poor accelleration

[ronnie]

hi there , my moggy is a 1968 2 door 1000cc . It has been fitted with a brand new carb and all the serviceables plugs points etc have all been changed , the automatic advance from the inlet manifold appears to be working ok , The problem is that if you hit the throttle hard the power is very poor and hardly accellerates but if you slowly progressively press the accellerator it pulls reasonably well.The compression and the timing ok .It also would appear to be using rather a lot of petrol .I would appreciate any info that can help.Also any tips on how to improve the brakes , the are all in good condition ,as in good shoes , drums , cylinders, i even changed all the drums but very poor at stopping .Any tips on how to stop this wee baby .As you can tell im new to the minor scene.
ronnie

[aupickup]

maybe the carb needs tun ing and timing ,may need advancing

[bmcecosse]

If it's 'gasping' when you put your foot down - you may get an improvement by using heavier oil (ie engine oil) in the dashpot. Worth a try. And just check - does the new carb have a spring on top of the piston - inside the 'bell'? Any idea what needle is in the carb ? Have you advanced the timing till it pinks - and then backed it off slightly? And yes - it could just be set too weak! Of course a compression check will tell us basic engine condition - and a check of the plug colour after a decent run (don't let it idle) will give an idea of the running mixture.

[ronnie]

maybe the carb needs tun ing and timing ,may need advancing

hi , ive strobed the timing and even adjusted by ear, Im not to sure about the carb though any tips on how to tune it
ronnie

If it's 'gasping' when you put your foot down - you may get an improvement by using heavier oil (ie engine oil) in the dashpot. Worth a try. And just check - does the new carb have a spring on top of the piston - inside the 'bell'? Any idea what needle is in the carb ? Have you advanced the timing till it pinks - and then backed it off slightly? And yes - it could just be set too weak!

gasping thats the word that describes it , so why is it when you press the throttle lightly it pulls away fine ?? thanks for all these tips
ronnie

[bmcecosse]

'Strobe' - to what??? The only way is to set it 'not quite' pinking. The carb piston may be rising too quickly - hence my Q about presence of a spring on the piston - and suggestion of slightly heavier oil in the damper. But it could also be (although i think less likely) that the piston can't rise quickly enough! In which case lighter (= 3in 1) oil may be worth trying..... Where did the 'new' carb come from ? Is the float bowl vertical - and any idea what needle is fitted?

[ronnie]

If it's 'gasping' when you put your foot down - you may get an improvement by using heavier oil (ie engine oil) in the dashpot. Worth a try. And just check - does the new carb have a spring on top of the piston - inside the 'bell'? Any idea what needle is in the carb ? Have you advanced the timing till it pinks - and then backed it off slightly? And yes - it could just be set too weak! Of course a compression check will tell us basic engine condition - and a check of the plug colour after a decent run (don't let it idle) will give an idea of the running mixture.

when you say advance until pinks, is this regardless of what the strobe says
ronnie

[ronnie]

'Strobe' - to what??? The only way is to set it 'not quite' pinking. The carb piston may be rising too quickly - hence my Q about presence of a spring on the piston - and suggestion of slightly heavier oil in the damper. But it could also be (although i think less likely) that the piston can't rise quickly enough! In which case lighter (= 3in 1) oil may be worth trying..... Where did the 'new' carb come from ? Is the float bowl vertical - and any idea what needle is fitted?

this is all great info , the new carb was on it when i bought it so not sure about what oil is in it or spring , will check it tomorrow, thanks ronnie

[bmcecosse]

Maybe there is NO oil - and a few squirts of 3 in 1 will sort it out........

[ronnie]

'Strobe' - to what??? The only way is to set it 'not quite' pinking. The carb piston may be rising too quickly - hence my Q about presence of a spring on the piston - and suggestion of slightly heavier oil in the damper. But it could also be (although i think less likely) that the piston can't rise quickly enough! In which case lighter (= 3in 1) oil may be worth trying..... Where did the 'new' carb come from ? Is the float bowl vertical - and any idea what needle is fitted?

this is all great info , the new carb was on it when i bought it so not sure about what oil is in it or spring , will check it tomorrow, thanks ronnie

Im strobing it to the markings on the front pulley and by the handbooks instructions
ronnie

[ronnie]

Maybe there is NO oil - and a few squirts of 3 in 1 will sort it out........

no there is defineatly oil in the carb and im sure there is a spring in the top , i used to have 1 moggy 30 yrs ago and remember it as being a bit more perky than this one . This wee car is in excellent unrestored condition and the engine sounds really sweet

[bmcecosse]

The handbook instructions are no use these days - modern petrol is a very different mix to that used when the handbook was written! So - pinking for timing, and plug colour for mixture.....

[ronnie]

The handbook instructions are no use these days - modern petrol is a very different mix to that used when the handbook was written! So - pinking for timing, and plug colour for mixture.....

invalueable info , ive just joined this site and cant praise it enoegh , great to see there are so many people wanting to keep these wee cars alive , im sure im going to have plenty questions in the future
ronnie

[ronnie]

to tune the carb, which way for to make it leaner and which way for to make it richer and whats the colour im looking for in the plug
ronnie

[robedney]

The adjusting nut goes down/rich and up/lean. Lift the piston just a tad (really a tad, like 1/32") with a screwdriver. The ideal response is the idle running a little faster -- not a lot. If it runs a lot faster, and keeps increasing as you lift the piston a tad higher, it's too rich. If it stalls when you lift it, it's to lean. Before you do this make sure that the choke is off at the carb (in other words, the choke cable is adjusted properly).

Here's a link to a good chart of photos for reading spark plugs. I know nothing about this website -- found this searching Google images:

http://www.verrill.com/moto/sellingguid ... rchart.htm

[ronnie]

The adjusting nut goes down/rich and up/lean. Lift the piston just a tad (really a tad, like 1/32") with a screwdriver. The ideal response is the idle running a little faster -- not a lot. If it runs a lot faster, and keeps increasing as you lift the piston a tad higher, it's too rich. If it stalls when you lift it, it's to lean. Before you do this make sure that the choke is off at the carb (in other words, the choke cable is adjusted properly).

Here's a link to a good chart of photos for reading spark plugs. I know nothing about this website -- found this searching Google images:

http://www.verrill.com/moto/sellingguid ... rchart.htm

thanks will try this at the weekend
ronie

[ronnie]

The adjusting nut goes down/rich and up/lean. Lift the piston just a tad (really a tad, like 1/32") with a screwdriver. The ideal response is the idle running a little faster -- not a lot. If it runs a lot faster, and keeps increasing as you lift the piston a tad higher, it's too rich. If it stalls when you lift it, it's to lean. Before you do this make sure that the choke is off at the carb (in other words, the choke cable is adjusted properly).

Here's a link to a good chart of photos for reading spark plugs. I know nothing about this website -- found this searching Google images:

http://www.verrill.com/moto/sellingguid ... rchart.htm

checked out the link , really helpfull thanks