Honda-SOHC

SOHC.co.uk Forums => CB350/400 => Topic started by: Athame57 on July 28, 2023, 08:27:16 PM

Title: Warm starting issue
Post by: Athame57 on July 28, 2023, 08:27:16 PM
These past few weeks I've found it very hard to start my engine again if I switch off with a hot engine. Keeping my finger on the starter and closing the choke usually gets me going again....any ideas?
Title: Re: Warm starting issue
Post by: 400 Cafe Racer on July 28, 2023, 09:32:46 PM
If you need the choke to start a warm engine, it sounds like fuel starvation or excess air. 

Could be blocked jet(s), restricted fuel flow, vent blockage on tank.  Excess air, could be flexible mounting rubbers leaking etc.

Let us know how you get on. ;)

Dennis 
Title: Re: Warm starting issue
Post by: Athame57 on July 28, 2023, 09:44:35 PM
If you need the choke to start a warm engine, it sounds like fuel starvation or excess air. 

Could be blocked jet(s), restricted fuel flow, vent blockage on tank.  Excess air, could be flexible mounting rubbers leaking etc.
Let us know how you get on. ;)
Dennis
I'm about to overhaul my carbs as it happens, just bought some bits of Julie  ;) I'll take those things into account and come back with results!
Title: Re: Warm starting issue
Post by: McCabe-Thiele (Ted) on July 28, 2023, 10:35:49 PM
I would have suspicions about an air leak between the cylinder head and the carbs as my first line of investigation.
Title: Re: Warm starting issue
Post by: Matt_Harrington on July 30, 2023, 10:48:55 AM
All I can add is that the non OEM air screws (probably chinese) as so different from the OEM ones that they are almost (perhaps I should say totally!) useless.
Title: Re: Warm starting issue
Post by: Mikep328 on August 02, 2023, 09:21:06 AM
Can you get OEM Honda airscrews/other carb hard parts like jets/needles?  I tried to find some and the few places I found them listed they were shown as "discontinued/no longer available."

Title: Re: Warm starting issue
Post by: Matt_Harrington on August 02, 2023, 09:53:35 AM
Have you tried David Silver? If none there, s/hand is an option....
Title: Re: Warm starting issue
Post by: McCabe-Thiele (Ted) on August 02, 2023, 11:53:03 AM
Hopefully you should be able to clean up your existing brassware.
I have quite a few good used needles, emulsion tubes etc.

Just PM me if you need anything if yours are damaged - Ted
Title: Re: Warm starting issue
Post by: Mikep328 on August 02, 2023, 12:54:28 PM
"Have you tried David Silver? If none there, s/hand is an option...."

DSS lists the hard carb parts as pattern parts, not genuine.  No idea who the actual supplier may be.

"Just PM me if you need anything if yours are damaged - Ted"

I haven't yet gotten into the carbs but the needles/needle jets on a Norton Commando's Amal Concentric carbs wear and require replacing at, say 20k miles (or less) so I was ASSuming the same is true with these bikes/carbs.  Of course, Norton twins 'shake' a lot; Honda fours don't!  :)

Title: Re: Warm starting issue
Post by: Oddjob on August 02, 2023, 02:49:14 PM
I can't remember seeing any wear issues on the brass ware on the SOHCs, not saying it can't or doesn't happen, I'm saying I personally have never seen it.
Title: Re: Warm starting issue
Post by: Bryanj on August 02, 2023, 04:37:20 PM
You mean you know of a commando that got to 20k?
Title: Re: Warm starting issue
Post by: Mikep328 on August 02, 2023, 04:57:32 PM
LOL!  Well, not with all-original parts!  ;)
Title: Re: Warm starting issue
Post by: Bryanj on August 02, 2023, 04:59:35 PM
Worst were the last white ones built from spares, like the Triumph cardinal
Title: Re: Warm starting issue
Post by: taysidedragon on August 02, 2023, 05:03:29 PM
Worst were the last white ones built from spares, like the Triumph cardinal

Or the 'Combat' Commando engines. ☹
Title: Re: Warm starting issue
Post by: Nurse Julie on August 02, 2023, 05:06:25 PM
NRP sell the original Keihin brass ware. But, it's very rare to have to replace any brass bits once they've been thoroughly cleaned, including the emulsion tubes.
http://nrp-carbs.co.uk/
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