Cota 247 Running Lean and Overheating

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And just one more thing both Ross Brown and Greg Harding felt that it was running hot and I agree it feels and smells hot. I think this problem goes right back to day one - I have managed to correct or overcome the other performance issues but the bike has been unreliable ( breaks down on a ride) since day one.

[David Lahey]

[quote="keychange"]Ok will do - but I have fitted an inline see through filter and wouldn't that also be empty

(David says not necessarily - what if the problem was the float needle sticking to the seat?)

I've thought of an easier test. Next time it stops and seems lean, tickle the AMAL and see if you can get fuel to come out the little witness hole for the tickler. If fuel comes out there, then the bowl is full. If you can't get fuel to come out the hole, then you need to work out why.

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Ok - I'll go with that - thanks David

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David

You are absolutely right the tickler is dry - I do wonder does turning the fuel off create an airlock. Anyway I once again removed carbie carefully and there was only half a bowl of fuel ( can't be absolutely sure it didn't run back out the fuel line) checked all fuel flow and refitted the original non adjustable float bowl. The only new components left in my carbie are the float needle and jet needle and filter gauze. I checked the float needle against the old and it looks identical.

I checked the tank breather and the fuel flow and the inline filter (which is new)

I noticed on reassembly that it took ages to get fuel through the tickler (it wasn't like this before) I started it and while I was adjusting the mixture it died (not actually while I was adjusting) and the tickler was dry even with the fuel on (but it did take ages to come through initially). I am tempted to remove the banjo filter gauze - I don't have an operational replacement.

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I found an old banjo gauze which I bastardised removing the gauze - tickler was flowing fine. I ran it to hot and it didn't conk but it isn't idling at all well and throttle response is poor it lags and then over-runs on release - I expected to see a wet plug but no it's still dry and lean looking (but it needs a decent run to be sure)

I will replace the old float with the newer adjustable version again tomorrow.

BTW - refitted the shim for the oil seal - reseated the seal and ran a soapy water test with no indication of any leaks. Retarded timing approx 1 degree past standard, fitted new plug (3rd in 2 weeks). Brownie suggests I check the cylinder base gasket so I will try that as well

[David Lahey]

It sounds like you have fixed the fuel flow problem but now have blocked the pilot jet

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I did remove and blow it out before I refitted everything along with the other jets and checked the two idle passages. I'll do it again...

[brownie]

What I found when I rode the bike a few weeks ago was when you rode it creating high manifold vaccum it went well off that it ran like it was extremely lean at high or low revs.
Ross

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Ross pointed me to a post from a guy (auscobul at ausvmx) on another forum who owned this very bike 2 years ago - the guy who bought it from him rode for only a few hours. I contacted auscobul and he replied

Hi Andrew,
The only thing I can suggest is that you throw the old Amal away and get a new Mikuni - I have spent months and months on my old Bultacos trying to tune old carbies and never got it right. Ever since them I have put NEW Minunis on all my Bullies and they start, idle and run beautifully.
Cheers,
Mark

[David Lahey]

Yes a Mikuni jetted properly for your 247 would be a joy to use and probably need less attention over time than the AMAL but here is a counterpoint to that story.
I have a friend who has two very nice Cota 247s
One Cota 247 has a 27mm AMAL concentric Mk1 (the standard carby for the bike)
The other Cota 247 has a VM26 transplanted from a DT175
I spent a few minutes getting the one with the standard AMAL to run right, soon after the owner replaced the wearing parts (at great expense).
I spent much longer on the one with the VM26 DT175 carby and it still does not run quite as well as I would like. I think I could get it right with a different needle, but each different shape needle costs about $60.

With patience and logic you will eventually get your 247 running like a swiss watch