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Discussion Starter · #1 ·
I decided to check the temps on my Majesty with an infrafred thermometer my wife gave me for my last birthday. This was after some highway, some city riding, nothing extreme. Ambient temp was 71
degrees (F) The temp gauge was in the middle.
Back of front fender (my control) 77
Front brake caliper 84
Front tire 86
Radiator (hard to get to ) 142
(right and left are as you sit on the scooter)
Right air box 91
Left air box 82
Rear drive housing 110
Rear brake caliper 101
Rear tire 94
Muffler 254
The only thing I can figure out for sure from this is the rear airbox is not in the best position as it is getting heated by the muffler. Hot intake air = loss of power. Also that muffler is HOT. Probably best to let it cool a while before you put on a cover, if you use one.
 

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An interesting study there...

Yes, I always keep the RH rear side of my cover up a bit when I put it on after my morning commute, so it won't contact that muffler...
 

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Discussion Starter · #3 ·
Thanks. One other conclusion I reached - I measured the final drive housing once before - got 113. To me this indicates the oil doesn't get that hot and that the heat resistant properties of synthetic oil aren't needed. Of course syn oil is also more shear resistant and the final drive oil is the ONLY (far as I can tell) place where oil is subjected to shear, not having a wet tranny or clutch so the syn vs dino oil debate will probably never end.... :wink:
Like a moron I forgot to check the temp of the oil filter cover :oops:
What I am going to do is change the oil right after riding next oil change and measure the actual oil temp as it comes out of the scooter.
Does everyone know the Majesty has an oil cooler? It is a coolant to oil cooler. Here's a link:
http://yamaha.motogrid.com/pages/parts/default.aspx
part #32 - it is called a heat exchanger in this diagram but an oil cooler in my shop manual.
 

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Ishabaka,

Thanks for the info ... very interesting ... keep it coming :)

Is there anyway to get a reading on the cylinder head? I think you can see it from the lower right.
 

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Discussion Starter · #5 ·
I'll try. From my car drag racing days (which is why I got the thermometer in the first place) cylinder head temps vary widely depending on whether you are near the intake ports or exhaust ports, or measuring over a coolant passage.
The other thing is intake air temp has an amazingly large effect on power.
One day it was 42 degrees at our strip and my car just made tremendous power compared to the 80-95 which is normal in the summer here.
If you look at the intake on the right airbox it is towards the bottom rear -right above the muffler - the worst possible place.
I'm not due for an oil change for about a month so please bear with me, I will post the temps.
Another of my brilliant :roll: deductions is the reason why so many members air filters are clogging so fast is the air intakes are a few inches above the ground - that means any dust kicked up by the front tire goes right into the airbox, vs. most cars and motorcycles which have their air intakes much higher up and towards the front of the vehicle. Or right in front as per the ram air bikes.
 

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Discussion Starter · #7 ·
This hot right air box thing got to me. So first I glued aluminum foil to the bottom of the right airbox. I made exactly the same ride at the same ambient temp (to the gym & back). Before the right air box was 9 degrees hotter than the left, with the aluminum foil it was 5.5 degrees hotter. I figured this wouldn't make any difference and the aluminum foil looked really bad so I took it off.
Then I measured the distance from the right airbox intake to the 250 degree plus muffler and it is 2 1/2 inches! That's pretty close.
So I got some scrap aluminum stock 4" x 7", and made a heat shield like the leg heat shield between the muffler and the right airbox intake. I bent a tab and it bolts on by the upper muffler bolt.
I don't know if it works but it seems like it would. The leg shield works. It will look nicer after I take it off and polish it on a buffing wheel. And it's free.
 

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the cold air thing is well noted just about everywhere in motorsport.

colder air is more dense (has more oxygen in the same volume of air) more oxygen = more power!

thats why turbo cars run an intercooler. to reduce the intake temps.
my old turbo nissan would run so much better in the winter months than the hot summer months.

your observations about the airbox on the maj, got me thinking too.
your heat shield sounds like a good idea too. i wonder if there is a way to make small air "scoops" to help direct cold/clean air into the boxes ?

jason
 

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Discussion Starter · #9 ·
Same ride again, ambient temp 68.
Right air box: 80
Left air box 76.5
Top of heat shield (side facing airbox intake) 92
Muffler right under heat shield 273
 
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