HPN or Richie Moore?

[Rob Farmer]

Dust devil,

are you saying you live with the offset of they standard 1100 wheel?

to be honest when I was mocking up the 1100 back end I thought the wheel base was enormous, I'd have preferred an 1150 swinging arm.

 

[DustDevil]

Dust devil,

are you saying you live with the offset of they standard 1100 wheel?

to be honest when I was mocking up the 1100 back end I thought the wheel base was enormous, I'd have preferred an 1150 swinging arm.

Nope not at all! I am saying that the standard GS has an offset of around 5mm if I am correct and on my HPN that would have been 13mm. This is acceptable and will not have any influence on handling.
When using the drum brake diff and rear wheel of the 80/100GS the offset is small enough to ignore. ( this being fitted to the HPN modified frame that helps to compensate for this offset)
Fitting the 1100/50 diff with disc brake will require the 1100/50 hub and here offset lacing IS required.

From HPN the 1100/50 swing-arm is likely machined away on the right where the pivot bearing mounts and a spacer is welded on the inside of the frame pivot mount on the left and the motor is rotated anti clockwise in the frame using spacers.

I will post some pictures later on.

 

[Rob Farmer]

Great stuff

 

[Canuck]

I can agree with Richie on this one; reducing the valve and carb size will accelerate the flow of air through the compression chamber at lower revs, improving fuel burning and increasing the usable torque.
There is a limit to how much the airflow can be increased and still get a performance improvement due to the smaller port the air has to flow through so as the motor accelerates there will eventually be a drop off of this extra power and the motor will feel less lively at higher revs. Increasing the port sizes will allow more airflow but at lower RPM's it will be slower causing poorer burning and reducing bottom end torque.

For bottom end torque choose the 32mm Bing carbs and use the 40mm if you want top end speed.

Top answer! Makes much more sense when written in plain english!

 

[Beemerboff]

People who should know suggest that a mean air velocity of 300 ft/ sec is around what you want in the middle of the power band you intend to use.
The airhead's short stroke for a relativity slow reving 1000 cc twin therefore means it needs a smaller than average carb.
BMW fitted larger, but of course, but they are Constant Velocity carbs, which tends to even things out a bit

With a 32 mm carb WFO an 1000 cc airhead reaches 300ft/sec around 4500 revs, with 40 mm carbs around 6700 revs, 34 mm around 5000 revs, 38s 6300.

Two 32 mm carbs flow enough for around 80 hp, two 40s over 110.

So if you run between 3500/5500 revs and your motor produces less than 80 hp 32s will be fine, but if you nun between 5700/7700 revs and you motor produces 80 hp plus then you want 40s.
All things being equal , of course, and they never are, but these are baseline figures which can be adjusted for other differences in the set up.

 

[Ras Thurlo]

Moorespeed Fairing for sale:

http://www.ebay.co.uk/itm/MOORESPEE...pt=UK_Motorcycle_Parts_13&hash=item2edeac2f46

 

[Canuck]

Moorespeed Fairing for sale:

http://www.ebay.co.uk/itm/MOORESPEE...pt=UK_Motorcycle_Parts_13&hash=item2edeac2f46

Hey Ras... thats where I bought my last r100 gs frame and matching numbered engine. It was almost yours until RIchie made me keep it.