Motor Problem

[Mick Milakovic]

Hi All, I had a glich with my 250 at Texas.
The bike started great, first kick, and ran strong off the line.  Good acceleration and throttle response.  At the end of the first lap it sputtered once, almost a miss instead of loading up, and then later again and more frequent.  On the second lap it acted up under load in higher gears and would clear out when downshifting.  Eventually that didn't work and the bike quit running.  I changed a plug and off I went on the first kick.  This repeated itself for the remainder of the race until I ran out of plugs, and when I went back to old plugs the bike would fire right up!  Could this be an over-heating problem?  Or Motoplat?  The Bing carb is quite old and needs a new slide, if not an entire carb change, but as I said the plug reading looks pretty good.  I've got another, newly rebuilt motor to put in it (the old one is real old, trust me), but I would hate to do all that work and have it still be something else.  Any suggestions?  Thanks in advance,

Mick

[brian kirby]

Motoplat.

Brian

'73 Berkshire

[Larry Perkins]

Mick,

Replace the slide and the needle jet.  Then put on a PVL and never look back.  That will fix all your ills.  You could disconnect the kill button to be sure it is not the prob but the Motosplat will be sooner or later and the slide will effect smoothness of power for sure if it has the smiley face.

Larry P

[firstturn]

Agree with everyone, but check the head first and go over all the grounds on the ignition.

Ron Carbaugh

[Speedy]

quote:Originally posted by Mick Milakovic

Hi All, I had a glich with my 250 at Texas.
The bike started great, first kick, and ran strong off the line.  Good acceleration and throttle response.  At the end of the first lap it sputtered once, almost a miss instead of loading up, and then later again and more frequent.  On the second lap it acted up under load in higher gears and would clear out when downshifting.  Eventually that didn't work and the bike quit running.  I changed a plug and off I went on the first kick.  This repeated itself for the remainder of the race until I ran out of plugs, and when I went back to old plugs the bike would fire right up!  Could this be an over-heating problem?  Or Motoplat?  The Bing carb is quite old and needs a new slide, if not an entire carb change, but as I said the plug reading looks pretty good.  I've got another, newly rebuilt motor to put in it (the old one is real old, trust me), but I would hate to do all that work and have it still be something else.  Any suggestions?  Thanks in advance,

Mick

Running out of(Short of) fuel because of plugged tankcap?

Helmut"Speedy"Clasen
 Ontario Canada
http://speedy_c.tripod.com
http://picasaweb.google.com/vindurospeedy
2 x Sachs MC-GS 250-7A
1 x Hercules 350-7A 77
2 x Hercules 250-7A 76
Zuendapp 125 GS 72-73

[G Ellis]

Mick it is a weak motopat, just ask Dennis Jones.  Later Gary

[brian kirby]

Mick, I have ridden several bikes with failing Motoplats and they did what yours is doing. The most recent one was an MC5 250. It would run for 5-10 minutes and quit dead. If you put in a new plug it fired up on the first kick and would run for another 5-10 minutes and quit. The bike was not running rich, the engine was tight, and the plug looked perfect when you would remove it, but it would not restart with out a fresh plug.

Remember, its not IF a Motoplat will fail, its WHEN. I say take Larry Perkin's advice and pop for a PVL or MZ-B if you want lights and more flywheel and dont look back.

Brian

'73 Berkshire

[tomale]

I don't think there is any thing inheritly wrong with Motoplats but we are talking about something that is 30+ years old. and that is the real problem. ignitions just will not last forever. I had the same kind of trouble with a bosch ignition. Once I put a PVL on and I went the extra mile to make sure that I had a really good ground all the way to the coil. Problem solved...

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)

[Dave Withrow]

Sounds like bad/intermitten spark.  I've had the coil work loose and it acted like a carb problem.

Big Dave

[firstturn]

So don't forget to check the spark plug cap....don't laugh as this is one of the most looked over easy fixes I have seen on bikes.  But I would still go in the order of checking the torque on the head, check the ground on the Moto Plat and then going to the carb.  I hope this helps as I am just saying again what has already beed said.

Ron Carbaugh