xbr power / torque graph

[Propellor]

What do you know about 250rs tuning?
Cheers

There was a guy that used to race a Yoshi tuned 305cc RS back in the day, it did well against the FT/XL engine specials, it was primarily a big-bore kit, cam and bigger carb with a little head work. Dixon Racing used to sell the kits over here and White Bros. in the US used to sell a lot of XL tuning parts that fitted.

Thank you.

[JOOLZ]

What do you know about 250rs tuning?
Cheers

There was a guy that used to race a Yoshi tuned 305cc RS back in the day, it did well against the FT/XL engine specials, it was primarily a big-bore kit, cam and bigger carb with a little head work. Dixon Racing used to sell the kits over here and White Bros. in the US used to sell a lot of XL tuning parts that fitted.

Dixon Racing, That brings back some memories, I did some work for them many years ago, still got a sew on patch from them somewhere around

[welland99]

I should still have a bunch of dyno runs but they would be on a floppy disc somewhere and I don't have a FDD anymore. I know that I did have some RPM/BHP plots but I wasn't that fussed by overall numbers I was just looking for more than I got before. The most bhp I got was with a Kent Cam but it was too peaky for the stock gearbox and lost too much power out of a corner on a twisty track.
For road use the best mod that I did was to replace the HRC exhaust with a Micron, I lost a lot of power at the top end but gained a massive amount at mid-RPM, I would say that it was much faster 99% of the time.

Wow, My XBR has a 2 into 1 micron exhaust.    I wonder how this has affected the power / torque compared with the standard Honda system?  I tried to find a Micron website to see what the say, but I found nothing. 

What does HRC stand for; is it jst another exhaust manufacurer?

[tj63]

You won't find a Micron website - they went bust a few years ago.

The only HRC I know is Honda Racing Corporation.

[guest564]

HRC= Honda Racing Corporation. HRC used to make the RS600 engine which was a works version of the XL/XR engine. Back in 1985 someone, I forget who, bought one and it came with the dimensions for the exhaust, Tony Cook (AC exhausts) used to make replicas.

Back in 1986 you could also order the HRC camshaft through your Honda dealer if you had the correct part number - it took a long time to arrive and was very expensive! Few other parts fitted as the works engines used an 80mm stroke crankshaft similar to the XL600LM

[guest564]

Somewhere I have a couple of old mags with dyno plots and they both show around 32bhp at the rear wheel so I don't think the press bikes were tweaked. This was mine with an HRC cam and exhaust:



Unfortunately it shows MPH rather than RPM. I've no idea what gearing it was on that day, I would guess its a fourth gear run.

I can't see the image now, is it just me?

[Propellor]

Somewhere I have a couple of old mags with dyno plots and they both show around 32bhp at the rear wheel so I don't think the press bikes were tweaked. This was mine with an HRC cam and exhaust:



Unfortunately it shows MPH rather than RPM. I've no idea what gearing it was on that day, I would guess its a fourth gear run.

I can't see the image now, is it just me?

I can see it fine (i pad).

[guest564]

Its back, the website dropped out for a while.