Best air cooled motor for conversion

Suns_PSD
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3/25/2014 12:45pm
There are adhesives that hold airplanes together, so I would imagine they could be used to "stick" pre-made fins on a cylinder.
That wouldn't transfer heat correctly.
3/25/2014 12:47pm
captmoto wrote:
What are those swing arms going on?
newmann wrote:
One of them is going on my 159 pound 76 CR125 lite bike project. [img]https://p.vitalmx.com/photos/forums/2014/03/25/49332/s1200_Lite_bike_111.jpg[/img] Another is going on my DG Team replica. [img]https://p.vitalmx.com/photos/forums/2014/03/25/49333/s1200_1087572.jpg[/img] And the...
One of them is going on my 159 pound 76 CR125 lite bike project.



Another is going on my DG Team replica.





And the other is for a buddy of mine here in Texas.
Smile
Bultaco
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3/25/2014 12:48pm Edited Date/Time 3/25/2014 1:08pm
newmann wrote:
One of them is going on my 159 pound 76 CR125 lite bike project. [img]https://p.vitalmx.com/photos/forums/2014/03/25/49332/s1200_Lite_bike_111.jpg[/img] Another is going on my DG Team replica. [img]https://p.vitalmx.com/photos/forums/2014/03/25/49333/s1200_1087572.jpg[/img] And the...
One of them is going on my 159 pound 76 CR125 lite bike project.



Another is going on my DG Team replica.





And the other is for a buddy of mine here in Texas.
Totally off topic…..To paraphrase the honorable Steve Bauer from about 15 years ago on Mototalk: "to heck with a 159 pound motorcycle, I'd just like to get my weight back to a 159 pounds".

The rider on the DG Honda does not look he'd weigh more than a 140 lbs. I am about to shed 50 pounds. When I do, perhaps I should celebrate with a DG replica of my own? Smile
Suns_PSD
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3/25/2014 12:52pm
The Rock wrote:
I for sure wouldn't use that shipping carrier again. This project bike would be complete with a air cooled 300cc KTM cylinder. I know people make...
I for sure wouldn't use that shipping carrier again.

This project bike would be complete with a air cooled 300cc KTM cylinder. I know people make water cooled after market cylinders out the yin yang but who can make a finned cylinder?

Just taking a WAG at the weight but can you imagine a 210 pound 300cc two stroke? Just taking a WAG at the weight. Speaking of weight anyone have the weight of two KTM radiators hoses fluid water pump and cap? A finned cylinder's fins couldn't possible add on that much weight over an water cooled cylinder could they? I have to believe there would be a weight savings and what weight remains would be centralized instead of hanging off the sides of the bike like radiators do.
My stock 2008 KTM 250SX w/ a 300 cylinder and heavy Flexx Bars weighed an honest 210# scale verified. Ready to ride, no fuel. Those bars were a 2# weight gain.

Buy a 2011 KTM 250SX (still PDS), add an Ohlins rear shock, another brand's air forks, tubeless wheels, $500 seat foam, etc you could get it to sub 200# quite easily and without even breaking the bank. Oh yah, you could keep the water cooling as well.

That particular model also happens to be the absolute fastest of the KTMs because of the straight air intake allowed w/ the PDS.
1

The Shop

The Rock
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7/22/2014 6:53pm


Now this is what I am talking about!
1
The Rock
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7/22/2014 6:55pm Edited Date/Time 7/22/2014 6:56pm
Here is background on that
piece of art.

EDIT: Suns_PSD missed your reply until now. Thanks for the great information. I have stored that away for future reference.
BobPA
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7/22/2014 6:57pm
The Rock wrote:
[img]https://p.vitalmx.com/photos/forums/2014/07/22/60669/s1200_THIS.jpg[/img] Now this is what I am talking about!


Now this is what I am talking about!
She's a real beaut Clark
newmann
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7/22/2014 7:04pm
The Rock wrote:
[img]https://p.vitalmx.com/photos/forums/2014/07/22/60669/s1200_THIS.jpg[/img] Now this is what I am talking about!


Now this is what I am talking about!
I really like that but it really needs the shrouds. Would like to see one done up completely stock in appearance like it came off the showroom floor.
newmann
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7/22/2014 7:04pm
And of course WITH the #13's.
The Rock
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7/22/2014 7:07pm
RJ fan?
The Rock
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7/22/2014 7:24pm
newmann wrote:
I really like that but it really needs the shrouds. Would like to see one done up completely stock in appearance like it came off the...
I really like that but it really needs the shrouds. Would like to see one done up completely stock in appearance like it came off the showroom floor.
I would like to see a shot for the rider's perspective looking down to see how narrow that thing is. I can only imagine how wickedly fast that thing is.

My 88 CR500 was a top fuel dragster for sure......was a bear to ride until I put a flywheel weight on it and life was good....good if you consider 8 or so broken bones in six years and a fractured pelvis good. LOL
CamP
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7/22/2014 11:16pm
newmann wrote:
I really like that but it really needs the shrouds. Would like to see one done up completely stock in appearance like it came off the...
I really like that but it really needs the shrouds. Would like to see one done up completely stock in appearance like it came off the showroom floor.
Agreed. Looks kind of odd without the shrouds, and a little too much red for my tastes. Cool bike though.
wow123
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7/23/2014 1:47am
very nice but I would fill in the gaps, something like this

if I maybe so bold as to ps the pic



Spartacus
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7/23/2014 5:41am
1. The motor has a large crankshaft mass making the chassis want to stand up when leaned over with the throttle on (Gyro effect) just go and ride an old school big bore and you will see what I am talking about.


A 250 flywheel in a cr500 motor totally changes that IMO.

Balancing the crank kills the vibration too.

nytsmaC
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7/23/2014 6:21am
Suns_PSD wrote:
My stock 2008 KTM 250SX w/ a 300 cylinder and heavy Flexx Bars weighed an honest 210# scale verified. Ready to ride, no fuel. Those bars...
My stock 2008 KTM 250SX w/ a 300 cylinder and heavy Flexx Bars weighed an honest 210# scale verified. Ready to ride, no fuel. Those bars were a 2# weight gain.

Buy a 2011 KTM 250SX (still PDS), add an Ohlins rear shock, another brand's air forks, tubeless wheels, $500 seat foam, etc you could get it to sub 200# quite easily and without even breaking the bank. Oh yah, you could keep the water cooling as well.

That particular model also happens to be the absolute fastest of the KTMs because of the straight air intake allowed w/ the PDS.
So a stock 2011 250SX is 4lbs under the AMA weight limit? Better have that scale recalibrated.
newmann
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7/23/2014 6:40am
nytsmaC wrote:
So a stock 2011 250SX is 4lbs under the AMA weight limit? Better have that scale recalibrated.
I seem to recall that being noted on more than one occasion. FMF built their 300 without going overboard and got it down to 199 lbs.
nytsmaC
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7/23/2014 7:18am
I know KTM was claiming 213lbs and MXA reported 212. Still super light, but 208 is 125 territory. 200 is reachable but it wouldn't be cheap to get there, that's for sure.
BobPA
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7/23/2014 7:36am
nytsmaC wrote:
I know KTM was claiming 213lbs and MXA reported 212. Still super light, but 208 is 125 territory. 200 is reachable but it wouldn't be cheap...
I know KTM was claiming 213lbs and MXA reported 212. Still super light, but 208 is 125 territory. 200 is reachable but it wouldn't be cheap to get there, that's for sure.
Pfft carbon and titanium bits are cheap as plastic.
stevee401
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7/23/2014 9:02am
I vote 82 RM465. My dad just got one and it runs really really good. I was totally suprised on how crisp it ran. Only thing I didnt like were the ergo's. Super fun bike.
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The Rock
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7/23/2014 9:20am
Spartacus wrote:
[b]1. The motor has a large crankshaft mass making the chassis want to stand up when leaned over with the throttle on (Gyro effect) just go...
1. The motor has a large crankshaft mass making the chassis want to stand up when leaned over with the throttle on (Gyro effect) just go and ride an old school big bore and you will see what I am talking about.


A 250 flywheel in a cr500 motor totally changes that IMO.

Balancing the crank kills the vibration too.

What year CR500 did you ride with a 250 flywheel? My 88 was difficult to ride but easy to stall until I made the flywheel HEAVIER not lighter.
Spartacus
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7/23/2014 10:37am
Spartacus wrote:
[b]1. The motor has a large crankshaft mass making the chassis want to stand up when leaned over with the throttle on (Gyro effect) just go...
1. The motor has a large crankshaft mass making the chassis want to stand up when leaned over with the throttle on (Gyro effect) just go and ride an old school big bore and you will see what I am talking about.


A 250 flywheel in a cr500 motor totally changes that IMO.

Balancing the crank kills the vibration too.

The Rock wrote:
What year CR500 did you ride with a 250 flywheel? My 88 was difficult to ride but easy to stall until I made the flywheel HEAVIER...
What year CR500 did you ride with a 250 flywheel? My 88 was difficult to ride but easy to stall until I made the flywheel HEAVIER not lighter.
My AF conversion had a 91 motor and I swapped for a 250 ignition/flywheel. Cornered much better but you couldn't be lazy and lug it around in 3rd gear anymore. IMO it's a better set up for MX but you need to ride it not just sit there.

My current under construction AF will use a 250 set up too.
Lefty Right
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7/23/2014 3:07pm
Beast666 wrote:
The coatings will not help one single bit with detonation as detonation is caused by the fuel lighting off at a second location inside of the...
The coatings will not help one single bit with detonation as detonation is caused by the fuel lighting off at a second location inside of the cylinder after the timed spark causing a collision between the 2 flame fronts. It is caused by the pressure on the squish band creating to much pressure making the fuel ignite on its own. The only way around it is raising the octane of the fuel or cutting down the squish band on the head or in some cases both. The problem with cutting the squish is you reduce compression of the engine. If you want to run the engine on pump fuel it may become so detuned that you end up with a slow or pipey big bore engine.

if you want a fun to ride air cooled 2 stroke in a modern chassis I would avoid the big bores. After all there was a reason why they died off. They were a handful to ride and less and less riders wanted to manhandle them around a track. When I raced the open class back in the 80's every time I had a chance to ride a 125 or 250 I jumped at the chance to go out and drag the grips through the turns and toss them around in the air. When my friends got back from ridding my 500's they would always be worn out and wonder how I raced that thing for 45+ minute motos.
TeamGreen wrote:
With KIPS and a Rekluse, you can turn a later model 500 into a Wondeful Torque-making scooter. My KX500s for BITD & Moto (late 90's thru...
With KIPS and a Rekluse, you can turn a later model 500 into a Wondeful Torque-making scooter.

My KX500s for BITD & Moto (late 90's thru 2004-5) were a blast to ride and more manageable than a lot of 450-4Ts I've ridden.
BobbyM wrote:
Real men ride 500's....clamp it!
So you're saying you were not a man Woohoo because you rode a maico and they didn't make a 500.
Spartacus
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7/23/2014 3:41pm
My bad, 91 not a air cooled but the point remains the same.
The Rock
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7/25/2014 1:13am
TeamGreen wrote:
With KIPS and a Rekluse, you can turn a later model 500 into a Wondeful Torque-making scooter. My KX500s for BITD & Moto (late 90's thru...
With KIPS and a Rekluse, you can turn a later model 500 into a Wondeful Torque-making scooter.

My KX500s for BITD & Moto (late 90's thru 2004-5) were a blast to ride and more manageable than a lot of 450-4Ts I've ridden.
BobbyM wrote:
Real men ride 500's....clamp it!
So you're saying you were not a man Woohoo because you rode a maico and they didn't make a 500.
Nah Bobby's saying always go for the big bore two strokes over a four stroke.

Check out this 2004 MXA comparison between CR500 and CRF450.

Would love to see MXA redo this test but this time with a Service Honda CR500 and a 2014 Honda.
Bearuno
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7/25/2014 4:42am Edited Date/Time 7/25/2014 4:55am
BobbyM wrote:
Real men ride 500's....clamp it!
So you're saying you were not a man Woohoo because you rode a maico and they didn't make a 500.
The Rock wrote:
Nah Bobby's saying always go for the big bore two strokes over a four stroke. Check out this 2004 [url=http://motocrossactionmag.com/news/motocross-actions-two-stroke-versus-four-stroke-shootout-2004-crf450-versus-2001-cr500]MXA comparison[/url] between CR500 and CRF450. Would...
Nah Bobby's saying always go for the big bore two strokes over a four stroke.

Check out this 2004 MXA comparison between CR500 and CRF450.

Would love to see MXA redo this test but this time with a Service Honda CR500 and a 2014 Honda.
Ah yes, the comparison that had an extra 15lbs added to the steel 500s weight.........

The same bike, in mid 90s tests by the mag, was weighed out at 230 / 232lbs. Perhaps they weighed the 500 with a full tank, in 2004? MXA , do write some things that don't add up.. My steel framed 500s, match the weight of the AFs I've made.

The aluminium frames, are actually heavier than the steel frames. Even the latest models, which have slimmed down considerably. The only weight an AF conversion can save from the donor bikes, is lighter ancillaries, such as thinner plastics ( plus the smaller tank - but, all the fuel weight is carried high on an AF, and it just gets worse if you need a decent fuel range), smaller rear caliper, lighter brake lever, etc. Hey, fit a CRF Kick Start lever, and you save a pound at least, over the original 500 one. I've made quite a few AFs, since '97. So much bullshit is spread about with regards to AF conversions.

Without a doubt, it's a far easier, and a far cheaper way to get a 'modern'ish bike with a 500 (or whatever size) 2t, what with so many idiots not taking care of their 4ts. I'm more inclined towards 2ts, as I go into my dotage, but most 4t 'disasters', are down to the bloody idiot riding it, not doing simple, easy maintenance. Plenty of Drongos = plenty of late model chassis, if you want to do an AF.

I'd like to get, say a Finner CR500 engine, and the Water Cooled 500 engine, rads, hoses and shrouds ( and not forgetting the coolant) to check the weight difference. It may not be as much as expected, as finned heads and barrels, do have some weight to them. I'd like a finner 500 in my current chassis.

I remember the weight difference between a std CR125 head, and a "Porcupine" one in the seventies - quite marked, but, worth the extra weight. Then, there were the Copper Cylinder Heads you could get for cooling ............... drop one on your foot, and you'd know about it! I'm sure I've one somewhere in my workshop - Webco brand (or perhaps FMF?), I think it was.

For a mid capacity AC bike, a KDX 200 KIPs 'finner', brought up in capacity, would be a sweet little bike, as it is a significantly smaller engine than, at least, the 250 Kawi finners, if I recall correctly.
1
mx317
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7/25/2014 6:14am
downard254 wrote:
As far as air cooled open motors, you'd be good with the '83 CR480 motor, or any of the later open RM's as those just weren't...
As far as air cooled open motors, you'd be good with the '83 CR480 motor, or any of the later open RM's as those just weren't crazy powerful. I owned and raced an air cooled '81 RM 250 and I've gotta say that engine was electric smooth and had plenty of power everywhere.
I loved that 480 engine, but with the right side chain it would create more issues installing it in a newer chassis.
dcg141
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7/25/2014 8:36pm
KTM 420..that was a great engine.
The Rock
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7/25/2014 10:46pm
Bearuno wrote:
Ah yes, the comparison that had an extra 15lbs added to the steel 500s weight......... The same bike, in mid 90s tests by the mag, was...
Ah yes, the comparison that had an extra 15lbs added to the steel 500s weight.........

The same bike, in mid 90s tests by the mag, was weighed out at 230 / 232lbs. Perhaps they weighed the 500 with a full tank, in 2004? MXA , do write some things that don't add up.. My steel framed 500s, match the weight of the AFs I've made.

The aluminium frames, are actually heavier than the steel frames. Even the latest models, which have slimmed down considerably. The only weight an AF conversion can save from the donor bikes, is lighter ancillaries, such as thinner plastics ( plus the smaller tank - but, all the fuel weight is carried high on an AF, and it just gets worse if you need a decent fuel range), smaller rear caliper, lighter brake lever, etc. Hey, fit a CRF Kick Start lever, and you save a pound at least, over the original 500 one. I've made quite a few AFs, since '97. So much bullshit is spread about with regards to AF conversions.

Without a doubt, it's a far easier, and a far cheaper way to get a 'modern'ish bike with a 500 (or whatever size) 2t, what with so many idiots not taking care of their 4ts. I'm more inclined towards 2ts, as I go into my dotage, but most 4t 'disasters', are down to the bloody idiot riding it, not doing simple, easy maintenance. Plenty of Drongos = plenty of late model chassis, if you want to do an AF.

I'd like to get, say a Finner CR500 engine, and the Water Cooled 500 engine, rads, hoses and shrouds ( and not forgetting the coolant) to check the weight difference. It may not be as much as expected, as finned heads and barrels, do have some weight to them. I'd like a finner 500 in my current chassis.

I remember the weight difference between a std CR125 head, and a "Porcupine" one in the seventies - quite marked, but, worth the extra weight. Then, there were the Copper Cylinder Heads you could get for cooling ............... drop one on your foot, and you'd know about it! I'm sure I've one somewhere in my workshop - Webco brand (or perhaps FMF?), I think it was.

For a mid capacity AC bike, a KDX 200 KIPs 'finner', brought up in capacity, would be a sweet little bike, as it is a significantly smaller engine than, at least, the 250 Kawi finners, if I recall correctly.
I'd like a finner 500 in my current chassis.

Now that would be interesting. BTW I am still tripping over the guy who said he went lighter on the flywheel on a CR500. How can you possibly ride a big bore CR500 with a lighter flywheel and not stall it coming into corners. Rekluse?
11/9/2018 1:04am
Ive ridden a ton of big bore,grew as hollister hills in my back yard... when it comes down to it ,its usable tractable power .who care what it weighs.there a lot of late model 2 strokes in steel chassis (ktm,husky,etc) .if were looking for a say 78-83 bike in a big bore 2 stroke id be looking for a 81 husky 430 or 500. Great chassis ,loads of suspenion that didnt bottom if u hit anything bigger than a cigarette filter ,tuned and jetted fairly easily and if you had balls enough to hang on flat hauled ass .ive seen them clocked in long desert flat straits in excess of 120 mph. ... how fast do you want to go ... sometimes lighter always isnt faster ....
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