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Author Topic: 1975F Cylinder #4 Running Hot  (Read 589 times)

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Offline RogueM3

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1975F Cylinder #4 Running Hot
« on: June 14, 2021, 10:56:27 AM »
Similar to another thread posted, but with a different set of air-screws (round top carbs on mine). I have an especially hot #4 after fire-up yesterday and am wondering if its a bad idea to richen just the (1) air/screw for the #4 cylinder or just potentially throw in a bigger pilot jet for only 1 cylinder to correct?

I would assume its not a timing issue given #1 seems fine. Potentially could be the result of valve adjustment being out on #4?

Thanks!
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Offline david 750f

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Re: 1975F Cylinder #4 Running Hot
« Reply #1 on: June 14, 2021, 11:06:39 AM »
Can you explain "running hot"? Are all the pipes equally warm at start up? Is the bike stock? Are the intake and carb rubbers in good shape? Checked for air leaks?
« Last Edit: June 14, 2021, 01:30:01 PM by david 750F »
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1976 CB 750F

Offline newday777

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Re: 1975F Cylinder #4 Running Hot
« Reply #2 on: June 15, 2021, 02:41:03 AM »
Quote from: RogueM3 on June 14, 2021, 10:56:27 AM
Similar to another thread posted, but with a different set of air-screws (round top carbs on mine). I have an especially hot #4 after fire-up yesterday and am wondering if its a bad idea to richen just the (1) air/screw for the #4 cylinder or just potentially throw in a bigger pilot jet for only 1 cylinder to correct?

I would assume its not a timing issue given #1 seems fine. Potentially could be the result of valve adjustment being out on #4?

Thanks!
That is a bad idea.

More likely a plugged carb port giving a lean condition.
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Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 1 K2, 4 K6, 1 K8, 1 F1, 1 F3
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A
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