Topic: 'Kerby' Honda 500 Racer.

[Doc.]

Me!

Really can't praise it enough.

It was running a little lean in the first session Saturday morning.
They kept us waiting in the holding area for too long, and it got very hot, so I switched off and got someone to push once they let us go out.
It went well enough, but I could feel it wasn't quite right.
It was either pinking, or the piston was slapping, if you tried to lug it out of a tight corner at medium revs, so I took it easy.
Owner was out in the first qualifying as soon as I came back in, so he jumped on a went out.
Did a couple of laps, then it just died on him.
He initially thought it had seized, but when we got it back to the paddock I saw there was a fair amount of water in the float bowl.
Probably from the Jerry-can we were using.
Whipped the carb off and drained it out, and squeezed the water out from the fuel 'screen' (a foam 'plug' that sits in the  fuel feed recess in base of the bowl).
I also wound the metering rod (the needle) in two turns (raising it) to richen the mixture.

Found the oil level was on minimum as well, so topped that up.

Second session it ran faultlessly, didn't get hot in the waiting area, just sat gently thumping away at a low idle, you had to keep blipping the throttle previously to stop it dying, that or wind the idle stop in.

Felt strong right from the off, and revved cleanly right through.
Tacho still wasn't working, so I was being cautious about how far I took it, but it never felt stressed, even when I got a bit carried away chasing some of the big twins 

Could probably drop the rod back a little to get it spot-on.
I've read you can do quarter turns on the adjustment, rather than just go a full 360° at a time (there's a flat on the thread for the locking grub-screw), but it doesn't seem to want to.

Other than that it was pretty-much perfect, nothing fazed it.
There are a couple of bumps/dips/uneven sections on the circuit, right on the perfect line, but it just floated over them all.
Everyone else tried to avoid them.

In one session I was trying to provoke it into doing something, giving the bars a little wiggle while hard on the brakes, just to see what it would do, but it just shrugged it off, brilliant. 

[Doc.]

. . . Tacho still wasn't working . . .

Found out why last night.
Took the Tacho apart, battery is kaput, most likely from sitting around unused for several years.
Ni-mHs do like to be used.

Just ordered a new one, £11 off ebay.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=290630833071&ssPageName=ADME:L:OC:GB:3160

[Doc.]

New battery soldered in, and it's working again 

Checked it on a friend's Bike at work before bonding the top back on, just holding the sensor wire on the HT lead, responded OK.

Now back on the Kerby and working fine.

[Doc.]

Well, Stuart (the owner) certainly has a soft spot for Singles, he's bought this little beauty now . . .



1996 Spondon SRX680.
Spondon Frame with gull arm swingarm, Integral oil tank and resevoir and spondon tank, air cooled srx 680cc single cylinder , Championship winning bike 1996, 68bhp to the wheel, with old printout (show what its capable of) tuned by parry's Cheltenham.
TZ USD front forks, TZ wheels, Keihin 'cr special' twin carbs, Ohlins rear shock, AP racing twin front brakes.

Hopefully I'll get to try it out at some point   

[scottly]

Hey Doc, are you going to put the Kerby on a dyno? I'd like to see the results with the big carb.

[Doc.]

Me too, but it's up to the owner, Stuart.
I expect the Spondon will be Dyno'd at some point.
We gave it it's first run at the weekend, at the Sywell 'Classic Pistons and Props' event.
It fired up OK, and pulled strongly until it hit the mid-range, where it hesitated and was reluctant to rev.

Checked the plug, which was sooty, so I put a new plug in, and dropped the needle in the left carb a notch, which seemed to improve it.

Will probably do it after the new cans are on though, the ones that came with it won't get past any Track-day or Race noise meter check, they're basically straight-through cans . . . lovely sound though!   

There were no noise limits at Sywell, silencing wasn't required . . . positively discouraged actually 
Nice to hear all the Race Bikes (and cars) just as their designers/builders intended 

[Doc.]

Hi, anyone still here?   

Apologies for the lack of updates since Oct, but I've had so many other things on my plate since then.

Stuart's been sorting out a new home (with garage this time), so the Bikes were put on hold (mostly).
His CB750 Racer sold at last, and a buyer came over from Belgium for the Spondon, then bottled it!   

He's decided to keep it (for now).

Spondon's had a 'softer' motor fitted, plus quieter cans, and been set-up again on a Dyno.
Fresh paint as well, will get some pics later.


We're off to Belgium again in July, to Chimay this time, should be fun.

[scottly]

I had been trying to remember who it was that had the issue with the tach plug on a honda XR/XL/FT for the last few days, Doc. I just finished swapping in a White Bros cam from an XR500 into my FT, and as the XR cam lacked the tach drive pin, I deleted the drive and used the stock XR plug. The plug is captured by the flanges on the sides, and only weighs about 10 grams. One could easily be made on a lathe. Installation would require removing the cover, which I understand would be more difficult with the Kerby frame.
 

[Doc.]

. . . Installation would require removing the cover, which I understand would be more difficult with the Kerby frame.

Thanks for the info Scottly.
The front-right bolt can't be removed completely with the Engine in the frame, but if I undid all the bolts and lifted the cover a half-inch or so, I'm sure I could fit a plug like that in easily enough.

I'll post the Dyno results when I see them, and those of the Spondon. They Dyno'd the Spondon with the original Engine and 'silencers' (loudeners more like!), and then again with the replacement Engine and quiet Cans (Arrows).

[Von Gamben]

A vest version of this bike! With Jane included.