- Joined
- May 21, 2014
- Messages
- 65

I've seen this question asked 1000 times on line, and the answer is always the same. I have a feeling I may be the only different one ...
So I worked on the '75 MkIII Norton this past winter. Lovely bike, but needed one or two things, like:
1) Heavier, longer shocks so Fay and I won't be scraping hardware so early in the turns.
2) Better, aggressive disk brake pads to improve stopping.
3) Handworking the oil pump and the pump outlet valve to stop wet-sumping without resorting to dodgy check valves or interlocks.
4) Electronic ignition to eliminate an automatic advance mechanism that worked slick when OFF the bike, but very poorly when ON the bike.
All done, so I crank the bike back up. It starts immediately and responds to the throttle, BUT will not run unless on full choke, and when the choke is open, will run only at 2000 RPM and up. Let go the throttle and it dies instantly.
We ALL know the answer to this one as the class raises their hands. The bike sat, the dodgy fuel we use clogged up the pilot jets, and so no idle.
So I got out the handy #78 drill bit mounted in a little red spray nozzle tube. I carefully removed the pilot adjustment screw, and carefully (don't want to scratch or scar anything in that little brass jet) worked it in and out of the jet, making sure it was bottoming at the end of the passage. I didn't feel or see any goop ... and sure enough, when I ran it again, nothing had changed. I held one hand on the throttle to keep it running while I sprayed the carb attachments with WD40, but no change in engine speed to indicate a leak.
So I took the carbs off and took them apart. Clean as a whistle inside, no varnish or goop. Made SURE about the pilot jet passages - the drill goes all the way to the bottom, and a squirt of carb cleaner in either end of the pilot circuit results in a strong round clean spray coming out the other end.
So, before I put the carbs back on, what might I be forgetting? I'm running up to the store in a minute for some fresh no-ethanol gas. I'm going to use new gaskets and sealer on the carb manifold. The floats are new and they're dry inside, and freely moving. The bike ran great last fall in all conditions, so there's nothing changed about the jetting or the float height. I'm going to make sure that the needle slides into the jet when I put the carb tops back on. Both pilot jets were set at 1-1/2 turns out from bottom when it was running good last fall, and that's where I'll start them.
Any Jethro Bodine-level items I might have forgotten?
Lannis
So I worked on the '75 MkIII Norton this past winter. Lovely bike, but needed one or two things, like:
1) Heavier, longer shocks so Fay and I won't be scraping hardware so early in the turns.
2) Better, aggressive disk brake pads to improve stopping.
3) Handworking the oil pump and the pump outlet valve to stop wet-sumping without resorting to dodgy check valves or interlocks.
4) Electronic ignition to eliminate an automatic advance mechanism that worked slick when OFF the bike, but very poorly when ON the bike.
All done, so I crank the bike back up. It starts immediately and responds to the throttle, BUT will not run unless on full choke, and when the choke is open, will run only at 2000 RPM and up. Let go the throttle and it dies instantly.
We ALL know the answer to this one as the class raises their hands. The bike sat, the dodgy fuel we use clogged up the pilot jets, and so no idle.
So I got out the handy #78 drill bit mounted in a little red spray nozzle tube. I carefully removed the pilot adjustment screw, and carefully (don't want to scratch or scar anything in that little brass jet) worked it in and out of the jet, making sure it was bottoming at the end of the passage. I didn't feel or see any goop ... and sure enough, when I ran it again, nothing had changed. I held one hand on the throttle to keep it running while I sprayed the carb attachments with WD40, but no change in engine speed to indicate a leak.
So I took the carbs off and took them apart. Clean as a whistle inside, no varnish or goop. Made SURE about the pilot jet passages - the drill goes all the way to the bottom, and a squirt of carb cleaner in either end of the pilot circuit results in a strong round clean spray coming out the other end.
So, before I put the carbs back on, what might I be forgetting? I'm running up to the store in a minute for some fresh no-ethanol gas. I'm going to use new gaskets and sealer on the carb manifold. The floats are new and they're dry inside, and freely moving. The bike ran great last fall in all conditions, so there's nothing changed about the jetting or the float height. I'm going to make sure that the needle slides into the jet when I put the carb tops back on. Both pilot jets were set at 1-1/2 turns out from bottom when it was running good last fall, and that's where I'll start them.
Any Jethro Bodine-level items I might have forgotten?
Lannis