Hitchcocks Forum

As per the past thread, had the bullet back together and running well, re-torqued the head and 'heath Robinson-ed' the air box assembly using inner tube till the new box to carb rubber arrives, still no sign of the mysterious disappearing old one.
Fired it up yesterday, initially ok, suddenly only runs in coke and then starts cutting out, sounds like revs picking up before it stalls suggesting leaning out soI'm guessing a fuel feed prob.
Drained the tank, stripped and cleaned the tap which seems ok though doesn't seem to be flowingV quickly, about 250ml per minute! Does anyone know what the flow rate should be?
Carb off later and check to see if all ok, it was spotless when it went back on so, not sure. Annoying stuff.

Sounds same symptoms I get when I switch off the petrol tap on my bike and let the carb run dry deliberately so it don't sit in the carb bowl for weeks between use. Maybe its just the fuel level dropping in the carb caused by the float sticking or needle valve is sticking closed causing the fuel level too drop in the carb bowl.

Its the small holes in the pilot jet blocked thats my guess had the same one morning meeting grunda and once since. Clean them and bobs yer uncle

I wonder what it is that's blocking up your pilot jet Noel?.............250ml per minute sounds awfully slow

You don't need a big fuel rate when you get around 80mpg

Right, that ones solved.
Having stripped, cleaned and refitted the tap, checked the hose and run the fuel, (just a litre in the tank to see it was flowing adequately at a low volume), it was flowing freely enough from the hose so the problem had to be flow into the float bowl.
I briefly wondered if my bodged airbox to carb inlet rubber Mk1, (old inner tube) was in some way to blame, then I realised how ludicrous this thought was, i mean, come one, since when has a good old bodge caused problems, ahem, , moving swiftly onward.
I checked all that naturally and seemed OK, took off the float bowl with carb in situ and worked the float by hand, flowing and stopping at what seemed a reasonable rate, took the float off and needle valve out just to make sure and flush through in case of a blockage, reassembled and fired it up, same again, start, idle, race, cough splutter fart, stop.
So float bowl off once more, once more checked, yep, flowing, odd, right i'll strip the float and needle valve and needle valve seat out and check for crud in there, (I knew it was unlikely anywhere else as the pilot and main are new, cleaned anb blown through and the rest of the carb has been thoroughly cleaned very recently too.
Well, it seems, for once in my mechanical meanderings, i've actually been too gently gently in my reassembly technique.
The fault was that the needle valve seat had vibrated loose, (obviously had been too careful when nipping it up) though this wasn't apparent until I started to unbolt it and discovered it was undone a few turns, this in turn meant that the needle valve was shutting the flow earlier as the seat was lower, making the level way too low and therefore running lean but if left a while it initially ran rich presumably due to the slight dribbling of fuel around the thread.
Re-assembled everything and fired and ran very nicely, warmed it through and had the colourtune on, pilot is spot on and it's a bit rich on the needle but before I fiddle with that i'll wait till the proper replacement airbox to carb rubber arrives as the inner tube bodge is very likely restricting airflow a little.

One other thing though.
While running I went through the electrical checks, 30v+ at Ammeter feed, OK, feed coming from regulator 15.7 topping out at 15.9v.
Replaced the reg with a new reg/rec unit, i'm still getting a high charge, slightly lower but about 15.5 topping out around 15.7v, tried it with another battery from my ZXR which I know to be good, same charge there?
Any ideas anyone, does anyone else get a charge across the batt terminals over 15v? or is it likely the replacement unit is faulty straight out of the packaging? (reading is same across the terminals and straight from the reg feed.

14.7 volts should be the tops. To push a battery up to 15.7 wil take a very high charge rate and boil it dry quite quickly. Are you sure your meter is reading correctly? Don't assume because it is "digital" it must be accurate. Do a direct meter comparison to check.

Pretty sure but I'll double check it against my second meter later today.

Got back from work and dug out my backup multimeter, there is a variance but only a slight one.
My main one is a Gunson Digimeter i've had for years and has been very good, (for what it cost it should be but it was bought as it has a dwell angle feature, great for checking points gap when timing and I ran a Citroen 2CV6 then which it was ideal for).

Anyway, the Gunson reads 15.29 max, at idle it's around 15.19.

The backup meter is reading 15.04 max and 15.01 at idle.

With these readings i'm assuming a faulty Reg/Rec though it's new, (from India), and am arranging a replacement.