Engine build prep (2014)

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With all of the new bike excitement, I hope you haven't missed your appointment.
It's marked on my calendar, September 27- Dental appointment for Glen, Dyno appointment for Nigel and his Norton.

Glen
 
worntorn said:
With all of the new bike excitement, I hope you haven't missed your appointment.
It's marked on my calendar, September 27- Dental appointment for Glen, Dyno appointment for Nigel and his Norton.

Glen
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Blimey, you're a tough task master you are sir!

The day got postponed... it is now happening tomorrow (Thursday) so watch this space...!
 
I'll be checking this thread tomorrow too, working on MQ-1's 7 days a week for 12 hours a night & never leaving the base means that looking at these posts is the highlight of my day :shock:
 
Ok Ladies, here it is...

First, an apology, dyno man had a problem and couldn't read my rpm on his machine, his machine was therefore unable to show power against revs and worse, unable to show torque figures.

But all was not lost, my electronic tacho is rock steady, and I have the previous Dyno chart, so I can easily compare the two to relate the RPM / BHP relationship.

So, the headline is:

Previous best was 55.83bhp at approx 6200.

New figure, after fitting a Comstock ported RH10 head is...

64.60 at approx 6300.

That is a near 9bhp increase!!


Also:

Previously, 50bhp was reached at approx 5300rpm.

Now 50bhp is reached at 4500rpm.

There is now much more power than previous all the way from 3000rpm to 6300. Its then virtually flat through to 7500 with no drop off. I didn't go beyond that.

So, my earlier seat of the pants reports seems to have been about right, there is much more power over a far broader rev range than before having the head re-worked, and it makes its full power longer.

BTW, thats with 1 3/8 pipes, no balance pipe and peashooters. The Dyno man actually said he has never seen a carb bike with such good AF ratio figures, so the FCRs are earning their keep!

The Dyno I use is known to be very conservative. I'm sure I'd get more on another Dyno. But to get a 9bhp increase from the head work, on the same Dyno, has exceeded my expectations by a long way, so BIG thanks and respect to Jim Comstock for his knowledge and work on the head.

So power junkies... Get your emails into Jim quickly...!

Foot Note: I also tested the Maney system, bizarrely, it gave about 1/2 BHP LESS than the stock pipes! But it gave even more mid range power, even though it was running rich in the middle. It is clear than with adjusted jetting, the Maney system would give a much better 'real world' curve.
 
Congratulations on a very potent street bike! This proves that Jim is doing something right. Can you please tell something about the torque curve.
 
Kvinnhering said:
Congratulations on a very potent street bike! This proves that Jim is doing something right. Can you please tell something about the torque curve.
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Thank you!

No I can't explain much about the torque curve over and above what I explained I the 2nd / 3rd line... ie that I didn't get this data sadly.
 
Impressive results :shock: It was a good move sending the head to Jim (who is a genius) for porting. 8)
 
Excellent result Nigel. Now get out there & give it a good spanking at every opportunity!
 
Fullauto said:
What about under three grand? What shape is the curve?
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Power curve under three grand? Doesn't much matter on a Commando as long as it runs from idle to 3 k. Three thousand and up is the isolastic zone, below that is the paint shaker zone best avoided whenever possible.

The Rider's manual tells you to shift down when forced to go slow so that revs are back in the smooth zone above 3 k.

Glen
 
Very nice, Nigel. Very respectable power for a streetable 850.

Ken
 
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