Correct Tillotson main Jet for 1967 XLCH Sportster

[Tony Blain]

Hello, might any of you learned XLCH folks know what the CORRECT TILLOTSON main jet size is for a 1967 XLCH??
Factory motorcycle, only modification is the mufflers have had the baffles removed.
Thanks in advance,
Tony Blain

[vph-d]

My -71 parts book shows 057 as standard.
VPH-D

[Tony Blain]

Thanks VPH-D, i presume 057 is the same for the XLH AND XLCH??
I would have thought the CH would be a richer jet??
Regards, ^Tony.

[Sportster Jerry]

I would have thought the CH would be a richer jet??

Why? The engine is the same with the exception of the magneto vs. "timer" ignition.

[Tony Blain]

Why? The engine is the same with the exception of the magneto vs. "timer" ignition.

Thanks for the response.
I was thinking the CH cams being the large overlap, longer duration and higher lift, basically "race" cams would suggest a richer mixture.

[vph-d]

As was stated, the engines were identical, excluding ignition systems. CHs were faster because they were lighter, and much more cool!
VPH-D

[Tony Blain]

As was stated, the engines were identical, excluding ignition systems. CHs were faster because they were lighter, and much more cool!
VPH-D

Thanks for the responses!
Regards, Tony Blain

[Sportster Jerry]

Thanks for the response.
I was thinking the CH cams being the large overlap, longer duration and higher lift, basically "race" cams would suggest a richer mixture.

Same cams, same everything. The XLH and XLCH engines are identical in every way.

[dlxl66elxl]

Main Jets

Same cams, same everything. The XLH and XLCH engines are identical in every way.

My experience with these carbs and today's gas being lower in specific gravity is that the main jets sizes need to be increased by anywhere from 15 to 20%. I had a 68 with a .57 main jet and needed to increase jet size to between .65 and .7 to get good response in the mid range and good plug readings at WOT. Hopes this helps. Dave

[Tony Blain]

My experience with these carbs and today's gas being lower in specific gravity is that the main jets sizes need to be increased by anywhere from 15 to 20%. I had a 68 with a .57 main jet and needed to increase jet size to between .65 and .7 to get good response in the mid range and good plug readings at WOT. Hopes this helps. Dave

Many thanks Dave, your detailed advise was very helpful and appreciated.
I am new to this Forum process, and chose to put up my issues in an attempt to have the XL specialists offer advise to assist.
I did EVERYTHING to try and have it idle and be tuned correctly- I followed all the rules, and matched parameters to my Factory Manual and parts book, like I do my other earlier Harley-Davidson motorcycles, which most often are one kick starters. This 1967 XLCH had me stumped!!
I have now chosen to fit an adjustable Tillotson main jet, and altho early days yet, Dave's bike now idles and revs smoothly through its range.
I think we may have done it!
I believe the 057 jet was super lean and believe I have now enriched the mixture by AT LEAST 20%.
Once run in and the motor loosened up, I will address final settings.
Thanks once again for the advise, if you ever need anything from my end regarding VL, UL, RL, WL, Knuckleheads and Panheads let me know.
Regards,
Tony Blain #7543

[dlxl66elxl]

Tony,
I pulled out some old measurement data I did on the Tillotson adjustable main jet over 30 years ago. 2 turns = .054, 2.5= .058 and 3= .062. You can keep adjusting until you are satisfied that you are jetted for leanest, good plug readings and and most power., Also you want to run a Champion J11Y in front and a J12Y in the rear as the front cylinder runs hotter than the rear (yes its true). Also cut the timing back to 40 deg (mark just disappearing at the front of the timing hole. Do the timing first then play with jetting. Hopes this all helps.
Dave

[Tony Blain]

You are a good man Dave, thanks very much.
This is the sort of assistance enthusiasts should share on Forums and the intent of a Forum in the first place.
Information based upon your experiences, that you can share with fellow enthusiasts.
Way to go!
I have printed out your advises and will definitely address.
Regards and thanks again,
Tony Blain.