Commando racer rebirth

Greetings to fellow commandoers!
Seeing as how I have been lurking on this brilliant forum trying to glean what info and experiences other Commando enthusiasts have to offer I may as well give an insight into my current project of ressurecting my commando racer that I campaigned for a few years till the crank shaft failed. I would welcome any comments or suggestions from more learned member of the forum.
Freddy.
here are some snaps of her being used in anger in her last incarnation as a 750.




here is a pic of the crank shaft that I built and campaigned with good results for four seasons



it developed a crack through the pri side journal but did not fail disastrously as I detected an odd vibration that I did not like and shut her down

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G'day Fred, thanks for more broken Norton prono shots. I know little but do recognize strained hard tire patches, cool!

Steve hobot Shiver
N. W. Arkansas.

Racing in the post classic division (1968 - 1972) we are able to run these bikes on methanol, this really makes a commando bark!
The 750 I was running was built for the strength needed to cope with 12 - 1 compression, steel flywheel, reinforced crank cases and through bolted barrels.
It had a 4s camshaft, lightened followers, polished and lightned rocker arms, some nice high comp venolia pistons, and a pair of 36 mm mikunis, blair style two into one and short mega phone with vestigal silencer, using a bob newby belt drive and alloy clutch set up.





The reading off Phill taintons dyno showed she had 65 rear wheel horsepower at 7500 rpm not too shabby for a 750!

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Methanol- makes Commando's Bark. My mouth is hurting from grinning on that sensation. Await you getting that tire ripping power going again. Ride safe eh.

The plan now is to rebirth her as a 920!
I have recently taken delivery of Steve maney alloy 920 barrels and pistons, a Maney crank, I have had a set of MAP rods in stock for a few years and plan to add these items to an 850 crank case and head that was used in a motocross sidecar out fit.





as you can see I have done a job on the primary side case to strengthen her a bit. That is a flange I made up to be a shrink on fit over the bearing spigot shrunk on and with the aid of Devcon alluminium epoxy and six button head cap screws.
One of the motors I built before had the flange welded on but this gave me problems with shrinkage that I had to remachine the bearing bores, this solution has no distortion factor, how well it will last remains to be seen.
also you will note the breather arrangement off the back of the cases. The sidecar boys had machined a hole to take a Joe Hunt magneto so I have made up a reed valve arrangment to breathe the crank case via a short length of pipe to one of the holes inside the timing cover, an idea I got off one of the forum regulars, bewolfie i think thanks.



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fredful said:

I have made up a reed valve arrangment to breathe the crank case via a short length of pipe to one of the holes inside the timing cover, an idea I got off one of the forum regulars, bewolfie i think thanks.

Click to expand...

Ludwig did that, just giving credit where it is due, to go a bit further, the whole idea was from Jim Comstock aka commoz.

Great job on the bike BTW

Jean

Now a question.
I have a set of new old stock cam followers that i have had on the shelf for some time, these have the trademark Wassel on them and installation notes refer to lapping them in before use. and its obvious they are not going to fit in the maney barrels as is.
Does any one know or have experience of doing this?

Jeandr said:

fredful said:

I have made up a reed valve arrangment to breathe the crank case via a short length of pipe to one of the holes inside the timing cover, an idea I got off one of the forum regulars, bewolfie i think thanks.

Click to expand...

Ludwig did that, just giving credit where it is due, to go a bit further, the whole idea was from Jim Comstock aka commoz.

Great job on the bike BTW

Jean

Click to expand...

Thanks Ludwig!

I'm a bit jealous of those lovely Cam followers Fred, why dont you get some nice "Race" ones from somewhere and send those over to me. I need some real bad... (Compound fracture of the Crankcase).

Gday Fredful, mmmm.... some lovely goodies and ideas in that Norton build, Maney barrels and 920 pots to boot. Wish I had gone down that path with my motor and spent an extra $150 on top of purchasing an RGM 920 kit plus machining & fitting, I would have had the benefit of the lighter alloy barells and Maney bits bragging rights.

On the subject of cam followers, have you checked out Jim Schmidts BSA style bronze lifter blocks for Nortons? They're a good design and at $150 not badly priced considering what you have already invested. http://www.jsmotorsport.com/products.asp

Over this past week theres been some good threads starting up, yours included!
Foxy

fredful said:

...head that was used in a motocross sidecar out fit.

Click to expand...

Hmmmmmm....

Did you use my starter rollers when I met you at Bonneville in 2008?



Welcome to the forum, many of us are looking forward to commenting on your project from the peanut gallery.

P.S. If the cam followers are oversize, the fitment is completed by honing out the bores in the cylinder to spec clearance.

Hi

Well done Fred. The more the merrier. Building up a Rickman 750 for a friend to use this season.

all the best Chris

Fred you do very pretty and functional modifications, good to the bone!
The other weak place in the DS case is the gap between rear upper through bolt and the next one down. A plate is welded across those. I did mine with a plate on both sides that I then put a hole through to add 11th clamp bolt right where they tend to weep oil.

Deer and big animals knock me down too often so I've really looked into side car designs and handling methods both civialized legal to the racer drifts, both on and off tarmac.

Might consider cryogenic tempering of the highest stress items, lifters and cam, crank and even the bearings. Dry friction coatings do work detectable in response and temperatures for a season or 3 then tend to wear off.

My main fascination is handling limits. Any of that you ran into I'm all ears to understand it through your experience.

On the subject of cam followers, have you checked out Jim Schmidts BSA style bronze lifter blocks for Nortons? They're a good design and at $150 not badly priced considering what you have already invested. http://www.jsmotorsport.com/products.asp

Thanks Foxy !
I only wish I had looked over Jim Shmitts products before ordering the MAP rods and js pistons as I realy like the look of the longer carillo rod and piston set up, and those lifters and beehive springs look the goods as well, Jim is obviously a guy who has put a great deal of thought and pride into his gear and maybe as I progress and if the budget allows they will be on my shopping list.

My main fascination is handling limits. Any of that you ran into I'm all ears to understand it through your experience.

Thanks for your comments hobot !
In regards to handling mods I have tried a few different things with varying levels success.
First is a isolastic type top head steady, then 18" wheels, wm2 front and wm3 on the rear mainly for the better choice of tyres, the immediate result though was running wide into the turns.
The Quick fix was to make some 1" extension peices for the rear shocks, lifting the rear end thereby reducing the the rake of the front end.
This alleviated the running wide problem but was a compromise at best.
The next thing I tried was lower triple clamps top and bottom, ajusted with the aid of heat so I could slide the forks through them to lower the ride height, again reducing the effective rake, this wasnt too bad but still a compromise.
The best thing I did was to make a set of triple clamps to the offset dimensions of 47mm as compared to the stock items 70 odd with the weird angle difference between the fork tubes and the steering stem. I used a bit of aircraft alloy and machined them to keep the look of the orignals as eligibility regs here frown on this sort of thing.
This was the best mod yet as the result is a very balanced handling bike with quick steering, fantastic on the tighter circuits though a bit unstable at speed on the faster tracks like Phillip Island, but nothing a good steering damper cant controll and not bad enough to encourage me to slip the forks back down again!









sorry about all the dust guys but she has been sitting idle since 2006

grandpaul said:

fredful said:

...head that was used in a motocross sidecar out fit.

Click to expand...

Hmmmmmm....

Did you use my starter rollers when I met you at Bonneville in 2008?

Welcome to the forum, many of us are looking forward to commenting on your project from the peanut gallery.

P.S. If the cam followers are oversize, the fitment is completed by honing out the bores in the cylinder to spec clearance.

Click to expand...

I will certainly need those starter rollers next time I am in town!

So that WAS you?

I had so much fun, I'm STILL smiling!

Sorry Paul
I have been to Bonneville in spirit only, Maybe I could do a pilgramage trip there one day.

grandpaul said:

So that WAS you?

I had so much fun, I'm STILL smiling!

Click to expand...

Rebirth update.
Well after checking finances with the Leader of the Opposition, (Missus) It was decided to dip a bit deeper into the slush fund to purchase some Items from Jim Schmitt, specifically carillo rods, lightweight pistons, and stage 2 radius camshaft with the sexy lightweight followers, consequently this will put the build back a month or so but it should be well worth the wait.
Now what are the chances if I butter her up a bit we may be able to look at a TT industries gearbox? Questions Questions ?

Nice stuff. Should make for a very zippy lump.