Hi Guys,

Me again with a challenge with my new-to-me panhead (’58 Duo Glide). I think my issue is with adjusting the high speed mixture, but maybe you have some pointers or other thoughts. I started with it two turns out and tried up to a full further turn out (incrementally) and up to a full turn back in (incrementally) but still can’t get responsive power out of it.

Sorry to the length of this post, but I thought some details may be useful:

I was able to start it and ride it home about a month ago, but it never ran well. I’ve checked (new components) condenser, plugs, points, etc. All specs right on. Manual advance and retard limits spot on to the marks. I thought there might be a fuel system issue, so I drained the tank (no sediment or moisture), rebuilt the carb (thinking it might have an old cork float), and that’s now all confirmed good. New gaskets including intake manifold.

Good blue spark, but they are running a bit carboned – so I think the mixture is too rich, but I'd like to confirm that by having it run well. I can start it and she now idles very well after the rebuild. I wanted to take it out for a run to get it up to normal operating temperature so I could fine tune the idle a bit lower, but it doesn’t have enough power to get up the driveway – about 50 feet and maybe a 30 degree slope. As mentioned, I’ve tried many variations of the high speed mixture. Tried various spark advance positions, but no joy. When I “crack” the throttle, she lugs…If I slowly roll on, she’ll ramp up begrudgingly, but I can’t get enough RPMs sustained to get up the driveway; really seems to have no power… Very frustrating – I can ride my Ultra up the driveway just a bit above an idle…

Most recently I thought there might be a compression issue, so I checked. Both cylinders (within 2-3 PSI) are about 75 PSI “dry”, and the “wet” check is about 85 PSI. I thought that since both cylinders were within a couple pounds of each other in both tests, that was okay…

Does anyone have any “rules of thumb” for a better starting point for the high speed mixture valve or other tricks? Any other thoughts on things to check?

BTW, it’s an OEM Linkert M-74B carb and has manual spark advance. FWIW, when she stalls going up the driveway, I roll her back to the flat spot in front of the garage, retard spark, bit of throttle, neutral and she fires right back up on first kick.


Just for fun, here’s a pic of my rebuilding efforts.

Thanks for any and all feedback.

 

How is the filter on the carb? Are your tanks oe?
I had a problem when I was sold the wrong fuel caps. I have my oe tanks with no vent crossover. A shop sold me a set for aftermarket and later tanks that had vent crossover. The later tanks had one vented cap and one sealed cap (so that fuel didn't run out of the tank while on the stand) If you have the wrong caps it will cause restricted fuel flow due to no air getting in the tank to vent.

 

The fuel strainer is clear...

I believe the tanks are OEM. The fuel caps look newer. I looked at them last night and they appear to be a vented type, but just for fun, the next time I get it running, I'll try loosening them up to see if that changes anything. Thanks for something else to consider.

Potentially related questions regarding the carb rebuild I did (I couldn't find anything in the manual on these):

1. Is there desired orientation of the hole in the venturi tube? When I put it back in, it seemed reasonable that the hole was on the bottom, lined up with the bowl assembly passage.
2. Is there a (rotational) allignment requirement of the main nozzle? There are five holes in the side of it, and the man port through it...When I put it back in, I essentially just dropped in it place before putting the spring and bowl cap back on. I didn't know if those side holes needed to oriented be a certain way...

Thanks,

 

I'm sure someone on this forum can give you the right answers, but there's a member on this site http://www.hydra-glide.com/index.php that is a linkert expert and can probably give you the right solution. If it's a carb issue and he can't get it straightened out, nobody can... name is Tom Cotten. Post your problem in the "Panhead" area.

Good luck

 

It is good to see the compression that close between the cylinders...it leads me to think your tester is may be the problem with your results, but, those numbers are low. I'd check your compression again and look at your tappet adjustment if the numbers don't come up a bit. You want to see the numbers as high as possible...better than 120psi...under 100psi and I start rebuilding(assuming a lot of variables)

 

Ultra 08, thanks for that link and POC. I may very well give that a go.

Last evening I took it (the carb) off again to double check the float (soldered brass) for leaks and to double check float level. Both were fine. I did notice that my question about venturi orientation above is a stupid question. If that hole wasn't at the bottom, the main nozzle would not go in and seat properly.

Scott, the manual says 90 PSI compression from the factory, so I thought less than 10% below that number was pretty good...Its a new compression gauge, so I'm curious now.

Does anyone else have more than 90 PSI on a non-modified top end?

Thanks,

 

Here's some food for thought. If you are carboning up your plugs, they might be too cold a plug. Also, when your bike is idling, when you retard the timing, doe's it run even, only slower? Have you tried dialing in your high speed needle until it seats, then backed it out 2, 2 1/2 turns, and then the low in, then back out 5-6? this will be a "rich" mixture, but it is a start, then you can fine tune it from there. Also, when setting up your carb with the bike running, dont have it on its "jiffy" stand, prop it up, this will make a difference.

 

put a s&S on it.. pre evos should have came stock with them..

 

I had a problem very close to yours on my 46 Chief..Cleaned tanks,carb, float,fuel lines,everything..Installed a glass filter to see the gas flow,and look for crap in the filter.After running for a period of time problems would start..Removed the petcock from the tank and found a piece of what looked like steel wool which would impede the fuel flow at some point..apparently it was used as a filter way back when..Good luck..

 

Ok, sorry. That must be correct. I've only worked on shovels and irons