Commando attack at Mallory

jseng1 · Jul 12, 2015

Ideas?

You've got enough carburation but free breathing pipes will help a lot and this is what holds down your top end. If you already have 1-1/2 headers and 1-1/2" bore RPM type silencers then the next step is racing megas lined with 1/4" hardware cloth and woven roving fiberglass with 1-5/8 headers. Ron Wood could get 84 HP with that cam so you are looking at porting, big valves, longer manifolds/velocity stacks etc. Its a gorgeous bike and looks very street worthy, I wouldn't go beyond a stage 2 cam for combo street usage.

Fast Eddie · Jul 12, 2015

Interestingly Jim, I have tried some megas and 70mm long velocity stacks, both seemed to add some top end, but not much, but both caused significant problems in the bottom end of the revs, so although the tests were far from properly scientific, I think they are ruled out for street use.

I have some short stacks to try, plus a set of linked headers, plus a full Maney system. I intending to Dyno this lot soon.

Steve, clearly the head is a bottle neck right now. If I had a cracked RH4, then a FA would be obvious, but as I have a perfect RH10, it is not so obvious! The performance difference between a Comnoz ported FA and a Comnoz ported RH10 seems to not be a lot. But the cost difference is.

Many people tell me the current JS1 cam is the best option. But a JS2 is still an option for more power.

But, as Rohan says, it would be really nice to do a back to back Dyno comparison of only a head change.

We'll see...

worntorn · Jul 12, 2015

Fast Eddie said:
But, as Rohan says, it would be really nice to do a back to back Dyno comparison of only a head change.

We'll see...

Uh oh, I'm must be starting to sound like Rohan. Hanging around this site too much I guess :mrgreen:

Glen

Fast Eddie · Jul 12, 2015

worntorn said:
Fast Eddie said:

But, as Rohan says, it would be really nice to do a back to back Dyno comparison of only a head change.

We'll see...

Click to expand...

Uh oh, I'm must be starting to sound like Rohan. Hanging around this site too much I guess :mrgreen:

Glen

Oops, sorry Glen!

Fullauto · Jul 12, 2015

Fast Eddie said:
Fullauto said:

I know this guy........

Click to expand...

Any ETA on your new alloy barrels yet sir...?

Nope. Before I die I hope.

jseng1 · Jul 13, 2015

Fast Eddie said:
Interestingly Jim, I have tried some megas and 70mm long velocity stacks, both seemed to add some top end, but not much, but both caused significant problems in the bottom end of the revs, so although the tests were far from properly scientific, I think they are ruled out for street use.

I have some short stacks to try, plus a set of linked headers, plus a full Maney system. I intending to Dyno this lot soon.

Steve, clearly the head is a bottle neck right now. If I had a cracked RH4, then a FA would be obvious, but as I have a perfect RH10, it is not so obvious! The performance difference between a Comnoz ported FA and a Comnoz ported RH10 seems to not be a lot. But the cost difference is.

Many people tell me the current JS1 cam is the best option. But a JS2 is still an option for more power.

But, as Rohan says, it would be really nice to do a back to back Dyno comparison of only a head change.

We'll see...

It may be impracticable because of space restrictions but approx 10" from the head to the end of the velo stack is what Ron Wood, Axtell and Leo Goff found to work the best. I don't know how this would work on the street.

john robert bould · Jul 13, 2015

Fullauto said:
Fast Eddie said:

Fullauto said:

I know this guy........

Click to expand...

Any ETA on your new alloy barrels yet sir...?

Click to expand...

Nope. Before I die I hope.

Better be quick, i have just had the mat snatched from under me!...... :twisted:

SteveA · Jul 14, 2015

jseng1 said:
It may be impracticable because of space restrictions but approx 10" from the head to the end of the velo stack is what Ron Wood, Axtell and Leo Goff found to work the best. I don't know how this would work on the street.

Seems to be working fine in my Rickman frame, straight run too, but I don't see how you will do it in a Commando frame without a lot of other compromises....

Bernhard · Jul 14, 2015

re; "Any ideas...?"

there have been eariler posts, I would dial in the camshaft with a degree disc to check that ALL four lobes are in the correct place.................
aso;
inlet-manifolds-t14099.html

jseng1 · Jul 16, 2015

To put loooong intake manifolds on a Commando (10" from head to end or velo stack) you have to cut out the frame web and make a new oil tank. The photo below shows a bike I built for Rod Hurick in the 1980s. The frame web was cut and an alloy oil tank was fabricated. Carbs were Dellorto supplied by Ron Wood. JS Box section swing arm and pipes etc. Alum engine cradle. Axtell cam. The return oil line dumped into the backbone to serve as an oil cooler.

When test riding this bike I remember it having a wide and even powerband.

acotrel · Jul 16, 2015

All the cams, head mods, changes to intake length pale into insignificance if the exhaust system is not right.

Commando attack at Mallory

Similar threads