Rad cap effect on cooling

[budd]

I know the rad cap pressure rating as an effect on the cooling system (higher pressure rises the boiling point ?? ) and I've noticed the VTR gets hot when air isn't flowing through the rads, anyway I'm dismantling a race Subaru Impreza which is fitted with a 1.3 bar rad cap (same fitting), would there be any benefit (however slight) in fitting a 1.3 bar cap instead of thr OE 1.1 bar item? I already have the cap but wander if there's any point fitting it, I'm going to flush the system and refill with decent coolant, does the VTR require a specific spec coolant ? I was thinking Motul Mo-cool or VW G12+ or similar (altough it will probably be the G12 as I've got 5 litres in the garage for the Golf) would this be suitable for the VTR ?

[tony.mon]

IIRC there are two possible cap ratings for the Storm, I assume earlier and later ones.

A higher rating might prevent venting of excess pressure when the bike's been run hot and then turned off. (heat soak).
In those circ's it's not unknown for the coolant to boil as it soaks heat from the heads and cylinder areas, as with the ignition off the fan can't cut in.

(Unlike cars, and a lot of other bikes, that have a power supply to the fan circuit without ignition on, a security risk but better for the engine).

[sirch345]

Personally I'd stick with the right radiator cap. As for coolant/anti-freeze, the main thing is it's silicate free, and suitable for alloy engines which most are now-a-days,

Chris.

[budd]

thanks for the input, the difference between 1.1 and 1.3 bar is only 3 psi so it's not a lot but may just be enough to prevent loss of coolant in the circumstances Tony described, in all honesty I've never had my current or my previous VTR actually boil over but they have both got very hot (worryingly so) on occasion, usually when queuing and filtering is not possible (getting into a race meeting etc)
I may just try it in any case as I have the cap anyway, it can't do any harm.

Re coolant, I'm pretty sure VW G12 spec coolant would be OK for the storm it's the same stuff recommended by VW Audi Group for all their engines which include Bentley and even Bugatti, although it's possible there's a special (read more expensive) spec for the Veyron lol, either way I'm pretty sure it will be fine for the Honda.

[sirch345]

You must be expecting a hot summer

If you find the bike is still getting hotter than you would like with the different radiator cap, you could fit an over ride switch for the fan, which only works when the ignition is on.

Chris.

[budd]

You must be expecting a hot summer

If you find the bike is still getting hotter than you would like with the different radiator cap, you could fit an over ride switch for the fan, which only works when the ignition is on.

Chris.

I think fitting a override switch is a good idea, I could get the fans on at the first sign of queuing traffic etc , that way the fans are on before the coolant gets hot enough to trigger them, as for the hot summer I won’t be holding my breath, but in the unlikely event we get a scorcher then it will be nice to have given the big twin every chance of staying nice and cool.

[Diabolus]

ive never had mine go much above half way on the temp gauge even in traffic?? when does the fan kick in 3/4 s on the gauge??

[Wicky]

Never had a problem even in heatwaves. The most memorable was leaving Donington in 90+ degree heat at a snail's pace, and Hayubusas etc were falling by the wayside boiling over but the storm kept its cool and was nowhere near overheating. I was more hot and bothered in my black leathers acting as a heat sink in the sunshine.

[Stratman]

Never had a problem even in heatwaves. The most memorable was leaving Donington in 90+ degree heat at a snail's pace, and Hayubusas etc were falling by the wayside boiling over but the storm kept its cool and was nowhere near overheating. I was more hot and bothered in my black leathers acting as a heat sink in the sunshine.

Would have to agree - never recall the fans even having to kick in in such conditions (though they might) . The TDM, on the other hand, always runs hot in traffic on a warm day and the fans kick in and do their job.

[budd]

as I said I've never actually had the storm overheat, but both of storms I've had have got hot when standing for any length of time in hot weather , maybe I'm just been over cautious

[Wicky]

One of these...



or switch it off when standing still??

[budd]

not a lot of good when leaving Donington or similar, neither is switching it on and off on the plus side it soon cools down when on the move again.

[Diabolus]

ive never had mine go much above half way on the temp gauge even in traffic?? when does the fan kick in 3/4 s on the gauge??

any answers??

[Steve6088]

ive never had mine go much above half way on the temp gauge even in traffic?? when does the fan kick in 3/4 s on the gauge??

any answers??

Mine kicks in when the needle just passes 50%

[Hoppo]

Fit a second fan to the LH Rad? - If you haven't already