1007cc Maney motor for the road...?

Ken,

Holmeslice can elaborate on the fuel used. I think the bike had race gas as that is what was available.

I just don't have enough time on the bike to tell you much more other than first impressions - too busy with work. I mentioned the front end lifting and the rear wheel will step out on you in a heart beat with too much throttle (even at low rpm) while leaned over a bit. You will need to recalibrate your riding a bit.

As for cam selection, it depends upon what you want out of the bike. A Commando head flows fairly well so a moderate cam (say a Megacycle 560-020) would give you a good kick in the pants with lots of silly mid range torque while staying with the stock Commando cam followers. I have first hand experience with the 560-020 in my Commando race bike and that is one I would recommend. I would not recommend the N480 for long distance street use unless the riding were always up a long steep hill - both ways.

You need to look at the total package of what you want. Say a 9.5:1 compression ratio with a 560-020 will kick over differently than with a N480 grind and fuel requirements may be different. What you do have going for you is being able to get a decent amount of quench with proper pistons and chamber arrangement which should help mitigate detonation and improve burn rate.

I would carefully consider how you are going to seal up the head to the barrel as real estate is really used up on the 1,007cc. I had the pleasure of pulling the head of the Nourish 8 valve at Barber Vintage Festival a few weeks ago and appreciated the simplicity of two simple flat copper gaskets.

No worries about asking questions - fire away.

Dave Watson's 1007cc racer also used JS rods and pistons and the same sifton 460 cam profile (JS stage 3 cam & BSA cam followers) and it had 12:1 C.R. and approx .040" squish clearance without having to change or re-machine the valve pockets. It used a Maney stage 3 head with 5mm oversize intake valves and 3mm oversize ex valves. What is different with yours that it doesn't have as much compression and why would you need to cut the valve pockets? (I seem to remember something different about the combustion chamber shape.) I can give you any piston/valve pocket/compression/squish band you want but you don't hear much about anyone wanting more than 12:1 - even for racing Nortons unless unless they are on methanol. The heat gets to be a problem and there are diminishing returns with higher and higher C.R.

Dave Watsons racer below.

How many miles do you have on it now Dances with Shrapnel?

Alrighty Dances having to ALWAYs be careful with throttle opens up a lot of riding styles. May have to diddle the stance not to wheelie so easy and take more on leans. May also have to look into non DOT tires and stuff a 120 or 130 in.

jseng1 said:

What is different with yours that it doesn't have as much compression and why would you need to cut the valve pockets? (I seem to remember something different about the combustion chamber shape.)

Click to expand...

You can see the combustion chamber on http://www.accessnorton.com/head-flow-testing-t8640-180.html?hilit=head flow. I don't know for certain why we could not get the valve pockets in the pistons deeper only that the result would have left too little margin for the back of the top ring. It could have been that the head may have been milled, the larger than large intake valves, the re angling of the valves etc... It is all left to speculation at this point.

jseng1 said:

I can give you any piston/valve pocket/compression/squish band you want but you don't hear much about anyone wanting more than 12:1 - even for racing Nortons unless unless they are on methanol.

Click to expand...

I have often used around 12.6:1 as have others. This compression ratio was a recommendation by Norm White in conjunction with a re sphered combustion chamber and Herb Becker independently settled on this for the 750 USS. There's more to it than return on thermal efficiency at play as you strive to get a more compact combustion chamber for less ignition advance - always a good thing. As another data point, we were running 13.5:1 on the USS 500 (59.6mm stroke) Norton twin. And get this, it was happy on pump gas!

I have also found that the Norton big twin has a very good capacity to shed heat as I observed it during my Drouin supercharge days. The caveat is adequate clearances.

Dances with Shrapnel said:

jseng1 said:

What is different with yours that it doesn't have as much compression and why would you need to cut the valve pockets? (I seem to remember something different about the combustion chamber shape.)

Click to expand...

You can see the combustion chamber on http://www.accessnorton.com/head-flow-testing-t8640-180.html?hilit=head flow. I don't know for certain why we could not get the valve pockets in the pistons deeper only that the result would have left too little margin for the back of the top ring. It could have been that the head may have been milled, the larger than large intake valves, the re angling of the valves etc... It is all left to speculation at this point.

jseng1 said:

I can give you any piston/valve pocket/compression/squish band you want but you don't hear much about anyone wanting more than 12:1 - even for racing Nortons unless unless they are on methanol.

Click to expand...

I have often used around 12.6:1 as have others. This compression ratio was a recommendation by Norm White in conjunction with a re sphered combustion chamber and Herb Becker independently settled on this for the 750 USS. There's more to it than return on thermal efficiency at play as you strive to get a more compact combustion chamber for less ignition advance - always a good thing. As another data point, we were running 13.5:1 on the USS 500 (59.6mm stroke) Norton twin. And get this, it was happy on pump gas!

I have also found that the Norton big twin has a very good capacity to shed heat as I observed it during my Drouin supercharge days. The caveat is adequate clearances.

Click to expand...

Heat was always a problem with my racebikes - but I did most of my racing at Willow springs where it could reach 110 degrees air temp with a pavement temp of up to 140 deg.

I faintly recall something about the head in your bike having generously re-angled valves to avoid valve clash with those big valves. I've done some redesigning (lower rings) to give more distance between the top ring groove and the pocket. Also - If you can keep the head high then you can make the crown taller and raise the pockets further above the ring groove.

Jim,

Thanks for the offer to help. The lower top ring may be the remedy for this situation but I have too many other irons in the fire right now to explore it. The bike runs very well (something about tempting fate) and I want to rack up some miles on it as-is.

More to come.