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compression makes it hard to kick

Started by Dave_R, June 16, 2020, 09:05:24 AM

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Dave_R

Greetings,
Thought I would shoot this out there....
I have a 60 FLH that I got last year in pieces (previous owner passed, so purchased from his daughter).  Of course, engine was "rebuilt" and ready for installation.  I went through it some, and it looks like it was done very well.  Stock Cylinders were bored 0.010 over and correct pistons installed (one of the great pluses of why I bought this one in the first place).  everything is very clean.  Heads looked great.  Stock FLH cam.

Between swap meets to find missing parts, and everything, I got it together.  It's far from original, but still a good looking bike.  (neck was cut at one point in its life).

The issue I have is that it is very hard to kick.  I mean.. I am not a small man (plus side of 240), and it takes me a couple of "jumps" just to get through the compression stroke on one cylinder.  (I narrowed it down to the rear).  The front compression stroke is a bit easier, as I can stroke it through, and feels normal.  It is when the rear compression stroke is ready that I have to jump on it a few times just to get through it.  OF course, it makes for a very difficult start.

When it does start, it runs very well, pulls hard.  Always hate to shut it off knowing what I have to do to start it again.

I have a '53 that I have owned since 1978, and it starts very well,  A lot easier to kick.

Measured the compression a few times and here are the averages:

1960:  Front - 62 PSI,  Rear - 76 PSI

1953:  Front - 51 PSI, Rear - 53 PSI

So, being a FLH, is this normal?  I know that the compression "spread" is more of a factor than the actual number.  While it is higher on the '60, its the spread that has me scratching my head.

Any comments or advice is welcome!  Thanks everyone.

- Dave










rigidthumper

Re-do that test with the throttle held wide open?
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Dave_R

Yes, throttle was held full open during the test on both bikes.

-Dave

thumpr54

cool paint !.....I've seen starter kits for earlier Harleys in the Antique Motorcycle Club magazine....if that's something that would interest you....for us old guys, you know..... :smiled:
growing old is mandatory-growing up is optional
355 AMS(TAC)DMAFB 73-76 VFW6774

Excalibur

As I understand, there is potential differences in primary drive ratio depending on front sprocket size. Also there's differences in kicker gear ratio available. Might be worth some study...?

I have a '61 FLH which has the same cam as you. I have very little problem kick starting and I'm 71kg/ 156lb. It starts easily and that helps, especially since I fitted the SU carb. Starting is a bit of a knack even so.

I read where the FLH cam is known for reducing kick compression because of valve overlap. FLH had 8 or 8.5 compression, can't remember which but obviously it depends what was last fitted. Will see if I can find my compression figures to compare.

guppymech

June 16, 2020, 09:43:02 PM #5 Last Edit: June 16, 2020, 10:16:12 PM by guppymech
As far as compression testing with the kick starter.  When my '84 FXE had the stock 'S' cam I could only get 90 psi with the kicker but with the electric start it would do 130.  My point being don't be too dismayed about low readings kick only.

I also found that weak hydraulic lifters will shorten up the valve timing and make kicking much harder, at least on the first prime kicks. 
'84 FXE, '02 883R

drifter

Wild guesses, are the push rods/valves on the rear cyl looser?  Defective rear hyd lifters or rear cam lobes worn?  That would open the valves later causing more compression.  Is the cam timed correctly?  Any chance the valves are sticking after being in storage?  Those are the only options I can think of that would affect one cyl only, of course I've been wrong before.   :idunno:

Excalibur

Found these compression results for my '61 FLH...

Cold: 50 / 55
Hot: 72 / 70
Cold: 60 / 60


JohnnyCashPan

Quote from: Excalibur on June 16, 2020, 09:20:35 PM
As I understand, there is potential differences in primary drive ratio depending on front sprocket size. Also there's differences in kicker gear ratio available. Might be worth some study...?

I have a '61 FLH which has the same cam as you. I have very little problem kick starting and I'm 71kg/ 156lb. It starts easily and that helps, especially since I fitted the SU carb. Starting is a bit of a knack even so.

I read where the FLH cam is known for reducing kick compression because of valve overlap. FLH had 8 or 8.5 compression, can't remember which but obviously it depends what was last fitted. Will see if I can find my compression figures to compare.

I think Excalibur's point about the gears is spot on.  If the bike runs good that kind of leaves other factors off.  There is also the possibility you may have a combination of conditions contributing to the hard kicking.
Old, slow and fat...

Dave_R

Thanks all for the replies.

I do have it geared tall (to Excalibur's point).  24T comp sprocket on the engine.   Are the clutch basket sprockets all the same?  I do know that when I put it together last year I needed to special order a 84-link primary chain to make it work.  Even still, tranny adjustment is almost all the way forward.

When it runs, I do like the gearing, as I do a lot of cruising and still pulls strong at 60+MPH in 4th.  Still in the break-in period so I have not pushed it real hard.

I will look at the pushrods, as I did keep them a little more "loose" so that they will "find their spot" during the break-in.  I will adjust to normal and try it out.  I will also pull the side cover to verify the timing marks on the cam.  It just may be a while (kinda HOT outside.  Big guy don't like heat).

As far as the kicker gear, how do I find what I have, and where can I get a smaller gear (to give me more leverage)?  This is new territory for me, as I did not know others existed.

Thanks again.
-Dave

Excalibur

On Baker kicker gears there is mention of 14T and 16T starter gears (see fitment and detail tabs). Over to you to study and work out. Also possible to "Ask a Question".
Have heard very encouraging reports about Baker though haven't used any of their products.
Hope this helps. Please report back. Thanks.

Excalibur

Suddenly remembered I have a pic of mine... turns out it's 16T.

Ohio HD

A larger motor sprocket gives the kick start more leverage, not harder to kick. All four speed baskets are the same tooth count. 

Dave_R

UPDATE:

OK so I opened up the cam chest and verified that all timing marks are aligned.  All is good in there.
Re-adjusted the pushrods.  I have the stock hydraulics, so I expanded the rod until no slop up / down, then 4 1/2 turns (27 "flats").  Felt like the valves were being opened slightly based on the resistance. Let it rest for about 10-15 minutes, then was able to spin the rods by my fingers.  Looks like that is their "spot".

Kicking is slightly easier (may have been the pushrods were too loose  before), but still a bear to kick.  I will re-take the compression readings after I run it and see if they changed.  That will be another day, as it did not want to start during the 20 or so kicks.  Got to recover myself before another attempt later (legs feel like rubber now).  I do agree that the larger motor sprocket should be easier to kick.  may look into pulling the kicker cover off and see what gear is in there.

thanks for everyone's advice.

- Dave

Deye76

East Tenn.<br /> 2020 Lowrider S Touring, 2014 CVO RK,  1992 FXRP

wreck74

Keep riding it, get it broken in and it'll start to start easy.