Hitchcocks Forum

When I open the throttle on my 2006 350, it doesn't respond instantly. Thhere's about a half second or so when it sounds like it's beginning to stall, but then picks up fine. Any ideas on improving the response?
Cheers. Jools

It sounds like a shortaged of fuel on the pilot mixture or air going in where it shouldn`t making the mixture weaker,has any work been done on the carb lately?

Float height?
There's a tech note on how to check it here.

Hi guys---------JOOLS, as per JAFFA 90--- be honest now, have you done anything at all recently involving the carb. etc ??... OR... if the answer to that was "no" then when did you last drain down and clean-out the fuel tank, pipes and carb ?? ... From your description it sounds like you might have a partial blockage in the pilot fuel jet (OR possibly in the pilot AIR drillings)----------------- On the VM24/28 carb there is a nice, large drain cap on the bottom of the float bowl.... With a suitable collection tray underneath (I use an 18/8 doggy bowl) carefully remove that cap and retain as much of the fuel that comes out.....It should be totally clear.......Water will show as globules in the bottom......Whatever carb. you have on there why not give it an early "Birthday" present and have it Ultrasonically cleaned ?? Then, as per PETE F check or re-set that float height.......

Hi Jools. I agree with all the above, but having checked all that if you still have a problem here's my 2 pennyworth. The bit of the carb controlling response just off throttle is the throttle slide cutaway. You can't adjust the cutaway but you can buy slides from our hosts with different cutaways. The lower the slide number the richer will be the mixture - and it sounds like the mixture is too weak just off tickover. Slides are not cheap so I would try richening up the pilot mixture first to see if that works (remembering the number of turns so you can put it back to where it was if it doesn't work). Good luck. Riggers.

Hi guys----------- Ah, but you CAN adjust the cut-away, but you'll need a couple of spare slides just in case you want to go back to the original slide No.------ It's an old dodge that the Amal boys might recognise ??... Basically, as RIGGERS correctly says, the lower down the slide is (hence the LESS cut-away you have) the richer ie quicker the carbs' initial response will be.....Using 1/16" (0.062") increments and a lathe, you shorten the slide by the required amount that you want to try..... BUT }---- you will also have LOWERED the needles' fixing position in relation to the carbs' main body and thus main jet, SO}--- for every 1/16" removed, you put a 1/16" packing washer UNDER the needle clip, but still keeping the needle-clip SETTING at the mid point.............Remember to "bag & Tag" for accurate record keeping.. I have a couple set-up like this...

One otthercause is an open exhaust pipe which results in insufficient back pressure or megaphoneitis - this symptom is compatible with that, which I have on my velo. Hold throttle open and it takes off!

Hi all and thanks for your responses.
The bike is a 2006 which has been off the road for the last 3, I've been bringing it back to life again and doing a respray. Can't wait to get the mot done and be back on the road. (I've been riding a deauville but it's nothing like riding the enfield) It's not a recent problem though, it was always like it. I tried to solve it before and ended up giving up. I dismantled and cleaned the carb, checked float height, fitted a richer slide, moved needle position, changed jets, begged pleaded & bribed it with silkolene... Nothing. I'm now wondering if it was ok before I changed to a free flowing exhaust (thanks sofiaspin). I've been toying with the idea of adding a baffle to it as it is pretty loud. Would be interesting to see if it makes a difference.

I suspect that if you have kept the old Micarb or whatever it is called it is completely incompatible with a free flowing exhaust. If that is the case you should upgrade to the appropriate Amal Mark 1 concentric from Hitchcocks, probably a 28mm?? They will have it jetted to suit - if they offer one with an anodised slide (which Amal now do) go for that it is much better and worth the extra dosh. I have a 30mm Amal on my 500 married to open header exhaust and triumph 6t pipe and it rips!

Jools, sounds like you need to re-jet your carb to suit the pipe. Go into the Carburettor section of the Accessory Catalogue here (on the left sidebar,) and you'll see pilot jets and slides for richer running at low throttle openings. The text describes exactly your problem and thankfully they are cheap so easy to experiment!
REgards, Mark