TOPIC:

strate6 wrote: Just on the off chance.............someone on this site had a simialr problem earlier this year and found the metal "neck" off the top of the radiator next to the cap, which the catch tank pipe pushes onto, was blocked. This caused similar probs to you, but was rectified as soon as unblocked.

That was me I initially thought the radiator cap was at fault as it was venting as soon as the cooling system pressurised, but it was in fact doing it's job & venting excess pressure as it couldn't lose it into the expansion tank. The hose between the radiator neck & expansion tank was indeed blocked. I flushed it through from the radiator neck end using a small hose pushed down the hole in the radiator neck then attached the small hose to a washing up liquid bottle & squeezed water in quite a few times until the water exiting at the reservoir end ran clear. Quite a bit of brown crap came out.

Kawboy wrote: Don wrote-We did find the timing to be retarded by ~10 degrees. It was reset to correct, although we did have to slightly elongate the holes in the pick up plate. After this, the majority of the heating issue went away AND the motor is much crisper, easier starting, and pulls strong, STRONG to redline.
What happened here? Somebody install the timing chain/water pump drive chain off one tooth?
I would need to talk with the engine rebuilder. Otherwise I might put out something less than a fact, LOL.
Also, the coolant tank flow to and from only comes into play with the rad cap on.
The first two tests were done with cap off, the only variable there was rad fans in Auto or Manual. For burping, the cap was on.

strate6 wrote: Just on the off chance.............someone on this site had a simialr problem earlier this year and found the metal "neck" off the top of the radiator next to the cap, which the catch tank pipe pushes onto, was blocked. This caused similar probs to you, but was rectified as soon as unblocked.

Other thank that, are you using a standard stock rad cap and is it allowing the pressure past to the catch tank or not ??
I am using an OEM two stage cap. Actually have tried two new ones. Before install, tested in a pan of water on the stove top, temperature monitored with a thermocouple temperature indicator. They both open and close correctly.

If the incorrect width of rubber pipe for the catch tank is used and its too thick, it will be blocked where it pushes into the retainer / recess on the tank itself at the rear of the tank. ??
I'll take a look. Headed to the shop in a bit..

Pete F
UK

I have a few of points to add.

1. You will not get ' communication ' to the expansion tank without the rad cap in place.

2. Is the thermostat the correct type?. I mean does it have the bypass port blanking function.? Without this, some coolant will always circulate around the cylinder block and not pass through the radiator. I have seen some on ebay without the bypass port blank advertised as z1300 thermostats.

3. Can you measure the coolant return temperature FROM rad to engine with fan running... that will give a good indication as to what is occurring.
If its close to the flow temp from engine it is likely some tubes are blocked.
If its say 20 deg f lower, I would go for the bypass not getting fully closed.


Ebay item listed as z1300 thermostat without bypass blanking ..item 274220334369

Ebay item with correct bypass blanking item 154101184335

Stiggy wrote: I have a few of points to add.

1. You will not get ' communication ' to the expansion tank without the rad cap in place.
Agreed. For the attempted burp, the cap was in place.

2. Is the thermostat the correct type?. I mean does it have the bypass port blanking function.? Without this, some coolant will always circulate around the cylinder block and not pass through the radiator. I have seen some on ebay without the bypass port blank advertised as z1300 thermostats.
Thermostat is correct, OEM, 2 stage. I've tried two brand NOS t-stats and tested them first in a pan of water and calibrated thermometer.

3. Can you measure the coolant return temperature FROM rad to engine with fan running... that will give a good indication as to what is occurring.
If its close to the flow temp from engine it is likely some tubes are blocked.
If its say 20 deg f lower, I would go for the bypass not getting fully closed.
Good idea!


Ebay item listed as z1300 thermostat without bypass blanking ..item 274220334369

Ebay item with correct bypass blanking item 154101184335

2020-12-14 Overheating Troubleshooting (cont)


Decided to pull the fairing to get a better view.. It's a barndoor..


More and more, want to make this a semi-cafe bike.


Removed heat shrouds for better access with IR heat gun..


Out of focus, but spark plugs look ok.. Not perfect, but OK.


Ran into an issue with my 1977 Yamaha TT500 fuel tank leaking past the petcock..
So no attempt at burping tonight.

BUT! I did find the hose from radiator to catch tank was crimped... Could not blow it down using lung power..
Removed catch tank, disconnected hose from catch tank, and it was clear. Huh?
Long of short, blew hose down with air compressor, reconnected to catch tank, and the circuit is open.
Perhaps the hose was crimped at catch tank rear?

Tomorrow off to NAPA for cheap fuel cut off so I can attempt burp and take measurements per recommendations from KZ1300.com peeps.

Forgot to add.. Took radiator flow video from my 1988 Honda Accord Lxi.
As you can see, the flow rate is less than the KZ1300's.
KZ1300 flow rate (3:40 or so)


Honda Accord flow rate (About 15 seconds)

To be fair, the KZ was at 1500 rpm, the Accord at about 800.
Just another reference point..

And so tomorrow dawns and I'll keep after it.