Panhead compression... still chasing potential problems..

[JAWS]

Make a leakdown tester... I know you can do that. Canabalize your comp testers hoses.

[[JP]]

I was going to.... then I got in the garage, got distracted and tried a 21 front.
Now i'm ordering wheel bearings for a 5/8 axle..... i'm easily distracted ahahaha

I'll get to that compression tester...

[farmall]

I'd test your tester using your shop air. If the gauge is bad you can cannabilize the plumbing for a leakdown tester and replace the gauge.

[KCgran]

Just knock the center out of an old spark plug and braze a barbe fitting into it, connect a hose to that and then put aT on the end of it. On one side of the T put a gauge, on the other put a ball valve with an air fitting to hook your compressor quick connect to. Get both valves closed and open the ball valve then close it. Then see how fast the air leaks off.

[[JP]]

Right, no need for me to start over engineering stuff like I usually do....
Finished work earlier than expected and managed to stop by my friend hotrod shop and borrowed these 2 beauties..... if I have time this evening I'll be putting it to the test....

[JAWS]

There it is...

10% or less is where I like to be. 5% or less on a real good motor. I might let 15% pass if its rings and know a rebuild is coming soon, but as long as its not smokin, Ill let her go til she does.

[Ibop7]

Something to consider on your not return to idle issue is that if your points weight springs cant pull the the weights back in the motor will idle high until the weights can return. Try lubricating the weight mechanism. Doesnt take much lube but must move freely.

[Larry Ritchey]

Find a guy at your local airport that is a mech. They use leak down tester. They put in 70 lbs and see how much stays in and you can see where the difference goes. Used one for 30 years.

[Larry Ritchey]

Didn't see the photo. That should do the trick though.

[Ratso]

[Off topic: The way the pic of your bike is cropped in post #42 makes me contemplate how good the thing would look with medium risers (same ht. as you have now) and drag bars.]

[[JP]]

Originally Posted by Ibop7

Something to consider on your not return to idle issue is that if your points weight springs cant pull the the weights back in the motor will idle high until the weights can return. Try lubricating the weight mechanism. Doesnt take much lube but must move freely.

There's no weights on the points, manual retard/advance.

I think I figured it out, idle mixture was off, I re adjusted it and seems to have cured it.

Originally Posted by Ratso

[Off topic: The way the pic of your bike is cropped in post #42 makes me contemplate how good the thing would look with medium risers (same ht. as you have now) and drag bars.]

you are not the first to say that...
Personally I don't like drag bars, but I have a set of smaller bars, kind of small size buckhorns, that I'll try out.
Or I can just make any type of bars I want really. I was keeping the bars she has just to keep it with the whole survivor thing..... trying not to make too many changes from original.

[rhysmort]

Originally Posted by [JP]

There's no weights on the points, manual retard/advance.

I think I figured it out, idle mixture was off, I re adjusted it and seems to have cured it.



you are not the first to say that...
Personally I don't like drag bars, but I have a set of smaller bars, kind of small size buckhorns, that I'll try out.
Or I can just make any type of bars I want really. I was keeping the bars she has just to keep it with the whole survivor thing..... trying not to make too many changes from original.

Did you do a compression test? Interested to see if the figures were much more palatable!

[[JP]]

Nah, no time yesterday. Will try do it this evening.

Need to get the front wheel mounted properly and put her on the bench, its currently balancing on blocks of wood as it's the only way to lift the front off. Blocks of wood in the middle, then tie the back end, push it down on the rear so the front lifts up.
It's quite a cool circus balancing act hahaha

[[JP]]

Quick update, just got home and had 20min before having to sort little one dinner, etc. Will be back in the garage after she goes to bed.

Done compression test with my friends gauge - similar results - 65 front, 55 rear.

Hooked up the leak down tester...
I haven't time to read again about how to do it - but I thought, spark plugs out, kick till feel compression and it's on compression stroke.

Hook up the gauge and let some air go in.

When it start to build up compression, like 20 i think it was I can hear air escaping.
I had nothing else at hand so I sprayed WD40 around and got my fingers in there to feel air and look for bubbles.
nothing around the head gasket.
However, putting my ear to it and my finger, feels like there's air coming out through the clamps on the intake manifold, just out the head.

Could it be....valves not seating properly? pushrods not adjusted properly and not letting valve close? (although I'm pretty sure they are properly adjusted - solids, so take slack off, then just twist between fingers)

I'll go back in the garage in about hour and half and I'll have more time.

[joe49]

Listen in the end of the carb.

[[JP]]

Right here we go. update time. just been in the garage with a bit more time.

First things first.. my air compressor can't kick much through the gauge... only like 75psi..
and I'm losing a little bit of air on the adaptor from the spark plug hole to hose, tried to fix it but didn't manage to.
Also got a spray bottle with soapy water.

Started with cylinder #1

Piston at TDC on compression stroke
Removed timing plug
Pushed air through it
Straight away I could hear air at the timing hole - so I plugged that back in to have one less area of air escaping. - question 1 so am I right saying this means there's some air escaping through rings right?

Could hear air on the end of the exhaust and also manifold.
So, undone both pushrods on the front pot, to make sure valves completely closed.
Air on exhaust stopped.
Could still hear it on manifold.
According to the gauge, I was losing 5psi - Had about 65psi kicking in by this time and showing 60psi on the second dial.

Sprayed soapy water all over - spark plug hole, head gasket, all clear, no bubbles. - Question 2 - I'm guessing we are good in saying head gasket is good correct?

Bubbles were around the manifold, but couldn't make it out if it was head gasket or manifold, so took the clamp out.

that's when I found little bubbles coming out from the actual head. like pin holes on this area here



On to cylinder #2

Done the same, piston on compression stroke, TDC.
Undone both pushrods.
pushed some air through it, again about 75 psi coming in, i'm losing 5, second dial showing 70 psi (as soon as i started pumping air)
Soapy water all over, no bubbles anywhere, no manifold, no head gasket, nothing.
Question 3 - I guess I'm right in saying no problems here with head gasket either?


Now the interesting thing here.
I have tried my best to listen to where the air is, but it's kind of tricky as it seems to travel.
However, I'm pretty sure I can hear the air inside the rocker covers.
and as I had the pushrod covers collapsed it did feel a bit like there was air coming out of there.

What's your opinions gents?
My valves not seating properly? all 4 pushrods were loose so those valves were as closed as they can ever be....
and also valve guides leaking a bit?

I have left everything apart, not even going to put anything together, in case one of you asks for something else to be tested.


Still doesn't explain the shit compression results I'm getting?
or is this a case that if I can't get over 75psi kicking in I won't be able to see the head gasket is bad or not?
but then saying that... if my head gaskets were really bad, then she wouldn't be starting first kick would she?

thanks
JP

[joe49]

Use a piece of hose to listen to exact places, if you don't have a stethoscope.
Are those screw in o-ring adapters on your heads? If so you can remove and reseal them.
If you're leaking past the rings the air would go up the oil return hole to the pans.

[[JP]]

Originally Posted by joe49

Use a piece of hose to listen to exact places, if you don't have a stethoscope.
Are those screw in o-ring adapters on your heads? If so you can remove and reseal them.
If you're leaking past the rings the air would go up the oil return hole to the pans.

No it's not screw in, the pin holes are right on the head, on the cast bit. I couldn't take a better photo of the area.
They are next to the intake port on the head, on the machined area to the side of the intake port.


Ok, so that explains hearing the air at the timing hole, then once plugged, I can hear it at the pushrods.
but... if it was leaking rings.. wouldn't the bike smoke too? I get no smoke at all.

this is turning into a mystery?? I'm even doubting if i'm doing something wrong.

[JAWS]

Take the pushrods out. Do it again. Eliminate the variable. Can do the same with the pipes and carb if you want.

Sounds like you did this already. ill catch up.

[JAWS]

You will get some air past the rings. That is normal... not a lot though. 5 psi isnt much.

If it was a valve you would hear it and get bubbles in the port around the valve seat.

Did you try the comp test wet? Now that the intake is off WOT isnt a concern. You would have to set the valves again though.