My 720cc M20 started and I rode it around the neighborhood yesterday! Thanks to Ian and Ron for all the generous help and advice! It sounds like a Gold Star with 7.5-1 CR and shaved flywheels, at least to my ears.

Just not running very well.

It snaps and stalls when I open the throttle past the idle jet range. I lifted the needle 2 notches and will try again. Complicating matters is my choice of an over bored 32mm 10TT9. I'm starting with a 320 main jet and #7 slide. Do any of you chaps have experience setting up a 10TT9?

Jeff Bandola

email (option): jjbandoo@aol.com

Congratulations!

Pictures? !

Jeff,

It?
Is that what Beeza owners call their motorcycles??
Or is IT a miracle that they even run?

Regards,

Sven
p.s. Just kidding

email (option): snvosselman@gmail.com

Here's a photo of my just completed 720cc WM20. Lifting the needle 2 notches and dropping to a 310 main jet has her running sweetly indeed!

Jeff Bandola

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email (option): jjbandoo@aol.com

Jeff, i cant help with your running issue, but your bike looks great !
Cheers Stu

email (option): stuartcameron66@hotmail.com

It?
Is that what Beeza owners call their motorcycles??
Or is IT a miracle that they even run?

Neither Sven us beeza owners just shorten the Norton owners name for their bikes just take out the SH

p.s. Just kidding Dave

No derogatory comments from this Norton owner, I appreciate how much work you've put in to building your engine and it's great to have it running right, it should pull like a train and be fun to ride

What made you go with the TT carb? The problem with some of the race carbs is the low speed set up, they are either on or off.

email (option): horror@blueyonder.co.uk

With the pop-up version of Ian's 90mm piston, Goldie touring cams, 2 inch intake valve and flow work, I thought she needed a bigger carburetor than a 286. A Monobloc or a Concentric just wouldn't look right and a Mikuni would be blasphemy. Six years ago I purchased the estate of an old BSA road racer and had a box of GP and TT carbs with slides and needles on the shelf. Two of the TT's were over-bored to 32mm, which seemed about right. The 10TT9 looks like a scaled-up 276 and makes the observer do a double-take.

One of my TT carbs has a slide and cap modified to provide a throttle stop screw. It's a straight spoke cut short and rethreaded, protruding from the cap alongside the cable adjustor.

Right now the bike is over geared with an 18 tooth countershaft sprocket and 19t crank sprocket. Fitting the 2-lobe cush primary from the later B33 was tempting since I had a box of them and the 4-lobe ones were pretty ragged out. But it's not an easy swap, since the 2-lobe is longer and doesn't quite fit in the tin primary case. I did work after shaving .060 off the nut on both faces and shimming the inner primary/crank face and using 2 cover gaskets. Worth the trouble only if you can't get good spares for the 4-lobe unit.

Jury is still out on the 4-spring clutch vs the single spring original.

The crank breather is overwhelmed by the 720cc displacement and it looks like it's breathing through the primary case. That's a question for Ian. Does she need a second breather?

Jeff Bandola
Rhode Island

email (option): jjbandoo@aol.com

Hi Jeff...The bikes looking great!..I found my 'standard' 720 manages OK with the original breather...However, my 720 B33 had the same problem that you describe..

On that one I fitted another breather valve to the rocker cover which solved the problem...

There are timing covers which have the small BSA 'script' and are machined to take the breather...That would probably be the simplest solution....Ian

email (option): ian@wright52.plus.com