thoughts on radiator design and aluminum bore

[100hp honda]

i rode my 250 today on some fast trails for probly 45 min and the cylinder temp never went over 150*. my 500 in the same situation would of been about 180* or maybe 175*. do you think the 250 rads and aluminum bore are letting it run 20*-30* colder ? maybe the aluminum bore just is better at disipating heat ? 250 rad design is just better ?

[MICK]

Are we talking a steel framed 500? If so they have larger radiators than the 250s did. I'm not positive how the 250F/450F radiators compare?

As far as the cylinders go, OF COURSE the 500 runs hotter bro! Aluminum has over x13 the coefficent of heat transfer than does steel. 12 lbs(?) of steel sleeve ain't gonna run cold blooded.

[dannygraves]

the 250 rads have wider cores and they are a much larger single core instead of 2 cores. the 250 rads are far superior.

[MICK]

the 250 rads have wider cores and they are a much larger single core instead of 2 cores. the 250 rads are far superior.

Only the Gen 1s...so how come Honda went away from that design if it was far superior?
I understand not everything Honda did made sense OR was in the best interest of the consumer

[100hp honda]

i wondered if the 250 rads were better but i dont know for sure

[dannygraves]

mick, I think you misundestood me, I'm not taking about gen-1 rads. I'm talking about if you cut the tanks off the old steelie rads and the newer rads, they look very different inside. the old steelie rads have 2 rows of tubes which are pretty much flat with very small openings (one of the reasons they plug up so easily) the newer ones have 1 tube per row and they are almost oval in shape which would give the rads higher flow and more capacity.

I noticed this when doing my gen-3 since I cut the tank off my '89 rads and attached part of it to my gen-3 rad. the gen-3 rad is a far superior design IMO.

[dannygraves]

here, I did a quick drawing because I don't think I'm explaining very well. I wish I would have taken pics because I'm running off memory here


I think the AL bore would transfer heat from the piston to the jug faster (fewer expansion issues) but shouldn't change the overall running temp, the same amount of heat needs to tranfer to the rads.

[MICK]

I understand now, that's all I needed...some big pop up pictures


...now for debate time. If a particular media had a lower coefficient of thermal conductivity, it means excited electrons cannot travel quickly enough through that particular object.

Now we have forces producing heat on one side (A) of this media, and forces on the other (B) trying to remove it. But side B is cooler than side A. Does this not produce higher cylinder temps

These guys encountered first hand steel sleeve cooling properties on two stroke PWCs (scroll down to Steel Sleeve vs. Nikasil Plating): http://www.groupk.com/y1390.htm

[CR500R7]

Danny you explained that well enough to understand without the need for pictures, but the pics top it off.

[MICK]

Speak for yourself bro...I'm a mouth breather. I need color pictures, demonstrations and somebody to hold my hand the first time I do anything Actually Danny I was gonna ask if you make me another picture would you place some information on the graphics so that I can orient myself to it...I don't know what side is up, down, left or right on your pic

[dannygraves]

[CR500R7]

[nmdesertrider]

It depends on where you are measuring the temperature. If your cylinder bore didn't conduct any heat, the water wouldn't even warm up but your exhaust temperature would be higher.