1988 Hawk NT650 resto

[DavidR8]

Pulled the forks off tonight in anticipation of the fork seal kit arriving.
Discovered the Metzler front tire is a MEZ1 with a "Racing" decal which was apparently Metzlers production class race tire back in the day.
Every fastener is drilled for safety wire, much of it intact.
So I suspect there was a fair bit of track time on my bike.
Suffice it to say there will be new rubber front and back.

The fork internals appears stock (no Gold Valve Emulators to be found) but wonder if these springs are stock.
They are as I removed them, the left one has the close wound coils on the bottom, the right has them on the top. So many odd things on this bike.

 

[mattthemuppet2]

those look like progressive wound springs. Coil springs are typically linear, X lbs force = X movement. Progressive coil springs compress alot at the beginning for X lbs force, then progressively less as the spring compresses. One way of dealing with brake dive and maintaining some suspension under braking.

 

[DavidR8]

Through the magic of the internet I have verified that I do indeed have a set of Progressive Suspension springs.
The factory springs are 13” long with an 8” spacer for a combined length of 21”.
These are 18” long with a 4” spacer for a combined length of 22”.

 

[DavidR8]

Changed out the fork seals last night.
One was a bit leaky!

And the new exhaust arrived from England!

 

[DavidR8]

This is a video of my exhaust being made. My. Actual. Exhaust.

 

[Toro5xi]

Just curious if there has been any more progress on your Hawk? I’ve had 3 Hawks over the years. Mostly stock. In my opinion one of the best looking bikes ever made.

 

[DavidR8]

Just curious if there has been any more progress on your Hawk? I’ve had 3 Hawks over the years. Mostly stock. In my opinion one of the best looking bikes ever made.

It's stalled as I reorganized my shop. Need to get cracking on it though!

 

[great white]

those look like progressive wound springs. Coil springs are typically linear, X lbs force = X movement. Progressive coil springs compress alot at the beginning for X lbs force, then progressively less as the spring compresses. One way of dealing with brake dive and maintaining some suspension under braking.

Actually, nearly any fork spring you’ll pull out of a set of Japanese forks after about mid-late 80’s is going to have a progressive wound spring.
The difference in an aftermarket spring is the spring rate of the steel itself. Oem japanese bikes (until lately) tend to be undersprung from the factory. I’m guessing its taken a while for the asian manufacturers to realize that the typical north american is….errr…..”ample”.

 

[mikey]

For decades, the world average body weight for males was 70kg and that is what Japanese bikes were sprung for. Nowadays, the average is closer to 78kg worldwide. For North Americans today, averages are much higher ... 198 lbs.

 

[great white]

Alrighty, time to update this thread.
I’m about to tear into the Hawk.
Pulled the carbs last night because a) they were completely gummed up with prehistoric gasoline and b) I needed to pull the jets so I could figure out if I need to order a jet kit.
There is no air box and it has a Two Brothers crossover pipe and can.
Stock jets are too lean with this combination so bigger jets are a must.

What a mess inside the float bowls amd jets. No way could I read what but 20 minutes in the ultrasonic cleaner did wonders. Turns out the pilot jet is the correct size but the mains are too small.

For a street bike on stock cv carbs I’d recommend you find a stock airbox and put ‘er back on the bike.
While you can make it run somewhat acceptably on pods on the street, it will never carburate as well as the stock airbox. Especially so in transient throttle settings (for ref, a street bike is constantly in transient throttle).

I’ve gone through that mess so many times I can’t count.

Now, I only install pods on bikes that will run mostly WOT (track,drag, etc) because pods on cv carbs just don’t have good transient response to throttle.
When my bikes that do have pods and CV's run right, they’re absolute monsters. But when they don’t run right (which is around 80-90% of the time) they’re absolute dogs and just a general maintenance nightmare (fouling plugs, over-heating, can't get out of it's own way, etc)


Stick with the stock airbox if its a mostly stock street bike. Or if you want to keep the pods, consider going to mechanical flat slide carbs. Pods don’t effect mechanical slide carbs at all, besides letting in more air that is. Of course, mechanical flat slides bring their own host of “quirks”….