Hey I have been having my mini tuned and the carbie rebuilt and i need some advice, the story goes,
The carbie specialist has rebuilt the carby, the engine has had a major service and been set up correctly, it idles seamlessly however it lacks power throughout acceleration.
The problem is that if fuel is sprayed in it goes like the clappers but when the carbie is used to increase the richness it just doesnt respond...

Now everyone involved is completely stumped as to what the problem is so any advice would be greatly apreciated

timing

My first thought would be, float level incorrect.
If it goes well when you squirt fuel down it's throat, it isn't getting enough fuel down there. So Float level, being low, could be the issue, otherwise the needle is WAY wrong.
If not, then it can only be timing left.

Cheers
Aaron

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Did you take it to a Mini specialist?

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Hmm the ignition timing and the whole fuel system has been checked and every component has been repaired or replaced in the carbie also he has tried changing the needle to no avail
and its at a carbie specialist who has a rolling road...
He desciribed the problem by saying its like as if when u try and accelerate there is like a vacume aplied to the fuel delivery which means it just lacks power?

Sounds crazy, man.

Have checked for manifold air leaks? Try blocking the throat while engine is running.

An air leak would explain lack of vacuum in the dashpot, hence needle is not rising on acceleration, therefore no fuel

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

Carby checks:

You haven't put air cleaners on upside down have you? That is the base of the air cleaners blocking the air outlet tube of the piston?

Otherwise, get a colortune and check the mixture.

Check float levels as above,

Check fuel pump capacity to deliver,

Check piston is free to move, and goes all the way from top to bottom no binding.

Try a weaker spring in the dashpot (blue if a HS2 or HS4)

Try a thinner oil in the piston.


Timing Checks:

Check ignition timing as per manual.
ALSO check valve timing as per manual.

Get back to us with the results!



Good luck
Matt

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68 Deluxe.... it's shiny..... I like shiny!!

Take it to The Mini Man!

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

To me it sounds like incorrect float level. Float level never seemed to bother my old HS2 SU, but the HS4 is a lot more picky. Try removing the dashpot and see where the fuel is sitting in the jet. If you can't see fuel at all then it could be float level. Especially if you still can't see fuel with the choke pulled out. On the topic of choke pulling the choke out will usually make it run a lot better if it is the float level.

You said he's a Carb Specialiest...is he a SU Specialst


Try running with the choke out and what do you get..I'd be interested

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Stop Licking the Dog...I Don't Care Who Started It

Don't have a dirty fuel filter somewhere?

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Good point Bat

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Stop Licking the Dog...I Don't Care Who Started It

Forget about the "carb specialist", any decent mini mechanic would be able to tune the car for you while adressing all parts, not just the carburation. I like quite a few mini owners I've spoken to have tried the "carburettor specialist" path years ago, given up and have taken the car to a mini mech who sorted out the "misterious" issues in half an hour.

I concur.... can't go past a good Mini mechanic, one I goto has never seen me wrong. I've found it's on the road again quicker as well.