'98 600 twin with no thermostat, need some advice

[thewhite]

Hi, i bought a 600 twin '98 motor that i put in a wide trak. it run good but it's
too hot, so i put an extra heat exchanger under it but the problem is that the motor has no thermostat and the head is not machined to have one, so my fear is that it run too cold. Is there someone that solved that problem without
changing the head? Someone talked to me about maybe put an outboard motor's thermostat, is that a possible fit?

Any advice is welcome Thanks Thewhite.

 

[xc6rider]

What head is on it?

The stock head housed the thermo right under the neck on the rear of the head.

 

[hudini]

I have always taken the thermostat out of the twins. You will be fine. I never ran one in a ported 600/700/800 or my 910.

 

[thewhite]

This is the stock head, and there's no return line under it like i saw on a '01 700. Could i put a thermostat with some small holes in it to slow down the flow until it reaches the operation temperatures without damage the water pump. thanks

 

[thewhite]

I have always taken the thermostat out of the twins. You will be fine. I never ran one in a ported 600/700/800 or my 910.

Hi hudini, i ran it this spring on icy snow with no problem, my concern is when i will run this winter in big snow and low ext. temp.(like -20degrees celsius)
Thanks.

 

[snowx22]

cold seize

i cold seized my 700 engine when i forgot to put a thermostat back in after summer racing without one. The snow was really nice and fluffy and it was like 10 below zero, dropped off the trail for a while after getting it warm and it seized quick. just my experience

 

[xc6rider]

The 97-99 engine, did not have a return line on the underside of the head.



For a racing application, especially drag racing you won't want/need a thermo however. Especially if you are going to require any kind of external cooldown following a run.

 

[thewhite]

xc6rider, do you think the idea of a thermostat with small hole could work. Someone explained to me that outboard motor have this kind of thermostat because they don't have return line

 

[retiredpop]

i cold seized my 700 engine when i forgot to put a thermostat back in after summer racing without one. The snow was really nice and fluffy and it was like 10 below zero, dropped off the trail for a while after getting it warm and it seized quick. just my experience

That's the reason why they put in the thermostat as I understand it. Riding on hardpack and having a fairly high engine coolant temperature and then diving in to the snow let the coolant get cooled off too quickly.

 

[xc6rider]

xc6rider, do you think the idea of a thermostat with small hole could work. Someone explained to me that outboard motor have this kind of thermostat because they don't have return line

If it were mine, i'd get and re-install a thermostat, especially with additional cooling. You can cold seize a piston from both running too hard before it's warmed up all the way, or if it is cooling too much (thermostat takes this out of the equation)



have you verified that you have no air bubbles interferring with flow of the coolant?? It won't flow correctly, and will overheat if air is trapped in the system........another thing to verify.

 

[thewhite]

For air bubbles it's okay, i ran for about an half day with my 9 year old son with his starlite at about 15 KPH on icy trail and the temp lite didn't went on(not sure about this term, my english is not too good!! excuse me!!). I will check under the neck if i can install one and i think i will go with the idea of the thermostat with holes in it
thanks

 

[hudini]

I have never cold seized any motor. Make sure you let it idle and warm up and then take off. I have also never seen a motor seize from getting hit instantly when going into the powder from hardpack due to the cold temps. I have experienced seized pistons from low elevation, bad fuel, improper jetting, and snow injestion through the intake.

I have personally ridden many times in -15F in pow all day long with no issues with no thermostat.

The reason I don't run a thermostat in my motors is specfically for cooler engine water temps. Struther's took it out of my old 700 and has done ever since then, on many motors.

Bottom line is if you are concerned about it you need to do what you feel is the best thing and go for it. Have a good winter riding.

 

[slash]

Find a storm t-stat and housing , temp 125 works inline with a return to motor!

 

[thewhite]

Find a storm t-stat and housing , temp 125 works inline with a return to motor!

That's funny you wrote that, today i found one in a Kimpex dealer. Now i have to find a way to mount it in the coolant line. I think it should be the closest possible of the head of the motor, am i right?

 

[X2Freeride]

Havent ran on in years. You will be fine without one. Never ever once experienced a "Cold Sieze" from not running on either. And the snow conditions in ND vary ALOT day to day.