Running on front cylinder only

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kell
Posts: 404
Joined: Sat Jun 19, 2004 2:58 am

Running on front cylinder only

#1

Post by kell » Fri Sep 08, 2006 6:56 am

If a panhead has spark and 95 psi compression in both cylinders, what could cause it to run only on the front cylinder?



Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Running on front cylinder only

#2

Post by Cotten » Fri Sep 08, 2006 8:13 am

You mean besides an Evil Manifold Leak?

DuoDave
Posts: 234
Joined: Tue Mar 16, 2004 10:45 pm

Re: Running on front cylinder only

#3

Post by DuoDave » Fri Sep 08, 2006 10:24 am

I have had this problem. Turned out that one of the pushrod lock nuts had loosened off and the pusrod adjuster had screwed itself in so the valve would not open. Haggis encountered the same thing recently. I've heard that a spark plug can test okay in the open, but when screwed back into the motor will fail under compression. I have not come across this, but worth trying a new plug if you have not already done so.

kell
Posts: 404
Joined: Sat Jun 19, 2004 2:58 am

Re: Running on front cylinder only

#4

Post by kell » Fri Sep 08, 2006 1:58 pm

I had to leave the bike in a small-town bike shop a day's ride away. That was a week ago, I called today and they said it's ready. Will post what I learn.

Jonderson
Posts: 54
Joined: Mon May 28, 2007 7:36 pm

Re: Running on front cylinder only

#5

Post by Jonderson » Sat Sep 09, 2006 5:14 am

I have also had the pushrod locknut problem. Didn't think much of it, and thought it was a flukey thing. Perhaps I ought to rethink that now.
Cotton, have you seen a lot of this?

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Running on front cylinder only

#6

Post by Cotten » Sat Sep 09, 2006 7:24 am

Uh,...no.

Normally, the adjustors are a very dependable and stable design, unless abused.
I've seen bent rods, broken rods, lotsa knarfed lock nuts and threads from over-tightening, etc.,...but otherwise, the only times I have seen rods drastically go out of adjustment was when fresh motors would beat a valve into a poorly cut seat, thus tightening the rod to where a valve would hang open; the opposite of what has been described.
Unless a valve is sticking or something gets under the valve, it is hard to think of a way it would loosen.
Beware of '48, maybe '49 rockerarms that had cups that would loosen.

panheadron
Posts: 24
Joined: Mon Mar 18, 2013 2:21 pm
Bikes: 56 Pan, 62 CH

Re: Running on front cylinder only

#7

Post by panheadron » Mon Mar 18, 2013 9:34 pm

Check for spark . Swap the spark plug wires at the coil. You may now find the rear not firing. Swap the plugs?

58flh
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Bikes: 1958flh 1969sporty,had a knuckle but sold back to original owner
Location: NEW JERSEY

Re: Running on front cylinder only

#8

Post by 58flh » Mon Mar 18, 2013 11:29 pm

GUYS doesent anybody use glypt on yer screws?-Never should a pushrod scrw itself up the tube!If yer running solids there are things to handle that POUNDING over & over--HYD are SWEET!,But im a solid tappet runner,always have been,just like to have things my way & I know about it.---spend time & pop the tubes watch the movement up & down put tubes on CORKS OLNY!--Have fun yer lucky thats all that happened!-(10 min of pleasure looking at pushrods go).& No mishaps in the back of your mind!---respectfuly----RICHIE

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