Leak Test, Compression Test

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Pan58
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Leak Test, Compression Test

#1

Post by Pan58 » Sat Mar 14, 2015 5:30 pm

Made a leak test and compression test today, after about 20 min warmup, at my 1958 FLH with following results:

Leak Test: Front Cyl 16-18% / Rear Cyl 15-17%

Compression Test (dry): Front Cyl 86 PSI / Rear Cyl 115 PSI

Copression Test (oil on piston): Front Cyl 101 PSI / Rear Cyl 138 PSI

During the leaktest with the timing hole plug removed, all the air noise came out of the crank case. No noise at the intake and no noise at the exhaust at all.

Here is what the plugs look like: (left Front, right Rear Cyl)
Plugs 03.14.15.jpg
I make about 600 Mi a year. The bike starts good and runs smoth at 30 and 50-60 mi/h. Any advise? Is this critical? Immediate action required?

Thanks to all comments
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james
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Re: Leak Test, Compression Test

#2

Post by james » Sun Mar 15, 2015 3:58 am

Is it a newly rebuilt engine?
I recommend a intake leak check and repair.
Next I recommend putting more miles on the bike.
That rear plug look new.
Jim

JR JOHNSON
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Re: Leak Test, Compression Test

#3

Post by JR JOHNSON » Sun Mar 15, 2015 6:00 am

do like what James says,but make sure the throttle is wide open when compression testing,are you running solids,or hydraulic tappets? noise at timing hole is normal .

58flh
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Re: Leak Test, Compression Test

#4

Post by 58flh » Sun Mar 15, 2015 11:30 am

Intake leak---The plug looks like it came out of the box.Remember to check the cover screws over the intake real good with soapy water/With a hole big enuff to run that lean-you probably can swipe your fimger accross the bottom of the manifolds clamps & it will be wet.Remember to do manifold first / then do another test with the carb. on.Those numbers rule out a head gasket.Let us know what you find.---Respectfully----RICHIE

Mark44
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Re: Leak Test, Compression Test

#5

Post by Mark44 » Wed Mar 18, 2015 7:31 pm

58flh wrote:Intake leak---The plug looks like it came out of the box.Remember to check the cover screws over the intake real good with soapy water/With a hole big enuff to run that lean-you probably can swipe your fimger accross the bottom of the manifolds clamps & it will be wet.Remember to do manifold first / then do another test with the carb. on.Those numbers rule out a head gasket.Let us know what you find.---Respectfully----RICHIE
Richie, can you elaborate on testing with the carb on? I am a believer in applying positive air pressure to the intake manifold (10 to 12 psi), but I'm not up on testing with the carb installed. By "wet" do you mean wet with gas?
Thanks,
Mark

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Re: Leak Test, Compression Test

#6

Post by 58flh » Fri Mar 20, 2015 2:15 pm

MARK---Sorry I didn't get back sooner////But yes If a clamp is leaking -You can run your finger under both & they will be wet with gas.---Its funny I got so use to getting guys bikes ready for the season & Anyone that didn't fire by the 3rd kick/It was always the Intake leaking somewhere.I always check timing & go over a bike before I try to fire it.If you don't get a Cough or kickback from to much adv. by the 3rd kick HOT!-after priming,To me somethings wrong!These bikes start very easy!--Just find compression-stroke & relax your leg-It has to start!-If everything is in order.Also a good suggestion that somebody said before----After you fix her PUT SOME MILEAGE ON Her!.The worst thing is letting them sit for long periods of time!-Remember when you shut down & put her up in your garage /As she cools WATER is forming!--& that's not good for anything.Its good to run her even if olny weekends,But def. run her.After you check your manifold for leaks /its good to put a shop/vac hose so it blows out & Affix to carb.--Spray soapy water on shaft ends To check for wear/& hold the throttle open.Usually I find a Manifold o-ring or two!.The carbs. usually are good /But if a LINKERT-Always check.Remember those are nice carbs. & have TONS OF USE on them.Those You find bubbles now & then.-----Respectfully----Richie

Pan58
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Re: Leak Test, Compression Test

#7

Post by Pan58 » Fri Mar 20, 2015 9:27 pm

Back with some findings:

to Jim: the engine was rebuilt back in 1989 and has about 2600mi since, the Rear Head was replaced (used one), new set of pistons +0.04 (inkl rings), new valves and guides +0.008. The plugs on the picture are new and have 150mi.

to JrJohnson: I made the compression test again, choke and throttle full open: Front Cyl 95 psi, Rear Cyl as before 115 psi. I run hydraulic tappets.

to Richie: I will do the manifold leak test, but first has to make this pressure plate with the nipple to put on the manifold. Let you know what I will find out

Pan58
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Re: Leak Test, Compression Test

#8

Post by Pan58 » Mon Mar 23, 2015 10:53 pm

ok, I think I found the troublemaker. I made the manifold leaktest and there was only one spot with bubbles.

I made some pictures: Rear Cyl Head
Rear Intake1.jpg
Rear Intake5.jpg
Picture taken from the r.h. side
Rear Intake4.jpg
Do I have a chance to fix this leak?

Thanks, Martin
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Re: Leak Test, Compression Test

#9

Post by Mark44 » Wed Mar 25, 2015 5:02 pm

The intake nipple on my front head looked like this, and I was able to get it to seal. I retested a couple of months ago, and it still wasn't leaking.

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