HP & Torque Thoughts

[Paul in NZ]

One of my favourite bikes ever is a mate of my dads MKI, full Stuchi (?) fairing, lump of 6X4 as an excuse for a seat. Open megaphones....

Lovely!

Wasn't that for sale recently?

Not sure but I'm sure I saw that on bikepoint????

Paul N

[White trash]

Wasn't that for sale recently?

Not sure but I'm sure I saw that on bikepoint????

Paul N

Can't imagine Pete ever selling it but maybe.

I hope not, I loved that thing. Used to blag a ride on the not so comfortable pillion seat every chance I got. The old man thought I was mental getting of a cushy GS thou' S seat onto that.

[Mongoose]

One of my favourite bikes ever is a mate of my dads MKI, full Stuchi (?) fairing, lump of 6X4 as an excuse for a seat. Open megaphones....

Lovely!

That must have been the delux export only model that came equipt with the 6x4 seat

[Paul in NZ]

Yes, I was suspicious too..

Mine has the std factory 2 x 4 petrified rubber building block with the square edges... What were they thinking??

Mind you.... bang it into a corner and whack it down through the gears and listen to the whine of the straight cut gears under the basso profundo note for the (ha ha) mufflers and all thoughts of sore bottoms disappear...

Cheers

[F5 Dave]

Zed, back to the thread. Before & after runs are good idea. I’ve done a million runs on my racebikes to determine whether the mods I’ve done are a good thing. Many non intuitive things have shown up. Carbs that are too big have produced more midrange than smaller carbs. Mid size ones have been worse than both. Didn’t ness feel like this on the track.

On my 750 putting on a K&N replacement (in airbox) filter made it lean on top. Maybe it felt a little less rampant after 10,000rpm. Turns out I’d lost over 10hp! Hard to tell on the road. Put some bigger jets until it got worse & then back to best position & the curve overlayed with the original pre K&N, so it had improved breathing but wasn’t the restriction. Removing airbox restrictions can liberate or lose significant power.

Obviously use the same dyno. Dynojets for any failings are the std you can compare with what you may read in mags. A couple of shops in wgtn have special Harley or Ducati friendly dynos that give the ‘right’ numbers , & that’s cool but you have to apply a conversion factor to the readings.

Manufacturers claim crankshaft horsepower, which is probably 25% higher than what you’d get at the rear wheel. Just use the same dyno (preferably in similar weather/pressure conditions) & at least your horses will be the same breed.

[speedpro]

I just had to have a look to see what F5 could possibly be contributing to a discussion about horsepower and "torque". Just thinking back to his RG50 powerbands as recorded on the dyno -

[Motu]

Just a note about K&N air filters that we all fit for performance (me included) the filter part of the name is just that,a word.Do an oil analysis before and after,they pull heaps of crap into your motor - who cares for racing,who cares if you're going to sell it,but if it's a keeper,dump the K&N.

[F5 Dave]

I just had to have a look to see what F5 could possibly be contributing to a discussion about horsepower and "torque". Just thinking back to his RG50 powerbands as recorded on the dyno -

Hey! it has lots of torque. Just in a very limited rpm range. . .

[Mongoose]

Lowest rerading on a print-out I have ever seen was 1.5hp and yes it was a motorbike.

[F5 Dave]

They put a bicycle on the dyno & we all had a go. Man it was sad. What was scary was Anstey’s attempt.

Low reading from a 250 was when we put on a Beta Trials bike at about 10hp. & yes my 50 would whup that quite easily.

[speedpro]

Lowest rerading on a print-out I have ever seen was 1.5hp and yes it was a motorbike.

Sounds like F5's RG50 below 18,786 rpm. From there to 19,000rpm though it was a real mean machine. I recall that Anstey actually managed more horsepower than F5's 50 below the aforementioned 18,786 rpm. Wasn't it over a horsepower??

[geoffm]

Zed, back to the thread. Before & after runs are good idea. I’ve done a million runs on my racebikes to determine whether the mods I’ve done are a good thing. Many non intuitive things have shown up. Carbs that are too big have produced more midrange than smaller carbs. Mid size ones have been worse than both. Didn’t ness feel like this on the track.

On my 750 putting on a K&N replacement (in airbox) filter made it lean on top. Maybe it felt a little less rampant after 10,000rpm. Turns out I’d lost over 10hp! Hard to tell on the road. Put some bigger jets until it got worse & then back to best position & the curve overlayed with the original pre K&N, so it had improved breathing but wasn’t the restriction. Removing airbox restrictions can liberate or lose significant power.

Obviously use the same dyno. Dynojets for any failings are the std you can compare with what you may read in mags. A couple of shops in wgtn have special Harley or Ducati friendly dynos that give the ‘right’ numbers , & that’s cool but you have to apply a conversion factor to the readings.

Manufacturers claim crankshaft horsepower, which is probably 25% higher than what you’d get at the rear wheel. Just use the same dyno (preferably in similar weather/pressure conditions) & at least your horses will be the same breed.

There are conversion factors. the great thing about standards is that there are so many to choose from...
Dynojet generally use SAE, being US based. Others are DIN and JIS. they are all slightly different. It also depends on where they are taking the readings from.

I have found Dynojet (and some other inertia dynos) tend to read a bit high when compared to brake dynos, like the old Heenan and Froude DPX2 I had for a while. There are a number of reasons.

It is interesting playing with dynos. On the FZR, an old beaten up Formula 1 can gave a consistant 1-1.5hp more than a shiny new Pipemasters can. Intake stack lengths made a difference, but the best one on the dyno didn't work on the track
The dyno is at http://pages.quicksilver.net.nz/geoffm/

If I can get some time to work on it, and get it running reliably and consistantly, we will have a KB dyno day at the end of the year or Jan next year (depending on the thesis research timetable). Everyone will have to sign a really bulltproof disclaimer tho.
Geoff

[Wonko]

. Everyone will have to sign a really bulltproof disclaimer tho.
Geoff

"I will not hold Geoff liable for any damages, and will slide a box of beer his way, as long as my bike dyno's at least 25 HP higher than anyone elses"