Hard kicking

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King
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Hard kicking

#1

Post by King » Tue Jan 16, 2007 11:48 am

Here is a problem I've had one or twice in the past with my 51FL and its back again. One cylinder is extremely hard to push thru on the kick when the motor is cold. It will stop the full force of my 230 lbs hitting the pedal and usually takes about two to three tries to get it through. With the ignition on, it the hard kicking cylinder will backfire and occasionally start after the backfire. It is obviously a compression problem as it goes away with the plugs out. By a process of elimination I have determined it is the rear cylinder, the front cylinder kicks through normally. Any Ideas on what might be causing this?

Thanks

King



fourthgear
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Re: Hard kicking

#2

Post by fourthgear » Tue Jan 16, 2007 12:10 pm

King
A hung up or sticking valve comes to mind or some other mechanical interference with the rotation of the motor . Just compression , unless the compression is not being released and you keep building it up . I have seen some that will stop you in your tracks when kicking , timing could also be a part of the problem. Are you running solids or hyd. ? You say its a reoccurring problem ? Have you changed any thing since it happened last?

King
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Re: Hard kicking

#3

Post by King » Tue Jan 16, 2007 2:53 pm

Hi Forthgear

I’m running solids with an Andrews #1 cam and STD heads. Since the last occurrence I did a full rebuild with a complete top end job. I’ve got about 45 hours on the motor since the rebuild. I too suspect a valve problem and it does feel like it is “pumping up” as I kick. Funny thing is the bike runs well and the problem goes away once it is well warmed up..

King

65 Eric
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Re: Hard kicking

#4

Post by 65 Eric » Tue Jan 16, 2007 9:08 pm

Hey King, I have the same problem except it happens when it's warm. I have a 65 with STD heads, Wiseco 9:5 pistons, Andrews "A" cam, solid lifters and kick-start only. Bike starts easy and runs great but if I try to start it right after shutting it off sometimes it will support my weight (210lbs.) and takes a jump to push it thru. I only have 250 miles on new top end, just finished putting it all together a month ago. This is my first Pan and top-end job, is it just because everything's new that this happens sometimes? Sorry I don't have any help for you King, maybe someone here will be able too.

Eric

mbskeam
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Re: Hard kicking

#5

Post by mbskeam » Wed Jan 17, 2007 3:39 am

when the engine is on the comp. stroke if the intake valve does not open fully, this will let the Cly build up more comp.
this is the same thing as adding a early closing intake, this will build comp. up

the Andrews A closes at 43 deg. so if you had trouble kicking over your bike you could find a cam that closes like at 53 or 63 deg. this in turn will bleed off some of the comp. build up from the piston that is comin up the Cly. to comp. the gas and air mixture.......

I had the rear intake back off its adjustment, and that Cly was very hard to kick thru. this in turn really boosted the comp..
readjusted and it was back to normal....


mbskeam

King
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Re: Hard kicking

#6

Post by King » Wed Jan 17, 2007 2:50 pm

Thanks guys. It sounds like the "A" cam and its "low compression" equivalent the "1" might enhance any mis adjustment of the lifters causing the hard kick.

Eric: my pan did exactly as you describe for about the first ~10 hours after my rebuild. I think it was due to things getting tight upon heating-up as it seemed to run quite hot.

Regarding break-in, one of my "oldtimer" club bros said to run the bike for 20-30 minutes at about 3/4 of normal revs and then shut it down and not restart until cool for the first 500 miles. He also swears by Marvel Mystery Oil. I followed his advise and with 18 hours on the clock went on two days of pretty hard jammin club rides totaling 300 miles and it ran and started perfectly.

That is a good set-up you have there Eric, what carb are you running?

This Sat I will do a 1.) a valve adjustment and then 2.) timing and will report the results.

King

65 Eric
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Re: Hard kicking

#7

Post by 65 Eric » Wed Jan 17, 2007 6:07 pm

Thx Mbskeam for the info on the closing of the cam, the "A" grind was in the bike when I bought it from a good friend and he never mentioned having problems kicking it over so I suspect it's something I changed like the pistons (.030 oversize), heads, and carb. It has the stock circuit breaker which I set the points on using the test light method I learned here. I haven't put a timing light on it yet because it starts so easy I hate to mess with it! but it might be a good idea huh? I'll re-check my solid push rods for adjustment and can someone tell me whether I need that phenolic spacer between the carb (stock 1999 CV) and manifold (S&S shovel) adaptor ? could running without it cause some sort of "vapor lock" which would result in hard kicking when first shut off? If it sits for 15 minutes it pushes right thru.
King, I have no experience with other carbs but this CV seems to work really sweet! Two primer kicks with the choke on and it starts on the ignition kick everytime! it's been in the 30's here in the morning and it never fails. I keep hearing good things about MMO so I'm gonna buy some and give it a shot. I hope my problem's just caused by a fresh top-end but I appreciate all the help from you guys here and I'll report back with my findings also.

Eric

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Re: Hard kicking

#8

Post by Billy » Thu Jan 18, 2007 7:05 am

Eric-
You asked:
"can someone tell me whether I need that phenolic spacer between the carb (stock 1999 CV) and manifold (S&S shovel) adaptor ? could running without it cause some sort of "vapor lock" which would result in hard kicking when first shut off? If it sits for 15 minutes it pushes"

No you don't NEED the insulating spacer, but it does help prevent a LOT of motor heat from transferring to the carb, as a Heat Soak.. This can create a vapor lock situation on a hot motor...

Personally I wouldn't go with out one.. IMO Try it you'll like it.. ;)

65 Eric
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Re: Hard kicking

#9

Post by 65 Eric » Thu Jan 18, 2007 3:23 pm

Thx Sleeper,
The CV carb with the adaptor sticks out quite a bit and I was just trying to keep it closer to the motor by leaving it off. But like you say it's there for a reason so it's going back on.
Live & learn!
Eric

Billy
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Re: Hard kicking

#10

Post by Billy » Fri Jan 19, 2007 4:45 am

Eric-

If it runs w/out any problems, leave it off.

You are using the correct adapter, aren't you ???

King
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Re: Hard kicking

#11

Post by King » Tue Jan 23, 2007 1:17 am

Hi all

Sat. I did a valve adjustment and hardkickin gone! I guess the old dear is a bit tetchy as far as valve adjustment. I found the rear intake somewhat loose (although not to the point of shaking) and set all to the "turns but with drag" setting. Both cylinders now kick normally. I'll have to wait a while to time it and give er a run as I got chased off to Barstow CA for a couple of weeks.

Thanks for the responses.

King

wreck

Re: Hard kicking

#12

Post by wreck » Tue Jan 23, 2007 5:35 am

are you turning your distributer clockwise ? just about a 1/4 turn and my pan fires right up, cold and hot.

fourthgear
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Re: Hard kicking

#13

Post by fourthgear » Tue Jan 23, 2007 4:24 pm

King
Some get a bit picky, even with stock components . I haven't adj. my Jim's solids for a long time , but I've been meaning to. Cam, valves , springs , ign. ,etc. can effect a lot of things , just enough to keep us on our toes.

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Re: Hard kicking

#14

Post by FlatHeadSix » Wed Jan 24, 2007 4:56 pm

I've got the same problem and I've always suspected the old "oil can" push rods.

Has anyone ever tried the SIFTON solid lifter conversion for the 48-52 engines. Mine is a stock 49 FL, the cases have not been drilled for hydraulic lifter conversion.

If you just throw in a set of solid push rods on top of the original adjustable lifters will it beat up the rollers and cam? Can you adjust the valve lash without pulling the pans? I'm seriously thinking about tearing into it, just need some advice from the experts on which is the best (and most economical) way to go.

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Re: Hard kicking

#15

Post by Cotten » Thu Jan 25, 2007 1:32 am

Please remember that "Sifton" can mean whatever Tedd has on the shelf.

But yes, popping in some simple pushrods is the quick, easy, economical, normal thing to do.
Colony's aluminum are good; S&S steel would be better if they still make them.

As far as wear on the valve train,..adjust on the tight side (more so for aluminum),... and replace the rollers with every top end or 30,000 miles, whichever comes first.

....Cotten

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