Opinions on spark plug and starting

[Keith Meatyard]

My 74 175 JP runs great, but is sometimes hard to get started when cold.  If it doesn't fire off after tickling the carb until I see quite a bit of gas dripping from the carb, kicking 5 or 6 times, I can pull the plug to find it black and wet.  I grab another clean plug and put it in, and bang, she fires first kick.  I have seen this with NGK B8HS, or B7HS, seems to make no difference.  The bike is std bore, plenty compression, has an ACE pipe, motoplat, and a 32mm Bing carb without a choke.  Carb set-up is: 148 main jet, 40 idle jet, 273 needle jet, and needle in 3rd notch down.  I'm running ethanol free premium and 32 to 1 hi quality oil.  Does this sound about right for sealevel on the gulf coast, or is the plug appearance typical?

Keith Meatyard

[Lew Mayer]

Could be a weak Motoplat. The main jet seems a tad lean. How did you manage to find a 32mm Bing?

Lew Mayer

[Keith Meatyard]

Lew, the 32 was on it when I bought it. 1/32/108 on the side of the carb.

Keith Meatyard

[brian kirby]

Classic weak Motoplat.

Brian

[brian kirby]

And for reference, the B8HS in my '72 JP with a PVL has been in there 3 years, it lights 1-2 kicks every time.

Brian

[Keith Meatyard]

So, would it just be smart to replace the whole Motoplat system with the PVL, replace just the coil with the PVL unit, or repair the Motoplat?  By the way Brian, the other bike, the one from Settles does pretty much the same thing.  I actually had to put another used Motoplat coil on it to get it to show fire when I reworked the bike.  You remember, it ran, but it wouldn't fire when I got it back together.

Thanks,

Keith Meatyard

[454MRW]

Since I started running an Auxiliary ground wire directly from the engine to the coil mounting bolt, the starting has been greatly improved than relying on a good engine mount to frame ground contact. I don't even have to clean the fresh paint off of the engine mount points on my frames. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R

[gooddirt]

All my bikes with old bings never start with the same numbers of kicks , sounds like when you tickle some over flow is going down the intake.  Or the gas is wepping over night from petcocks/ fuel lines /float bowl/ worn float needle and the first start up is a lot wetter [?] Also just got done tuning a new 32 bing on a GS monark with a PVL and does the same thing sometimes.

[tomale]

On my bikes with Bings, I make a habit of turning off the gas before I shut the bike off. If for some reason I do leave the gas on I will always kick it through a few times before I tickle the bike. I have also learned that if the bike pops and does not start, I tickle the bike again. this usually results in the bike starting.
on all my bikes with Motoplats, I have added a ground wire from the coil to the head of the motor, this has actually helped the spark to become a brighter blue, I have heard it said that if you can not hear the spark snapping then the spark is not strong enough. not sure how true that is especialy with PVL ignitions but I do remember being able to hear the spark back when these bike were new.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki

[brian kirby]

Keith, I think you might want to try having your Motoplats rebuilt by Vance Smith since you probably want to keep the lighting capability and the PVL does not have that. The MZ-B does, but its quite a bit more than a PVL.

Brian

[Keith Meatyard]

How do I contact Vance Smith?

Keith Meatyard

[brian kirby]

http://motoplatrepair.tripod.com/

Motoplat Repair
4804 Downing Dr.
P.O. Box 772
Lakeland, Mi 48143

Phone: (810) 231-3359

[email protected]

Brian

[Keith Meatyard]

Thanks guys, I've sent an email to Vance.  Hopefully, he will be available for business soon, so I can get this problem resolved.

Keith Meatyard

[gooddirt]

Hard starting Does Not mean 100% a bad Moto-Plat,[:0] have you done a OHM reading test? I have a  new rebuilt uint from Vance with the extra lighting coil he sells If you want as I have no lights on my rides. LG

[Mick Milakovic]

What does Vance charge, as an average price?

Mick