miss fire

[amherstscott]

you guys will get a kick out of this, last night I am about to close my place and I went over and sat on my penton, now this bike mostly sits and sat for a long time before I owned it, so starting it is to say the least a chore, so I'm sitting there and I give it a kick, and it farts, so of course I'm overjoyed, so I kick it again and to my amazement this thing fires up into a full blown howl at about half throttle, scares the hell out of me, uh kill switch, there is none, so here I am bike running sitting on a milk crate I,m running around looking for something to pop the spark plug cap off and the building looks like its on fire, I'm not about to grab that spark plug cap, pretty comical really, I guess the old girl likes being inside. so anyway where do I wire in the kill switch thats the next question.

[Patton]

Scott, a similar thing happened to me.

Purchased a 250. Drained tank, ultrasonic the carb. Reassemble.
Pull strap behind truck to bump-start in second gear.

No luck. Tinker and repull. Finally fires and wants to do wheelie...wow.

Kill engine. Repull. It starts and I ride up and down the street.

Time to tinker at the shop. Fire it up and the idle screw backs out. I try to put it back in and it goes to max/scarymax rpm. Go for kill switch and it didn't work. Didn't think to pull plug...that beehive was wayyy tooo scary. Pulled fuel line off and it died.

Figured I'd really messed something up at max rpm. Reconnected fuel line, no luck.

Stupid me.

Fiddle dinked around and noticed that in the excitement of the moment me or my buddy must have disconnected a coil wire. Reconnected and gave it a kick.

Wow it still runs.

Decided to send the carb out for the polish treatment/water blast that was recommended in another post. Will try the 250 crank-up again in another month.

RP

Oh yeah, good luck with the switch. I'm going to find one with a more positive feel to it 'cause I swear mine was full-pressed when that engine was screaming.

[brian kirby]

It sounds like a lean runaway from an air leak, in that case a kill switch or pulling the plug wire will not stop it because the engine is not running on spark, its running on ultra-lean fuel that is igniting by itself. Any time that happens the quickest way to kill the engine is to flood it with fuel, lowering combustion chamber temps and stopping the ignition source. If you have a choke, use the choke or with a Bing hold the tickler down until it dies.

Brian

[Patton]

Thanks, Brian, next time I'll cut off the air with a hand over the carb...maybe, remember it was zinging at a bazillion rpm. Oddly enough, it restarted and we ran it without the idle screw as the threads are so buggered that it they won't grab with the idle screw spring in place.

Don't know what to do when the carb is returned and I try to reassemble with the suspect theads. Prehaps just insert idle screw without spring and hope Loctite will keep it in place?

RP

[brian kirby]

Your air leak came from the missing idle screw probably. The high RPM is a key sign of an air leak, it will turn much higher RPM and it will have an unusual muted "smooth" sound because there is so little fuel being burned.

No matter what the cause, if the airbox is off and you can cover the carb it will stop it.

Brian

[amherstscott]

cleaned the carb starts and runs like a champ now.

[SouthRider]

Can also choke off the exhaust with a rag. Had a Rokon do that in the shop back in the day. Talk about scary. Rear wheel spinning like a demon on concrete floor, front wheel jammed between a bench & the wall. Ended up with three people on top of the seat and tank, frantically trying to lock up the disc  brakes, and one more finally thinking to shove a shop rag in  the pipe.

_____________________________________________________________________________________

"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."

1972 Penton Berkshire 100
1983 Husqvarna 250 XC
2011 Jayco 31.5 RLDS
2009 Chevy 2500 HD Duramax

[Daniel P. McEntee]

After looking for a 250 Penton since 1975, one finally found me in 2012. It's a long, funny story in itself, but the bike was just an hour or two away so I went to retrieve it. Incomplete bike with parts and carb just hanging on it. Left it in my van over night and unloaded it the next day with the help of my big brother Tom. He was holding the bike at the curb while I ran to the garage for something. as is his habit, Tom unfolded the kick starter to give it a stab just to feel what the compression was like. Suddenly I heard the bike fire up and run for a second or two! No fuel in the tank, and carb not even connected to the engine! I had a Hodaka Wombat that was completely rebuilt and I couldn't get that much out of it on purpose!! sometimes you just never know!
  Type at you later,
   Dan McEntee

[Toolsurfer]

That had to be something to see with that auto trans Toolsurfer

quote:Originally posted by SouthRider

Can also choke off the exhaust with a rag. Had a Rokon do that in the shop back in the day. Talk about scary. Rear wheel spinning like a demon on concrete floor, front wheel jammed between a bench & the wall. Ended up with three people on top of the seat and tank, frantically trying to lock up the disc  brakes, and one more finally thinking to shove a shop rag in  the pipe.

_____________________________________________________________________________________

"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."

1972 Penton Berkshire 100
1983 Husqvarna 250 XC
2011 Jayco 31.5 RLDS
2009 Chevy 2500 HD Duramax

[SouthRider]

It was downright scary. The last resort was to lay it on it's side & let it blow up.............

_____________________________________________________________________________________

"We the willing, led by the unknowing, are doing the impossible, for the ungrateful. We have done so much, for so long, with so little, that we are now qualified to do almost anything, with nothing."

1972 Penton Berkshire 100
1983 Husqvarna 250 XC
2011 Jayco 31.5 RLDS
2009 Chevy 2500 HD Duramax