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CB250k4 , can it run on one cylinder?

CheeseGromit

New Member
Joined
Nov 26, 2022
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8
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Location
UK
Hi all,

We are in the process of setting up idle/mix, and one tutorial that I watched (for a CB350) shows how to do this by essentially starting the bike, then removing one plug and working on the running side and vice versa.

My question is, should the CB250k4 idle on just one cylinder ok? We are struggling to get it to run on just one cylinder, and before we dive into why, I wanted to check whether this is normal behaviour or not first?
It can run on one (ish) if the throttle is played with, but I assume that is maybe due to coming off idle jets?

Thanks!
 
The method of making idle adjustments by disabling one cylinder is one of the countless backyard video methods out there, one of the many reasons we strongly caution about putting any belief in all the "instructional" videos on the internet (regardless the production quality) produced by people who did not work for Honda or their dealerships and are using their own garage (or shadetree) discovered methods. If you read the FSM, with specs and methodology published by the actual manufacturer of the motorcycle, nowhere in it will you find Honda utilizing that method. Obviously, on the later models Honda used vacuum gauges to adjust and synchronize the idle but the twin cylinder models prior to the use of vacuum gauges are adjusted by this method described by the factory in the FSM.

250-350 idle adj.jpg
 
Yep, I did wonder to be honest. And I did read the official manual and as you say, it does not mention removing a plug. Thanks for clarifying!
 
The Haynes manual for the CB175/200 suggests that method also, which doesn't inspire confidence, along with photos of a mechanic with filthy hands, such a contrast to the chaps in the Honda FSM.
 
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