just got a 1972 175cc jackpiner

[john_wayne]

i just got a '72 175 jackpiner.  i am looking for some of the parts that need replacing.  i am looking for the back shocks, would like a 30mm amal carb in good condition.  i am having some trouble getting this thing to run right.  It wants to bog down after i give it alot of gas.  i am thinking i have some seals gone on the crank.  if anyone has any input it would greatly be appreciated.

[qhut]

Howdy,
I have a 72 Piner also w/ the same sort of problem it has a new top end and Mikuni carb. When running, it will occasionally bog like you're describing. It most often happens when I need the power most, you know, wet muddy 40 degree embankment comming out of a creek, or if I need the front wheel
to come up it will bog. The seals were all replaced.  Im stumpped.
Ed.

[qhut]

Howdy,
I have a 72 Piner also w/ the same sort of problem it has a new top end and Mikuni carb. When running, it will occasionally bog like you're describing. It most often happens when I need the power most, you know, wet muddy 40 degree embankment comming out of a creek, or if I need the front wheel
to come up it will bog. The seals were all replaced.  Im stumpped.
Ed.

[SCOTT CURTIS]

Try a smaller main jet in the carb.

 

[Larry Perkins]

Most of the bogging troubles we have seen with Pentons were from an ovalized needle jet.  This is with the Bing in particular.  Over time the needle ovalizes the needle jet and what was once a 273 is now who knows what?  This prob will show itself when coming on throttle like out of a corner or just as you are accellerating.  You crack the throttle on needing zip and get BWAH and it falls flat.  On all Bings replace the needle jet to be sure.  Sometimes to zero it in the needle clip must also be raised one notch.  All of this advice assumes Bing carb is being used and a mechanically sound motor is being used.

 

[Chris Brown]

I had a 73 175 with Mikuni, and I don't think it had ever run right. Was a junker when I bought it, restored it. When the motor was pulled apart I found it had a new piston in it!
It ran great at idle, great WOT, but mid-range would just bog and load up. I ended up going to a leaner slide needle (from Sudco) and then it ran great. It had a 6f needle, went to a 5f. Can double check if there's any interest.
Chris Brown

 

[john_wayne]

that is the same problem i am having qhut.  whenever you need it most it wants to die out.  i have a 35 mm mikuni on it now and have a 32mm mikuni coming.  i have also been in touch with someone that has the setting for our bike with the 32mm.  if it helps i will let you know.

Johnny Wayne Brewer

[Doug Wilford]

Remember there a lot of reasons to cause the bog as you are discribing it.    It can be too lean or to rich,  Make sure the timing is correct, air coming in isn't restricted and the exhaust pipe and muffler are open.  All carburation has to have a transition from idle to full main jet, this is the iffy area that is controled by slide type needle size and position, needle jet, atomizer.  My rememberer isn't coming up with the specific numbers, but I hope this helps.

 

[Mike Lenz]

I have an amal carb on my 72 piner. Im looking for a bing to put on it.

 

[Larry Perkins]

Mike

I have a good amount of used Bings.

 

[john_wayne]

quote:
i just got a '72 175 jackpiner.  i am looking for some of the parts that need replacing.  i am looking for the back shocks, would like a 30mm amal carb in good condition.  i am having some trouble getting this thing to run right.  It wants to bog down after i give it alot of gas.  i am thinking i have some seals gone on the crank.  if anyone has any input it would greatly be appreciated.

Johnny Wayne Brewer

[john_wayne]

i am still having trouble with my penton.  i think i have the pilot jet.  i have a 35 in it right now.  but cant seem to get the last 3/4 throttle to come on.  it still wants to bog down.  the first 1/4 to a 1/2 will scream.  but i lose it after that.

Johnny Wayne Brewer