Author Topic: 1977 XLH engine ping  (Read 482 times)

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Offline rider7816

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1977 XLH engine ping
« on: June 12, 2017, 10:06:39 AM »
Well, moving from one problem to the next, I need some help with direction on this please.  Here is the rundown:

1977 XLH
400 miles on fresh rebuild
lockart oil cooler
10:1 wiseco pistons bored .10 over
balanced and blueprinted lower end
keihin butterfly carb 52 slow jet, 165 main jet
standard "P" cams
new cycle shack exhaust with baffles (not drag pipes)
single fire electronic ignition, new spark plugs and wires
new mechanical weight advance
only using 93 octane gasoline


I just put this thing back on the road since the rebuild and noticed that there was a NASTY dead spot on the carb from a dead stop even under light acceleration.  I also noticed that Im getting a decent ping (detonation) when rolling the throttle on or at highway speeds. 
In addition, the spark plugs were really black so I knew the slow speed jet was too big.

I just installed a 52 slow speed jet, now I have more detonation.  I also noticed the dead spot is all but gone but the get up and go seems to have got up and went.   Im thinking about changing the high speed jet up to a 170 and see if this helps.

I was thinking about upgrading to a crane high 4 or something like that but wasn't sure if that was my problem.

Frank

Offline wreck74

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Re: 1977 XLH engine ping
« Reply #1 on: June 15, 2017, 07:37:37 PM »

Offline tmwmoose

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Re: 1977 XLH engine ping
« Reply #2 on: July 18, 2017, 09:54:47 PM »
Is this the first time with the 10-1 pistons and what year is the keihin carb?

Offline Burnout

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Re: 1977 XLH engine ping
« Reply #3 on: July 20, 2017, 05:56:18 AM »
Back off the timing until it quits detonating!  NOW!

WHat is your ignition setup? You say single fire but then speak of upgrading to an Hi4?

You absolutely must use resistor plugs and suppression wires with electronic ignition (no low resistance spiral wound wires).
They don't call me Ironhead Rick just because I'm "hard headed"

Offline rider7816

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Re: 1977 XLH engine ping
« Reply #4 on: July 21, 2017, 05:41:28 AM »
Is this the first time with the 10-1 pistons and what year is the keihin carb?

Yea, this is the first time with 10:1 pistons.  I took some time last weekend and messed with the timing.  I think I I finally have the timing dialed in.  The detonation is all but gone, and the throttle response is amazing after I changed the main jet to 170.

As far as the year of the carb, I know its not original but not sure what year its from.  I know there is a part # on it... I can post that later and maybe someone can help out with that?

I do have resister type plugs and also the correct wires as well.

Thanks!