Thread: First ride out
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Old February 7th, 2023, 04:12 PM   #11
InvisiBill
EX500 full of EX250 parts
 
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Name: Bill
Location: Grand Rapids-ish, MI
Join Date: Jul 2012

Motorcycle(s): '18 Ninja 400 • '09 Ninja 500R (selling) • '98 VFR800 (project) • '85 Vulcan VN700 (sold)

Posts: A lot.
Blog Entries: 1
MOTM - Aug '15
Quote:
Originally Posted by Bob KellyIII View Post
From my observations the stock system on the Ninja is almost exactly the same as the Thermo-bob unit... I don't understand why you would recomend adding an additional unit to the bike ?
The Ninja's cooling system is almost identical to the KLR's, exept the thermostat is in a remote housing instead of directly on the side of the head, and it's a higher temp stat. It's still a single loop where the thermostat just restricts the amount of coolant flow.


Quote:
Originally Posted by Bob KellyIII View Post
I have not incountered any heating/cooling issues with My Ninja at all and I think the stock system works fine.... why change it ?
No doubt the Ninja is a cold blooded beast ...meaning it takes a long time to warm up.... and that may well be because of the outline of operation you gave above...having to get the hot coolant through the little weep hole to initially open the thermostat. I would think that if the slowness of the bike warming up bothers you, that increasing the size of the weep hole in the thermostat itself may well speed up the warming process.... as long as you didn't drill a great big hole so too much coolant could by pass the thermostat.... I would think that just doubling the size of the weep-hole in the thermostat would be all it would take to make the bike warm up faster..... In reality drilling a larger hole in the thermostat would in fact slow down the thermostat from actually actuating.... because of the greater volume of coolant circulating. but it would even out the tempiture of the coolant in the system faster than the stock system allowing what would feel like the bike reaches operating tempiture faster.
The "cold blooded" part is exactly what the Thermo-Bob fixes. A bypass setup lets the coolant flow from the engine to the thermostat and bypass the radiator if it doesn't need to be cooled. The whole loop can basically get up to the stat temp and stay there. Once the coolant gets above the stat temp, the radiator leg is opened up and the hot coolant can be cooled down. If it drops below the stat temp, the radiator leg is closed off again, and the coolant in the engine stays at the stat temp.

The size of the bleed hole is also addressed.
Quote:
Originally Posted by watt-man.com
The bigger the bleed hole, the better the response will be – but on the other hand, a bigger bleed hole will delay warm-up because more of your coolant is being chilled by the radiator, which you wish wasn’t being utilized yet. This is a legitimate problem on non-bypass systems... you're juggling thermal response with warm-up time, and to make one better the other must get worse.
It's inherently a tradeoff. You can make the hot coolant from the engine get to the stat quicker, but you're also sending that much more coolant through the radiator unnecessarily, causing more cold coolant to come into the engine.


Quote:
Originally Posted by Bob KellyIII View Post
the thermo-bob unit was designed to get the thermostat to react faster on the KLR 650 as it had a internal thermostat that took a long time to open up
and when it finally did it would shock the already hot engine and thus cause
issues that caused the cylinder to go out of round into an egg shape and that had drastic effects on compression and operation of the engine.
I don't thing there is an issue of the cylinders warping on the Ninja...
It's not that the thermostat is slow to react, it's that the single loop cooling system's flow is essentially turned on/off by the stat opening/closing. This causes half the coolant to sit in the engine getting hot, while the other half sits in the radiator getting cold. When enough coolant trickles through the bleed hole for the thermostat to get hot enough to open, the hot coolant rushes out of the engine and the cold coolant from the radiator rushes in. Like you said, it shocks the engine. Sometimes the coolant can even make it all the way through the engine and back to the stat while remaining cold enough to close it again. You end up with literally an on/off system where the coolant in the engine gets heat-soaked and the coolant in the radiator gets "cold-soaked", and then they switch places, repeatedly.

The Ninjas use the same single loop cooling system, just with a remote thermostat housing. The extra foot of hose between the engine and stat might help moderate the coolant temp as it trickles its way up to the thermostat, I don't know. The EX500 has a similar remote stat (but annoyingly with separate lines from each cylinder). It's not a horrible problem like with the KLR, but it's not super uncommon for the 500 to have the cylinders get out of round either. Having learned about the KLR's issues, I believe the cooling system isn't doing the 500 any favors there. Perhaps the 250's engine isn't quite as fragile, or the radiator is sized slightly better, or something else causes it to handle the situation better. I'm not saying that your 250 will get ovaled cylinders if you don't have a Thermo-Bob, but its cooling system is essentially the same as the KLR's, for whatever that's worth.


Quote:
Originally Posted by Bob KellyIII View Post
but there is a problem with it getting warm in cold weather....I have noticed that myself, as I have ran my ninja at 40 degrees and it took almost 45 minutes of idling to warm up enough to take throttle without hesitation....
although that is probably due to carb issues and not the cooling system
it is proof to me that the Ninja is slow to warm up....
.... so perhaps a bigger weep-hole in the thermostat itself is all it would take to get the bike up to operating tempiture faster I don't know...
The tradeoff with enlarging the bleed hole is that it contributes to staying cold longer. The tradeoff with a bypass is just the extra cost and complexity of adding the bypass. If you're ok with the time and cost of adding a Thermo-Bob, it fixes the warmup problem with no effect on cooling performance. It sounds like the TB3 can be installed in place of the stock thermostat housing (with some consideration for the temp sender), making the upgrade a little simpler even.

Here are actual Ninjette users' reports from the other thread:
Quote:
Originally Posted by greg737 View Post
Before the Thermo Bob my EX-250 was very cold-natured, it took forever to get up to anything even approaching a normal engine operating temperature and even then it ran pretty cool any time the weather was less than about 70 degrees, which is quite often here in Spokane. With temperatures anywhere below the mid 50s my EX-250's temperature gauge needle would only rise to just above the cold line.

Now, with the Thermo Bob installed I've been riding the last three days in temperatures from the mid 30s up to low 50s. In these temperatures the gauge needle now rises quickly to just below halfway on the gauge and stays there.
Quote:
Originally Posted by misfitsailor View Post
The ThermoBob is the way Kawasaki should have done the cooling system in the first place. Before I got one, warm ups were always slow. In cold weather, the bike never warmed up at all. The running temps were all over the place, sometimes too low, other times rather high. Now warm ups are fast year round and temps are constant within a close range. Having your engine run at constant temps will increase it's life.
Quote:
Originally Posted by rojoracing53 View Post
I've been running a thermo-bob for two years on my 2009 and it works great. I don't warm up my bike and instead I just start it as I'm rolling down my driveway and just cruise for about 2 mins. After 2 mins I'm already at 150f and only a min or so later I'm at a full temp of 190f. I'd imagine the fact that my bike warms up so fast now as helps with me never needing the choke because by the time I come to the first stop sign I'm already well over 100f.
Quote:
Originally Posted by choneofakind View Post
Very pleased with my Thermobob setup. Bike comes right up to operating temp on the gauge in about a mile, choke has to be turned off as soon as I start moving, or else I get the telltale bog that says my choke is making my bike too rich. Temp needle sticks at 11:00 or so, only comes up when I'm at a stop light, regardless of how warm or cold it is outside.
The conclusion I've come to is that the little Ninjas are cold-blooded directly because of the single loop cooling system. Even if that doesn't specifically cause KLR-level issues, I think it's better for my bike to avoid running so cold. That's why I'm currently working on figuring out a bypass setup for my 400.
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