MC5 Starting

[Cathump]

Can anyone give me tips on starting my MC5? I just cannot get it to kick off when cold, but it will when hot. I realize I have more experience with right side kickers, and feel like a dufus when I can't kick it.



 

[Larry Perkins]

Turn the gas on, tickle the carb until it overflows, kick good and hard no more than three times.  It should fire.  If not tickle once again till overflow and kick.  If ignition is timed right and good and the carb is all in good shape a Penton with a BING should start with this drill.  If the weather is REAL cold the choke might need to be used.  Otherwise check timing, ignition, and carb including jets, slide, etc.

 

[Cathump]

Larry, I'll try that, but I don't have a manual yet, so have no idea how to check the timing.

 

[Cathump]

I neglected to mention that this one has a Mikuni, although I plan to put the Bing back on when I can obtain some jets and an intake boot. The original intake boot has a tear, allowing an air leak, and I have plenty of Mikuni jets.



 

[lobo6y]

I've had a couple vintage MXers (with Mikunis) which had this annoying habit.  Both responded to the following:
Turn on gas and wait for float bowl to fill.
Put choke lever to on.
Put the bike in gear and gently rock it back and forth, once each way to turn over piston.
Kick firmly with no throttle - should start.

If this doesn't start it by 4th kick, put choke lever off, open throttle wide and kick - almost always works!
Good luck, dave

 

[Cathump]

I'll try the rocking deal. I am coming to the conclusion that the carb is too big, it's a 38mm. When the bike is hot, I need to open the throttle to get it to start.

I do use my left leg.

 

[lobo6y]

For whatever reason, the rocking seems to properly charge/prepare the cylinder.  

I had the trick shown to me back in the day and reconfirmed by some of the Bultaco boys (I'm one of them, too) - 360 Pursangs are notoriously hard to start - I have a 36mm Mikuni on mine.

I've always used my right  foot  - seems to give better leverage, but feels awkward at first.
Good luck!
Dave
PS. I obviously left out the "put it back in neutral" step, after rocking    


 

[Cathump]

I just read my last post, I wrote that I use my left leg to kick, which I mistyped, I use my right.

I robbed my MX 250 of the new 34mm Mikuni that has been bored by Pro Flo to 35.2mm. I believe this is closer to the size needed, and it runs crisply. The added benefit is it has much more bottom end and mid range.

I still cannot kick it cold, but it only takes a short roll to start. Hot it will start with one kick.

Another question, were there any Pentons made in '78, or were they all KTM's?



I am getting closer.

 

[Cathump]

I want to thank everyone for their advice. I tried Lobo6y's procedure, and it started on the 3rd kick, after sitting for 3 days, with cool temps.



 

[john durrill]

Cat,
 it sounds like the slide cut away and or the pilot jet is not exactly right for the engine.
 something else that can help is using a cable operated choke instead of the lever type. with the lectron i have a similar problem with cold starts if i pull the cable operated lever all the way to the stop. we just pull the lever till i feel the spring tension break and no farther . it starts good like that in one or two kicks
John

 

[Cathump]

I'm sure the jetting isn't spot on yet. I just installed this Mikuni, and will do jetting changes this weekend.