420c Died

Davie Sprocket · Post by **Davie Sprocket** » Wed Aug 29, 2007 7:08 pm

I just got a new 420 home from that states on monday and after running for about 15 minutes it died under load and has not started since, getting alot of fuel out the carb, its a zenith carb and the fuel is running out the bottom. I took the carb apart and checked the float and its working good, checked the fuel bowl, lost the gasket so i had to make a new one, now working fine.

Is there anything that might explain what happened. It turns over fine but will not run, I'll have to go through the wiring tommorow and make sure its all good. I didn't touch any of the wiring so i'm kinda in the dark on this one.

Any ideas would be great.

Dave

rvbarkley · Post by **rvbarkley** » Wed Aug 29, 2007 7:48 pm

Could be a lot of things, one thing to check would be the switch. My MC was intermittant/hard starting, could never quite pinpoint the problem. Replaced the switch, no more problem, in fact starts better than anything I have! You should be able to "hot wire" to rule it out.

gus · Post by **gus** » Thu Aug 30, 2007 9:03 am

The long ride home could have shook something loose.
Gus

Davie Sprocket · Post by **Davie Sprocket** » Thu Aug 30, 2007 11:08 am

Yeah thats what I'm thinking. I'm gonna go through her today.

Dave

Davie Sprocket · Post by **Davie Sprocket** » Fri Aug 31, 2007 12:30 am

Checked spark. Okay replaced coil just in case.

New battery, got power turns over fine.

Carb is working, or i may have too much gas as i played with the mix screw on the bottom of the carb.

So i have fuel have spark is there anything else that may have stopped it from running.

Dave

Post by **Lavoy** » Fri Aug 31, 2007 7:23 am

That should cover it unless there has been a mechanical failure of some sort in the engine, but I think you would have heard that.
Check the timing, and if you have not already done so, put in points and condenser. Also make sure the polarity on the coil is correct.
Lavoy

fogswamp · Post by **fogswamp** » Fri Aug 31, 2007 10:28 am

Dave, the only time It wouldn't run it was the plugs, they had spark but must not have been enough, because after changing them it ran fine. Hope you get it going, let me know, Lance

FarmLife · Post by **FarmLife** » Fri Aug 31, 2007 11:28 am

I would try replacing the spark plugs cause I have had it happen where the plug will fire out of the cylinder, but as soon as you put it back in, nothing. Rand into this with my Sattley hit and miss engine and it drove me crazy untill I tried a new plug. I am pretty sure that 420 plugs are much cheaper than the 15$ plugs for the sattley. Hope this helps.... Nate

Stan Disbrow · Post by **Stan Disbrow** » Fri Aug 31, 2007 12:05 pm

Hi,

That'd be a cracked center insulator causing that. Under atmos. pressure, the thing fires from the center to ground electrode just fine. Under the much higher (15 vs 120+ PSI) cylinder pressure, the spark fires out the crack in the insulator to the side of the 'tube' (for lack of a better word to call the insides of the threaded part of the danged thing).

These cracks are usually hairline and require several 'x' worth of magnification to see, so one usually does *not* and spends a lot of time messing with a plug that'll fire in the air but not in the engine!

Just go spend the couple bucks for a pair of new plugs to use while troubleshooting.

Stan

Davie Sprocket · Post by **Davie Sprocket** » Fri Aug 31, 2007 7:03 pm

Yeah didn't think of that, plugs looked pretty new.

I checked every thing else. I'm in Calgary at the tattoo show so i won't be able to work it out till Monday.

Funny thing is it was running 100% drove it off the bed, played around for a bit, next day same thing, then i went into the yard and it just stopped, weird. I've played with lots of engines over the years but i don't have alot of experience with the jd 2 cylinder.

I will post for sure when i get it running.

Dave

Davie Sprocket · Post by **Davie Sprocket** » Wed Sep 05, 2007 5:56 pm

This starting to freak me out, i've fired all kinds of engines, and never had this happen. I must be overlooking something. I check the distributor, new coil, new battery, repaired bad wires, turns over fine. Just won't start, i'm gonna go buy new plugs tommorow. I've never had this happen before, weird.

Frustrated....

Dave

TI420 · Post by **TI420** » Thu Sep 06, 2007 11:30 am

Dave - pull a plug wire while you are cranking and dtermine are you or are you not getting spark... Probably not your issue, but with mine, someone had replaced the coil with one that had a taller tower and the coli wire was not actually making contact inside the tower... Could be something weird like that...

Howard Yoder · Post by **Howard Yoder** » Thu Sep 06, 2007 3:33 pm

check and make sure someone didn't put an inline fuse in it. I had that happen on an mc and all I had to do was change the fuse.

Howard Yoder · Post by **Howard Yoder** » Thu Sep 06, 2007 3:36 pm

sorry I seen your earlier post where you said you had spark the only other thing I can think of is the condensor

FarmLife · Post by **FarmLife** » Thu Sep 06, 2007 5:06 pm

I am pretty new to the two cylinder crawlers and 6 volt systems (at least with the MC), but I do know that with older points systems if the ballast resistor cracks it will work when it is cold but once it gets hot enough it will break connection and kill power to the coil. But as I said I am not familiar enough with this system to know if it even has a ballast resistor or not.

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