Honda GB500 Thumper Performance Upgrades?

**sammcj** · 23rd January 2009, 16:01

Project almost complete now.
Go to page 3 for details!

Hi All,

1987 Honda GB500 in overall good nick.

I know the first thing you're going to say... 'Get another bike...'
BUT
I really like this bike and... (I don't have the money for a sports bike! - Unless someone wants to trade heh)

I'm looking at spending upto $1000 on this bike to make it a little more unique / peppy, Is there anyone on here with ideas on what I could do / Where I could get it from (I'm in Christchurch) within my budget? (Cams, Electrical, whatever).

Or am I really, really wasting my time?

http://i66.photobucket.com/albums/h2...0/P1010774.jpg

**riffer** · 23rd January 2009, 20:58

$1000?

I seem to recall our illustrious site owner spent over $5000 on motor work alone on one of these? He did end up with a pretty damn nice GB600 though.

Here's where you can get some performance parts for a GB500.

**xwhatsit** · 23rd January 2009, 21:36

You could flog a Dominator motor from somewhere, that's a common mod -- cheaper than upgrading the original 500 motor to 600. The Dominator motor has a bit more poke, but is still a `thumper', it's relaxed and isn't very high compression. Met a guy who had a GB400 just randomly in Parnell who stopped to talk to me about my bike, he'd put a stock Dommie lump in it and was a happy chap.

I reckon the ideal would be getting a Dominator motor that's burning oil for cheap, then whack a high-compression Wiseco piston kit into it for a few hundred. You could do that under a grand?

**pritch** · 23rd January 2009, 21:45

I wouldn't mind a stock GB500, I'd use it for a communter and for cruisy rides.

One of the mechanics at the local Honda shop has a GB 400 that he uses for a round trip of some 80 Ks each day.

**piston broke** · 23rd January 2009, 21:54

overhaul the suspension and brakes

**sammcj** · 31st January 2009, 11:52

I've decided to over-bore the engine to 600, changing piston to a 100x75 I think it was, should be done in two weeks time, I'll post photos etc... Can't wait!

**sammcj** · 28th February 2009, 17:32

Just got the bike back.

Shes done 230km on the new engine so far!
Going for a ride to clockup 500-600 km if the weather is good tomorrow, then back to the shop on monday to do the tappets / carb and oil.

**Bonez** · 28th February 2009, 17:43

Good one. I've got 84,000kms up on my 400. Once the motor packs up (at over 100,000kms I hope) I'm going the NX650 engine route.

**sammcj** · 28th February 2009, 18:30

Originally Posted by Bonez

Good one. I've got 84,000kms up on my 400. Once the motor packs up (at over 100,000kms I hope) I'm going the NX650 engine route.

Oh sweet, that'll be a nice machine!
I'm quite impressed with the power gain from the 603cc bore, a lot better at 100k (@ about 4300rpm)

**piston broke** · 28th February 2009, 18:58

hey so what is the suspension like?
the reason i ask is,i rode the old mans 500 and the rear let go.
swingarm bushes e,t,c are farked

**Bonez** · 28th February 2009, 19:16

Originally Posted by piston broke

hey so what is the suspension like?
the reason i ask is,i rode the old mans 500 and the rear let go.
swingarm bushes e,t,c are farked

Swing arms probably never been greased in its life. Mine just flew though a WOF on Wednesday, inspector was a qualified m/c mechanic. Pack Gerbles on a regular basis and no problems at all. There's a grease nipple on the underside of the swingarm.

**piston broke** · 28th February 2009, 19:26

Originally Posted by Bonez

Swing arms probably never been greased in its life. Mine just flew though a WOF on Wednesday, inspector was a qualified m/c mechanic. Pack Gerbles on a regular basis and no problems at all. There's a grease nipple on the underside of the swingarm.

it would'nt suprise me if it has never been touched.
the movement in the swingarm is very noticable

it got me a beauty

**Bonez** · 28th February 2009, 20:06

Originally Posted by piston broke

it would'nt suprise me if it has never been touched.
the movement in the swingarm is very noticable

it got me a beauty

You should be able to get sintered bronze replacement bushes for them.

**sammcj** · 28th February 2009, 22:19

Originally Posted by piston broke

hey so what is the suspension like?
the reason i ask is,i rode the old mans 500 and the rear let go.
swingarm bushes e,t,c are farked

Well mine is pretty mint, I rip it up round the port hills quite a bit and it's all good!

**Paulo** · 28th February 2009, 23:23

Yes why would you want another bike? , these are sweet little machines, I 'm onto my second, sold the first and regretted it straight away so tracked down another 500. I ride it every day rain or shine, it just goes and goes and goes, Like bones said the warrants always been a breeze. Perhaps good advice about the dominator motor if you feel you need more oomph.
I just enjoy the fact that its fun to throw around the twisties and looks and sounds nice, I did put some sticky Metz tyres on and some Tomaselli clipons with a more extreme look then the stock ones. Thinking of putting them under the triple tree further down the forks if it not too much for my back.
They are getting really collectible in the states where they are considered a cult bike and they seem to hold there value. You probably know all this already. Nice to hear from another GB owner, good luck whatever you do. Yours looks great btw , I like the knee insert grips and the paint job, hang onto it i think it will only gain in value and rarity.

oops just saw your post saying you've done the motor already, Nice one! That will be one sweet bike.