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Runs poorly when hot

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panomania
Posts: 83
Joined: Sat Jul 14, 2007 9:04 pm

Runs poorly when hot

#1

Post by panomania » Fri Jun 13, 2003 1:15 pm

My bike runs like a screaming banshee untill it gets really hot. Here in Alabama it is already seeing 90 degree+ days and 80 degree nights. After this bike runs about 30 miles it starts running like its really hot. It seems to labor when leaving from a stop. If I try and get on it a little it will ping. But only when hot. I have tried retarding the timing a bit at a time untill it really runs bad, but that doesnt really make a difference. Im using a mallory unilite and I have installed heavier advance springs and limited total advance, retimed and same thing. Runs poorly when hot. Im using a oil cooler and my dip stick/temp guage varys from 150 to 190 degrees. Im using kendall 70 weight oil, harley 3-4 plugs, and my plugs are running a bit rich. Carb is a super-e (68 main jet and 29 med. jet) with drag pipes.
Motor is a 80 inch s&s long rod/stock bore kit.
This is my 1st pan. Ive always had shovels. I have too much blood sweat and tears in this bike to call uncle now and get another shovel like my buddies suggest. They think Im a glutten for punishment. Tell me there is light at the end of the tunnel. Thanks...



52 Chopper
Posts: 14
Joined: Mon Apr 19, 2004 9:01 pm
Location: Chicago

Re: Runs poorly when hot

#2

Post by 52 Chopper » Sat Jun 14, 2003 2:09 pm

Yea me too, even here in Chicago. My runs best in the 70 degree weather. I'v thought about a oil cooler as mine runs as high as 200, but want less then more on the bike.

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Runs poorly when hot

#3

Post by Cotten » Sat Jun 14, 2003 2:41 pm

70 wt oil, drag pipes, and oilcoolers can all make a pan run hotter!
70wt is too thick to lube effectively in a tight motor, thus more friction, andit is denser,therefore holding more heat. Try 50wt (as the Factory prescribed) and see if there is a difference. (You will go faster as well!)
Drag pipes on a pan fail to stop the reversion signal back upon the exhaust valve unless you are WFO. They don't run efficiently in normal riding, therefore the motor has to work harder, producing more heat. You have more noise, not power.
An oilcooler is just that much more for your pan pump to work against when trying to get the hot oil out of the motor. And with 70wt, and you will make that even worse!
You need your oil to get warm to boil the water from combustion out of it. Stop looking at the thermometer and watch the road.

kell
Posts: 404
Joined: Sat Jun 19, 2004 2:58 am

Re: Runs poorly when hot

#4

Post by kell » Sat Jun 14, 2003 6:28 pm

Now that we're on the subject of pipes:
I got rid of the drag pipes the PO put on my 74 cid pan and ordered muffler pipes. When they came I found that down the middle of the muffler core was just a big open space almost as big as the insides of the drag pipes were. I put my old drag pipe inserts in the ends of the new pipes, got a little quiter and a little more power. So it's almost like drag pipes with inserts, but with expansion chambers at the mufflers where the new pipes have a larger diameter than the drags did.
Any idea how would this affect reversion?

dirtpandan58
Posts: 64
Joined: Sat Jul 14, 2007 9:38 am

Re: Runs poorly when hot

#5

Post by dirtpandan58 » Sat Jun 14, 2003 7:34 pm

Keil,
I think if you look in your pipes you will see that the inlet end of the muffler is more or less closed off, forcing the exhaust into the bigger part of the muffler and back out thru all those little holes that you see inside the muffler.
I just wonder if putting another baffle in there would cause too much restriction?

Dirt

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Runs poorly when hot

#6

Post by Cotten » Sun Jun 15, 2003 2:50 am

The restriction on flow in a Pan head is the intake and not the exhaust. (That ain't my original thought, I assure you!).
Any excessive capacity of the exhaust just compromises its ability to scavenge the cylinder. I found that for sure when I put on my first 2" drags in '78,... on an 86incher, S&Scarb,etc..)
"Reversion" is like ripples in a pond from a pebble: They bounce back. This signal bounces back from the 'end' of your exhaust against the next pulse out of your exhaust valve, if tuned poorly.
If tuned just right, it will actually pull gases out of the chamber!

That's the theory. None of it's mine. But it works.

57stroker
Posts: 84
Joined: Thu Apr 08, 2004 2:21 pm
Location: Burley Idaho

Re: Runs poorly when hot

#7

Post by 57stroker » Sun Jun 15, 2003 7:43 am

Had the same problem last year when the motor was only 74 inches. I just made the motor larger to compensate!!! Seriously, (I'm just guessing here), but I think the intake design has a lot to do with it. None of the other bikes I ride seem to have this problem. (Sportys, Shovels, Evos) Only the Pan has the intake manifold running between the cylinders. Next time you stop and the motor is hot, feel the manifold. It's as hot as the heads! I wouldn't get rid of the Pan - I'm saving up for a pair of STD heads so I can run a Shovel manifold. Problem solved! Now, how do you keep the new heads a secret from your riding buds?

kell
Posts: 404
Joined: Sat Jun 19, 2004 2:58 am

Re: Runs poorly when hot

#8

Post by kell » Sun Jun 15, 2003 6:24 pm

Couple of things. First, those muffler pipes are open all the way (this in reply to Dirt). I know 'cause when I was putting the anti-bluing inside them I examined them thoroughly.
Back on the subject Panomania brought up in the first post. I just recently realized that my idle mixture was too rich for the bike when it gets hot. Runs great when rich -- for the first half hour, forty minutes. Then it will have a tendency to die at idle. No problem kicking it over to restart, and runs fine when you're actually moving, but doesn't want to sit there and just idle. So now I lean out the idle after running for a while.
Chances are this won't help you at all Pano but I just can't seem to shut up.

P.S. I also have a Mallory and an oil cooler. Coincidence?

dereborn
Posts: 98
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Location: Halsingland, Sweden
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Re: Runs poorly when hot

#9

Post by dereborn » Sun Jun 15, 2003 10:22 pm

Regarding pipes; I received this tip regarding the optimized length of a 2-2 system.
Measure the length of the intake channel, from air filter to center of intake valve, and from there to piston in "low dead center" (don't know the correct english term, but the opposite of TDC). Mulitiply by 2 and add 10%. This length of pipe should give the best overall compromise, longer pipe gives better bottom. Of course, (needless to say) both pipes must have same length.
Any comments on this one?

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Runs poorly when hot

#10

Post by Cotten » Mon Jun 16, 2003 1:57 am

What's "2-2" mean?
Sorry if I'm clueless to this new stuff.

hd74
Posts: 30
Joined: Sat Jul 14, 2007 3:45 pm

Re: Runs poorly when hot

#11

Post by hd74 » Mon Jun 16, 2003 9:00 am

Thoughts about collectors?
I am a firm believer that you can increase the back pressure and still get the power, sound, and your engine will run at the normal temp. with a 2 into 1 collector. Anyone share the same thought?

hd74

panomania
Posts: 83
Joined: Sat Jul 14, 2007 9:04 pm

Re: Runs poorly when hot

#12

Post by panomania » Mon Jun 16, 2003 3:08 pm

Well, this weekend I took the drag pipes off and put the 2 into 1/muffler & fish tail back on, and it really seemed to increase power but is still acting like some possible ignition trouble when hot. With these pipes on my plugs still burn pretty good but when the motor gets hot it spits back thru the carb.(just off idle). Im guessing its leaning out after hot. Right now its jetted a 68 main and a 29 medium.(S&S-E) Any suggestions? Thanks folks

dirtpandan58
Posts: 64
Joined: Sat Jul 14, 2007 9:38 am

Re: Runs poorly when hot

#13

Post by dirtpandan58 » Tue Jun 17, 2003 1:01 am

Pano,
You might try rejetting. I just put an S&S super E and a mallory unilite on my pan about 500 miles ago. Everything is working fine. The carb came with .0295 intermediate jet and a .072 main. Changed the intermediate to .031 and the main to .068 . I have stock stroke,.060 over pistons,sifton 412 cam W/ solid lifters and two mufflered pipes. I have the ex. pump adjusted pretty low so when it's cold I have to give it about 6 squirts and one hot kick with throttle closed and she'll fire. Then I bring the enrichener up a little 'till it warms up. When it's warm it will start with one hot kick right into an idle. Never been able to that before.
You might even try a thunder jet. They say that they work real good. Especialy for a bigger motor. I was gonna put one on mine but I guess I don't need it.
Good luck,
Dirt

dereborn
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Location: Halsingland, Sweden
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Re: Runs poorly when hot

#14

Post by dereborn » Thu Jun 19, 2003 7:32 am

2-2 is probably a local swedish expression... Simply meaning 2 separate pipes, with or without mufflers. Opposite to 2 into 1 system.

panomania
Posts: 83
Joined: Sat Jul 14, 2007 9:04 pm

Re: Runs poorly when hot

#15

Post by panomania » Sat Jun 21, 2003 6:58 pm

hey dirtpan, do you know about how much cylinder pressure you have? both of mine are right at 90 lbs. with a hot motor.

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