Honda GB400 now GB650

[Sable]

You know a big single popping on over run is not a bad thing right?

[ICE180]

now i do
I just wanted to make sure it was not running lean

but its a tad loud when leaving for work at 600am the De acceleration back pop

[ICE180]

Done 3 good long runs now it goes way better no odd engine staggering when at constant throttle for a period of time…
Getting 55MPG or 5L/100KM so much better economy

Having lots of fun on it need to sort out gear shifter to a better set up eventually
The dyno tune was the best thing for it

[durp]

This is awesome. Good work. I was trying to get a hold of the same motor when my gb400 seized. Just ended up buying a donor gb400.

Keep up the progress, and get some good pics!

[ICE180]

all I have done now is ride it but over winter I will look at sorting the small things out

Its to much fun not to did 480kms on Saturday and still thumping strong

[SteveNZ]

Looking at putting one of the Cycleworks pipes on my GB as part of the "tidy up" project (a restoration of sorts but replacing sub-par parts with near-enough identical looking better replacements). I've stripped the carb, giving it a good clean and replacing the float valve which oddly had corrosion on it, it still splutters at low revs so think there's an air leak somewhere I need to sort out first, but you reckon that it'll run ok with the standard jets with one of these pipes like Damon @ Cycleworks reckons? The thing is so economical that I'm not too worried about losing a bit of the economy if it gains an hp or two and/or improves reliability.

[vifferman]

I did cheat and get the shop to do it as I would have possible stuffed it up and had to get them to sort out my stuff ups

I cheated even more - my bro-in-law at the time gave me a CB250RS with an XR500 engine shoehorned into it. All I had to do was help him paint his roof and put up some new guttering.
Actually... not quite that simple; my uncle who was a tutor at Waikato Polytech at the time got his students to give the head a valvegrind, while I painted stuff (tank, guards, Cycleworks pipes, etc.), fitted new tyres and chain, re-jetted the carb and stuff. Still a cheap bike though, and a wheeliemonster. The bits I had to do were just an entertaining bonus.

[Yamahardman]

My 600 runs outta puff after 5k, pulls hard between 3k and 4k. gb400 bottom end xr500 head and xr600 barrel. gb500 carb with manifold for the twin inlets on the xr head. Thinking about changing it to twin carb though......

[koba]

My 600 runs outta puff after 5k, pulls hard between 3k and 4k. gb400 bottom end xr500 head and xr600 barrel. gb500 carb with manifold for the twin inlets on the xr head. Thinking about changing it to twin carb though......

Ever Dyno'd it or run it in anything measurable?
I'm curious to see how warmed GB's go.

[Yamahardman]

Ever Dyno'd it or run it in anything measurable?
I'm curious to see how warmed GB's go.

yeah its been run in, and i think the jetting is pretty spot on. it just really goes in that powerband. it can do the ton, and it's quick through winding roads. Got sweet power out of corners and good engine braking into them. Paradise valley road is one sweet road, probably my favourite, to be honest.
I haven't bothered dyno'ing it, it's expensive, and it wont have huge hp figures, so i'm not overly bothered about it.

http://www.youtube.com/watch?v=sKaggeljrxc
^^^ paradise valley road on a gixxer. (not me, lol)

[koba]

yeah its been run in, and i think the jetting is pretty spot on. it just really goes in that powerband. it can do the ton, and it's quick through winding roads. Got sweet power out of corners and good engine braking into them. Paradise valley road is one sweet road, probably my favourite, to be honest.
I haven't bothered dyno'ing it, it's expensive, and it wont have huge hp figures, so i'm not overly bothered about it.

http://www.youtube.com/watch?v=sKaggeljrxc
^^^ paradise valley road on a gixxer. (not me, lol)

Surely a standard GB would squeak in over the ton? If only just?

[Yamahardman]

im not sure if they can on the standard sprocket sets. mind you, i was doing 160 on my speedo and pulling 7k, and my mate beside me on his vfr reckoned we were doing 185, so im not sure, i know my speedo under reads, a bit, but not as bad as that though...

[koba]

The speedo cannot be trusted.
It's pretty common to see 299+ (They stop there) on Kawasaki's that re doing 260kph.

[Yamahardman]

ive been through one of those things that say how fast youre going, and at 4000rpm im doing 100km/ph but my speedo reads 90km/ph so wouldn't 170km/ph be around the 7000rpm mark?

[SteveNZ]

I've managed to get a GB400 to an actual 163Km/hr on a GPS, as far as I know it was totally stock. Speedo said it was doing ~180. (Redlined, ducked down behind the fairing on a MK2, on a slight downhill slope, way back when I wasn't a huge fatty).

Still got overtaken by the Harley though