Rocket 3 Roadster Possibly Overheating?

I recently took my bike to the dealership, got a full service, which includes new oil, coolant, brake fluids; the usual. Before I had noticed the bike running extremely hotter than usual, which I thought was due to the lack of coolant. So I took the bike for service thinking that would solve the issue. It hasn’t.

I plugged the bike into Tune ECU, coolant temp rises to 100 C, within 4 minutes. Radiator fan does kick in at 102 C and as long as the bike is idle it stays at that range.

Afterwards, I took the bike out for a ride on a cool night, wishing minutes the heat is excessive. After 30 minutes of riding, I quickly plugged in Tune ECU, and the bike temp coolant is reading at a constant 117C, and even rose to 118C at idle.

This isn’t normal right? Trust me I live in NYC and I ride all the time, and it only gets this hot if I’m in stand still traffic for like an hour. But there’s no traffic, cool night, normal few days, and I’m guessing the bike has been running this hot for quite a while.

I doubled checked the oil and coolant levels, all seem normal.

Can anyone give me any insight on this issue?

Best,

Budda

First thought would be trapped air in the coolant system.. wouldn't assume the service did it properly but the problem was there before the service. Still I'd like to bleed the system properly and see if there was any air trapped.

Next would be fan issue e.g. the relay going faulty. But it seems that the fan kicks in at 102°C reliably you say? Been watching it on TuneECU?

Lastly would be some kind of lean condition is causing temperature gain that the stock cooling system can't cope with. But checking this needs an O2 sensor and unless there's a Power Commander or some such gizmo or the ECU has been mapped..

Fan works, fuses are ok, and yes I've been keeping my eye on Tune ECU.

How does one fix trapped air in coolant system? Because from what I experienced, fan is working but its just blowing hot air, thus its heating up the engine and the surrounding tank (according to my research), and yes I've heard that it may very well be a trapped air in coolant system, and yes the problem was there before the service.

Is there anything that I can do to fix it?

If the cooling system worked ok before but then not so good, and was due to trapped air, the only way i can see it getting into the system (aside from someone opening the system and not bleeding it properly after) is if the expansion bottle ran dry (say from a faulty rad cap allowing coolant to be pushed out) and air got sucked in.
Radiator caps going faulty is not unheard of on Rocket IIIs.

There's a 10mm head hex bolt just above the thermostat (thermostat is on the front left side of cylinder head, on the other end of the big coolant pipe that comes out of the top centre rear of the radiator).
This is used to bleed air from the head by opening the bolt almost all the way out.

The rad cap is the highest point in the system. When bleeding, with expansion bottle emptied and rad cap removed, one should tilt the bike left and right, ideally with front wheel higher than rear to aid the movement of air forward and up.
The tilting left and right helps move air out and over to escape via the open rad cap/filler hole.
Then prop the bike with a bit of wood, while tilted right - and top up via filler.
Repeat until satisfied all air is out.

The on with rad cap, and fill expansion bottle to the max mark.

When the bike is cold (ambient) what is the coolant level in the overflow tank? If it's between MIN and MAX that's OK. If it's below MIN then your system is pulling in air on cooldown and that is migrating to the water pump suction side, and coolant flow is hampered. When your coolant was changed the coolant overflow tank should have been filled to well above MIN mark, then engine started to heat the system up. Any air in the system should migrate to the high point and when the system pressurizes and rad cap opens purge to the overflow tank and vented to atmosphere thru the quench volume and vented cap. That should have made your system water solid while running and temps holding normal. On cooldown the vacuum draw from coolant contraction will draw fluid from the overflow tank back to the rad thru the rad cap maintaining water solid conditions. The fluid exchange between rad and tank occurs every time you run the bike. Since the tank is vented to atmosphere water in the mix can evaporate out if the quench volume is too low leaving behind only antifreeze which isn't a great coolant.

The other options are; clogged rad air side (unlikely because the fan still affects coolant), bad water pump, or clogged coolant channels in the radiator.

atomsplitter said:

When the bike is cold (ambient) what is the coolant level in the overflow tank? If it's between MIN and MAX that's OK. If it's below MIN then your system is pulling in air on cooldown and that is migrating to the water pump suction side, and coolant flow is hampered. When your coolant was changed the coolant overflow tank should have been filled to well above MIN mark, then engine started to heat the system up. Any air in the system should migrate to the high point and when the system pressurizes and rad cap opens purge to the overflow tank and vented to atmosphere thru the quench volume and vented cap. That should have made your system water solid while running and temps holding normal. On cooldown the vacuum draw from coolant contraction will draw fluid from the overflow tank back to the rad thru the rad cap maintaining water solid conditions. The fluid exchange between rad and tank occurs every time you run the bike. Since the tank is vented to atmosphere water in the mix can evaporate out if the quench volume is too low leaving behind only antifreeze which isn't a great coolant.

The other options are; clogged rad air side (unlikely because the fan still affects coolant), bad water pump, or clogged coolant channels in the radiator.

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So update, i took it to the dealer, told them that its running hotter. I'm only semi-comfortable taking apart my bike, I'm not an engineer/mechanic by any means.
Right not coolant is between MIN and MAX. When I took the bike in, coolant was so low probably only drips left, but that was after a year.

I had some electrical problems with my bike, fuses were popping off, and at one point the radiator fuse went out, which cause liquid to sizzle out of the water pump during a ride in the winter (i believe its called) underneath my bike. This was last October. Since then I got the wiring harness fixed, no more electrical problems. Bike was fine but performance was off, this was due to 9 year old spark plugs which i finally changed.

The dealer took it for a ride this weekend, plugged in my bike, and even checked for trapped air in coolant system, and told me that they "burped" it sort of speak to purge out air that was there if there was any. According to them my Rocket is fine.

But for the life of me, maybe I'm paranoid because I recently fixed so much stuff on my boke, that maybe I'm paying to close attention to the heat? I just dont remember it feeling this way.

I remember the moment it felt hot, it was right after when I poured the fuel injector cleaner into my tank with a fresh supply of gas. I turned the bike on and honestly noticed it soon after, BUT that was weeks ago, and still it feels hot today.

The temps I displayed in the beginning of this post. Are those normal? What is considered dangerous levels?

I wish someone from NY was on here so I cans top by and they can teach me more hands on, I'd buy them dinner lol

So there was trapped air in it? Run OK/normal temp now?

R-III-R Turbo said:

So there was trapped air in it? Run OK/normal temp now?

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That's the thing, I don't know. They told me that they purged it, just in case there was trapped air. But it still feels hotter than usual to me. But they plugged my bike, rode it, and said that it wasn't overheating. So, I plugged it in my self after a ride, Coolant temp was between 110C and 115C. Is that normal?

buddazero said:

That's the thing, I don't know. They told me that they purged it, just in case there was trapped air. But it still feels hotter than usual to me. But they plugged my bike, rode it, and said that it wasn't overheating. So, I plugged it in my self after a ride, Coolant temp was between 110C and 115C. Is that normal?

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Is this the same dealer that had it recently?
Not sure if they're bleeding it right.

Just to verify the temp gauge is reading somewhat accurately. Could you leave the bike acclimatise for several hours then check what the ambient/intake air temp is and the coolant one too.
They should be close

R-III-R Turbo said:

Is this the same dealer that had it recently?
Not sure if they're bleeding it right.

Just to verify the temp gauge is reading somewhat accurately. Could you leave the bike acclimatise for several hours then check what the ambient/intake air temp is and the coolant one too.
They should be close

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I've had the bike off since 7:30pm, its 3am, I'll check it before I leave for work in a few hours and take a picture.