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I think I had a good idea - radiator relocation!

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Consider the new space available under the seat. Ignore the seat, don't look at the seat:D This (old) pic is exaggerating it, the battery has to go back in it's place, like daveinmichigan has done. Still, a lot of room.

727side1.jpg

Now look at this pic. See how only the radiator and turn signals protrude on the sides? I can move the signals, or get small ones, but the radiator:thumbsdn: It is a really draggy thing, and increases the frontal area, and is vulnerable to damage. Now, in the picture above, look at where the rad hoses run - back behind the engine. Hmmm...

0812front.jpg

What about putting the radiator and overflow bottle back in the triangle where the airbox used to be? A duct, if needed, to pull some cool air in front of the rad, keep exhaust heat away, a screen or something between it and the rear wheel...

Potential to be sweet?

/dh

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Potential, but I don't see it working in this case. The RC51's have side mount radiators, and have constant heat problems. I'm not saying it can't be done, but you'd be hard pressed with that small a radiator, and the lack of overall airflow.

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I think you're getting a little carried away with the space savings there Hermit. I don't see how you could get enough air back there to keep it cool. Any kind of ducts you install will have to stick out also, thus defeating moving the radiator because it sticks out. I can only suggest moving it down and towards the center a little more than it is in the stock location.

You ever gonna put that bike back together and.... :) ???

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You ever gonna put that bike back together and.... :D ???

I second that. I think its time to put some miles on that thing

and go enjoy already. I suffer from OCD too, but enough is

enough. You have a really unique bike, not my style, but definitely

one that nobody else has. So go wear down some rubber already.

:)

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If you give the radiator equivalent airflow (cooling ability), you are going to incur the same amount of drag from the radiator no matter where you put it. If you want to reduce the drag from the radiator area, you can rip off the fan. Of course, that will only be "safe" if your bike stays cool enough that the fan never needs to run.

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I think you're getting a little carried away with the space savings there Hermit. I don't see how you could get enough air back there to keep it cool. Any kind of ducts you install will have to stick out also, thus defeating moving the radiator because it sticks out. I can only suggest moving it down and towards the center a little more than it is in the stock location.

You ever gonna put that bike back together and.... :D ???

I second that. I think its time to put some miles on that thing

and go enjoy already. I suffer from OCD too, but enough is

enough. You have a really unique bike, not my style, but definitely

one that nobody else has. So go wear down some rubber already.

:)

I'll ride as much as the ankle can stand this weekend, and maybe a little more:) I certainly agree, it's been way too long.

I can only work on the bike at home at night. I think about stuff during the day.

I just gave the seat another trim:D It's ready to go - I'm happy to now defend it cheerfully in the face of all comers - if I like it, that is. Now, tonight, I'm going for the rear subframe, airbox / intake (needs cutting first), and gas tank, with some of the bolt-on for those bits. I've gotta plug in the PCIII and connect the tach before putting the gas tank on. That may slow me down, software is involved:)

Later/dh

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You really ought to consider getting a Montessa trials bike, instead.

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If you give the radiator equivalent airflow (cooling ability), you are going to incur the same amount of drag from the radiator no matter where you put it. If you want to reduce the drag from the radiator area, you can rip off the fan. Of course, that will only be "safe" if your bike stays cool enough that the fan never needs to run.

That's more or less completely incorrect. Aeronautical R&D has been pretty extensive in this area, as you might imagine. The worst case is when air piles up in front of the radiator, and spills around back - the "flat plate" case. that could be one reason why the current radiator is slanted, it lets air slide off downward - which makes the front right side lift at speed, not a particularly good thing.:) But that may be less bad than if the rad was square with the wind, when drag is highest.

Think about it - the rad cannot possibly flow air transparently. So it piles up in front. I can't find the page right now, but the optimum inlet area is around 1/2 the radiator frontal area. The air expands and slows upon entry, and doesn't pile up creating drag. Then for the outlet, you "pack it back together", to about 1.1x the inlet size, IIRC, so it can merge with the outside airstream with minimal disruption, and you don't get backflow coming in from behind...

or something like that. In any case, the cooling inlet to the radiator doesn't need to be nearly as big as the radiator itself.

But this is something for me to ponder further for a while to see if it is practical on my bike.

Cheers!

/dh

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I'll ride as much as the ankle can stand this weekend, and maybe a little more:) I certainly agree, it's been way too long.

Later/dh

Damn...thats right. I keep forgetting about your ankle. That

thing better hurry up and get better or you are not going

to have a bike left to ride. You might have some type of

URO (unidentified ridable object), but not a motorcycle.:)

:D:worthy::ride:

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Zadok, you're worse than my wife :ride:, but she has had time to get used to me:D Actually, I have a great wife. Hung around for 25 years now, and you have a few posts that give you a vague idea of what that has been like:busted:

For the past couple days, things have finally been going *back on* the bike, and to stay a while. I'm sick of no bike time, and I'll ride one-legged if I have to. It's the left one, thanks for asking:)

So far I have everything on the front fork sorted - bars redone, controls remounted, headlight repainted and installed with PCIII, etc. And I got all the other painting done, and the stock header back on. So I'm getting there, and I desperately (no s**t) want to be there by Friday night (or early Sat a.m.).

So get out of the airchair quarterback mode and give me a hand, guys, i got a problem. I am determined to get it back together ASAP, but also determined to get some things sorted along the way.

One thing I am going to sort is flipping the peg brackets, to get me 1/2" down and forward. I know, it's trivial, but :worthy: it is gonna happen. And i can't get *any* of those T-xx bolts out:banghead: :):D T-50 is what I got and think, but they ain't budging. I've tried:

PB-Blaster soak (a frozen bot/nut spray)

600 degree heat gun (had the brackets up to about 200, and the xxx FRAME pretty warm.

Hitting socket wrench with 20oz hammer

I hate to buy a bigger impact driver, cause I think it still ain't gonna work.

You say ride, I say yes, tell me how!

Yow! /dh

i'm gonna go get some other stuff back together now. I hope I get some sunshine from yall on this problem. Otherwise I'm gonna get ugly with the frame with a drill:thumbsdn:

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That's more or less completely incorrect. Aeronautical R&D has been pretty extensive in this area, as you might imagine. The worst case is when air piles up in front of the radiator, and spills around back - the "flat plate" case. that could be one reason why the current radiator is slanted, it lets air slide off downward - which makes the front right side lift at speed, not a particularly good thing.:) But that may be less bad than if the rad was square with the wind, when drag is highest.

Think about it - the rad cannot possibly flow air transparently. So it piles up in front. I can't find the page right now, but the optimum inlet area is around 1/2 the radiator frontal area. The air expands and slows upon entry, and doesn't pile up creating drag. Then for the outlet, you "pack it back together", to about 1.1x the inlet size, IIRC, so it can merge with the outside airstream with minimal disruption, and you don't get backflow coming in from behind...

or something like that. In any case, the cooling inlet to the radiator doesn't need to be nearly as big as the radiator itself.

But this is something for me to ponder further for a while to see if it is practical on my bike.

Cheers!

/dh

That makes a lot of sense. I didn't think about it that way.

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That makes a lot of sense. I didn't think about it that way.

Dont encourage him.......:)

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i'm gonna go get some other stuff back together now. I hope I get some sunshine from yall on this problem. Otherwise I'm gonna get ugly with the frame with a drill:thumbsdn:

Get yourself an air compressor and an impact gun. Hold the frame with one hand and kind of make yourself a press. Zip em off.:)

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I'll ride as much as the ankle can stand this weekend, and maybe a little more:)

Hi Hermit,

Sounds like good physical therapy. :) Gotta get the rehab goin' to get those joint working right again. No fun, I know.

Regarding frontal area, don't forget that your leg is out probably just as far as the radiator, so you may not reduce the frontal area much, if at all. You might reduce drag by just angling it backwards in the plan view (kick the inside edge forward and the outside edge to the rear). But your radiator will get less air going through it that way. I'd worry about long term reliability if it doesn't get proper cooling, and that's tough to develop without a full lab and a bunch of engineers and technicians... I'm happy to leave it where it is on mine. :worthy:

If you're thinking about that 100mph goal, I think your best bet would be a front bubble fairing to crouch your upper body and head behind. You know, that shape you always see on those salt flat bikes. With the right gearing I'm sure you could hit 100 easy with something like that on there.

Then you can just take the bubble back off and ride it. I'm having all my fun with this bike at 30-60 mph. :D

Now I have to go find your thread on the seat rework. I could use some better comfort myself...

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I think you already lost some of the cooling of the radiator because the shroud directed air into the radiator. Even if the radiator can't use all 100% of that air flow with the shroud, without the shroud you created an easy path for air to just bypass the radiator and flow around outside of it. In its current direction deflecting off the forks and fender. Which could possible leave you at 80% effectiveness. Anyways its a theory and only a problem if your overheating and fan is coming on a lot, which you can road test.

To try and help you with your min/maxing of the bike. To reduce form factor drag of the radiator sticking out. Only other place I see good airflow is behind the front wheel attached to the frame. If you could keep it far enough from the exhaust and wheel so that it wouldn't interfere with the front wheel when the suspension compresses.

I would leave it where it is personally =) But I've been reading your posts and think its pretty unique idea your running with.

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I think you already lost some of the cooling of the radiator because the shroud directed air into the radiator. Even if the radiator can't use all 100% of that air flow with the shroud, without the shroud you created an easy path for air to just bypass the radiator and flow around outside of it. In its current direction deflecting off the forks and fender. Which could possible leave you at 80% effectiveness. Anyways its a theory and only a problem if your overheating and fan is coming on a lot, which you can road test.

Just FYI, my radiator is fully exposed (no shroud around it or front deflector) and after a few weeks now my fan has only come on once: sitting in stop and go crawling traffic for 20 minutes on a 90+ degree day. But I'm up in Michigan, so we're ususally running mid 80s or less... FWIW.

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Just FYI, my radiator is fully exposed (no shroud around it or front deflector) and after a few weeks now my fan has only come on once: sitting in stop and go crawling traffic for 20 minutes on a 90+ degree day. But I'm up in Michigan, so we're ususally running mid 80s or less... FWIW.

Break time:) I'm shaving the rear subframe with a hacksaw and file before bolting it back on. Maybe halfway through, a surprising number of little bits to get off. Gonna shoot it with black gloss to match the other bits when I finish (late tonight, I'm behind schedule:thumbsdn:)

Anyway, the shroud contribution from thehozz makes sense on the surface. And it may have that effect in gross, but i don't think that was what the Yammy guys were after anyway. Here's why:

- Look inside the shroud, where the radiator *should* meet it on the outside edge, and on the inside edge. It's not sealed, is it? So air will leak right there on the outside and inside. And the top and bottom, all inside the shroud.

- Look at the shroud edge. Curled in on the side, and especially at the top. Not what you want from a scoop, if that's what you need.

- Look at the exit of the rad, where the black plastic :air guide" or whatever, and the shape of the shroud. if they want to get airflow, the shroud get wider, not severely tapered in.

I've thought through all this stuff in way more detail than is healthy.:D

So I don't think it hurts to run without the shroud. The shape didn't make any sense to me at all until DiM mentioned "getting high" (towards the front) or something like that. Then I understood the purpose of the design:

1) looks

2) direct hot air away from a hot spot on the rider with the black thing

3) give the rider a smooth area for the knees to go up and down.

i still don't get the wide groove in both shrouds running front to back. It could be a good knee place for a minority of riders, but it hit me wrong. Maybe just for strength, I dunno.

I know the idea of putting the rad under the seat is better than my idea of putting the stock gas tank back there.:) Custom tank, maybe:D

More shaving now.

Cheers/dh

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You really ought to consider getting a Montessa trials bike, instead.
Not at all what I want to end up with. I agree that mine looks like one for now. But not a week from now.

cheers!/dh

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