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[dazza]

Hi all I'm after advice on my 350cc bullet I've had it now for only one month and love ridding it around I'm getting use to her another problem I'm having is especially when I go up hills I open her up and its like it's running out of fuel like splutering if I kick down gear and then accelerate she's fine and also on the flat she runs ok but now and then she's like she's missing with the accelerator fully open but the power not felling as it should the last owner has changed the airbox to an amal carb she starts fine and pulls of fine ect any ideas please thanks

[tsflyer]

Hey Dazza. Sounds to me that you're not getting enough fuel into the carb at bigger throttle openings. You mentioned carb change out. Did he do the air filter too? Stock exhaust or shorter pipe? Perhaps you would need to change the main jet to a larger size. This should always be done when altering the air intake cleaner or exhaust. Although, I'd start with just a good cleaning. Could be just a semi-clogged jet. Remove carb, float, jets, etc. Lots of info on our hosts site for that. I'm not sure of the 350cc carbs, but the 500 Mik carb has 3 jets...main, pilot and needle. Each responsible for delivering fuel for different throttle settings. I'd suspect the Main Jet, which is delivers fuel at the 3/4 throttle and up.
Good Luck!

[PeteF]

Or just lift the needle a notch might do the trick. Certainly cheaper to try.

[dazza]

Thanks for reply I looked at the exhaust it has been changed to a goldstar and the filter on the carb is s&b one looking from page 279 in2013 parts page I just tried it without the air filter on and no difference is there a way to tell what carb is fitted I see it stamped amal is there only one type that fits my 350cc 2007 bike also any good tec guys around my area south Wales valleys as my local bike shop look at my bike like an alien meanwhile I will try to send a message to the last owner to see if he changed the the main jet for a bigger one

[Riggers]

Hi Dazza - I'd say it is almost certainly the main jet which is not large enough. I'm not familiar with Amal carbs but I'm sure some of the guys on this forum are, and will offer advice on how to change the main jet.

[dazza]

Just had a look at the carb it looks like Monobloc type with two cables on the top choke and throttle ? And two air holes when I take the filter off How do you tell if it's 376 or 389 type also I have also to texed the last owner to try and find out if he changed the main jet over also if I want to try cleanlng the carb out is it just take the filter off and spray some carb cleaner in it also how much thanks

[sofiaspin]

The advice to increase main jet is sound - call hitchcocks to ask best size for a 350. Also needle should be mid point. Plus ensure air screw is 1.5 turns out. Had same issues with my 500. It is an easy fix. Air filter best removed and replaced with hosts short bellmouth.

[dazza]

Is it easy to replace the main jet thanks I also had a reply off the last owner and said that all of the mods were done before him so no record of jet change ect

[Riggers]

Hi Dazza - The difference between 376 and 389 types will be the 'choke' size (i.e the diameter of the main air/fuel passage through the carb). If you measure this it should tell you which type you have. There may also be other markings on the carb which will tell you, perhaps a call to Hitchcocks would help. Regarding cleaning your carb, it should be completely dismantled and thoroughly cleaned in petrol / carb cleaner, but this may not be necessary if it's working ok. As I said I'm not an expert on monobloc carbs but there is a diagram on page 286 of the Hitchcocks catalogue showing the carb in bits, and it looks very easy to change the main jet. Also look under "Amal Carburettors" here on the left of this web site for more information. I think you simply remove nut Number 44 (Main Jet Cover Nut) and then the main jet Number 43 can be removed. Its size should be stamped on it. Hope this helps. Tony.

[Paulk]

Dazza,

You could do worse than read the tuning notes in the technical section for the Amal concentric/monobloc (they are the sane for both carbs). For pilot air screw setting 1.5 turns out is only a starting point and the right setting can be away from there, and as said a strip and clean and check for wear is a good idea.