Carb needle question - amongst others!

[dave.vitesse]

The Rough Guide is correct. However, remember the 1500 engine is long stroke with three bearings and without a lot of work on the crank and bearings its best not to tune for high revs.

 The art is to increase the mid range power. I never doubted you would get it running, even so well done.

Dave

[Anglefire]

Thanks Dave - was a bit of a school boy error to be fair - though I really thought I'd checked it before I first ran the engine - but clearly I didn't! One for the memory banks!

I hope if I have got the cam timing slightly out (It is within a degree I think) that its advanced as that will benefit the engine! Does feel good and strong at low revs however its timed though!

Snowing again now on and off so not going to do anymore for the time being - just happy that I know it runs!

[Anglefire]

Well, the sun was not shining, but the rain has held off this morning and I got the old girl out with the intention of getting the idle better. 

First checked the balance and was as near to spot on as you would want.

But idle too high - so turned the idle screws - and nowt. Checked the choke and that was a bit tight to the cams, so backed them off - and still a bit too high - backed off to nothing and still too high - so took the needles back to basics and adjusted and whilst better is still a bit high - but snap the throttle shut and it almosts stalls, settles and then runs high again.

I've sprayed around the obvious places and no leaks that I can spot - but does seem to have too much air going in.

My carb balancer is showing about 4 on each carb. So its not as if all the air is from elsewhere.

Anyway took it for a short run and it drives nicely. got to about 50 and felt nice. Exhaust is "sporty" though not too loud - not sure what the missus will say though.

Got a couple of water leaks by the looks of things so will have to look at them another day - as well as the leak from around the dizzy - which is a bit annoying.

But its getting there - can't wait until I can get the roof off again (Though no idea where I'm going to put that now I also have an engine crane and engine stand in the garage..........)

[rogerguzzi]

Hello Mark

                   Is it hanging on the throttle cable?

I had 1 pull off spring fitted and anchored to the heat shield 

I am surprised you had to adjust the choke cams as I set them with feeler gauges(hanging on cable?) 

It just sounds as though throttle plates are not seating.

Is the connecting shaft loose ie a bit of movement side to side and the carbs level(not twisted on bolts)

When the cable is disconnected you should be able to waggle it up and down in the fork ends.

What about the rocker cover to carb pipes!

Roger

[Anglefire]

Hi Roger

I checked both choke and throttle cables for hanging as that was my first thought. 

But we’re ok  as far as I could tell. I even undid the choke cable to make sure and it was ok  - not sure how loose it should be - it’s not tight but then it also doesn’t have much in the way of slack.

The throttle I made sure it was sat with the fingers between the bridge and that both butterflies move at the same time.

I had an issue with my old carbs not closing the butterfly’s properly and added a couple of springs - it didn’t “seem” to be that problem, but I confess I haven’t tried that! 

If the weather is ok tomorrow I will try that. 

As a matter of interest, what size is the choke fast idle screw as I’ve tried ever spanner, metric and imperial and nothing fits. Either too small or too big! 

[Pete Lewis]

Good chance its bsf    or 2ba   ...from old designs syndrome

[Anglefire]

Typical. About the only size spanner I don’t think I have ?

[Guest]

Mark.

A 2BA tap takes a 4mm drill bit, so that is about the size spanner you need.

Regards.

Richard.

[Anglefire]

23 hours ago, rogerguzzi said:

Hello Mark

                   Is it hanging on the throttle cable?

I had 1 pull off spring fitted and anchored to the heat shield 

I am surprised you had to adjust the choke cams as I set them with feeler gauges(hanging on cable?) 

It just sounds as though throttle plates are not seating.

Is the connecting shaft loose ie a bit of movement side to side and the carbs level(not twisted on bolts)

When the cable is disconnected you should be able to waggle it up and down in the fork ends.

What about the rocker cover to carb pipes!

Roger

I've had another play with the carbs - and checked it all out - the one clip holding the rocker cover pipe was essentially bust - so replaced it - not sure it was really leaking though.

Re-checked the throttle and choke cables - and I have adjusted them slightly - the throttle might have been a bit tight in the forks - but again, not really sure.

Adjusted the mixture which was a bit lean, checked the balance again and tweaked that - idle still too high - rear carb in particular - so I added a couple of springs from the forks to the holes in the throttle cable bracket and that seems to just pull the butterflies back a smidge. But it makes the throttle very stiff and a lot harder to drive smoothly - in fact I took them off half way round my test run and the idle is a little high still (Around 1000-1100rpm)  - so have to find a happy medium somehow!

[Anglefire]

Went out for another spin - well took my eldest to a friends - so was a good excuse!

Came back (running sans springs) and put a drop of oil on the linkage and they seem to work ok (They did before), The video you can see there is some slack in the forks.

Sen

[Pete Lewis]

There is a designed float in the levers so when on fast idle with choke you are not trying to operate the whole throttle .

This is so The choke just operates the spindles not everything back  to the pedal

They  look fine ,  just check both sit the same place on each spindle lever  so they are equal float and both open the throttles together when you operate the cable pull ,  video it looks ok e

Pete

[Anglefire]

Just to hopefully put this to bed. 

After sorting the oil pressure out yesterday and it having a decent run of a few miles I decided to have another look at the carbs as it’s still running 200rpm too high at idle. 

Stripped them down so I could get the needles out as well as check the jet heights and decided to change the needles for some leaner ones - I have a few choices from Roger and decided to go for the ABT rather than the AAU fitted. I would have gone for the ABG but don’t have any of those unless there are some in the other carbs I have. Never thought of looking till now ?

Anyway fitted the needles exactly how Roger described - level with the housing by using a straight edge and turned the jets down by 12 flats - one didn’t look the same as the other ( I’d put the top on before doing the second one) so took it apart again and measured the distance down and both were 0.08” down from flush - so put everything back together. 

Started her up and immediately it sounded better - just a minor adjustment to balance the carbs.

Took her out for a spin and is driving even better than yesterday. Feels nice - sounds lovely on acceleration but goes quiet cruising. Picks up and accelerates strongly.

Just need to adjust the handbrake as it’s not holding very well - but that is fine probably just the brakes having bedded in finally.