Inlet manifold insulator

[DJM]

Geoff,
Pretty sure I have one of those, don't know where it came from as I've never had a C72 or 77 and, as far as I know never had parts for them either.

[Geoff Hastings]

Hi there DJM,
If It's the right one Id be happy to buy it off you. The ones I've seen on eBay America have a semi circular groove on one side and what appears to be a tiny hole drilled through the larger inlet hole. The one the previous owner has fitted has the right size inlet hole but the flange is too small so doesn't cover the o ring fully.

[G-Man]

DJM

They are highly distinguishable from the 'normal' CB72/77 with that little cut-out and hole.

David Silver claims he can get them and is selling at £7 if yours is not the real deal.

G

Geoff,
Pretty sure I have one of those, don't know where it came from as I've never had a C72 or 77 and, as far as I know never had parts for them either.

[Geoff Hastings]

DJM

They are highly distinguishable from the 'normal' CB72/77 with that little cut-out and hole.

David Silver claims he can get them and is selling at £7 if yours is not the real deal.

G
Thanks G man,
Just phoned David Silver and they tell me my bike is 1964 but the Vintage Japanese motorcycle club dated it as a 1966. Anyway, the result is David Silver can't get the isolator block for that model. I can adapt one from another bike but I'm puzzled as to what the groove and small hole do or even if they are used on the model I have.
Geoff H

Geoff,
Pretty sure I have one of those, don't know where it came from as I've never had a C72 or 77 and, as far as I know never had parts for them either.

[G-Man]

How about a good picture of the carb on your bike and we may be able to help.

I have a 1962 C72 motor on my bench. I'll pull off the carb and take a look.

Graham

DJM

They are highly distinguishable from the 'normal' CB72/77 with that little cut-out and hole.

David Silver claims he can get them and is selling at £7 if yours is not the real deal.

G
Thanks G man,
Just phoned David Silver and they tell me my bike is 1964 but the Vintage Japanese motorcycle club dated it as a 1966. Anyway, the result is David Silver can't get the isolator block for that model. I can adapt one from another bike but I'm puzzled as to what the groove and small hole do or even if they are used on the model I have.
Geoff H

Geoff,
Pretty sure I have one of those, don't know where it came from as I've never had a C72 or 77 and, as far as I know never had parts for them either.

[Geoff Hastings]

Thanks Graham,
I intend on riding the bike this weekend so have just put the carb back on. I've managed to offset the existing insulator so it covers the o ring but will take the carb back off on Monday. Another question while I'm here, when timing the engine using a strobe, which of the two marks should line up with the pointer?
Cheers Geoff H

[G-Man]

Geoff

T is Top Dead Centre
F is 'firing' (spark)

The two parallel lines show full advance. (when you rev up the engine)

Carb Insulator.



Carb



This insulator does two jobs. The O-ring covers the cutout at the bottom of the flange.(seals the flange)

The aperture in the insulator provides some kind of low-throttle feed to the engine. It could be to generate some turbulence in the air stream or to fix some other problem that Honda found.

Clearly the insulator is made specifically for the carb and a CB/CL insulator is not really going to work properly.

G

Thanks Graham,
I intend on riding the bike this weekend so have just put the carb back on. I've managed to offset the existing insulator so it covers the o ring but will take the carb back off on Monday. Another question while I'm here, when timing the engine using a strobe, which of the two marks should line up with the pointer?
Cheers Geoff H