QuackKer Overheating - dcarver's 79 A1

After the first ride, with subsequent water puking , I finally have time to troubleshoot why she's overheating. My first thought is, hopefully something simple. Like a stuck thermostat. Or spring under t-stat missing. And not something complex like a clogged water passage in the head. Or not enough radiator volume given the first-overbore.

So here goes.

Barn-door fairing, radiator, fan, removed. I like the look. Just might make her a naked bike. Wish I could relocate the radiator too.
[img]https://candybuttorg.ipage.com/pix/motobikes/wrenching/KZ1300/2016-06-11 TroubleShootingOverHeating/1.jpg[/img]

Another issue, for a later day, is the leaky tachometer drive. I have a new assembly. For now, I'm trying to get to the T-stat.
[img]https://candybuttorg.ipage.com/pix/motobikes/wrenching/KZ1300/2016-06-11 TroubleShootingOverHeating/2.jpg[/img]

[img]https://candybuttorg.ipage.com/pix/motobikes/wrenching/KZ1300/2016-06-11 TroubleShootingOverHeating/3.jpg[/img]

My thought is that by removing this upper housing I can remove the T-stat. Just like on a 225 slant-6 Valiant. Yeah, just like that.
[img]https://candybuttorg.ipage.com/pix/motobikes/wrenching/KZ1300/2016-06-11 TroubleShootingOverHeating/4.jpg[/img]

In the meantime, how about some header porn?
[img]https://candybuttorg.ipage.com/pix/motobikes/wrenching/KZ1300/2016-06-11 TroubleShootingOverHeating/5.jpg[/img]

Oooh, uh, I can't think!
[img]https://candybuttorg.ipage.com/pix/motobikes/wrenching/KZ1300/2016-06-11 TroubleShootingOverHeating/6.jpg[/img]

So then, as any KZ1300 tech knows, and now so do I, the T-stat comes out from the bottom, not the top. So I gave up and BBQ'd some chicken before I did something stupid.

The end - for now. Workday tomorrow.

I apologize to the Admins. I have several threads now dealing with this overheat issue. I don't post often enough to recall what I've shared or not. I'll get better, promise.

On another thread , some good questions and suggestions. Thought I'd compile them here and let this thread take over.

Wondering if it may be an impeller issue. Shouldn't be too hard to check when you have the radiator off.
Where were you puking coolant out of? I went through my 1300, and could never figure out where the exact overflow outlet was....

The engine was freshly rebuilt with new impeller and all nylon gears were replaced. She has good flow in the radiator. It puked through the overflow bottle.

Be absolutely sure you took the engine heat way past the boiling point- that is 100 degrees C. or better
When filling the rad with coolant to the top, replace the cap, then fill the coolant bottle with the hose attached to the rad and held higher that the rad and fill it to the correct mark- gravity will fill the rad and over flow hose and bottom of coolant bottle - you are trying to expel as much air as you can before you even start the engine.

Thank you. I've monitored coolant temp at the catch tank using a calibrated digital thermocouple probe and measured it at 220F.
Here's a video showing the thermostat is opening..

I've heard that some bikes, KTM's, require the front to be elevated by > 30 degrees to purge the system.

From above..

You also mentioned a 3-row radiator. I have to admit that's on my list too. I live in HOT summer country, well over 100F on many days. Where did you have the radiator built? Any custom brackets or interference points?
.

Make sure the FAN SWITCH is working correctly

It is, and I have a new one in stock which I intend to replace. Cheap insurance. The relay is new now, too.
.

The 1300 has a nylon gear which runs the water pump impeller via a chain driven shaft . If this gets too hot it begins to melt and loose teeth which means the pump no longer works.

Brand new part, and the video above shows really strong flow through the radiator. I don't think that's it. Hope not..

it's your radiator cap not sealing and not keeping the system pressurized correctly, and perhaps she's running a bit rich by the looks of the headers, so a bit of overheating there ???, just guessing really

First off I want to thank you for your build blog, fantastic resource and was helpful in my restoration.

Overheating can be air, if its boiled over a couple times it shshould be purged out. Check the simple stuff first.

It's your coolant properly Mixed? Is the radiator cap ok? You can have it checked at most auto parts stores.


I'm ruining a big bore kit with a shaved head and I have no issue, a simple .5mm over bore shouldn't cause an issue. Mine did act up when I first ran it, but after a good boil over it was fine. My problem was the air buble was trapped near the temp switch for the fan, my fan wold shut down for no reason. Once the air passed all was well.

Duplicate post deleted.