Quote:
Originally Posted by Bob KellyIII
Oh I thought the Thermo-Bob regulated the bypass as well....ok thanks !
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The bypass always being open is also addressed in the TB info. There's always a bit of coolant bypassing the radiator and therefore reducing the cooling performance. However, that also means slightly less coolant going through the radiator, so there's a bit more dwell time in the radiator, increasing the cooling performance. Theoretically, these cancel each other out. In reality, he saw about 3°F increase in temps compared to a complex system that completely closed the bypass off.
Quote:
Originally Posted by Bob KellyIII
I'm just trying to figure out how to do that sort of arrangement using the stock thermostat housing... like maybe run 2 Y connectors in the line that bypass the thermostat.... that should be easy enough to accomplish but I would think that was make the bike run colder all the time.... it would assure coolant circulation no doubt but it would keep the motor cold doing that.... so I don't think it would help "Warm up the bike" though all the coolant would reach the ambient temp faster....
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do either of you have any ideas on how I could accomplish the thermo-Bob's workings on the stock system ?  |
Generically speaking, you want to tap into the coolant line at the engine side of the thermostat, and the bypass line will just T back into the lower radiator hose. The coolant will flow out of the engine, past the stat, and then either through the bypass line if it's cool (stat closed) or through the radiator if it's hot (stat open). Then into the return hose and back to the engine. The bypass has to be near the thermostat though, so that the coolant from the engine actually flows over the stat and causes it to open when it's hot. Just to keep things perfectly clear since you used the phrase "bypass the thermostat", this type of system causes cold coolant to bypass the radiator, not the thermostat. That's why it causes it to warm up faster.
The EX500's cooling system design makes it nearly impossible to splice a TB into the system. The guy that I quoted above DIYed his by using the temp sender port.
He used a 90° elbow in the port, into a T, with a 90° 1/4" hose barb on top for the bypass line, and a reducer in the other side to hold the temp sender. It technically works, but there are some issues. He had problems with the threading - I think it might be BSP rather than NPT. With the temp sender relocated, it's actually only measuring the temp of the coolant going through the bypass, not in the main loop. In the simpler carbed bikes, that should only be running the dash gauge as opposed to actually giving the ECU data, but you're still making your engine monitoring less accurate. And while the pile of parts does technically get the job done, it's obviously a lot more Rube Goldberg than the simple Thermo-Bob housing.
I think it might be possible to tap another hole above the temp sender location to make a port dedicated to the bypass. This leaves the temp sender untouched, but still gives you a hose barb in a similar location, without needing all the adapters.
The NewGen's stat housing is much simpler. The PreGen's is pretty much the same as this too, just a bit more compact.
As stated, if you transfer the temp sender to the Thermo-Bob, you could probably just drop it in place of the stock housing to keep the cooling system simpler overall.
It doesn't look like there's a good spot in the stock housing to drill and tap a new hole for a bypass line fitting. You could probably rig it up the same way the EX500 guy did, and use the temp sender port and some fittings (with the same caveats mentioned above). Maybe try this as a temporary test, to see how it works out for your bike?
Keep in mind that with the bypass setup, the engine should pretty much sit at the thermostat temp. The stock stat is 180°F, while 195°F is probably a little better (and what the TB comes with). If you wanted to bump your DIY setup up to 195°F, you'd also have to find a Ninja-compatible stat at the higher temp too.
Personally, if I had an EX250, I'd probably just install a TB3 in place of the stock stat housing since it seems to fit there. You'd just need to splice the bypass return into the lower radiator hose and maybe add a ground wire for the stock temp sender. Minimal modification to stock parts, no fabrication needed, and no "extra crap" on the bike (early installs had you cut apart the stock stat to retain its sealing gasket in the stock housing, while also splicing the TB housing into the hose). As it is, I may just end up removing my 400's stock thermostat and splicing a TB3 into the radiator hoses. It's not as slick as it could be, but it's definitely the most straightforward way to accomplish it.