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ICE180
17th October 2012, 20:02
I finally found a NX650 engine for my 400GB I was told that they bolt in
well it bolts straight into the frame which was great even the top mounts are the same
The only difference was the stator had some extra wires coming out of it......

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
so I though best to get it done right the first time

I am putting a braided brake line on the front and some decent brake pads as I might need more stopping power now

BAD DAD
19th October 2012, 21:13
Can't wait to see some pics ? Sounds interesting

cave weta
20th October 2012, 09:07
Ooooh - PM me your address- I want to see the beast- Ive owned so many bikes that Ive lost count -but My GB is the most fun road bike Ive ever had!

Road kill
20th October 2012, 10:31
So how does it go ?

ICE180
20th October 2012, 12:29
It goes really well now still some fine tuning as it is back firing when you come off the throttle will put a bigger pilot jet in the carb
it has the 650 carb on it .
The gear shaft is about 40mm shorter so we are putting the GB400 gear shaft in the engine so I can change gears while have my foot on the foot peg

the really bad part is it looks no different as the engine is the same as the 400 just a bigger bore etc

I did take it for a spin today but I think the gearing might be a it high so I will probably put a smaller front sprocket on it as I was in 2nd doing almost
95km/h and it still was trying to pull past 7000rpm.

I have the 400 CDI on it as the 650Cdi did not work .

will take some pics soon I will also do a dyno run as I have what the old 400 was putting out on a dyno to compare

ICE180
1st November 2012, 16:21
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=272520&thumb=1&d=1351743445http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=272519&thumb=1&d=1351743433

some pixs as you can see I need to sort out the gear shifter

but it fits in really nice

ICE180
3rd November 2012, 17:48
Well we ground of the welded gear leaver last night and decided to try and keep the change pattern the same 1 down and 4 up

so I pick up a Gear leaver with a complete linkage system on it from the wreckers to see if we can do this
might have to make some extra bits to attach but will keep you posted
otherwise I will have a race pattern 1 up and 4 down........

ICE180
17th November 2012, 16:17
almost done put a larger Pilot jet in 50 still too small so I drilled out the 48 to 56 as the next size up was 55

Just a matter of putting it in and testing tuning etc

The clutch was slipping so used the old fibers from the GB 400 and put new steels and springs in the NX650
fibers same part for both engines so that was handy as i have a couple spares now

ICE180
20th November 2012, 21:09
Damn the CV carbs being so temperamental The pilot jet is good but still back fires on close of throttle
pulled of the air cut of valve and had a look at it seemed OK
will look for air leaks now as I want to get it sorted so I don't feel as though I am running the engine too lean and hurting it

spent more time in the shed found that the standard GB 400 carb jets were 45 pilot and a 165 main
so I think that I will up the main jet on the carb and the pilot as well as I have added an extra 250cc to feed fuel into I might be too lean over all

the 165 main jet on the GB400 seems rather large but it must be for a reason
I had a 2 spare carbs from GB400 that i pulled apart to check jets sizes

will try a 60 /160

ICE180
23rd November 2012, 15:06
The Carb is all sorted for now minimal back firing occasionally runs a lot better sits on 100k a@3700rpm
put in a 160 main jet left the pilot at 56 and did these mods as it was the same Carb


Daves carb Mods -XR650L
http://www.4strokes.com/tech/honda/xr650lcarbmods/

Will get it onto a dyno soon to check Air Fuel mixture and power of course

ICE180
26th November 2012, 13:15
Just an Update on the CV carb


the back firing has almost gone but I think I might need to look at the needle now to get it perfect so some more tweeking to be done

I lifted the needle up some more the other day and the Back firing got worse and you could see the black fumes comming out out the exhaust so I think It was too rich
put the needle back to what it was and the black smoke out the exhaust has stopped

the black fumes happened when you blipped the throttle.

gloplg
12th December 2012, 16:07
Just an Update on the CV carb


the back firing has almost gone but I think I might need to look at the needle now to get it perfect so some more tweeking to be done

I lifted the needle up some more the other day and the Back firing got worse and you could see the black fumes comming out out the exhaust so I think It was too rich
put the needle back to what it was and the black smoke out the exhaust has stopped

the black fumes happened when you blipped the throttle.

Hi Ice. Just found this thread. Does the nx650 have a hemispherical combustion chamber as the gb does??? I am an interested GB400 owner and have sometimes wondered about re-engining my bike.

ICE180
14th December 2012, 19:40
the Carbs are the same apart from the NX carb has the semi-foced CV type with a link arm to force open the carb piston the first mms

I have 2 GB400 and this is the only difference between them ops also the Main jet holder has 3 holes round the top on the NX carb

I was still getting popping on De-acceleration after hard acceleration but under normal use and mild acceleration no popping/backfiring
put in a larger pilot jet 58 but still was happening not as much but I had black smoke coming out the exhaust unburnt fuel so I have put a 52 pilot
in no black smoke but more popping after WOT
Look at header pipes found some black soot on them so I will replace the Copper exhaust gaskets hopefully this is where the extra air has been getting in and causing the backfiring

ICE180
15th December 2012, 16:16
put in the new copper gaskets on the 52 pilot jet was too small put a 55 in it still a little to small
back to the 58 and I put a larger Main jet in 165 pulls much better at WOT fells more like it should might go 170 yet

The reason for all the jets etc is because I am running a cycle works exhaust headers and pipe its a straight through system

got taking the carb of and changing the jets down to 45 -60min now depending if any of the rubber connectors refuse to go round the carb

ICE180
18th January 2013, 16:43
well I got it on a dyno at last

https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-snc6/p480x480/230676_10151252363458883_671588578_n.jpg

went to a 50 pilot jet and a 165 main

the biggest improvements were made when we drilled so holes in the side of the air box to let the sonic wave out the air coming back into the air box was more than the 400 so it was not a happy slider in the carb sounds odd but it just worked
was running lean in the mid range so we sanded the needle down a bit to richen it up
also routed out the intake manifold to as large as we could get it .need to do the engine intake side next time i have it apart

do some other small tweaks and got 36.15hp at the rear wheel so I am happy as factory 25 years ago it was 40hp at the crank 276492
It also has 40ft Pounds of Torque so very easy to leave in 2nd gear round town
so I am happy might have to get a hot cam next

Sable
19th January 2013, 02:29
You know a big single popping on over run is not a bad thing right?

ICE180
19th January 2013, 07:52
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 :shifty:

ICE180
27th January 2013, 15:05
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
4th March 2013, 17:45
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
4th March 2013, 18:36
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
22nd January 2014, 08:48
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
22nd January 2014, 19:23
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. :eek: The bits I had to do were just an entertaining bonus.

Yamahardman
22nd January 2014, 20:03
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
22nd January 2014, 20:30
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
22nd January 2014, 20:47
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
22nd January 2014, 21:41
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
22nd January 2014, 21:48
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
22nd January 2014, 21:53
The speedo cannot be trusted.
It's pretty common to see 299+ (They stop there) on Kawasaki's that re doing 260kph.

Yamahardman
22nd January 2014, 21:58
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
23rd January 2014, 09:05
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 :(

koba
23rd January 2014, 17:37
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?

www.gearingcommander.com

ICE180
23rd January 2014, 18:17
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.

the standard Jetting on the GB400 is slightly rich from factory so it should be fine I think i went up 2 jet sizes on the pilot jet but it was too rich it stopped the popping on deceleration but i could see unburnt fuel coming out of the exhaust and the fuel economy was crap round town. that was with the GB400 engine and the open pipe like the one you are looking at

ICE180
23rd January 2014, 18:19
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......

the CRF Carbs work really well with the GB engines see if you can get 2 small ones of an old CRF