Zephyr 550 -> 600 conversion

[proximity]

As some of you may know my gearbox went on the zephyr. Instead of fixing it (will do that later) i got hold of an old GPX600R to fiddle with and me and edd of this forum have decided to have a little project and we are putting that in the zephyr. Power should go from 50hp to 84hp plus it has a set of micron downpipes so a little more.

Part 1: Stripping the bikes

Zephyr when i got it:
https://homepage.ntlworld.com/jason.lovell/project/zephyr%20new.jpg

GPX after i'd stripped it down:

https://homepage.ntlworld.com/jason.lovell/project/gpx%20stripped.jpg

Zephyr stripped:
https://homepage.ntlworld.com/jason.lovell/project/zephyr%20stripped.jpg

Zephyr engine out:
https://homepage.ntlworld.com/jason.lovell/project/zephyr%20no%20engine.jpg
[/b]
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2004 Aprilia Tuono

[proximity]

Part 2: The GPX top end rebuild

Here is the GPX top end:
https://homepage.ntlworld.com/jason.lovell/project/gpx%20cams.jpg

It has 8 cam lobes and 16 valves, it uses rocker arms and screw and locknut type adjusters.
https://homepage.ntlworld.com/jason.lovell/project/gpx%20head.jpg

I took the head off first:
https://homepage.ntlworld.com/jason.lovell/project/gpx%20head%20off.jpg

Here are the barrells:
https://homepage.ntlworld.com/jason.lovell/project/gpx%20barrels.jpg

And then i spent absolutely ages lapping all the valves in and replacing the valve guide oil seals. I didnt take many pictures, here is the seat and valve during lapping:

https://homepage.ntlworld.com/jason.lovell/project/gpx%20seat.jpg
https://homepage.ntlworld.com/jason.lovell/project/gpx%20valve.jpg
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2004 Aprilia Tuono

[Kickstart]

Does it fit?

Interesting project.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[proximity]

Part 3: Mounting the GPX.

2 of the mounts lined up, the rear one i had to make a bracket.

Here is the engine mounted:

https://homepage.ntlworld.com/jason.lovell/project/gpx%20mounted.jpg
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2004 Aprilia Tuono

[Kickstart]

Hi

Wouldn't have thought that. How are you mounting the radiator? Go on, do it Benelli style under the seat to really confuse people .

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[proximity]

Part 4: The exhaust.

I bought a set of micron downpipes off ebay. They were cheap but they come out on the left hand side of the bike (wierdly) and the link pipe wont fit there.

I took a piece of bed:

https://homepage.ntlworld.com/jason.lovell/project/bed%20exhaust.jpg

Cut it up like so:

https://homepage.ntlworld.com/jason.lovell/project/exhaust%20peice.jpg

Taped it together in place:

https://homepage.ntlworld.com/jason.lovell/project/exhaust%20taped.jpg

Welded it (im not very good but its strong):

https://homepage.ntlworld.com/jason.lovell/project/exhaust%20welded.jpg

And bobs your uncle:

https://homepage.ntlworld.com/jason.lovell/project/exhaust%20finished.jpg

It looks really cool with the can on, im just paintin it and then i will take a picture of it mounted. You will be impressed

Edit heres the can on:

https://homepage.ntlworld.com/jason.lovell/project/exhaust%20done.jpg
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2004 Aprilia Tuono

[proximity]

The radiator is getting mounted up front, i am in the process of making a bracket. I have mounted the top where the oil cooler went originally, but the bottom of the radiator im still trying the think of where it can mount.

The coolant tank fits snuggly under the seat.
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2004 Aprilia Tuono

[Whosthedaddy]

Nice little project there

I take this is nt the 1st time that you've messed about with bikes. How difficult is it to have and build a hybrid bike?
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy

[proximity]

Oh yeah if you look in the pictures above you can just see i put the GPX front end on aswell, with both 16" wheels and calipers.

When i got it, it had a GPZ front end which was crap and the original rear which meant it had an 18" rear and 16" front and crap single piston calipers.
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2004 Aprilia Tuono

[proximity]

This isnt the first time ive messed about i always make little modifications but its the first time for all the big bits, for example ive never done a top end rebuild or swapped an engine before.
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2004 Aprilia Tuono

[proximity]

[edd]

[proximity]

Mine were too shit to warrant a picture.
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2004 Aprilia Tuono

[chalky143]

looks good...nice bike u got there in the fist place good luck
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Current bike :: sv650 minitwin race bike
Previous bikes::cbr600 steelie race bike, 1989 Honda vfr750f, 2013 Honda fireblade, 2013 Ducati multistrata 1200s, 2012 Triumph street triple R, 1999 yamaha r6, vfr 800, ducati 600ss, vfr 400x2, ntv 650, bandit 600, cagiva mito 125, aprilia rs 50, honda c90x2, honda hornet 600x2, cbr 600, aprilia rx50, suzuki katana
My bike pics: https://www.bikepics.com/members/chalky143/

[colin1]

part bike, part bed
cool
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colin1 is officially faster than god

[proximity]

Its now got a removeable baffle made from part of a VW polo silencer to go with the race can.
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2004 Aprilia Tuono

[edd]

have you finished the baffle?
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[proximity]

Almost, it just needs shortening and then the cover pipe welding on, 5 mins jobby. The radiator is mounted too.
I primered the rear wheel then ran out of paint. I need to get some from derrick wards.

All thats left is the can hanger then VROOM.

Heres an updated pic:

https://homepage.ntlworld.com/jason.lovell/project/zeph%20almost.jpg
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2004 Aprilia Tuono

[DaveH]

Looking good

The disembodied hand as a radiator hanger is a nice touch

[Whosthedaddy]

A stumpy can is a must, its far too long

Its looking good so far
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy

[zephyrgirl]

Hi there, I just realised that you are also on Zephyr Zone!

Saw your pics on there ages ago, but only just found this thread on here!

Great project, well done!


PS I'm Vikki Mc on ZZ.
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Fly away on my Zephyr?
I bloody wish.

[edd]

Im on zephyr zone too, Im edd on there as well.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[proximity]

Hey edd its finished pretty much. Im just waiting for some gasket sealant to dry so i can start it.

The only thing im having trouble with is the coolant tank pipes and where they go.

I think the bottom tank pipe goes to where the radiator cap is (highest point to fill up), and then the top pipe can be an overflow, but there is a pipe left just at the top of the engine where the other coolant outlets are. It is lower than the radiator cap.
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2004 Aprilia Tuono

[edd]

hmm... Ill come round tomorrow unless you are working and give you a hand.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[proximity]

Well its done.
All connected up now. Thing is, the coolant tank must drain into the system somewhere right, but it needs to be higher than the rest. Problem with this is, you cant open the radiator cap because water will pour out.

How do other bikes work?
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2004 Aprilia Tuono