1983 KZ750 L3 front forks? Fork oil?

Hello all.. thank you for adding me.. 1st post here.

I am presently rebuilding a 1975 Kaw H1 2 stroke triple . One of my dream bikes when I was a kid!

The front end is from what I believe to be a 1983 Kz750L3. I don't think its the N model.. the fork seals for the N did not fit

The down tubes are 36 mm, the seals are 36mm X 9.5 mm tall. There is a pneumatic cap on top and the axle mounted to black fork lowers is concentric rather than leading.

I've taken them apart and cleaned them up, reassembled and find much conflicting information about fork oil quantity due to the proliferation of Kaw 750 models.

I _think_ 248 cc is correct.. but I read alternatively 12" from top or 355 mm (which is quite different from 12 " )

Does anyone know for sure or can point me to a manual with specs.. I have searched this forum and others and find no definitive information...

Think the stock spec is for 10 weight.. but can't figure the volume.

Help anyone?

Located is south central CT.
Thanks in advance.

Take at look at your private messages. I sent you the link to the K750-L3 Kawasaki Service Manual. Ed

Welcome!

I had written a long post on my phone and then Firefox crashed

Well, the short version: I am fixing the front on my bike too and have done quite a bit of reading on fork oil. Let's just say that the "W" number is close to useless on its own. You can find a 5w that is thicker than another brands 10w easily. I would use a brand others on here have had success with (I have seen Ed mention Belray I believe?).

Here are two great links for comparing oils and why SAE weight is a bad way to measure fork oil viscosity (you need cSt or ISO numbers):

transmoto.com.au/comparative-oil-weights-table/

bobistheoilguy.com/viscosity-charts/

10W fork oil will be fine.

The volume isn't overly important. It doesn't take tons of oil to cover the damping orifices so the damping will be fine regardless of how much oil there is (within reason). The oil volume does have an effect on the size of the trapped air pocket inside the forks though. More oil equals less air, so when you hit a bump and the forks compress the trapped air will increase in pressure and act as a spring to some extent. The effect of the trapped air is relatively minimal though. The spec for the L3 is the same as the E model, 355mm from of the top as measured with the springs removed and the forks fully compressed. Before you measure this way though it's important to pump the forks a few times to be sure to remove any trapped air inside the damping rods.

The KZ750-L3 forks are somewhat different than a lot of KZ forks; they have air valves and take up to a max of 36 psi pressure. Ed

Nessism:

Wrote a long reply and think it evaporated..

I see the spec for the "L" on page 364 of the service manual referenced by 650ed.. it reads for "L"... (not L3?) :
297 +/- 4 ml from dry
which should be
103 mm from top with legs compressed and springs out.

with this type of sealed / air cap fork.. think volume does matter quite a bit .. overfill will get harsh.

I think you ref the E spec on page 212 that indicates 248 ml from dry and 355 mm from top.. which is vastly different.

I hope "L" equates to "L3". But should be able to check the volume with the height measurement.

Thanks!

ed650:

Thank you kind sir for your assistance. If I read correctly p364 has a spec for the kz650L .. which I hope means L3

297 ml +/- 4
which should be 103mm +/- 2 mm with the springs out and the legs collapsed or compressed... doesn't leave much room for what was the initial 8 psi charge, especially after you add the springs back.. I find that kinda scary !!! not much compression volume!!!

Danny

The top of Page 364 says it's the supplement for the 1983 models, so a 1983 KZ750-L model should be the L3.

I read and understand it the same as you, and I agree that doesn't seem like it leaves much room. Of course, since that measurement is taken with the forks collapsed or compressed there should be more room once the forks are extended (no longer compressed). Maybe someone else with a 750L has some first hand experience they can share. Ed

Smdddanny wrote: Nessism:

Wrote a long reply and think it evaporated..

I see the spec for the "L" on page 364 of the service manual referenced by 650ed.. it reads for "L"... (not L3?) :
297 +/- 4 ml from dry
which should be
103 mm from top with legs compressed and springs out.

with this type of sealed / air cap fork.. think volume does matter quite a bit .. overfill will get harsh.

I think you ref the E spec on page 212 that indicates 248 ml from dry and 355 mm from top.. which is vastly different.

I hope "L" equates to "L3". But should be able to check the volume with the height measurement.

Thanks!

Interesting. Those numbers are drastically different from those stated earlier in the manual. Humm...

Again though, I don't think it matters much what the oil level is. I'd use that 103mm level and don't worry about the volume. I usually use 6" from the top, but 103 is only 4".

I can definitvely say that 300 ml of fluid does indeed bring the level up to 4" from the top of the fork leg with the leg fully compressed and the spring removed.

Thank you gentlemen for your assistance!

Danny