Mike-
I don't know much about Mikuni's but let me relate my similar recent
experience. I had almost the same symptoms. Mine turned out to be a chunk
of rubber hose in the needle valve chamber of my Z-S carb (freakin chunk
would plug needle valve at sufficient suction!).
Here are some of the other suggestions that I received from the list and
elsewhere:
1) Fuel pump - check output ( aprox 1 pt per minute)
2) Fuel filter - plugged/restricting flow
3) Vapor lock - insulate offending fuel line
4) Vacuum build-up in fuel line from tank (vented gas cap? plug in fuel line
from tank?)
5) Vacuum from carbon canister - pull line from carbon canister to carb
Hope this helps!
Steve Conley
Marysville, WA USA
'76 MGB Roadster
swconley@foxinternet.net
MGB Online: http://web3.foxinternet.net/swconley
NW MG Golf Tournament/Rallye : http://web3.foxinternet.net/swconley/golf.htm
----- Original Message -----
From: Michael E. Blair <mblair@nfis.com>
To: <mgs@autox.team.net>
Sent: Saturday, May 06, 2000 7:22 PM
Subject: Is this vapor lock?
> My 78B has a Mikuni carb on it. I have finally got it tuned to the point
> that it idles good but am still going to replace it. My problem is this;
the
> car starts and runs great for about 15 to 20 minutes. After this point it
> seems to lose all power. Still idles great at 800 rpm, but step on the gas
> and it spits and sputters. It seems to be related to heat and this is what
> steers me towards vapor lock. The heater hose line that was hooked to the
> original auto choke on the original carb is now routed directly under the
> mikuni... could this be heating up the carb enought to vapor lock it?
>
> Any thoughts?
> Mike
>
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