Forum

[mjp]

Sirs please offer some much needed help.
I have a single mono bloc 389 on a twin A65 the fuel supply is good as well as the float level. Carb is clean jets and passages are clear.
The bike will start fine when tickled and also once warmed up but dies the moment the throttle is cracked open

[simon]

Cracked open hard or just gently accelerated? Is it the original carb for the bike or a replacement? The reason for my questions relate to slide cutaway and needle height. If the bike has previously run well on the carb then its obviously a whole different shooting match.
S:)

[Mark M]

Well, not much background information in your question! As a starting point, Amal list the 1967 single carb Thunderbolt standard settings as: 389 Mono, 1&1/8", main jet 300, pilot 25, needle jet 106 (std), needle position 3, slide 3&1/2. I'd start with those settings but I suspect timing should be checked first!

REgards, Mark

[Exile]

Mark may be on to something... I'd have a look at the timing.

[Count Johnny]

I had the same issue with Slo Poke. Turned out the points had closed up a smidge.

[Alan R]

Hi -------- I'm with Mark M on this one...ie}-- Set it up AS PER THE BOOK, then test and change ONE THING AT A TIME, then test again... Sorry if I sound a bit pompous but this steady and logical approach is the best way in the end....Pretend this is a Customers bike and not your own ie}--- be HONEST with yourselfrather than emotional... and don't look for that "Easy-Fix".....At least it's the single carb. model eh ??............ PS}--- TIP.. Intermittent air leaks via a warped mounting flange or hardened gasket will play havoc with both the results AND your nerves...won't they guys ??