Haha - after replacing Hall sensors, coils, and rubber boots I find my '85 K100's problem is ... faulty thermostat (the one in the radiator system). I heated mine in a pan of water and it never opened.

I read old forums that said a Toyota Corolla thermostat will work, so I bought one for $8 but I can't get it to seat in correctly. Seems like the gasket around it is possibly too big to fit, and/or the spring (which is longer than the OEM one) is too long, I can't get the plastic cover panel to seat correctly without leaking now.

So I have two questions:

1. Is the Toyota thermostat OK and I'm installing it wrong, or do I need to buy the OEM version (for $70!) 

2. How do I look up the O-ring that fits into the roundish plastic housing cover, since I need to replace that too?

timz1000 wrote:1. Is the Toyota thermostat OK and I'm installing it wrong, or do I need to buy the OEM version (for $70!) 
2. How do I look up the O-ring that fits into the roundish plastic housing cover, since I need to replace that too?

What is the part number of the thermostat you are using? At what temperature does it open?

In your previous threads you mentioned the engine's shutting down when hot but did not mention the overheat light being lit. Was it ever lit during those occasions? Was the fan running during those occasions?

The thermostat number is 17 11 1 460 716


As for my earlier posts - the temperature light never did come on, but I am guessing it doesn't work. Now that I tested the thermostat and saw it doesn't work, the way the bike dies when hot seems consistent with overheating.

The fan would turn on.

Also - the o-ring is this one - I'm ok with paying almost $9 for a piece of rubber if it makes the bike work

04

17 11 1 460 718

O-RING - 47,29X2,62

1

$8.43

Here's the diagram on Max BMW http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51747&diagram=17_0625&partnumber=17111460716

timz10000 wrote:The thermostat number is 17 11 1 460 716

That's the BMW part. You are discussing a Toyota part so I was seeking its part number and opening temperature.

Laitch wrote:

timz10000 wrote:The thermostat number is 17 11 1 460 716

That's the BMW part. You are discussing a Toyota part so I was seeking its part number and opening temperature.

Ah - sorry - I don't have the part number with me, but from this thread http://www.motobrick.com/index.php?topic=4903.0 I got a 94 Toyota Corolla thermostat that opens at 85 degrees. Others in threads said the springs are a little longer but they can be depressed a little and still work fine but I can't get it to work

Years ago, I tried a Toyota thermostat as a replacement for the BMW one but I failed to get it to work for exactly the reasons timz10000 outlined - the gasket is too large.  The unit I bought was a Motorad 7214-180JV.



And the gasket was ROL Gasket WO8285-001.



Both were sold by Canadian Tire as Toyota compatible.  The gasket is too thick and adds too much to the diameter of the thermostat body (besides being square-ish in cross-section.  I gave up and went with a BMW OEM thermostat.

I spent many hours with a parts specialist looking for a replacement thermostat but found nothing that was the correct length to turn the bypass of at the right temp but found nothing that came even close. There were plenty that fitted in and plenty that had the right temp settings but none that was suitable to use except the OEM thermostat.
Maybe there is a new model that does match up but the main sticking point was the depth of the bypass shut off valve.

RicK G wrote:I spent many hours with a parts specialist looking for a replacement thermostat but found nothing that was the correct length to turn the bypass of at the right temp but found nothing that came even close. There were plenty that fitted in and plenty that had the right temp settings but none that was suitable to use except the OEM thermostat.
Maybe there is a new model that does match up but the main sticking point was the depth of the bypass shut off valve.

Ah OK thanks much for the info! I don't mind paying a premium if that's what it takes, I'm ready to get this baby back on the road