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
Could be a weak Motoplat. The main jet seems a tad lean. How did you manage to find a 32mm Bing?
Lew Mayer
Lew, the 32 was on it when I bought it. 1/32/108 on the side of the carb.
Keith Meatyard
Classic weak Motoplat.
Brian
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
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
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
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.
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
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
How do I contact Vance Smith?
Keith Meatyard
http://motoplatrepair.tripod.com/
Motoplat Repair
4804 Downing Dr.
P.O. Box 772
Lakeland, Mi 48143
Phone: (810) 231-3359
[email protected]Brian
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
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
What does Vance charge, as an average price?
Mick
Mick,
I just got one back in the mail from Vance yesterday, for re-winding the ignition coil in the motoplat, replacing my dead coil with working red wire coil and sending it all back to me it came to 175. Best part is, everything I have had him to in the past came back with super spark!
Thanks,
KD
Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
73 Yamaha AT3
71 Suzuki TS125 (Project)
Thanks Kevin, I have a couple that need rebuilding.
Mick
I wouldn't mind finding a 32MM Bing, if one's available.
Lew Mayer
After checking out my Motoplat per Vance's instructions, it appeared that the ignition wasn't the problem. I thought maybe I was tickling too much or not enough. Anyway, I tried swapping to a spare Bing I had. The bike starts right up now, so far. When I checked the old carb I took off, I discovered that I had the idle air adjust screw only 1/2 turn out. I adjusted the installed one per the Penton manual. One question that I still have: When I tickle it, gas drips out from somewhere, but it doesn't go through the 1/8" overflow tube. Any thoughts?
Keith Meatyard
Inside the bowl of the Bing there's a standpipe. When you hold the plunger down and therefore the floats down, the bowl fills up over the standpipe. The insert spot where the pipe presses into the bowl has a pinhole out the bottom, right next to the bowl plug. That's where you're seeing the overflow drip out.
Thanks Mac, that makes sense now. So the Penton manual is referring to the hole in the bowl bottom rather than the brass 1/8 nipple that sticks up out of the carb body? That nipple must be just a vent then? My 30mm has the nipple, but the 32mm has a blank spot in the same place.
Keith Meatyard