Dropped valve?

The air cooled engines put exhausts at the front to maximise air cooling. Full liquid cooling allows a down draught intake and exhaust. The cooling medium can be water or oil. Oil however needs a faster flow rate because it's less efficient at absorbing heat. By the way Rolls Royce Merlins ran on 100% glycol and most vehicles use a 50/50 water glycol mix.
Glycol improved the metal wetting - better active surface area to transfer heat. Oil is already very good at wetting the metal surfaces.
Here's another water cooled engine with down draught intakes. All the way back to 1975 - and its a four-banger
130175991c50f8c80070d342b49d0d1e.jpg
 
Water-glycol cooling allows a smaller fluid flow rate and smaller galleries inside the engine. However a leak or failed cooling pump will quickly boil the small fluid volume.
Car engines have run small volume cooling systems for many years but over 10 years old (usually with minimal maintenance) risk at least a blown head gasket when the coolant leaks or pump fails.
 
When the Gold Wing was introduced it was seen as huge, both physically & in engine capacity. Nowadays it's looks a nice compact motorcycle.:rob
 
300kg and 80bhp is pretty lardy, but it was based on the Honda Civic car engine. Kawasaki Z1 900 was no featherweight at 230kg dry but gave similar power.
Strangely the Yamaha XJ900 was only a few bhp higher (90bhp) with Kwak similar weight (238 kg dry).
 
Some good news. It turned out to be a distorted pipe on the fuel injection. Mechanic wonders if the bike has been dropped on its side at some point. Bike now repaired and am collecting tomorrow. Relieved it wasn't a valve issue after all. Now, should I get a Hilltop remap to get the lean fuel mixture altered to prevent any future valve heat issues...?
 
The Bear said:
Some good news. It turned out to be a distorted pipe on the fuel injection. Mechanic wonders if the bike has been dropped on its side at some point. Bike now repaired and am collecting tomorrow. Relieved it wasn't a valve issue after all. Now, should I get a Hilltop remap to get the lean fuel mixture altered to prevent any future valve heat issues...?
Click to expand...

Yes, you'll love it.
 
Thank god it was an easy/cheap fix. The remap would be beneficial for correcting the fueling I expect so it doesn't run to lean with associated heat issues . Would like to have mine done when money is available.
 
Last edited:
The Bear said:
Some good news. It turned out to be a distorted pipe on the fuel injection. Mechanic wonders if the bike has been dropped on its side at some point. Bike now repaired and am collecting tomorrow. Relieved it wasn't a valve issue after all. Now, should I get a Hilltop remap to get the lean fuel mixture altered to prevent any future valve heat issues...?
Click to expand...

The hilltop remap is the best thing I've done to my bike,I have no interest in wether or not there is more power but what you get is a smoother power delivery and more pull from less revs.
 
Norfolk Tiger said:
The hilltop remap is the best thing I've done to my bike,I have no interest in wether or not there is more power but what you get is a smoother power delivery and more pull from less revs.
Click to expand...

With the money I saved from not having to get a new valve and seat fitted, maybe I can get a remap. It kind of makes the remap free doesn't it? :D
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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