Cooling down the HOT beast (spal fans?) - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 13 (permalink) Old 09-09-2013, 10:29 AM Thread Starter
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Cooling down the HOT beast (spal fans?)

Alright, total noob here, had an RC before but not long enough to dicker with it.
What is a SPAL fan and how is the install (easy, hard, curse-your-mother hard?)
When I bought my baby on friday the first part of the ride was fine, made a couple stops, IKEA for 2 hours with the wife...but the 45 min ride home I saw my temps spike to 235-ish in traffic.
And the next morning it wouldn't start.
Turned the key, everything came on, fuel pump primed, hit the starter....nothing. It was making contact because the headlights went off. Anyway...long story short. After hours of tinkering and the glorious (albeit tedious) process of elimination, I followed the wires from the starter housing on the handlebar to behind the fairing (which I had to pull off for the first time in my life :O ) after some more investigation turns out the previous owner rigged the wire cluster around the fairing stay and the radiator fan rubbed right through the yellow/red with that is responsible for activating the starter motor. So...needless to say I believe that is why my temps were so high because the wire cluster was slowing the fan. However, after splicing and taping and zip tying that whole mess away from the fan, I notice my temps still float around 220. I'd like to see them cooler...
Sorry for the novel, just patting myself on the back for fixing it and not paying someone else to do it.
It gets really really hot here, in the summer, 100+ for weeks straight, and sometimes I have to sit in traffic.
I've been perusing the forum, and mostly what I've gathered is front mounts help mostly when moving (logical...makes sense) so changing the fans and adding a manual switch seems best for a preemptive strike against the sweltering heat that threatens my twig 'n' berries...

Sorry for the novel
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post #2 of 13 (permalink) Old 09-09-2013, 10:54 AM
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If you are comfortable fabricating up a few small brackets to hold the fan(s), it is not a big problem. They are not a direct (plug and play) replacement.
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post #3 of 13 (permalink) Old 09-09-2013, 10:59 AM
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220 would be a normal temp in hot weather and especially if you are in stop and go traffic. The fans will come on at 220 and go off around 209.
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post #4 of 13 (permalink) Old 09-09-2013, 11:00 AM
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On a different, although related, topic ... I met a guy that was heavily involved with RC51's back when they were being campaigned. He is, and was, a top shelf mechanic with loads of RC knowledge. He mentioned that Honda was aware of the shortcomings on the RC cooling system and added in a little "tweak" to band-aid the issue. It seems that the ECU will go "pig rich" on fuel when the temps go much over 200 degrees, in a effort to cool the cylinders down. I have experienced that when stopped at a light, the temps rose to 220 and the light turned green. I took off but the throttle response was really odd. Once the bike cooled down, all was well again.

That is the primary reason that I added the Spal fans and manual switch. With the fans running, the bike stays around 180 degrees. Without the fans, the temps fluctuate significantly, depending on the air flow.

Last edited by 92VFR; 09-09-2013 at 11:02 AM.
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post #5 of 13 (permalink) Old 09-09-2013, 11:42 AM
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I noted on a ride in about 90-deg weather yesterday that at a constant 45 mph my bike seems to just maintain whatever temps it's at*. It took 50 mph or higher to actually lower the temp. 185 is what it would consistently drop to whenever we'd maintain 60 - 70 mph speeds.

* unless it was 219 or higher, then of course the fans come on, and I agree with Mike that the fans bring it down to about 209 and then shut off

It's just a hot runnin' beast.

However ... a 2012 Kawasaki Concours (with 9K miles) riding with us ... when we stopped and shut down after having just ridden 65 mph for ~10 miles his fans were running. So we're not the only ones.
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post #6 of 13 (permalink) Old 09-09-2013, 12:03 PM
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People accused me of being OCD for wanting to keep the temps under 200, saying that Honda intended the engine to run over 200, as evidenced by the fact that the fans do not start until 220+, and only bring it down to 210. I have noticed the motor running different when over 210, although I have not seen it over 222.
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post #7 of 13 (permalink) Old 09-09-2013, 01:48 PM
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Back before emissions equipment was mandated (pre-'70s), 180 deg F was the normal operating temp.
Engines (cars and bikes) these days run around 200 deg F by design, purely for emissions control.
I wouldn't get too bothered by temps around 218-221.
On the other hand, 251 deg F is a cause for concern. Pull off, kill the engine, and let it cool off of risk damage.

Even my FZ1 routinely cycles up to 218 deg F during traffic stops (and it has a front mounted radiator and two fans).
If I ride it on the freeway for a short amount of time, it will eventually drop to around 180 - 195 on average.

And my VFR800 at a stop will ramp up to 228 deg F., and no amount of freeway running seems to drop it below 200 deg F during the summer.
Like the SP1, it too has side mounted radiators and a single fan on the right.

Last edited by SubSailor; 09-09-2013 at 01:52 PM.
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post #8 of 13 (permalink) Old 09-09-2013, 01:53 PM
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I wish these bikes could be cooled if for no other reason than to keep the heat from blowing on me.
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post #9 of 13 (permalink) Old 09-09-2013, 02:20 PM
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On Sunday I went for a ride around 2:00pm, hottest part of the day. I got to a long traffic signal and flipped the manual fan switch to keep the bike from getting hot. When the light changed, I forgot about the switch and got on the interstate. After a few minutes, I noticed that the bike was running a solid 175 degrees and realized that the fans were still on. I flipped them off and the temps slowly got to 180 and remained there while I was on the interstate.
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post #10 of 13 (permalink) Old 09-09-2013, 03:02 PM
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Quote:
Originally Posted by extrapolator View Post
I wish these bikes could be cooled if for no other reason than to keep the heat from blowing on me.
I wish the frame was cooled! I cannot believe how big a heatsink that thing is.
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