14 replies to this topic

[enigma1966]

Hi all , don't know if anyone can point me in the right direction here as this is now doing my head in

Mini City E - with MG Metro Engine and stage 3 head and Honda Fireblade carbs
1986
When fuel pressure is below 3 psi car will not idle smooth , Idles smooth at 5psi but overfuels at 4 psi the car idles and can be revved but looses power if you try to pull away

I think the carbs may of been dynajetted to stage 1 and the jets are 118 and 42 which doesnt appear to be standard

[enigma1966]

Manifolds where made by a friend , same as Bogg bro's ones and yes the float chambers are level.

starting to wonder now if the pressure gauge is giving a faulty reading

[enigma1966]

Does anybody know what size the main jets need to be drilled out to ?

[enigma1966]

Giving up on the bike carbs , going to fit HIF instead

The conversion is causing nothing but trouble as no matter what I do it either will not run or over fuels in a big way

[R1mini]

Whatever the carbs are from get the matching electric fuel pump, no need for seperate regulators, guages, etc

David

[enigma1966]

Really you need to think about what sort of fuel pressure a bike runs, 3psi is about right for most bikes. Anymore than that and it's gonna just overcome the float and piss out the overflows as you've found.
I would suggest for a start, drill the jets out to 1.3mm and report back your findings.

If I set the pressure at 3 psi the car will not even run , will try drilling the main jets and see what happens ,

Its not just over fueling and pissing out of the overflow , its throwing that much fuel into the engine its flooding it and not just a bit I might aswell put the fuel pipe straight into the inlet

Edited by enigma1966, 25 April 2011 - 11:56 PM.

[enigma1966]

Going to get the car running and sort a few small issues first using the HIF then get a pump to match the carbs and drill out the main jets as DILLIGAF suggests

[enigma1966]

Really you need to think about what sort of fuel pressure a bike runs, 3psi is about right for most bikes. Anymore than that and it's gonna just overcome the float and piss out the overflows as you've found.
I would suggest for a start, drill the jets out to 1.3mm and report back your findings.

Carbs now back on and matching pump fitted , jets are at 1.2 (didn't have a 1.3 drill at the time) idle great at 1000rpm put once you raise the revs the engine goes to stall , tried driving it and it does pull away but you have to build the revs up first , listen to it in the youtube link below

http://www.youtube.c...player_embedded

Edited by enigma1966, 15 May 2011 - 07:59 PM.

[enigma1966]

Thats a weak mixture flat spot, if you don't have access to a bigger drill you could try raising the needle. To do this you need to remove the slide from the carb body and take the needle out. The needle will either have washers under it setting it's height or a 'C' clip in one of the grooves in the top of the needle. Move the C clip down one position and see how it goes.

moved the clip tonight and she runs a lot better (now on the middle slot) , will get a 1.3 drill tomorrow and drill the jets as now the flat spot is a lot higher up on rev's

[enigma1966]

slight set back today , did not get a chance to adjust again or drill jets.

when I test drove the car it developed a nasty rattle , on inspection it was from the clutch housing so I have taken the clutch out and the bearing is b****cked ( lucky I had a spare complete clutch ).

Will adjust needle tomorrow before I drill jets

[enigma1966]

OK managed to get the 1.3 jets in and she runs much better but still holding back a lot , guess I try 1.4 now and see what its like

[secondopsman]

Just as a comparison im using R1 carbs (bank of 4)on my vauxhall mini 1600 twin cam (c16xe engine)and the jets are 1.6mm.I wouldnt use the pump from the R1 carbs as it wont (or mine didnt) last long.Just think how far the pump has to push the fuel on a motorbike then compare it to how far it would have to push it mounted in the rear off a mini.Also if your using a filter king pressure regulator you will need the weaker type spring as the standard spring does give you 3psi but not a constant 3psi it fluctates (spelling) badly.It also doesnt matter if the fuel bowls arent level have a look at the gallery on bogg brothers some of theres are mounted vertically.Also have you set the air jets up approx 2.5 turns out.

[enigma1966]

Just as a comparison im using R1 carbs (bank of 4)on my vauxhall mini 1600 twin cam (c16xe engine)and the jets are 1.6mm.I wouldnt use the pump from the R1 carbs as it wont (or mine didnt) last long.Just think how far the pump has to push the fuel on a motorbike then compare it to how far it would have to push it mounted in the rear off a mini.Also if your using a filter king pressure regulator you will need the weaker type spring as the standard spring does give you 3psi but not a constant 3psi it fluctates (spelling) badly.It also doesnt matter if the fuel bowls arent level have a look at the gallery on bogg brothers some of theres are mounted vertically.Also have you set the air jets up approx 2.5 turns out.

I had it set up at first with a facet pump and filter king but no matter what I did it over fueled.

set up now is jets at 1.3 , needles 2nd notch.

starts first time and runs well , then when she is warmed up if I stop her and then try to start again it takes quite a few turns to fire then this happens

Edited by enigma1966, 21 May 2011 - 04:56 PM.

[enigma1966]

jets now 1.4 , needle still set on second notch

flat spot seems to of gone but will test drive the car tomorrow and see how she runs

[enigma1966]

Update on this

the flat spots are due to the carbs having Air correction jets to compensate for the airflow in an airbox , I have now blocked these off and it runs a lot better , just got to get the jet size and needle setting right now

Edited by enigma1966, 09 July 2011 - 04:26 PM.