Author Topic: pilot jet quickie  (Read 835 times)

Online bsa-bill

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pilot jet quickie
« on: 06.07. 2018 15:01 »
Hi guys save my grey cells a bit of work please, getting confused about pilot jet setting or air screw, got out on the flash two nights back after a few years lay off and new rings fitted, it started first kick (actually started when I was just prodding it over to get some fuel through), a bit of work to stop a carb leak (twas that washer not needed on the filter banjo thing - DOH), and fantastic, no a whiff of smoke .
Any how off I went to give it runnout, it's been along time what with operations, sorn, domestic things to do et al...., for b oth the bike and me I might add.
So it toodled out of the square fine but opening it up it was rough for the first 1/8th 1/4 throttle,  bit worrying but on opening it up a bit it smooth out and flew, god I'd forgotten how fast these beast are, I was hanging on, closing the throttle  brought the roughness back, so I'm thinking pilot jet adjustment and got around to it today, screwing the air screw in results in it getting lumpy, screwing it out it get better but that's it it does not get weak again no matter how far you screw it out.
Don't think I can recall having this before, so simple question is this an indication pilot jet is to big or to small ? or something else ?
Should add this carb is made up from spares so possibly I got the wrong jet in there ,but have spares
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Greybeard

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Re: pilot jet quickie
« Reply #1 on: 06.07. 2018 15:14 »
Hi Bill,
I think we need to know the carb type.
Greybeard (Neil)
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A Distinguished Gentleman Riding his 1955 Plunger Golden Flash

Online bsa-bill

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Re: pilot jet quickie
« Reply #2 on: 06.07. 2018 15:33 »
oops yes would help  *smile*

Amal monoblock  stamped 389/83
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online chaterlea25

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Re: pilot jet quickie
« Reply #3 on: 06.07. 2018 15:44 »
Hi Bill,
Is the pilot jet screwed in tight before the cap is fitted
Old mono's do not have a fibre washer under the float needle jet holder (fitting this will cause rich mixture)
There are two tiny passages from the pilot circuit going to under the edge of the slide and to the engine
side of the slide, make sure they are clear

John
1961 Super Rocket
1963 RGS (ongoing)

Online bsa-bill

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Re: pilot jet quickie
« Reply #4 on: 06.07. 2018 18:01 »
Quote
(fitting this will cause rich mixture)

Thanks John
Didn't get that far, it caused constant flooding out through the tickler, took me a while to see that (shed's a bit dark compared to outside in the brilliant sunshine these days).
Looks like the carb needs to come off, will check the airways.
 
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online bsa-bill

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Re: pilot jet quickie
« Reply #5 on: 19.07. 2018 10:31 »
update
turned out to be a bit of a marathon this one.
The constant flooding turned out to be a combination of stuff, the actual flooding as such was the not need washer under the float needle housing (cured) but fuel dripped from the carb once again, this turned out to be the float chamber and the float chamber cover, float chamber is slightly off round,looks like it's had a bash on one side at some time, a sheet of glass and some wet n dry level that off but the cover still rocked when in place, placed on a good carb it still rocked so think it may have got warped when pull up to the off round flat chamber, new cover cured that one.
Guess what the carb still leaked , drips of the jet housing, this took some finding as first I suspected the float chamber again, just could not see where the hell it was coming from so made a tower of three wooden boxes and sat a cast head on then with carb on and fashioned a fuel feed to it, this allowed me to watch at eye line height, defo was the jet housing leak, changed fibre washers a few time, pulled the nut up as tight as I dare, still leaked.
Took  the jet housing and the jet block out and screwed them together out of the carb boddy and walla the jet housing was bottoming before the fibre washer could seal, it wasn't much and screwing the two together at time or two and  an extra thin paper washer under the jet block was enough, at last leak proof.
A few other issues arose,  I had been trying other parts from a known good barb to cure the various ills and whne it came to put the good carb back I noticed the needles where different lengths - which was which ???, I could have stripped the carb off my other bike but would still have been a correct needle short so got a new one, in the process I found a chart on Andy Teirens (sp) site giving info on monobloc needle  dimensions, I mention this aas it may be usefull to somebody here at some point.
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco