Hitchcocks Forum

Hi All,
Bought an electric start bullet 500 a while back. The bike hadn't been used much since new and had been stood in a garage. Only done a few hundred miles and still has the original PAV system fitted. Initially running reasonably well (no smoke from exhaust, pulled OK but sticky throttle slide and erratic tickover) except electric start was u/s. Replaced the solenoid on the starter so now turns over OK. Took the carb (Micarb VM28) to pieces, cleaned the gunk out, cleaned the jets (using a nylon "wire" from a kitchen brush so I didn't damage them), topped up the fuel tank, put everything back together. Result; difficult to start, black smoke from exhaust, no tickover and sooty plug (but throttle slide OK!) Took carb to pieces again and dismantled and cleaned out the choke and jets again. Even harder to start. No adjustments of throttle screw or air screw made any difference. Read lots of the technical advice from our hosts and the tech forum messages to see if anyone has had the same problem. Checked the obvious; fuel getting into the cylinder but spark seemed a bit weak. Replaced and regapped the points, replaced the condenser, fitted a new plug cap and replaced the plug for a new iridium one, all from Hitchcocks. Fully charged the battery. Now starts but won't tickover and adjusting the throttle and air screws makes no difference. Black smoke from exhaust and is hesitant and reluctant to pull when accelerating. Next step is to replace the rubber hoses from the air box to the carb and the carb to the manifold and replace the manifold gasket, just in case of any air leaks. Think I'll drain the fuel tank and replace with fresh petrol while I'm about it. Any suggestions as to what I may have missed or next steps to take would be much appreciated as I'm running out of ideas. If the PAV system is gunked up would this give the same symptoms?
Cheers.

Are you missing the washer under the main jet, that often gets lost when the jet is pulled out

What Norm said. I nearly forgot the little bugger when I re-jetted.

Not wanting to teach you to suck eggs, but it's been known for people unfamiliar with REs to get the choke control mixed up.
Lever down is choke on - normal running is lever up (not a choke as such - enrichment circuit) A lot of these engines will start OK without the choke which sometimes causes the confusion.

Black smoke = burning oil

"Black smoke = burning oil" Really? I've found that black smoke is more likely to be over-rich mixture, and burning oil makes more of a blue haze, or even grey. Just my experience - others may disagree!

What the other Alan says is right in my experience

Thanks for the advice. Unlikely to be burning oil as the bike has only done 250 miles from new and wasn't smoking until I dismantled the carb (so probably my fault more than the bike's). Thanks for the choke suggestion and, yes, I am running it with the lever up, not down. Good suggestion about the main jet washer; time for another dismantle to check whether I left it out by mistake. I'll let you know how I get on. Any thoughts on the PAV?

Most of us i think have dumped the PAV completely, serves no purpose.. Just block the hole in the exhaust and the pipe from the carb manifold…

Missing washer is a good shout, only other thing to check is the float height and that the float needle is stopping the fuel ok.

Theres also a spring loaded pin in the end of the needle, just make sure its not stuck in and is free to move or level will be too high.

Just another oddball cause, if the bikes been laid up in a garage and its sort of a rural setting, just strip out and check the air filter box and hoses..

It is not unknown to get a family of mice to move in and nest in the filter box.. Cut down the air somewhat.. I know just get my coat…. gwilly