Tech Tip #3 Honda Helix CN 250 Throttle Cable Replacement

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Tech Tip #3 Honda Helix CN 250 Throttle Cable Replacement

Postby zozman » Wed Jul 03, 2019 2:59 pm

You’re driving along with your Honda Helix and you notice that your throttle has some excessive play and that the throttle grip does not come fully to the closed at rest position. Where did all this play suddenly come from?

Chances are your throttle return cable has broken. If it had been the throttle accelerator cable you would have an idle but no acceleration. Having a correct and functional throttle cable is also safety issue.

It’s time to check out the cables which run from the handlebars to the carburetor.

Honda calls their throttle cables handle switch cables. The problem is one cable is throttle “A” and the other is throttle “B’. On the Honda parts diagram, both look the same.


One cable has a short threaded screw which goes into the off-run switch and is mounted inboard and the other is a longer threaded screw bolt which is mounted outboard. One cable has a sixty-degree bend going into the carburetor bracket and the other an almost ninety-degree bend.

One cable is for acceleration/pull and the other is return/push.

One cable mounts on the top of the carburetor bracket and the other mounts on the bottom.

Both cables are marked either KS4 or KFR. Really?

Which one is which?


Cable “A”
17910-KS4-000 (6Z21)
17910-KS4-010 (6Z21)
17910-KFR-700 (3G16)
Acceleration/pull cable
Long bolt thread into hand control, outboard side.
Carburetor mount bottom.

Cable “B”
17920-KS4-000 (6C28)
17920-KS4-700 (6C28)
17920-KFR-700 (3G15)
Return/pull cable.
Short bolt thread into hand control, inboard side.
Carburetor mount top.

Now the real treat of the replacement-everything reward from the handlebars to the carburetor has to come off to thread the new cable on.

No wonder the manual doesn’t talk about this service!

Here are the steps working front ward from the carburetor to the handlebars. Remove the following:

Seat (manual 13-2).

Loosen the throttle cable adjusting nuts and lock nuts. Disconnect the broken throttle cable from the carburetor (4-3)

Body center cover (13-5)

Rear lower covers R/L (13-2)

Side rails R/L (13-5)

Passenger footboards R/L (13-5)

Rubber floor mats L/R (13-5)

Floor panel (13-8)

Handlebar two upper covers and lower cover. (14-3)

Master cylinder cover (14-3)

Maintenance cover (13-4)

Side (wind) visors L/R (13-6)

Inner box, fuse coupler (13-8)

Handlebar switch, disassemble, two screws longest screw outboard (20-5)

Remove broken cable housing and pull it out. Then replace with the new part into the handlebar switch and reassemble removed parts in reverse order.

This is a long replacement procedure because all of the plastic parts between the handlebars and the carburetor have to be removed. It took me four hours to remove all the body parts just to be able to remove the throttle cable and another three hours to install new cable and re-assemble.

Randy Pozzi (Rev. 7/2019)
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Re: Tech Tip #3 Honda Helix CN 250 Throttle Cable Replacemen

Postby birdmannn101 » Thu Jul 04, 2019 5:41 am

Thanks for the Tech Tip Randy,

Especially this one because you don't really think about it till it happens to you after cleaning your jets.

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Re: Tech Tip #3 Honda Helix CN 250 Throttle Cable Replacemen

Postby scootcat » Fri Jul 05, 2019 11:50 pm

Well done zoz .
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Re: Tech Tip #3 Honda Helix CN 250 Throttle Cable Replacemen

Postby Double56 » Wed Jul 10, 2019 5:35 am

Thanks for this post. I just bought my 1st 1986 Helix and had noticed the throttle not returning to where it should. I had read some tips to oil the cable. Keep in mind this is my first ever 2 wheeled vehicle. I was able to get oil to one cable but the other was giving me a little problem. Checked the cables at the carb and found the problem. Only 1 cable attached and no idea where the other is. So it's time to order a set. Question is, where is the best place to order from?
Thanks in advance,
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