Model 7 Pre-Monobloc...running rich?

Many Thanks Barry, Robert and Paul, an excellent comprehensive set of information... Yes it does seem to be too high a fuel level and now I have the complete range of testing information and also how to change the settings. The carb is bottom fed and the float is the original brass one, still perfect. I did notice thatBurlen Amal shop sells the bottom fed float set up with the needlecut withtwo grooves so I could do as Robert suggests and cut another groove lower down with his clever method.

Now I have all the info, it will be best to go over the entire carb, checking it stage by stage and seeing where things can be set correctly following Paul's superb info....Will be back when it is all done....very much appreciate your help I'm sure otherreaders will find your information very useful too.

Les

Well as promised I am updating with the results of what I found.

Doing a fuel level check I found this to be OK. (It has the old copper float) I then ordered and replaced the needle (pretty sure it was new before and I already had a new slide) and the needle jet and main jet. The hole in the new needle jet looked very much smaller than the old one making me think they had sent me the wrong one but no it was correct (stamp-wise) so I obviously thought this must be the cause as the old original needle jet must have been extremely worn. Anyway everything put back and initially I thought there was some improvement but alas, after a while, I realised the motor still seems to run slightly rough when cornering around bends to the right AND to the left!

Phoned AMAL Burlen but they had no idea what might be causing this but confirmed the fuel height as 1 5/16" down from the top of the float bowl. So the only thing to do is to lower the fuel height to see what happens but I am reluctant to as the mixture is genuinely perfect (plug clean as a whistle) so don't want to weaken it any more...

Ah haa!... it just strikes me as I type this.... maybe the rough running whilst cornering is fuel starvation and NOT richness ...so maybe I need to raise the fuel level....Oh dear now I have thought of this, I will have to try that approach....Let you know what I find....ta-ta...Les

PS...just coming back again.... with some more scientific thinking...I was wondering if the increased G force on the float would cause the float to sink deeper into the petrol and open up the bottom fed valve causing the fuel level to rise temporarily? OR does the G force push on the fuel as well and maintain the equilibrium?...Fuel is incompressible so the Specific gravity of the petrol would remain the same but the float would indeed become heavier!....Any thoughts?.....Les

Hi Robert. Thanks for your thoughts. Although the float needle and seat are old and likely to be the originals they shut off the fuel very reliably and positively, in fact if I leave the fuel tap on it never floods or even seeps slowly. The recommended level Amal supplied is the fuel height rather than float height so even if the petrol SG is different (and it will be with ethanol added) and the seat worn, the two combinations seem to result in the correct fuel height at the petrol surface being obtained. The engine starts with no more than two kicks when cold (with the correct procedure as per the old road tests) & ticks over reliably...it really is baffling to what is causing this odd response on cornering. I have even considered it might be the ignition side of things but everything on the mag is equally in perfect adjustment with a new armature rewind, new bearings and no end float. Maybe I do need I higher fuel level as you suggest but what seems crazy is that the problem occurs when the bike is cornered in in both left and right directions, so with the float chamber slung off to the left of the carb main body it does not make sense....but yes I will try a higher fuel level and report back....Les

PS Hi Gordon just seen your post as I did this one. You are quite right about the scissor clip on the float my one was very loose but I spotted this and with thin pliers tweeked the clip to really grip the groove so I have now to eliminate this possiblity but useful info all the same....Thanks again.

Many thanks Robert for giving this odd problem some extra thought, but everything mechanical, float wise, is or appears to be quite intact. What you suggest would indeed create a problem but the needle does fit and move freely in the top cap hole which is completely unblocked. Because of the continued rain showers here, I have to wait for a good dry spell to retest the bike to remind myself what is happening. I've never known anything like this problem ever before, One could just ignore the slight change in engine tone and feel that occurs on sweeping bends but I know it's not right but I could get used to it. I will try a lower and higher fuel level by making extra needle grooves below and above as you've already suggested. To make certain the adjustment is being "seen" by the engine I will make them + & - 4mm and do some more test runs weather permitting. Thanks again will eventually come back on this.....Les

Thanks for the warning Paul....I shall look out for that possibility before making the new top needle groove....Les