76 kz900 Overheating

If stock NKGB8ES spark plugs are fitted, could experiment with NGKB9ES (cooler running plug).

Good Fortune!

Were the pistons just bored by you? Are they in correct tolerance's? Forged? Cast? You trust your machinist? Could be expanding to tight? Cam shell bearings / cam caps messed with? Could be binding / tight
Just wondering if something is too tight?

In addition to the other suggestions, I think it would be a good idea to get the battery load tested. Many auto part and dedicated battery stores will test it for free.

F.Y.I. The needle you have listed, 5DL31 is the standard needle for the Mikuni 29mm Smoothbore carbs.

Don't remember Mikuni using that needle anywhere else. Might be wrong, its been 37 YEARS since I played with them!!!!

Along with other suggestions to check, I'd consider checking for retarded ignition timing and possible, tight valve clearences.

Patton wrote: If stock NKGB8ES spark plugs are fitted, could experiment with NGKB9ES (cooler running plug).

Good Fortune!

The plugs may run cooler, but the engine won't.

5DL31 is in the 76 26's, 77 LTD, and 78 Std,
Steve

FuelnFlamez wrote: Hi, My bike runs great, my question is why is it overheating and is there anything i can do about it i heard that i can't ride it daily but would like to ride it as long as I can without it overheating any feedback would be thankful


Pods
Vance & Hides 4 into 1 exhaust with baffle
Main jet - 130
Pilot jet - 17.5
Air Jet - 2.0
Needle 5DL31 - 4
Float bowl height - 26mm
Air screw - 1 1/4 turns out
Pilot fuel screw - 2 turns out

Having both air and fuel mix screws indicates you have Suzuki GS750 or 1000carbs and it looks like you have them on the rich side.
Fuel mix screw (under carb) should only be 1/8th to 3/4 turns out.(factory sealed preset)
Air mix 1.1/4 to 1.3/4 out.
Main jet looks too big for the engine spec and should be closer to 117.5 to 120 .
The Suzuki carbs run smaller mains from stock, only 95's on the GS1000 compared to around 105 on the Z1000 depending on model so this needs to be compensated for.
I run these carbs on the above setting (Fuel 1/4, Air 1,1/2, 117.5 main) with similar spec motor but I also run high lift cams and the carbs are bored to 30mm,

Suzuki VM's run about 3/4-1 turn open on the pilot fuel screw. The pilot air screw runs about double.

The fuel screws have a very sharp and pointy point. Some times people turn in these screws trying to count how many turns open they are and in the process the point gets jambed into the carb body and the point busts off. Checking this is one of the critical items when rebuilding a set of VM's with fuel screws.

members.dslextreme.com/users/bikecliff/i.../vm_carb_rebuild.pdf

members.dslextreme.com/users/cbsaunders/...ot_screw_removal.pdf

Some pics of your spark plugs were helpful

Sorry for the late response I have a job and can't work on it every day, but here is a picture of the spark plug.

Is that fuel or oil?
Steve