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Discussion Starter · #1 ·
the front cylinder to run hot?
I'm restoring a '74 XLCH and noticed that the front cylinder is running HOT (exhaust pipes are blueing). Wondering what I can do to determine the cause.
The bike hadn't been running for at least 8 years prior. I've rebuilt the carburetor, points and adjusted the timing, not to mention put on different (got rid of the straight pipes) exhaust and got it running. But something is definitely wrong.
Where do I go from here?
FWIW, the front cylinder appears to be running lean, but the rear is definitely running rich. Will a compression test help?
 

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Always nice to know what your compression is, should not be more than 10% difference between cylinders. Double check and make sure you don't have an intake manifold leak. I had a 73 XLCH had the same problem, ran a hotter plug in the rear jug and a colder one up front. Hope that helps.
 

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What could be causing.......

Valves are a definite possibility.

Check the fit of the intake manifold, be sure the O-rings are in good shape and put a couple of wraps of electrical tape around the manifold over the O-rings before you reclamp the manifold (aircraft style clamps are the best).

A leaking intake will also cause hesitation on acceleration (engine runs lean also).

Plugs of different heat ranges may also help,this is, in fact, a factory suggestion.

I always run my engine a little on the rich side.
This helps the engine run cooler and helps prevent
the pipes from turning color.
I run a '69CH which I bought new and my straight pipes show only the mildest yellow at the top end
after all these years.

SPORTSTERS FOREVER,especially XLCH
 

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Dont want to worrie ya.

I have straight pipes. I didnt want to work on engine this year but now Im going to have to. This is a pic of the rear exhaust valve after being slamed by the piston a few times. It looks like it cracked right off the stem. (could have been stuck open i guess no evidence stem still looks straight the guide dosn't look screwed up & the spring was still on ????)

Try checking out the tappet adj.

I made my pipes blue once by leting the bike run at a high rpm with the timing advanced too far.

Dont worrie too much about the pipes you can polish them back to a shiney chrome with "Quater" Pronounced "water" It takes a while but it works great.

good luck!!

 

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Discussion Starter · #5 ·
thanks guys!
Really appreciate the help and advice.
Hopefully I'll get a chance to work on her soon. I'll let you know how I make out.
 

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MarkO, depending on your year, but are you running the stock Harley Keihn equipped carb w/accel pump? These accel pump jets were usually adjusted from the factory aimed too far to the rear jug. Under quick twists of the throttle, it would squirt more fuel to the rear jug, richening the rear jug, while the front cylinder would run a bit leaner, and a bit hotter.

It's a pressed in brass "squirt" jet, and can be rotated with a small wrench to squirt more directly to the center of the intake manifold.

This is probably fairly minor, but may be contributing to the front cylinder running hotter than the rear.
 

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Discussion Starter · #7 ·
cruzencoach, it does have an accelerator pump in the carburetor (Bendix/Zenith) and I know where that jet it located. Yes, I will definitely take a look at it and make the necessary adjustment.
Thanks for the advice!
 

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Discussion Starter · #8 ·
cruzencoach, it does have an accelerator pump in the carburetor (Bendix/Zenith) and I know where that jet it located. Yes, I will definitely take a look at it and make the necessary adjustment.
Thanks for the advice!
 

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8 year lay up?

interested in what state your engine was in(inside mechanically).when you started the restoration?.was engine stuck(pistons)excetra.what did you have to replace in the rebuild?.i have similar rebuild to start one day.many thanks.
 

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Discussion Starter · #10 ·
Bike was out exposed to the "elements" for a year or two. Most of the damage was on the exterior of the bike. Rust, etc...
The carburetor needed to be rebuilt and anything electrical was in shambles. Points and ignition system was replaced.
Fortunately the pistons and cylinders were in good shape.
Here's a crappy shot of the bike before I started working on it:
http://home.attbi.com/~ohary/wsb/html/view.cgi-photo.html--SiteID-245635.html
here's an after shot... still needs a little more tlc:
http://home.attbi.com/~ohary/wsb/html/view.cgi-photo.html--SiteID-245642.html
I've found that anything rubber is in tough shape. I'll need to replace the tires, etc...
good luck!
 
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