I have just removed the theromstat


33 replies to this topic
  • BrettJ

Posted May 29, 2005 - 03:58 AM

#1

Sure enough arfter my bike has over heated many times I decided to check the theremostat, the needle was stuck in the half way position. :) FFS honda!!! So I have now completely removed the thermostat, I havent gone for a ride yet I've just have it on idle. My observations the outside of the cylinder was much cooler but I could feel the heat from the radiators is much hotter. Is this normal and is there any ponit me going and buying a new thermostat, I fear the replacement thermostat might suffer the same fate. But the most important thing is that I dont damage my bike

thanks Brett

  • Roll_it_on

Posted May 29, 2005 - 06:16 AM

#2

There are lots of guys here in California that I know including myself that have removed the thermostats on our bikes with no problems what so ever. I didn't like the idea of a failure when I least expect it and my bike runs fine without it. The only thing I noticed is that it takes a bit longer to warm up at first start up in the morning but other then that no issues. I guess if I was in a real cold climate I would use it but I'm a wimp when it comes to cold so that why I live here in the great dictatorship of Ca.

  • BrettJ

Posted May 29, 2005 - 06:28 AM

#3

So your bikes radiators didn't seem to heat up fast? So if I was sitting at trafiic lights for say 2mins my bike wouldny boil over or anything like that? Isn't running the bike without a thermostat bad for the cylinder walls?

  • Miker

Posted May 29, 2005 - 06:37 AM

#4

I believe you can get a replacement thermostat from an auto parts store that is the same only reliable. I do not know the part number. When I was in school they they taught us that removing the thermostat let the water circulate too fast through the radiator not cooling it down enough. This was theory for a car system though.

  • XR-Det

Posted May 29, 2005 - 07:24 AM

#5

Those thermostats have a purpose! If you remove it completely its a temporary fix but will not keep the engine in operating temperatures. It takes much longer for the engine (not the radiator) to reach the temperature range it was supposed to run with and if you are at colder temperatures you will not reach the correct temp at all. its then like beating a cold engine...

The thermostat also restricts the flow compared to no thermostat. Well, I admit at hot climate that thermostat might cause the thing to overheat because of that restriction while not moving the bike. If you try to solve your boiling problem at the traffic light by removing the thermostat then in my opinion you are doing that over engine wear.

The entire thing why a watercooled engine puts out more horsepower its mostly because the cylinder and other parts are made to a tighter fit while the water cooling maintains a constant temperature to minimize expansion due to temperature changes.

If you are afraid that it will fail then put it on your maintenance list for parts to be replaced once a year or so. Those thermostats are cheap compared to a premature worn engine I would guess.

Just my 2 cents... but I would ride that bike here at any temperature so it might not apply if you only head out if the outside thermometer reads a certain temp :)

  • needsprayer

Posted May 29, 2005 - 10:33 AM

#6

With my thermostat the pin was able to move sideways,get outside of the bridge and become wedged against it. Is this similar to your problem?

All I did was tap the bridge down so the pin could not move sideways. Never had the problem again.

If you still have the thermostat take another look at it. If the pin is stuck free it up. Suspend the thermostat in a pan of water, heat the water and watch the pin move. Mine moved up and sideways.

Tap the bridge down and do it again. Once you get it right the pin cannot move sideways.

  • Supplicate

Posted May 29, 2005 - 11:43 AM

#7

you guys really should start reading the Pig Pen for info.

It lists right there how to fix the thermostat.

quoted straight from the above link:

The fix here is an easy one. A lot of the guys just remove it, but Honda put it there, so there's a reason. You don't want the bike running too cool, as that will accelerate cylinder wear. The better fix is to throw in a Napa thermostat #115, MotoRad for a Suzuki Swift, or Carquest #31978. These are meant for small GM cars. It's an almost drop in fix. All you need to do is drill a small hole in the outer ring of the 'stat to allow fluid to flow when it is closed. This is a must do to prevent hot spots in the engine.



  • BrettJ

Posted May 29, 2005 - 02:52 PM

#8

So has honda fixed there theromostats, if I went and purchased another from them is it the same shonky one as one that comes out in the bike?

  • Roll_it_on

Posted May 29, 2005 - 08:40 PM

#9

The XR650R is the only water cooled bike that I have run across that even uses a thermostat. The restrictions in the hose are smaller than the restriction in the unit itself and it would only regulate the temp assuming the water temp got below 180 degrees and it shut down in order to heat the water up. Once it is wide open it is wide open and for warmer climates I believe that once it is warmed up you are good to go. I could see in a very cold climate perhaps the thermostate would be needed but not in the majority of the users. I think the fact that most bikes do not use a thermostat speaks volumes.

  • BrettJ

Posted May 30, 2005 - 02:06 AM

#10

Well it does get bloody hot here in western australia and generally the temperature we ride in is at least 20°C. Thanks everyone for your input but agian it seems there is no definate answer :) I just wish I knew what to do, every ride I went on with the buggered thermostat whenever I really thrashed it it boiled and boiled hard, I'm talkin steam train boiling. When ever I rode it on the street even at night time at like 10°C the bike was F@CKIn hot, not boiling but if I wore shorts my leg would get burn just from the heat radiated from the engine. My last bike a KDX200 never got hot street riding and only boiled if it lost traction and was reving hard without moving, and it hard no thermostat. If what everyone says is true and the xr650r is the only dirtbike with a thermostat I think i'll leave it out.

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  • KeithBoyd

Posted May 30, 2005 - 03:48 AM

#11

When I checked my spark plug,when my thermostat had been stuck open,it showed the classic signs of running on an overcooled engine. Now my plug runs fine. I ordered a new `stat from Summers Racing Components(as I was getting other stuff posted)and put it in.The side casings are hotter to the touch and after I had to adjust my clutch as it was slipping under heavy acceleration because it was now warmer and the freeplay tolerance tighter.This proves to me that the changes in engine temp` do actually matter.Conversely then by running too cold things are not as they should be? I use mine for quite a lot of road use too and I find for peace of mind,I know that its running at the proper temperature especially over a sustained period of time.For example I did a 3.5 hour road ride sitting at 100kms/hr constantly yesterday starting in the morning,which means when the temperture was cooler,I was happy to know the bike was running spot on.I know that when the weather gets hotter the `stat will adjust to let more water through to keep it at the proper temperature.(I have not been off road since the `stat has been changed so I cannot comment until my next enduro,which is coming up soon)

  • frankstr

Posted May 30, 2005 - 06:46 AM

#12

I would not leave the thermostat out completly, Coolant won't stay in radiators long enough to do the heat exchange........
I removed the middle guts of my thermostat, no more moving parts to worry about.......and it will restrict the coolant flow....... :D
you guys with the heating problems might want to check your jetting...just a thought...Mine has never boiled over.... :)

  • Miker

Posted May 30, 2005 - 07:05 AM

#13

My KTM 525 has a thermostat.

  • Supplicate

Posted May 30, 2005 - 08:55 AM

#14

Mine has never boiled over.... :)

mine never boiled over until yesterday. We were stuck on some serious Wyoming Single Track (cow path on a sheer sidehill) and the BRP was idling or traveling at less then 1mph for a long time. Boil over like you wouldn't believe. This week the 'stat is going to be checked as well as changing the radiator cap to a lower pressure rating and see how she does from there.

  • Max Power

Posted May 30, 2005 - 10:08 AM

#15

This week the 'stat is going to be checked as well as changing the radiator cap to a lower pressure rating.


I think you mean a higher pressure rating.

  • BrettJ

Posted May 30, 2005 - 05:47 PM

#16

HONDA want $105 US for a new thermostat which will break in a year!!!!!!! :) Doesn't matter thou i'm just gonna head down to the spare parts shop and pick up a suzuki thermostat for $23 US.

  • Max Power

Posted May 30, 2005 - 06:19 PM

#17

HONDA want $105 US for a new thermostat which will break in a year!!!!!!! :) Doesn't matter thou i'm just gonna head down to the spare parts shop and pick up a suzuki thermostat for $23 US.



Ouch. It better come with a lifetime warranty.

  • Supplicate

Posted May 30, 2005 - 07:36 PM

#18

I think you mean a higher pressure rating.

er... yeah... my bad. go from the 1.1 cap to a 1.6 or something, see if that helps any.

  • BrettJ

Posted May 31, 2005 - 02:15 AM

#19

The damn suzuki thermostat doesn't fit as easy as I had thought It would, I will have to grind the side support pieces then it should fit ok. Amazingly enough I managed to fix my old thermostat right after I had bought the suzuki one, I have tested it and it works, and I have put it back in. Do you guys think I should just keep using my fixed thermostat or modify the suzuki one then use that?

  • Max Power

Posted May 31, 2005 - 07:19 AM

#20

The damn suzuki thermostat doesn't fit as easy as I had thought It would, I will have to grind the side support pieces then it should fit ok. Amazingly enough I managed to fix my old thermostat right after I had bought the suzuki one, I have tested it and it works, and I have put it back in. Do you guys think I should just keep using my fixed thermostat or modify the suzuki one then use that?



Throw the old one back in. Check it again in a couple of rides.





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