Hates Warm Starts

[48grglvs]

All,

Just got my 48 panhead running recently. I have done all of the necessary things to get it to wear I believe it should be in order for it to run properly. I.e. timing, vacuum testing, etc..

Im running a super e with the long s&s panhead manifold, on top of late panhead outside oiler heads.

Ive figured out my cold start technique. two squirts, two kicks, enrichener on, ign on, a squirt for good luck and crack the throttle and usually in 1 or two kicks it comes to life. After I run it for a few minutes or so around the neighborhood, I notice that it pops out the exhaust and stutters in third with power. Is the main to lean? I have a .072 in there with .0295. I inherited the bike without taking the top end down but im pretty sure it has 3.4375" pistons. Based on a receipt that I have with 92-2720 std as an indicator

Anyways, I turn the bike off, and getting it started again is so hard I cant even explain. For motor testing purposes I was just running straight fuel line from the petcock through the heads and jugs to the carb. I considered vapor lock maybe? I dont have a gas cap vent yet so I just crack it before trying to start. Ive got a fuel filter showing up soon, so I will have that on as well.

I know all bikes have different personality's but im sure something is wrong. My 53 just kicks right over when its warm. I'm stumped.

Thanks guys. Looking forward to some advice.

Best,

Dave

[Panacea]

I would try opening the throttle wide open then kick it over several times listening for a pop. If it does pop close the throttle and try a normal kick or two. You may be over rich on the hot start. If this doesn't help you may have an intake leak. Have you done A PRESSURE/BUBBLE TEST?

[1950Panhead]

Boiling gasoline.
Check two gaskets or insulator between manifold and carb.
Check for vacumn leak.
Cold panheads start easier then hot panheads.
Jerry

[RussW]

The number that you gave indicating piston size would seem to be the S&S designation for a standard bore set of 2720 cast stroker pistons, the kind that came in their 4 1/2" and 4 5/8" stroker kits. Do you have S&S stroker wheels? Is so, what cam are you running? Many times strokers are outfitted with long duration, short overlap "power" cams that makes for VERY temperamental starting. I'm not sure, but if you have stock wheels, wouldn't those pistons give you a rather low C.R.?

[48grglvs]

Thanks guys so far...

So sometimes it starts with the throttle wide open, like it doesn't get enough fuel to air mixture.
The bubble test was hard because the solution I made just boiled of the intake. I need to take a better stab at this.

I think this motor def gets hotter than my 53. I believe that it is definitely got something in their because it rips when it runs. Like it is really strong. So potentially the bike is so hot that it is boiling the gas passing through the piston and head area.

As far as the cam arrangement and stroke, its hard to say. I haven't had it opened up. I was really just trying to get it running reliably.

When the exhaust pops like that and there is a loss of power say in third gear on the move, am i running to lean? As I keep increasing the jet size wouldn't that indicate there a beast living in this motor?

Thanks again guys. Everything helps.

[Cotten]

...The bubble test was hard because the solution I made just boiled of the intake. I need to take a better stab at this.....

48grglvs!

Are you bubbletesting like this?: http://virtualindian.org/11techleaktest.html

Here are porosities in S&S manifolds:

Wish I could remember who to credit.

S&SPORE.jpg (31.68 KiB) Viewed 3047 times

...Cotten

[RussW]

Remove your timing hole plug and slowly rotate the motor. Watch for a series of numbers/letters to appear on the flywheels. S&S marked their stroker wheels this way. If you see four serial numbers followed by a -2 (for 4 1/2") , then letter "E" ( for '36-'54 cases), you know you have an 84" motor and can gauge your jetting accordingly.

[48grglvs]

Ok I need to do the test. Thanks Cotten for the images. these manifolds have porous problems?

I will check the flywheel Thanks guys.

Dave

[Cotten]

Dave!

Porosities might show up anywhere.

But if you find problems, they will most likely involve your O-ring conversion.
(You have '48 heads, correct?)

You will also want to test the pan cover screw over each intake port.

.....Cotten

[RUBONE]

(You have '48 heads, correct?)

Cotten,
As he said in his initial post!

on top of late panhead outside oiler heads.

[58flh]

48 sometimes those pops thru the ex. is a ex.-LEAK at the head & pipe where they meet!---This is prety much where I use alot of Black hi-temp silicone!---Did it pop when you let off the wick?--if yes its a leak.---Richie----You really got to know what your dealing with!-Cam Stroke,comp.---hell just the cam would answer alot!

[48grglvs]

Ok. Work got the best of me last night. I will be jumping in tonight. Here are some pictures.

Richie, Thanks for the help. I wanted to open this up to the group because I feel like I keep nagging you about my problems.

P.S. Richie in a recent post said the discoloring of the front head is an indicator of a vacuum leak. Any thoughts?

DSCN4218.jpg (80.5 KiB) Viewed 901 times

DSCN4219.jpg (66.08 KiB) Viewed 901 times

DSCN4220.jpg (55.55 KiB) Viewed 901 times

Definitely popping out from the exhaust clamp and the head. Are these later heads or were they drilled 48 heads? I know I could look through the Palmer Book but I just thought I would ask because maybe someone can spot them a mile away.

DSCN4221.jpg (70.41 KiB) Viewed 901 times

Also these were the pictures I took when I had the Linkert Intake on. I put the Super e on because I was having a real struggle starting it with the Linkert and someone suggested dialing it in with a carb that had a throttle pump and then reverting back to the Linkert, Which I should have Cotten do his magic on anyway.

DSCN4225.jpg (50.37 KiB) Viewed 901 times

If you need anything else I can get pictures. I will look at the flywheel numbers tonight.

Best,

Dave

[Panacea]

The heads are 63-65. The first year with bosses was 62 but they were left un-drilled...Mike

[Cotten]

... on top of late panhead outside oiler heads. ..

Doh me bad.

But don't forget the pan cover screws.

....Cotten

[48grglvs]

Yeah thats what I thought but wasn't 100% sure. Thanks Mike.

Cotten, Do the soap test on the pan cover screws? I never even checked the snugness, so that would be good. Also I have to make sure both intakes are closed on each head before putting pressure on the manifold? Im struggling finding something to use around the garage/house for the intake cover apparatus.

Dave