1981 Kawasaki GPz550: Restoration

[Guest]

One of these days I'm going to have to get one of these. After seeing yours Todd I've had a real itching to have one. We don't see them up for sale very often around these parts, it's probably the same everywhere I guess. Not sure what their production numbers were like back in the day.

 

[srsupertrap]

Is that and M E oriented logo?
Could be Moriwaki Engineering.

What do you think? I think we have an answer . . .

I also sent a picture to Escondido Cycle Center in CA. which is a Moriwaki importer. Scott said he would forward the picture to Moriwaki Japan to verify.

Another picture

PS: They never replied . . .

 

[JEEPRUSTY]

excllnt we have a winer
that is the bike of my dreams I recall 30 some yrs ago the articles for hopping up these lil bikes.

First gen 550 gpz is the bike of my dreams.
It probably the only mc that I would go without lunch for

 

[Big T]

One of these days I'm going to have to get one of these. After seeing yours Todd I've had a real itching to have one. We don't see them up for sale very often around these parts, it's probably the same everywhere I guess. Not sure what their production numbers were like back in the day.

Rob,

They sold thousands of them over the years

They were very popular, especially with racers and canyon racers, as the 81 was ground breaking machine. As a result, most were crashed/blown up. I know of 2 others locally

The 82-85 unitrack models are more common as the became less competitive as racers with the rise of the 500 Interceptor and 550 Seca

 

[JEEPRUSTY]

To say noting of the uber powerful and sublime gs550e 83 onwards.

 

[srsupertrap]

Thanks JeepRusty

Guys, I need the Moriwaki cam valve lash specification also. If anyone has the Moriwaki cams installation instructions in their magazine collection, aftermarket catalog, performance archive etc please let me know. I have Andrews GS1000 specs (.004 - .006") but that's no help here

I decided to check the valve lash and found some interesting measurements

Looks like the Intake Cams were adjusted to give maximum lift. While the Exhaust Cams were set very loose to perhaps prevent burning a valve? Measurement (In)

Let's review the Moriwaki cam timing specs that JeepRusty found below. Assume I have the street cams would you guys agree with the following cam centerline calculation?

Intake: R1(BTDC) + R2(ABDC) + 180/2 - R1 where R1 = 15 & R2 = 45
15 + 45 + 180/2 - 15 = 105 Centerline

Exhaust: R1(BBDC) + R2(ATDC) + 180/2 - R2 where R1 = 40 & R2 = 13
40 + 13 + 180/2 - 13 = 103.5 Centerline

I got this info from http://medlem.spray.se/biker661/Camtiming/htm (Opps no longer there, I have the hard copy)

 

[blowerbike]

IMO 1&3 intakes need to be made the same or near to 2&4.
you could live with the exh. or tighten them up a couple thou.
the cams will be whatever the engine builder degreed them to as far as lobe centers go.
i would get the tools to check the cam timing and you can check the cam lift at the same time.
i'm not sure where to set the lobe centers on an engine of this size or where you want the power to be made.

 

[srsupertrap]

No reply from Moriwaki Engineering (via Escondido Cycle Center). If I don't receive a reply I will adjust the valves to .005 to .008" like some have suggested. I removed the cams this afternoon and found the following

This mark by the screwdriver tip is like the Suzuki arrow indicating alignment with the head; the GPz550 manual shows the X line should point to the lower cam chain pin. It currently points to the upper pin on the link.

According to GPz550 manual, the Intake Cam sprocket Z/5 mark should be flush with the head.

BUT the Z/5 mark should also be centered between the 43rd & 44th cam pin on the same link plate. It's not

Removed the Exhaust Cam, the bolts from #5 Cam Bearing cap were difficult to remove even with vice grip. The 6mm bolts threads were stripped. Going to need Helicoils.

Exhaust Cam came out clean . . . . funny Kawasaki does not recommend using vice grips during the camshaft removal

Now to measure the cam lobe lift: Width of Cam lobe - Cam Base Circles. The Intake & Exhaust both measure 36.25mm

The base circle measures 28.01mm for both the Intake & Exhaust. Subtract the two and the lift is 8.24 or 8.25mm lift. Unfortunately not the same number as the Moriwaki Cam Specs which Jeep Rusty posted. IMO the 8.25 mm lift is not radical which makes it a good street cam

I need a dial indicator with a flexible arm to check the duration and the C/L angle. Works on hold. I suspect the guy who did this engine work was not an expert.

 

[tkent02]

I have a dial indicator if you need to borrow it.

Looks like a really fun bike.

 

[blowerbike]

when cams are degreed....the factory marks are no longer exactly in the same place because of the slotted sprockets and the lobe center changes that was made.

 

[Nessism]

Why would the sprocket position change just because the cams were degreed?

 

[srsupertrap]

when cams are degreed....the factory marks are no longer exactly in the same place because of the slotted sprockets and the lobe center changes that was made.

Agreed, I will verify everything when I get to that point but I suspect the builder is off a tooth. I copied this from Corey's GPz550 manual so everyone will have a better visual to compare the pictures with.

 

[blowerbike]

Why would the sprocket position change just because the cams were degreed?

i should have mentioned "along with after market cams".
throw in chain stretch/different gasket thickness/head milling/chain guide wear.
i seldom had marks line up exactly on modified engines.
once you degree the cam's then you know all is good.
just saying....

 

[Big T]

So, what you're saying is that the sprocket can be one tooth off and you can "degree" the cam into the correct position?

I know you degree the cams after everything is all lined up

 

[blowerbike]

i'm just saying things don't always line up exactly...could be a half off front or rear.
if he put's a degree wheel on it and used a positive stop and find's true TDC...
his marks may not be off...if they still are then go a head and check the lobe centers and if they're close to say 102-105 then everything is probably lined up correctly.
being a tooth off changes the cam timing by around 10 degree's give or take.
maybe 8 degree's...maybe 12 degree's ect...

i'm not the best at explaining via typing...
must be an age thing

 

[daturat100r]

Good score ,should be a better bike with these mods,i had one for a few years but got sick to death of its narrow powerband and havin to rev it to death and changing gear constantly.
Dont change anything you dont have to ,so far it seems full of the choice stuff,but I prob would have(from experience, doh) degreed up the engine prior to disturbing the cams to get a base point to start from,too late now but goodluck and keep us all posted on progress

 

[srsupertrap]

I will work on my Z-1 order tomorrow, next I move the Mikuni Flatslides onto the workbench and spray all the linkages & screws with PB blaster to soak overnight. Looks like the none of the screws were ever disturbed.

Installed a new battery in the Mitutyo D/C so we can see the readout again and the intake measures 26.89mm.

 

[srsupertrap]

So, what you're saying is that the sprocket can be one tooth off and you can "degree" the cam into the correct position?

I know you degree the cams after everything is all lined up

I suspect that is the case with the exhaust cam considering it's current skewed position.

 

[srsupertrap]

Mikuni RS27

Mikuni RS27

Made good progress yesterday taking apart the RS27. I carefully took things apart since I know of no source of supply for the gaskets. I will need O-rings but I will be able to run these Carbs. So lots of photos and if anyone has good stock of O-rings let me know.

The carbs were never drained. . . varnish in the bowls & main jets. Plastic floats probably none adjustable right?

Remove the plastic floats, looks pretty good. I break out the magnifying glass standard N100 mains (107.5) & VM pilot jets (32.5). The pilot is probably way too BIG

These were pretty stubborn but with PB Blaster they broke free.

After I remove the four main jet holders, I look at the throttle linkage

As I hoped the varnish had merely fused the jet needle and needle jet together. The photo below shows full travel . . . enough said.

NICE

Remove the float needle & seat assembly . . . O -rings still look ok

Take of the top covers, Carb #3 appears to be the master.

Remove the throttle shaft, remove the slides & mark them.

 

[srsupertrap]

This Primo impact driver always breaks loose screws easily and never screws anything up

Choke plungers were removed next

Top and bottom brackets along with choke linkage removed

Carb separation

Removed throttle linkage, spacers etc

Check out the needle bearings visible in this photo . . . Safe to Dip?

This cover facing the engine had tamper proof Torx screws which were Loctited in place. Lucky to get them out undamaged.

Got them off w/o damaging the gaskets. I will need new O-rings on that carb body below the choke tube (wrong term)

What a good mess