Tire Pressure

I have 1981 KZ650-D4, with 1981 z750L engine. with new tires. I have found a table in the service manual, please see attached table.
My weight is around 115 kg = 253.5 pounds.

What will the optimal pressure be then ?

Rear = 29 psi ?
Front = 26 psi ?

Oh nooooo! Tire pressure threads can get as controversial and angry as threads about the proper way to measure valve lash or which oil to use.
Most of the replies will fall into four categories----
1. Do what the factory service manual / frame info sticker says, no matter what. Always. No deviation at all.
2. Check with the tire manufacturer's website for recommendations. Tires have improved quite a lot since KZs were new. (This is my position.)
3. My great-uncle Bob knew a guy who said he once drove by a race track where somebody said that motorcycles one raced. He said that you should multiply the width of the handlebars by Pi, add your shoe size, then subtract the date, to find the proper pressure.
4. There is air in the tires? How did it get there and where can I buy more?

Good luck.

TexasKZ wrote: Oh nooooo! Tire pressure threads can get as controversial and angry as threads about the proper way to measure valve lash or which oil to use.
Most of the replies will fall into four categories----
1. Do what the factory service manual / frame info sticker says, no matter what. Always. No deviation at all.
2. Check with the tire manufacturer's website for recommendations. Tires have improved quite a lot since KZs were new. (This is my position.)
3. My great-uncle Bob knew a guy who said he once drove by a race track where somebody said that motorcycles one raced. He said that you should multiply the width of the handlebars by Pi, add your shoe size, then subtract the date, to find the proper pressure.
4. There is air in the tires? How did it get there and where can I buy more?

Good luck.

haha I take your point

I use what is suggested on the tire.
Steve

SWest wrote: I use what is suggested on the tire.
Steve

Steve, what tires do you use and do they have the recommended pressure printed on them? I ask because I've never seen this before. I've seen tires with the MAX pressure shown, but never the standard recommended pressure.

And speaking of recommended pressure, I'm in the camp of following the recommendation of the tire manufacturer. Honestly though, I think the absolutely best method to set pressure involves measuring the tire pressure cold, riding the bike for a good number of miles in a manner befitting your personal style, and then stopping to measure for pressure rise. You should ideally see a pressure increase in the front tire of about 3 psi and the rear more like 5 psi. This is just a rule of thumb but the idea being there should be a noticeable increase. If the pressure isn't increasing, there is too much air.

I generally run a few PSI lower than listed on the tires. Far cry from what was listed for the old Dunlops of the day in every way.
Steve

SWest wrote: I generally run a few PSI lower than listed on the tires. Far cry from what was listed for the old Dunlops of the day in every way.
Steve

Steve,
Be careful you are not baselining off the MAX pressure. That's way too high, even if you are a few psi under.

Nessism wrote:

SWest wrote: I generally run a few PSI lower than listed on the tires. Far cry from what was listed for the old Dunlops of the day in every way.
Steve

Steve,
Be careful you are not baselining off the MAX pressure. That's way too high, even if you are a few psi under.

+1

37-40 seems to be the popular pressures for the 230's.
Steve

Accordign to the tire pressure table I`m thinking:
Front: 28 PSI = 1.9 bar
Rear: 32 PSI = 2.2 bar

Can these be a good start point....

I have found on other forum for Pirelli MT66's the recommendation is:
front= 32-42
rear= 36-42

But these is higher than Kawa. recommend in the service manual?

Shall I start with front 32
and rear 36 then ?

I mean the pressure as physics force has been the same as long as we human has lived on the earth, and I assume the Kawa has sent up these numbers
based on weight + suspension + etc etc... ?

So why have higher pressure in 2018 then in 1981, is the reason because the old tire doesn't handled higher pressure?

I wiill start with:
front = 34 psi = 2.3 bar
rear = 38 psi = 2.6 bar

And see if I`m happy, I understand I can monitor the pressure and the wear and tear to see if its okay.

Stop me if I`m wrong

gordone wrote: I wiill start with:
front = 34 psi = 2.3 bar
rear = 38 psi = 2.6 bar

And see if I`m happy, I understand I can monitor the pressure and the wear and tear to see if its okay.

Stop me if I`m wrong

34 psi in the front tire sounds way too high to me as I suspect that will make the front tire hard as a rock. My front tire is a 100/90 V 19 Pirelli Sport Demon, and I run 26 - 28 psi in it. It works great. Ed