No compression?

Forum rules
Please do not start new topics here, but here: New Panhead and Flathead topics
Post Reply
mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

No compression?

#1

Post by mogman » Sun Apr 27, 2008 4:30 pm

I have noticed a strange phenomenon several times with my Panhead, At times it seems as if it has no compression with 5-6 or more kicks with no resistance, It happened the other day at the bar and a 39 UL driver was sitting there and said he has the same thing happen to him from time to time, What is up with this???
Craig



ozwick86
Posts: 756
Joined: Sat Jul 17, 2004 4:06 am
Bikes: '59 Pan FLHF
Location: N. California

#2

Post by ozwick86 » Sun Apr 27, 2008 4:49 pm

I would check your clutch adjustment as the plates may be slipping or have oil on them causing the issue.

51Hog
Posts: 664
Joined: Fri May 20, 2005 7:29 pm
Bikes: 1951 Fl
Location: Wasilla, Alaska

#3

Post by 51Hog » Sun Apr 27, 2008 5:12 pm

I have seen it before.
My belief is that it is a valve or two sticking, then coming loose.

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#4

Post by mogman » Sun Apr 27, 2008 5:15 pm

I'm pretty sure it's not the clutch, just went through all that with the rebuild and it has not tried to slip at all pulling my fat butt around.

FlatHeadSix
Moderator
Posts: 2681
Joined: Sun Jun 06, 2004 5:14 pm
Bikes: '31 VL, '34 VD, '45 WLA, '47 WL, '49 FL, '51 WL, '58 ST (Hummer), '71 GE (Servi)
Location: Lonoke, Arkansas

#5

Post by FlatHeadSix » Sun Apr 27, 2008 6:17 pm

Its probably a valve thing. That used to happen quite a bit on my bike before I replaced the original "oil can" hydraulic push rods with solids. Since the switch it hasn't happened again.

With the original hyraulic push rods the exact opposite thing would happen just as often. After 2 or 3 kicks the engine would build up so much compression that you couldn't kick it over at all. If the valves don't open and close, at the right time, it could go either way.

mike

Joe G.

#6

Post by Joe G. » Sun Apr 27, 2008 7:10 pm

I have had the same problem with my Indian, I always figured it was the valves.

Joe

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#7

Post by mogman » Mon Apr 28, 2008 2:26 pm

I was thinking that somehow the lifters were "pumping up" and holding the valves open, (this also may explain some of my starting problems)I am at my first oil change and am going to AHR 60W synthetic oil, it will be interesting to see if it makes any difference. With the hydraulic lifters if a valve did momentarily stick open the lifter would try to take up the slack and then be too tight. I would be disappointed if the valves are sticking as the shop that rebuilt my heads have a very good rep. and the oiling system should be working correctly......
Craig :shock:

51Hog
Posts: 664
Joined: Fri May 20, 2005 7:29 pm
Bikes: 1951 Fl
Location: Wasilla, Alaska

#8

Post by 51Hog » Mon Apr 28, 2008 6:08 pm

How common of an occurrence is it? the valves sticking.
Please post here if it has happened to you. If it happens regularly, and under what conditions it happens to you. Hydraulic valve train or solid?
Does your engine run well at all rpms?

It has happened to me several times in the last two years. Usually when the engine is warm---not hot. You know----When you are not sure if you want to use the choke or not.
It usually happens when engine is warm---I should not have used choke and did.----Key off 1 compression stroke with choke--Choke off,retard spark, key on, kick hard. Back fire-- Look slowly for compression for another kick--none to be had. Key off--Hard kick with no compression--Compression returns. Three or four kicks with the key on, timer retarded no choke wide open throttle usually gets her going.

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#9

Post by mogman » Mon Apr 28, 2008 11:45 pm

I would say that's pretty close on the conditions, usually warm an hour or so after shutting it down, not sure if it is always after it farts but always after it has failed to start! and lately that is becoming more common :cry: :cry: Otherwize the bike is running perfectly.
Craig

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#10

Post by mogman » Tue Apr 29, 2008 12:01 am

AHH let's think about this a second or two. The cylinders grow about .040 when hot (I read this somewhere) at that time the lifters take up the slack, then the cylinders cool down and the valves get too tight, this does not explain it all but may be contributing to the problem... and may be why it farted in the first place!!
Craig

mogman
Posts: 103
Joined: Sun Oct 01, 2006 4:29 pm

#11

Post by mogman » Tue Apr 29, 2008 12:05 am

I even took a bucket of lifters and hand matched them for the least amount of leak down, maybe some leak down would be a good thing!!

51Hog
Posts: 664
Joined: Fri May 20, 2005 7:29 pm
Bikes: 1951 Fl
Location: Wasilla, Alaska

#12

Post by 51Hog » Tue Apr 29, 2008 12:37 am

I would think that if that were the case, then all of them would do it all of the time.
Mine is not hydraulic and it looses compression---very rarely. Only when there is an audience. LOL

wantapanrealbad
Posts: 34
Joined: Wed Jan 11, 2006 2:21 am
Location: Eastern Tennessee

#13

Post by wantapanrealbad » Tue Apr 29, 2008 2:43 am

Let's see what Cotten says. I have a hunch he knows exactly what it is...


Cotten, you out there?

Joe G.

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

#14

Post by Cotten » Tue Apr 29, 2008 3:11 am

Sounds like they are all female to me.

...Cotten

51Hog
Posts: 664
Joined: Fri May 20, 2005 7:29 pm
Bikes: 1951 Fl
Location: Wasilla, Alaska

#15

Post by 51Hog » Tue Apr 29, 2008 3:13 am

HUH???
Got it---I'm a little slow these days. :-)

Post Reply

Return to “Motor”