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Post by tom93gts on Sept 3, 2013 17:43:21 GMT -5
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Post by pmcburney on Sept 3, 2013 17:59:49 GMT -5
I thought I read somewhere that the RE5's cooling system was way over-engineered, and that you could transplant the much smaller GT750 radiator onto an RE and still have plenty of margin ? There's a reason why Suzuki had the fan switch set the way it is. As much as you'd never want an engine (especially one like the RE5's) to overheat, you won't get the best out of it if runs too cool either. I live in sunny, humid Brisbane. It gets to a balmy late 30C to early 40C in summer with 75-100% humidity. I have NEVER had the fan cut in on my RE5, even at the height of summer in gridlock. In fact, the temp gauge has NEVER risen much above halfway, ever. My bike actually runs slightly hotter in the cooler months as the thermostat is set to open somewhat above halfway, i.e. if the thermostat opens above the halfway mark on the temp gauge, it's hardly likely that you need the fan to cut in at that point. Personally, given the amount of redundancy built in to the system (as long as its in good condition and working correctly), I think your reservations about your fan and its switch are entirely unfounded.
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ap951
2nd Gear
Posts: 280
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Post by ap951 on Sept 3, 2013 22:32:43 GMT -5
well....since you brought it up
my GT750 does not have an electric fan (although the mounts and wire connections are there) Many times I have ridden that bike in stop & go traffic on 100+ degrees F and NEVER did I see the needle on the temp gauge move from the first dot that indicates when the thermostat opens. I think Suzuki put fans on the first year or two GT750's but then realized that the bike just does not need it
overkill indeed
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Post by tom93gts on Sept 3, 2013 23:44:59 GMT -5
Humidity actually helps with cooling, moist air has really good thermal conductivity. In the dry Phoenix air with 110F (43c) temperatures my fan runs all the time and the temp gauge hangs out up on the last line just before the red marks if I get stuck in any kind of traffic. The re5 cooling system most certainly isn't over done unless the bike wasn't intended to be ridden in hot weather.
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Post by wayne on Sept 4, 2013 5:05:33 GMT -5
Going way back to what Rog said in one of the earlier posts to this thread, I agree. If you're running hot easily, then the general set up is not right but you're onto that now.
When my RE came out of storage 14 years ago, it would run hot easily, fan would come on in traffic etc. After everything was setup as best I could, radiator cleaned and all hoses clear, it never overheats. I've ridden the bike on a 42 C day with no issues. Paul seems to be finding the same thing. And further to what Paul suggests re the radiator, I've heard, perhaps from Sam, I don't recall, that the RE radiator was so large because it was intended to also support the twin when it came out.
Normal running, the bike is always to the left of center. High speed open highway, say something over 70 mph the temperature will drop to around 1/3 needle deflection. Only in traffic on a hot day will I see it over the half way mark and then only by a bit.
As for GT750's, same same Bill. In fact the general rule we followed back in the day was that if the needle moved, something was wrong. I knew one bloke once who ran his GT out of injection oil and rode some hundred miles or so. He said that the only thing he noticed was that the temp gauged moved a fraction from just to the left of centre to the mid mark.
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Post by pmcburney on Sept 4, 2013 6:34:05 GMT -5
And further to what Paul suggests re the radiator, I've heard, perhaps from Sam, I don't recall, that the RE radiator was so large because it was intended to also support the twin when it came out. I'm sure you or someone else in the know told me that Sam raced his REs with GT radiators as they were smaller and a bit lighter, and the engine just didn't require the larger radiator to stay cool, even under race conditions . I know the temp on mine only stays fairly constant in warm to hot weather. In cool conditions, it fluctuates wildly as the thermostat opens and closes in a vain attempt to maintain a constant temperature. That to me points to the stock radiator being way too capable of cooling the engine.
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Post by Glenn RE5 on Sept 4, 2013 7:01:09 GMT -5
Safe to say that the stock thermoswitch for the fan on my bike is close to 40 years old so maybe its slow to respond to turn the fan on/off, Any one who finds the fan coming on close to red could maybe give the honda one a try, And yes i worry about overheating, Like i said its fine on the open road,
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Post by goandy on Sept 4, 2013 7:28:17 GMT -5
From memory the fan switch cuts in around ?110 celcius. I'd imagine that would be just under red on the guage, if it's reading correctly. Mine reads way out because the voltage reg in the dash is obviously on its way out.
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Post by Glenn RE5 on Sept 4, 2013 13:54:36 GMT -5
I just can"t understand why Suzuki/ RE5 owners would want the fan to come on close to the red line, Modern vehicles hold a steady temperature,If my car temp gauge ever moved above half way i would worry,I understand for most it not problem but one day it could save your rotor from overheating by having a wider safety margin,Is it safe to run a RE5 in the red zone ?
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ap951
2nd Gear
Posts: 280
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Post by ap951 on Sept 4, 2013 16:58:52 GMT -5
I think having the cooling fan turn on earlier is a good idea. True, engines need heat to run properly but this is what the thermostat (restricting coolant flow) is for. All you want to do is have the fan come on sooner to keep the temp closer to the point that the coolant thermostat fully opens
I am concerned about the condition of your radiator Glenn.
You're bike seems to run hotter than mine or what others are expressing on this forum. The fan on my bike never turns on when I'm riding it however the needle on the temp gauge seldom goes any higher than the half way mark. If the bike sat for a long time it could very well be that the radiator has deposits & the coolant is not flowing through it like it should.
can you find someone who can clean the inside?
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Post by Glenn RE5 on Sept 5, 2013 0:00:41 GMT -5
Thanks for that,I was asking in part a theoretical question, For me and other members who may be running the bike while working on it or in other circumstances when it runs hot the manual switch helps, A thermoswitch with a lower heat range could help to keep a more even temperature over a longer period, In may this year my thermostat failed to open and it went into the red zone for a short time, Did this sow the seeds to my other post RIP ? The rad has had a recore and all hoses replaced etc, To be honest i don"t ride at high speed and mostly urban riding,
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Post by wayne on Sept 5, 2013 1:23:10 GMT -5
With a new core and hoses I would imagine that you've gone a long way to ensuring a good system there Glenn.
I wonder if it's as simple as a dicky temp gauge regulator as Andy is experiencing ? I've recently replaced one that was reading very hot all the time. Turned out to be the gauge, not the coolant temperature. When I tested another (per the book), it was well off what it was supposed to be.
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Post by Glenn RE5 on Sept 5, 2013 16:21:11 GMT -5
Ive fitted a 7.4 volt regulator from a model car and works well, Most of the time the gauge is in the middle, The thread is open to anyone to view lets hope some where down the line the advice is a help to someone, Thanks for your views on the topic,
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Post by HGH 770N on Sept 6, 2013 16:09:18 GMT -5
Glenn. on my way to Derbyshire from Coventry my bike started to miss and splutter and run hotter, I pulled over and checked the plug, and then the oil and water, All were fine and the bike had been fine before and covered 160 miles , My thoughts were CDI unit or something more serious as yours was, It turns out it was my points were loose, I adjusted them by eye and continued my route for a further 70 miles until I was home. The Temp gauge showed it was running a bit hotter especially in traffic, this was due to the timing being out with me guessing the points adjustment. This can also happen if your advance and retard "BOB Weights" come loose or jam open with no spring . This BOB weight issue has been covered before, the timing on these bikes is very important and can make a world of difference from how they perform and the temperature they run at. Set your points and the use a Strobe light to check you advance curve .
Rog
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Post by Glenn RE5 on Sept 6, 2013 17:48:16 GMT -5
Many thanks for your help HGH 770N [rog], Sorry thread on this is closed as its turned cooler in the north of UK today and the bike runs fine now no fan needed,So the switch is for hot still days when stuck behind a a--- h--- in a car stuck in traffic on the seafront when the air temp above 25degres
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