't handle a load does this sound right any thoughts
thanks Erik

JDT · Post by **JDT** » Fri Feb 13, 2009 11:03 pm

JDT wrote:Check compression. Maybe burned down a piston an it is running on one cylinder.

Crank seals, head gasket or similar failure.

While a figure can test for lots of other things it does not work for compression.

Cabindweller · Post by **Cabindweller** » Sat Feb 14, 2009 1:03 am

You should check your compression with a gauge. But if you pull it over real slow you should be able to tell if both cylinders have about the same amount of compression.

AZspitfire · Post by **AZspitfire** » Mon Feb 16, 2009 1:59 pm

this morning started up the spitfire it ran great lots of power drove it around for about 15 min then it lost all power let it sit 1/2 hour to cool off it started up ran great for 10-15 min when i get into town this week i will try to find compression gauge so i can check it the temps around have been in the 40/50s is it to warm for the air cooled motor i talked to the guy i got it from last time it was registered was in 81 he said he only put about 10 hrs on it since he's had it what is the proper belt for this spitfire it came with two john deere m66345-178a / ms66345-279d any ideas what might cause this to happen next storm tonight 10 plus inches

Spitfire79 · Post by **Spitfire79** » Mon Feb 16, 2009 3:48 pm

40s to 50s is very warm for that little Spit. That could be part of the problem. Could also be a bad coil or cdi
Does it lose spark when running poorly?

Jeff

79 Spitfire · Post by **79 Spitfire** » Mon Feb 16, 2009 3:51 pm

40s/50s Sounds a little to high the max I'll run mine is at 35* or lower.

JDT · Post by **JDT** » Tue Feb 17, 2009 7:56 am

At 20 below a Spit is a rocket. At 20 above I would not even ride it.