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Another (minor) heating issue

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Ayep
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Another (minor) heating issue

Post by Ayep on Thu 26 Feb 2015, 10:30 am

Hi all,

Firstly, I hope this is being posted in the right section ; if not, apologies in advance.

Now, regarding my issues, I think I have a good plan of action to work out what's going on, but I figure I may as well share and bounce ideas around. Feedback and ideas are always useful and welcome!

The symptoms
The Bike suddenly started heating more than it used to. This means that even during spring and autumn, and mild winter days (dry), the fan can potentially switch on whilst driving in town. This never used to be the case. Outside of towns, on hot summer days, it's fine as long as it keeps driving, but still seems to run warmer than it used to on mountain climbs etc. I have to be more weary and alert and kill the engine in town on mild/warm days.

First thoughts
is it really the bike heating more, or is the thermostat being ill-behaved (fan switching on earlier than before, gauge badly calibered or defective)? I suspect things are running generally warmer (I think it's simply more likely). Based on that assumption, two possibilities : either the engine is running a lot hotter (bad news for sure), or it is the cooling system that is no longer as efficient (this is what I have been exploring most)

What has been done
Over a year ago, February/March 2014 :
- The thermostat beneath the radiator cap was tested (boiling pan of water) - seems to open up fine.
- coolant was changed. No mayonnaise in the old one (phew).
- Water hose was inserted at top end (radiator cap), to try to flush any sediments out of the bottom end. No sediments were seen. It is possible I didn't flush correctly (how do you force flush in the opposite direction of normal coolant flow?
- New coolant : Engine was left idling until warm, coolant topped up to get rid of any bubbles. Expansion vase level was checked ; seemed OK.
- First long summer trip, just after this. The bike had a piddle on the pavement as I parked it in a town. Possibly related to the fresh coolant change, and a excess of coolant?
- Checked radiator fins - seemed fine, no blocage (outside blocage, that is).

Today :
Forgot about it until recently, apart from having to be a little careful, the bike seems to run fine so I left it (time is always lacking). I have ridden 9000 miles since then (around Corsica, in the alps, in the blazing hot sun...), no change in behaviour. Apart from towns, it's OK. Am I right in assuming that things would have worsened if it had been a head gasket?
My aim is to try to fix it before the spring/summer...

Plan of action :
- Change of oil next weekend (check for mayonnaise, in case)
- Remove fuel tank, check coolant level (plus level in the expansion vase, although very difficult to see!)
- Possibly, I could try running without the thermostat (under the cap), which means the coolant should be free flowing all the time (--> bike should take longer to warm up), but I fear I may be wasting my time here, as it was checked and opens in boiling water.
- Removing coolant, checking for mayonnaise
- Possibly, trying to give the system another flush (reversing flow somehow?)
- Pump inspection. That has never been done yet. I am dubious though, as it is mechanical, and the change in behaviour was sudden (apart from the fins corroding out progressively, can a pump give in suddenly)?
- Pressure check. Could it pressure related? A cooling circuit than can no longer maintain a high enough pressure, which leads to air bubbles? In which case maybe I should check the cap...And what else?
- Failing that, I'm out of ideas.

Suggestions?
Thank you for reading ! If you have any answers to my questions, or any suggestions on what do to or what I might possibly have missed out, I'd love to hear about them...
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Flyingbrick
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Re: Another (minor) heating issue

Post by Flyingbrick on Thu 26 Feb 2015, 11:13 am

Hi there,

a destroyed waterpump is unlikely, but there has been one issue that happened to a friend of mine who bought a CB and wondered about the heating problems. This is what he found:



The pump blades broke off and metal parts have been disposed all inside the engine, radiator and hoses. Even that engine was still running and the cylinder head gasket survived that disaster although the problem did not occure suddenly.

But, once again, this is very unlikely and would mean that the fluid colour appears brown instead of blue, green or pink.

What happens much more often is that the radiator cap is faulty, which means, the gaskets do not seal how they supposed to do. This may cause a leakage (the fluid is going to boil and its volume increases), but this happens not in any case. So, if a cooling problem occurs, a new filler cap sounds like a good plan.

The thermostat is not prone to fail on a CB, I haven't seen any faulty one by now. It may be checked when the fuel tank is off. Just keep the engine running and check if the hoses leading to the radiator are getting hot after a while. An infrared thermometer can be usefull; the opening temperature should be about 85-90 degrees centigrade.

What I've heard about are leaking hoses (including the "Y-shaped" junction next to the thermostat) and faulty fan switches. The fan switch can be checked easily by shortening its wire to ground, i.e. to the frame bolts next to it. If you do so, the fan should rotate immediately. According to your description, it does.

Which type of fluid did you use? I prefer the G12+/C12+ which is pink/violet, this fluid may be mixed up with any other fluid. It can be seen inside the coolant expansion tank easily using a torch. An insufficient mixture will cause overheating as well. By the way: it is not recommended to mix the elder fluid types such as G11 and G12. This would cause a corrosive mixture and interferes the cooling. So, when changing the fluid, assure that the expansion tank is emptied as well. Opening the drain plug at the water pump is not sufficient, the tank contains another 500cc of fluid.
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Re: Another (minor) heating issue

Post by eternally_troubled on Thu 26 Feb 2015, 12:32 pm

Sorry to ask more questions (esp. after your long descriptions):

So today, if you were to intentionally let the bike get hot (say, leaving it to idle), what would happen?

On my bike the coolant temperature would rise (observed from the gauge) and when it gets about 1/4 away from the hot end the fan kicks in and the gauge falls to about half and the fan turns off again.  It continues to do this ad infinitum (assuming it stays warm enough).

If yours does something else then there is still a problem...  luckily as Michael says it might be as simple as your cap not sealing properly (if the system does not seal properly and a high enough pressure cannot be reached, the coolant will boil at too lower temperature, steam will be created and the coolant can be pushed out all over the floor).
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Thu 26 Feb 2015, 12:48 pm

Hi,
 
Thank you for your suggestions.
 
@Flyingbrick
Quite a scary happening that water pump! Presumably they are easy to remove, once the fluid has been emptied? Just a few screws? I figure it can't do any harm to take a quick peak at it next time I change the coolant...
 
The radiator cap is an interesting one. I guess it could explain the problem. presumably a faulty cap means it won't hold the pressure in the system, which will leak a bit initially hence allowing air bubbles back in the system afterwards? I'll pursue that hypothesis. Although I still think fluid flow in the system could also explain it.
 
I've checked the thermostat using a pan of boiling water. I don't know the exact temperature, but it definitely opens up when the water starts boiling.
 
Another thing I'll check more thoroughly is any signs of leakage (but I have already inspected). Regarding the fan switch, I haven't checked it ; pretty sure it works fine since the fan switches on! And the overheating is not related to the fan not switching on, it's a general symptom.
 
Thank you for the comment about changing the fluid in the expansion tank too, I'll keep that in mind. i've no idea what type of coolant I'm using, I bought some standard car coolant, it happens to be yellow. I'll take a look next time...


 
@eternally_troubled

I’ll check to be sure. But what I assume will happen is that cycle of fan switching on, cooling down a little, and getting hot again. Except I suspect it will also « piddle » through the expansion tank overflow tube (where the centre stand is), as it did initially. Once coolant is pushed out, I assume this can lead to air bubbles in the system, which in turn will lead to less efficient cooling and therefore hotter running temperatures ?


Edit : I respond to my own questionning, with more questions. But if initially (after topping up the coolant), the first "hot run" caused the bike to release excess coolant via the expansion tank overflow, that would mean the excess pressure is driven through there, and that the cooling circuit, as it cools down, would then suck any missing fluid back in via that same expansion tank. This would mean air bubbles would not be the cause of the overheating?
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Flyingbrick
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Re: Another (minor) heating issue

Post by Flyingbrick on Thu 26 Feb 2015, 2:46 pm

Regarding the Pump: yes, as shown in the picture you could disassemble it easily. Anyway, I wouldn't suspect the pump as long as any other fault is excluded.


The filler cap has two sealings. The upper one assures that no fluid is leaking out at the radiator. The other one is inside the thermostat housing. If that one leaks, coolant fluid will flow constantly to the expansion tank as soon as pressure exists. The end of this process is reached when nearly the complete fluid has flown to the tank. This is why the tank overflow leaks and not the radiator.

So, in my humble opinion the filler cap is likely to cause the trouble as long as the coolant mixture is sufficient.

BTW: to empty the overflow tank, you could use a brake bleeder (Mytivac or what else is available) or, if none is available, just pull away the overflow hose coming from the radiator. It is accessible next to the swing arm.
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Re: Another (minor) heating issue

Post by HomeBrew on Thu 26 Feb 2015, 4:38 pm

My bike had almost identical symptoms, a new radiator fixed them. The old radiator was old and corroded, had mud deep in the fins that wouldn't wash out, and was not cooling as it should.
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Fri 27 Feb 2015, 9:13 am

Hi,

@Flyingbrick
I found another post on this forum where someone had a faulty pump, which physically looked fine :
http://www.cb500club.net/t203p60-engine-overheating-and-hot-water-steam-coming-from-overflow-pipe
Not sure how that can be, as it is a mechanical pump. But I've PM'ed the person to find out more.




So, in my humble opinion the filler cap is likely to cause the trouble as long as the coolant mixture is sufficient.


Presumably, you mean the filler cap is NOT likely to cause the trouble as long as the coolant mixture is sufficient? I presumably have to check both levels : in the cooling circuit, and the expansion tank.


@HomeBrew
Thanks for sharing. I'll double check. How thin are the tubes within the radiator? Could the blockage be inside? My garagist had a quick visual inspection of the radiator, and said the fins looked fine (no apparent blockage on the outside of the radiator).

Looks like I still have quite a few things to explore. Next time I run the bike I'll leave it to idle and report on it's behaviour...

Thanks again for the ideas.
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Re: Another (minor) heating issue

Post by Flyingbrick on Fri 27 Feb 2015, 9:47 am

No, you probably got my wrong. Sorry for my broken English, I'll try to improve it Wink

First of all, what you need is a sufficient mixture of 50 % water, 50 % coolant. Do not mix up different types of fluid as this could cause corrosion and insufficient cooling.

If a proper mixture is assured, it is likely that the filler cap is causing the problem.

Yes, you have to check both levels. Fill up the radiator to the top and the expansion tank to maximum -use a torch to judge the level. In total, nearly two liters are needed in a 50:50 mix. If you cant fill in as much, a scrap of old fluid remained in the expansion tank.


I've read the thread regarding the faulty pump but I have no clue why a pump that was looking as fine as it did could harm the cooling.
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Fri 27 Feb 2015, 10:41 am

@Flyingbrick wrote:No, you probably got my wrong. Sorry for my broken English, I'll try to improve it Wink

First of all, what you need is a sufficient mixture of 50 % water, 50 % coolant. Do not mix up different types of fluid as this could cause corrosion and insufficient cooling.

If a proper mixture is assured, it is likely that the filler cap is causing the problem.

Yes, you have to check both levels. Fill up the radiator to the top and the expansion tank to maximum -use a torch to judge the level. In total, nearly two liters are needed in a 50:50 mix. If you cant fill in as much, a scrap of old fluid remained in the expansion tank.


I've read the thread regarding the faulty pump but I have no clue why a pump that was looking as fine as it did could harm the cooling.



Ah OK, thanks for clearing that out, got it. More of a logic problem than an English one ; getting technical things across on a forum is not always easy I find!

I'll flush everything out, including expansion tank (I'll check liquid colour etc), and replace with new (darker!) cooling fluid. I'll also check the pump for physical signs of wear and tear, and take it from there. Also, i'll see if I can find a cheapish second hand rad cap, it may be worth changing it anynow...
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Re: Another (minor) heating issue

Post by eternally_troubled on Fri 27 Feb 2015, 1:54 pm

To add to all that (and answer one of your questions from above):

When the coolant gets hot it expands a bit and gets shoved into the expansion tank; when the system cools and the coolant contracts it should suck coolant in from the *bottom* of the expansion tank and hence not suck in air.

If you completely fill the system and *completely* fill the expansion tank (to the brim) and then run the bike up to a (hot) temperature, some coolant will overflow out of the expansion tank - you could catch this in a clean bowl just in case you need it later. This is normal (the expansion tank isn't meant to be full to the brim). The overflow should stop once the bike is up to temperature.

If you let the bike cool down (say, overnight) the coolant should be sucked back into the system and you should see the level in the expansion tank decrease; if you then do the same thing again (and get the bike hot) no coolant should be ejected from the tank as it will now be at the correct level.

Hope that helps. Good luck!
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Sat 28 Feb 2015, 11:57 am

Thanks for the additional ideas. In the past, I have only filled the expansion tank up until the "MAX" mark. It's still possible that there is a leak somewhere (cap...), which could lead to air bubbles and and inefficient cooling. I've yet to leave the bike to idle and see how it behaves once it's get hot.

However, I found a cheap pump that is is in alleged working order (pictures look fine, looks new), and bought some G12+/G12++/G13 VAG (volskwagen) purple coolant, which is miscible with other coolants. The colour should help considerably when checking for levels. I may as well check the pump and change it ; something to rule out (or possibly solve the problem!) Will report back once I have new info!

Cheers again for the help.

Tony
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Re: Another (minor) heating issue

Post by Ayep on Tue 14 Apr 2015, 2:18 pm

So, here's an update, at long last.

I've changed the water pump. The whole bl**dy thing. I nearly soiled myself when I saw the dark liquid in the hole, stuck my finger in it, before realising it was oil! Of course, makes sense, but well, had forgotten my schematics. 

The old pump visually looked fine (annoying in a way). Let's hope I haven't worsened things with possible leaky gaskets from changing the whole thing now. Also, the 2 pump screws (attaching the whole thing to the carter) from the old pump were in a weird state. Top one was completely white and calcinated ; bottom one had loads of dark oily muck on it.

Anyhow, I filled the whole cooling system with the G12/G13 purple VAG coolant, as recommended. The expansion tank was massively overfilled, I presumed it will piddle like crazy once it gets warm for the first time. I'll keep a bottle under the overflow...

However - I did notice one thing, seems strange. The purple coolant is translucid new. But once in the expansion tank, it's seemed very opaque. How could this be? Incidentally, the previous coolant was yellow, and translucid when removed, both in the expansion tank and the circuit. Incompatible coolants? Seems unlikely...

Next plan of attack :
- Let the engine running, let it heat up, up until the fan kicks in. Let it cool down.
- Top up coolant under the fuel tank.
- Drive a bit and see how it behaves... I'm hoping for a miracle cure. Really. I may even drive it down to Lourdes if it carries on like this. Smile
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Re: Another (minor) heating issue

Post by teamster1975 on Tue 14 Apr 2015, 5:07 pm

Would be worth getting a sniff test done on the coolant as even if there's no mayo you can still get a head gasket leak between the water jacket and one of the cylinders.
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Wed 15 Apr 2015, 8:16 am

Hi,

Thanks for the advice, but I've driven 10000 miles since the problem first appeared - wouldn't a head gasket problem have worsened considerably since then?

Can sniffer tests be acquired cheaply (couldn't seem to find cheap ones), or is that something to get checked through a garage?

Cheers
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Re: Another (minor) heating issue

Post by stormbringer on Thu 16 Apr 2015, 9:53 am

I can provide this bit of info:

Recently, I had the valves checked by my local Honda pro. I was recommended to have the thermostat checked while it was in for this service, as the mechanic had seen all too many cases of neglect on this part of the bike. Two parts fail; the thermostat and the filler cap. And yes: thermostat had gotten 'slow' (documented by photos of Old & New in hot water) and the filler cap rubber had cracked - I saw the old one myself when I picked up the bike.
Both components renewed, fresh coolant, valves done. Proper job.

So, filler cap and thermostat.
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Re: Another (minor) heating issue

Post by jchesshyre on Thu 16 Apr 2015, 11:41 am

I had a similar problem a while ago (here http://www.cb500club.net/t2839-another-puzzling-cooling-issue) and I solved it more or less with what I think was a combination of actions. I replaced all hoses and clips, replaced the o-ring in thermostat housing, replaced the pressure cap, and flushed the system several times.

I still think the bike's running a tiny bit hotter than it 'should' be (based on my previous CB500 and the general consensus that they run very cool) - the temperature stays very low on the open road but increases once in town a bit faster than I'd like.

One think worth checking is the three hoses that route coolant through the carbs - they can be tight enough to not leak coolant but still let a tiny bit of air in as the system cools down. Also I think I had a blockage somewhere in that system meaning that the coolant wasn't flowing through there, possibly even leaning the mixture a tad and thus compounding the problem.

It's a frustrating system to work on because there are so many factors which can cause it to run OK but not optimally. I'd say be patient and systematic and basically check every single point in the system that could either be leaking coolant when the system is pressurised, or air when it's under vacuum as it cools down.

I would say definitely replace the pressure cap, and if at all possible get a new, OEM one. A second-hand one could look fine but still not work properly.
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Fri 17 Apr 2015, 9:42 am

Hi,

Thank you all for your advice. This is the latest news ; I've driven it 25min in town (hot day, 26°C). No fan switching on, but still, got warm rather quickly. When I arrived, left it to idle on purpose to see what would happen. After a few minutes :
- The temperature gauge got to half way (ever so slightly above), before the fan kicked in.
- The fan would take the gauge down a tiny bit (back down to half way), before switching off.
- Fan cycles were as following : ~50 seconds fan OFF, ~20-25 seconds of fan ON . Temperature gauge didn't shoot up at any point, nor did coolant leak anywhere. Good sign!

I still believe the bike runs hotter than it used to. I've yet to understand why. I believe my next steps are the following :
- Continue checking the cooling system (change the filler cap, change the thermostat (in case), possibly, try flushing the whole system and using a special product to decalcinate/clean muck before filling it up again (although, the change in behaviour was sudden, so seems unlikely)).
- Figure out whether it's the engine that's overheating : sniffer test (no idea how to go about this yet) to check the gasket... Anything else? (Of course a leaky head gasket would imply insufficient cooling of the engine, not necessarily an engine running too hot (too lean for example). Could bad valve clearances be an issue?

It's a strange problem. i'll have to be methodical and  patient. It doesn't seem critical, especially as I've driven 10000 miles since it first happened ; and yet I'd love to figure it out!

One thing I'm considering is getting an oil temperature gauge. Getting an accurate reading on engine oil temperature could help me understand if the bike is actually heating too much or whether it's fine as it is... Of course I could compare, in similar condition, the oil temperature of one CB with another...

Cheers,

Tony
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Re: Another (minor) heating issue

Post by jchesshyre on Fri 17 Apr 2015, 9:46 am

Your description of the timing of the fan cycles sounds identical to mine.
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Re: Another (minor) heating issue

Post by eternally_troubled on Fri 17 Apr 2015, 12:53 pm

Yeah, sounds pretty similar to mine too - as far as I know my cooling system works fine.

If I were you I would be tempted to leave it for a little while longer (and a few tanks of petrol) before taking anything else apart, just in case it either:

a) goes horribly wrong and spits the coolant out everywhere

or

b) gets better (cooler) and the problem goes away


Also, in this time the weather will get hotter as we get into summer, so the load on the cooling system will be greater which will exacerbate any problems that are left.
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Re: Another (minor) heating issue

Post by Gonzumzum on Fri 17 Apr 2015, 1:09 pm

Is there any possibility for a lean mixture to cause this?
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Re: Another (minor) heating issue

Post by jchesshyre on Fri 17 Apr 2015, 1:24 pm

Yes, and I wondered whether this was the cause with mine. I use a Fuel mini exhaust with the baffle in, which shouldn't require a re-jet, but my spark plugs are on the grey side of ideal, not tan coloured. 


Eternally_troubled's advice to leave it for a few tanks' worth of riding is good. I did this and mine definitely improved. When I removed my pressure cap yesterday (it's been nearly 10,000 miles since I last did) the coolant was right up to the filler neck, so I have no leaks or bubbles. I think I'm right in thinking that providing there aren't leaks, the cooling system is self-bleeding of air - bubbles work their way up to the top and out of the expansion tank, and then the space they were occupying in the system is replaced with coolant from the expansion tank as the system cools down. Correct me if I'm wrong. 
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Re: Another (minor) heating issue

Post by eternally_troubled on Sat 18 Apr 2015, 12:26 pm

[quote]...tell me if I'm wrong...[\quote]

Maybe... Smile

Yes, any bubbles that end up going to the expansion tank will be removed, however I don't think the expansion tank is the highest point of the system (I believe the cap is pretty much the highest point), so any air knocking around will eventually end up as an air-gap under the cap, as far as I understand it.

Now I think that I might be wrong... hopefully someone that knows will inform us!
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Ayep
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Re: Another (minor) heating issue

Post by Ayep on Mon 20 Apr 2015, 9:11 am

Well, thank you all for your input. After running a fuel tank worth of fuel, not sure what to think ; things could possible be a little better, but still not optimal.

I'm going to remove the tank, top up the coolant (make sure there were no air bubbles), and let it run throughout a few warm weeks and see how it goes. At least it doesn't appear to be critical, since the temperature remains well within standards and there are no apparent coolant leaks when the fan cycles start.

If I can find a cheapish way of doing a sniffer test I may as well do one, just to be on the safe side... I'll keep in mind the thermostat and the cap, as well as the carburettor hoses.

In addition, valve clearance checks and a good syncing of the carbs can't do any harm (I'm struggling with the latter - need to research it on the forum!.

Will report back in a few weeks or months !

Cheers,
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Re: Another (minor) heating issue

Post by eternally_troubled on Mon 20 Apr 2015, 1:21 pm

@Ayep wrote:
In addition, valve clearance checks and a good syncing of the carbs can't do any harm (I'm struggling with the latter - need to research it on the forum!.

Which bit were you struggling with?

If you want to do this properly you'll need some gauges...

they can be made for almost nothing:

http://www.instructables.com/id/DIY-DualTriple-or-Quad-Carburetor-Sync-Tool/

you can get some from ebay, or more expensively you can get some Morgan Carbtune ones:

http://www.carbtune.co.uk/


and you'll probably need an auxiliary fuel tank, something like this one:

http://www.ebay.co.uk/itm/SEALEY-MS029-MOTORCYCLE-BIKE-PORTABLE-MAINTENANCE-FUEL-TANK-1-LITRE-/310546489269?_trksid=p2141725.m3641.l6368

it is possibly to balance the carbs using the fuel left in the carb bowls (hence no need for the fuel tank), but it is easier not to have that time pressure!
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Re: Another (minor) heating issue

Post by Ayep on Mon 28 Sep 2015, 10:43 am

Hi all,

A quick update on the situation!

The hot summer months are over ; bike never got to the red zone, so things are not critical. It still heats up more than it should do, but I guess things are manageable. Now, new info :

Yesterday I noticed a fes drops under the water pump, coming from the hole --> means whole water pump is a dudd basically, those gaskets can't be changed. So, I reverted back to my older water pump (I had changed it for a cheap ebay one, bad luck, but for 5 euros can't complain). Yesterday, I filled the bike back up, evacuated bubbles as best as possible, and noticed that the bike seemed to be running hotter still. Next steps :

- remove tank, check I was effective in removing air bubbles initially... ANd if so, look for another pump. Maybe that explains at least part of the problem. Still weird, as the pump looks just fine (fins are all OK...)
- I'm going to go search for : new(ish) filler cap + thermostat (may as well change just to rule them out).
- check the valve clearances (time is the issue! And while the bike is apart, I can't use it...), although engine runs great and the change in behaviour was sudden, so seems unlikely
- THis winter, if I find a secondary bike to run in the meantime, take the engine apart and check / change the gaskets, do the works.

Not much luck in resolving that one so far. ANd I'm still adamant : that CB is running hotter than my other one... Strange.

Anyhow - will keep you posted!

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