Where would you spend your money?

All, I have a 70 Commando that is pretty much standard except for a single Mikuni VM34 carb. I plan to take it apart to fit a crankcase breather and am considering some performance enhancements while I'm there and just wondering where the biggest bang for the buck can come from as I don't have a huge bucket of $$$ to throw at this project.

From you experience, if you had the bike apart and could change anything from the following four options, where would you priortize the spending of cash:

Performance Cam - PW3 or similar
Maney crank to replace the standard crank
Standard head rebuilt with new springs and valves
FCR 35mm carbs to replace the Mikuni

The bike runs well as it, but I think the top end is limited by the Mikuni compared to a fully worked Norton I rode recently with all the go faster Maney gear, Fullauto head and FCR 35mm carbs.

I appreciate the above improvements aren't mutually exclusive but if you had to limit your spend on one or two of the above, where is the biggest improvement to be gained for a 750cc bike?

Appreciate your thoughts.

Cheers and merry xmas.

Brakes

I took the head off of my '74 850 'just for a look' and thinking I might skim it and replace the single Mikuni.

It led to a tad more than that in the end.

So, strip with caution sir, Norton's can seriously damage your wealth.

Here's my saga:
engine-build-prep-t18461.html

Brakes are phase 2.

splatt said:

Brakes

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freefly103 wants to emulate Ettore Bugatti who said "I build my cars to go, not stop!"

Slick

Send your head to Jim Comstock for a refresh. Best bang for the buck.

Freefly, in all seriousness, a Commando is pretty much a wallet vacuum. Not much that you won't want to change.

That being said, a Maney crankshaft is pretty much what I'd consider if I were racing the bike. If this is a street bike, I wouldn't spend my money there. You don't mention your skill level, shop equipment, etc. If you are looking to have a nice, reliable, upgraded Commando, it can easily run over $10,000. Commandos are sweet when they are right, but that takes considerable time and money.

freefly103 said:

The bike runs well as it, but I think the top end is limited by the Mikuni..............

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You may have answered your own question.

Personally, I think that using everything you already have to it's fullest potential is the best first step
instead of just throwing money at it.

Obviously mandatory items are good carbs and a good ignition system.
after that.... a great tune-up to get it all working in concert and running it's best.

Only then would I consider upgrading any parts.

freefly103 said:

where the biggest bang for the buck can come from as I don't have a huge bucket of $$$ to throw at this project.

The bike runs well as it, but I think the top end is limited by the Mikuni compared to a fully worked Norton I rode recently with all the go faster Maney gear, Fullauto head and FCR 35mm carbs.

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It really depends on what you want, and how you ride. If you are $$$ constrained, as you say, then you are really not going to get off lightly with the route you have described above.

If It was my short dollars, I would spend it on three things: brakes, suspension, and better carbs. This will enable you to go faster, turn faster, stop faster. And do it in short order and relatively inexpensively (compared to a full engine tear down and performance rebuild).

swooshdave said:

Send your head to Jim Comstock for a refresh. Best bang for the buck.

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But just like installing a bigger cam - a modified head is a waste of time with a single carb.

Of course a correctly done stock head can make a big improvement over a worn out or poorly rebuilt head. Jim

The old timers all used to say to me as a lad, make it stop. make it handle, make it go, in that order. Not sure I listened much, made them go till they didn't stop mostly. Still doing it now,

Brakes for sure.

Start with electronic ignition if you don't already have one, i think you will find a pair of Amals will be better than a single Mikuni and as others have said making sure the brakes and suspension work properly will make the bike safer and a joy to ride. As others here have also pointed out many performance mods work best in concert with other things, so a camshaft replacement without a boost in compression ratio and carburettion will generally give limited or no benefit. A trick crankshaft will be stronger and give better reliability and perhaps smoother running, but a standard crankshaft dynamically balanced is also beneficial and much cheaper, but pulling the engine down to crankcases is quite a big job and expensive if you get someone else to do it.

Assuming you want to be able to keep up with the worked over Norton you rode, it's going to cost a LOT of money.

If you're not ready for that then just getting your bike running perfectly will go a long way.

Refreshen everything and only then should you start hot rodding.

brxpb said:

The old timers all used to say to me as a lad, make it stop. make it handle, make it go, in that order. Not sure I listened much, made them go till they didn't stop mostly. Still doing it now,

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I started riding motorcycles at age 15. I'm 62 now, so believe I might qualify for old timer status. Disagree with the order. Go first, handle second, stop third. If it doesn't go, no need to make it stop better.

In 1980 I did my first major work to my stock 850 Commando, I was in my early 20s didn't have lots of money to spend (but things where a lot cheaper them days) the first thing was handling, I went with a Wideline Featherbed frame ($400 at the time) next was the motor, balanced crank for the Featherbed 72% ($45) then build up my cam and regrowned to 2S cam profile ($42) new Hepolite oversize pistons and rebore (was just over a $100 I think then) new amal carbies ($81 for the pair) then rebuilt the head with new guides, kept the orginal valves, head shaved and all the ports opened up and cleaned and springs replaced, just enough to make it breath better, new exhaust headers made by a muffler shop with a mandal bender ($20 + $20 to get chromed) and open mufflers (cocktail mufflers with the baffles removed but kept the ends in place $55 the pair), a boyar ignition ($75), the Commando disc brakes worked well in them days and Akront rims ($90 each and relaced with new spokes $80 for both wheels, Koni shockies, they were the most expensive at the time ($240) but well worth it, still running them to this day but were rebuilt last year for the first time ($80 for the rebuild kit).

To this day my Norton is still running most of this set up, just over 5 years now I had to replace the crank cases (hairline fractures) but also done a few improvements, this time around replaced the front brakes with a complete Grimcia set up, Lansdown frontend interals, rebuilt the motor still running the 2S cam, abit more work to the head (still am running the orginal valves, why replace them when they are still sealing) head shaved a bit more, new PWKs carbies and one of the best upgrades I have ever brought for my Norton was to replace the ignition system with a Joe Hunt maggie, but after 40 years of ownership I am always doing things to improve it, but its been a very reliable bike in the 40 years, has never let me down (except losing a chain joining clip while giving it a handfull off the lights) after riding it this way for 35 years now I still get a big smile on my dial when ever I am out on it and it surprises a lot of moden bike riders and when the cam kicks in after 4,000 rpms thats when the fun starts.

Hope this helps.

Ashley

You could start with a leakdown tester. These can be had for under $100 and will tell you quite a lot about the condition of the engine without any dismantling. If the leakdown test is very good, you might decide to leave the engine together and just fit new twin Amal Premieres on there and maybe have a look at a modern ignition, if not already fitted.

On the other hand, a poor leakdown test tells you that motor work is needed. Lots of hissing sounds coming from the exhaust or intake lets you know there is substantial power loss occurring via valve leakage, and valve work is needed.
Air hissing out the crankcase vent tells you there is a lot of ring blow by and air leaking out the head joint means a new gasket is needed, or possibly some head studs are stripped and thread repair is needed before replacing the gasket.

If you do need to fit a new gasket, consider the inexpensive flame ring composite type. They are thinner than the thick copper type and seem to seal well. This will give you a little compression boost for free. It's not much, about a half point, but the bike will be sharper just from that.

If you can get the engine back to it's full original output, you have a 13.0 second 100 MPH quarter mile machine and that ain't bad even today.

Glen

Well, if your gonna split the cases, I'd consider some of JSMotorsports lightweight piston and longer rods. Get the crank dynamically balanced and check for the radius to remove any stress risers.

Go first, handle second, stop third. If it doesn't go, no need to make it stop better.

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There aren't many OLD riders with that philosophy.

Priority is to go fast first and then improve the brakes later. Yes, there are old pilots and bold pilots but not many old, bold pilots. I'm 50 wanting to be 25.

The bike's head was recently reworked by Jim C with new valves, springs and guides. Is there that much difference between a standard reworked Norton head compared with a FullAuto?

Still the difference between that bike the other with all the go faster Maney stuff really blew my hair back. Just wondering if the lightweight crank and twin 35mm FCRs are the real source of the difference i.e Mikuni and standard crank vs FCRs and Maney bits.

The bike is fitted with a Power Arc EI. Starts most days 3-4 kicks. Some times its a tempramental bitch and needs a dozen kicks or so. Probably my crap technique, to be fair.

Lansdowne fork internals were fitted about a year ago along with a front drum brake stiffening kit. Handling and stopping are pretty good for a drum brake bike.

I fitted with bike with new pistons and rings before refitting Jim's re-worked standard head.

Am thinking at this stage that FCRs and a Maney crank are the path forward.

Thanks for all your input. Merry Christmas all.