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53 pan head project

1086 Views 13 Replies 10 Participants Last post by  Hoges
Hey now from NJ,

Finally getting to my pan head project, and looking for some guidance.

53 pan head with super B carb. I purchased it in 2019 as a future project. Last owner said it was rebuilt into a stroker some time ago.

Bike was a bit difficult for me to start at first, but figured it out. Rode it a few times then noticed a valve cover leaking. Decided to put it away until I finished a few projects.
Here’s a video link of it running before I put it away back in 2019.

So now it’s really hard to start. Have to full throttle prime kick multiple times and kick start it flooded just about.
Also, it wouldnt idle without the enrichment up. I had to run idle screw in so it would idle. Didn’t need to do that before. Here is a video link:

So I pulled the plugs to get some ideas on issues. They looked fouled from running rich. what you guys think?

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Also did a compression test. About 90 psi on both cylinders. Front was a little higher than rear.
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So my plan is to go over ignition system and rebuild carb. Bought a rebuild kit.
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Any advice/tips/experience would be greatly appreciated.
once I get it running better I will be looking for advice on replacing valve cover gaskets. I’m assuming the engine will have to be removed, but will be looking for guidance from you all.

Please provide thoughts and I will update you all with updates

hope to hear back. Thanks guys
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Could be as simple as a clogged pilot jet. Those holes are tiny, and crappo ethanol gas sitting for extended periods will clog them up, leading to those kind of symptoms. When I worked in a bike shop, can't tell you how many non-runners I got going again after extended storage simply by hitting the pilot jet with a needle type cleaner and putting in some fresh gas. Good luck on your project 😃
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From the exasperatingly little I can see of it, that is a very good-looking bike! Have you stuck up any pics of it elsewhere on the JJ (and if so, where please)?
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Welcome from Pa. Nice ride👍. Keep posting on the fix. Seems like a carb issue, like previous mentioned, considering as soon as you flicked the enrichment off, it quit.
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As mentioned, before you pull anything apart, clean the carburetor real well— blowing out all of the jets and passages. Old fuel can really clog up a carb after a bike has sat for a long time. Given that the bike isn’t starting well and you’ve been priming it a lot, the plugs would get fouled easily. Once you get the carb cleaned and put fresh fuel and plugs in the bike, see if she starts. Of course, while you ‘re at it inspect / adjust the timing, valves, and ignition components.
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  • Compression looks good. No issue
  • Super B work well
  • Take the carb all apart and soak in cleaner or ultrasonic
  • Starting point for jets is .0295 and .070 assuming stock 74" motor not worked over
  • Super B suffer from throttle shaft leaks and wear out quickly. Remove the spring from the t-shaft and see how much it wiggle around. Might need to be rebushed
  • Starting point for screws: idle MIX is 1.5 CCW from bottomed, idle SPEED is 3 CW from screw just touching throttle arm
  • Check those manifold seals
  • Many people (almost all of them! ) set S&S carbs too rich to account for shitty pipes (like wide open short pipes)
  • The idle MIX and SPEED screws ONLY. AFFECT. IDLE. Not mid-range, not acceleration, not top end. Can only adjust mid-range by changing intermediate fixed jet. Can only adjust top range by changing main fixed jet. Can only affect acceleration by changing your throttle hand habits.
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From the exasperatingly little I can see of it, that is a very good-looking bike! Have you stuck up any pics of it elsewhere on the JJ (and if so, where please)?
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I've had these kind of issues on bikes and small engines that have set a long time.
My go to for any spring start up: Add a low amount of fuel in the tank, throw in a few caps of transmission oil, let the engine run. Sometimes it takes a few runnings but this has bailed me out of many PITA spring start up headaches.
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Sorry, my mistake. It's hideous.

Just kidding, bike looks fine, thanks for confirming my suspicion that it did.
I have a pan with a Super B and I love it, but the Super B is notorious for leaking around the throttle shafts from wear. This, or an intake manifold leak, will make any motor hard to start and tune. Did you install the new throttle shaft included in the rebuild kit? Sometimes that's enough. I see your kit also includes two steel bushings. Be aware that if these aren't installed extremely accurately you'll end up worse than before. It's a job for a Bridgeport. Also, you said you were giving it full-throttle primer kicks. The enrichener circuit on the Super B doesn't do anything at full throttle. It needs manifold vacuum to work. And 90 psi compression on both cylinders is definitely enough to get the motor started and running okay. Good luck.
Hey now, thank you all for the support!!

Got all apart except for this orifice. Looks like someone else had trouble also.
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Soaked it in penetrating spray and even applied heat. Won’t budge before breaking apart groove edges even more. I ran a poker through it and it clear, but can’t remove it.
Does it really need to be removed? Is there more holes in it that need to be checked? If so I could try cutting another groove in it and try again.

Any advice would be great.

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So that carb has been modified.

Looks like a Thunderjet kit or equivalent.

Here's what it does:

Remember I said above that there are only idle, intermediate, and main circuits and that the latter two can only be adjusted by fixed jets? Well, that can limit tuning ability. It can also result in situations where you get problems at the TRANSITION point between two ranges. This kit gives you some more knobs to turn.

The hamfisted jet in the side with the cute red smiley face is an air bleed modification which allows you to tune the transition point between the intermediate and main jets by adjusting the amount of air that can get to the main jet emulsion tub. Handy, especially when running shitty pipes (also mentioned above) that would otherwise fall flat here.

The other hole appears to be a third jet in the main range to add fuel at wide open throttle, but I can't be sure. It allows you (if I'm right about what it is) to tune the main jet in two separate ranges. The orig main jet from maybe 3/4 throttle to 7/8 throttle and the add-on jet at WFO. Also helpful.

If the air beed is the right size, no you don't need to remove it. But it'd be nice to take it fully apart and clean.

Did you check the fit of the throttle shaft yet?

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62 is big for airbleed 42 is stock i am running 50 to bring on main jet a bit later
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