Toying with the ideal of a cr500 road weapon ...

[Wabby]

Should it be done or is it genuinly more effort than worth?

Was thinking nobblies for winter and trail fun, with spare wheels and road tyres for back lane hooning and the occasional wheelie to work.

Am I loosing the plot?
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What restriction?

[stevo as b4]

You cant have a good set up for both supermoto and off road use if you really want to do it properly.

Making an MX'er road legal is one thing, but decide if it's a legal MX'er you want or a proper supermoto bike. Changing wheels and expecting it to be good for both is extremely stupid IMO.

The CR500 is an expensive bike now to buy, and restore/rebuild. Anything 500cc and two stroke is because of reputation and rarity these days.

Unless you already have the bike, you'll need to spend a lot of cash, and it's a shame and a bit wrong IMO to be ruining or chopping around classic open class MX'ers to build very compromised supermoto bikes that will never be good road bikes.

[G]

My current object of desire is a KTM250SX (motocross) with SM wheels.

For my level of riding, the setup would be fine, I'm sure.

Similar peak power, but less mid-range - from what I've seen the 500 over the 250s just has more 'easy to use' power - and it's the revvy buzz I particularly like, otherwise might as well get a 4 stroke (consider a late model Husaberg 650).

[Sean.S]

500 two stroke on the road? you madman!

Ive got whats basically the 250cc equivalent which i ride on the road with supermoto wheels and i can tell you that even this bike is a lot more difficult to ride on road than a 600 sports bike. And lets not forget the bike your talking of has twice the power! i guess what your proposing is possible, just not at all practical. To make it ridable on road you would need to change the sprocket down to about 38tooth and about 52 for offroad i reckon, which also means that you'll need to replace the chain every time you change the wheels

Sean

[TbirdX]

https://www.ebay.co.uk/itm/HONDA-CR-500-road-legal-Supermoto-/152004173320?hash=item2364279e08:g:JMQAAOSw5dNWo4Na

https://www.ebay.co.uk/itm/Honda-CR500-Supermoto-1991-Road-Registered-since-1998-VGC-Rebuilt-Engine-MOT-/231865642328?hash=item35fc44ed58:g:7WsAAOSwvgdW2Yth

[G]

[Fladdem]

Yeah, I'd imagine a CR500 would make around 55BHP, us CRM'rs only have 38-42, official figures say 40 for an AR, but some claim more with a pipe and blah-blah blah.

Our CRM's are nothing like a crosser, even a proper enduro bike is way out of our leagues.

Weirdly, I find my CRM adequate on the road, not too buzzy, not too low gearing, enough poke not to be too scary but enough to overtake stuff up to 50-60 ish. Stupidly low maintenance, I've changed the gearbox oil once, only because I snapped a chain and punctured the crank case, done a chain and sprocket set after that. Now, I have done loads of miles on it, and the gearbox oil still looks mint inside the box.

I think it's my ideal bike, two stroke, road manners, easy to use, decent suspension, after a previous owner spent loads on springs and valves and stuff, only think lacking is decent brakes as standard, I'm going to try some super grippy pads in it and see if that helps at all, it's scary, even at off road speeds.
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Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[thx1138]

I was tempted to by a CRF250M, and have it alongside my CRF250L.

One clean and pampered, the other beaten up and dirty.

[G]

I quite like the CRM250, but if I already had a more road-orientated bike, I'd go for a full-on enduro bike personally.

[Fladdem]

[Sean.S]

Ok i know the CR and CRM are a different beast underneath whats a very similar looking bike but to keep it simple i just meant 2 stroke 250cc and 500cc as comparables. The CRM i beleive is a more tame/reliable alternative to the CR. The CR250 of the early to mid 90s era generally had 5hp over the CRM250 (even though ive seen the newer ones tuned to over 60) but over the years the hp of a standard CR has been inconsistent. I didnt know the CR500 only has 10hp more than the 250 though, i assumed twice the cylinder size meant twice the power but +10hp doesn't seem a lot for an engine twice the cc. Must be thirsty though!! I dont think i would ride a 2 stroke dirt bike on the road if it had any more than 40/45hp though, theyre fun bikes and quick anyway for the engine size, yet any more power i wouldnt necessarily think is a good thing, although these bikes aren't all about power anyway

@fladderm: i think the mk1 was rated at 37hp, the mk2,mk3 and AR all 40hp but ive heard people say the AR doesnt have the peaky power of the earlier models

[G]

It does have a lot more low down power - not only is twice the power actually quite difficult from twice the size of cylinder. More top end wouldn't help you go faster generally - just throw more dirt backwards.
As it happens, that was true of more bottom end too - people were generally faster on 250s, which is partly why the big ones died out.

None of the CRMs I've ridden have had peaky power - most are a lot less peaky than a 250 4 stroke, for instance.

[Ste]

[Fizzer Thou]

[Fizzer Thou]

[stevo as b4]

Sean where are you getting your power figs from, they are all over the place!

CRM's as said are 37-40bhp depending on the model, and later AR's are said to be far flatter and more torquey, which when you think how the part load combustion cycle occurs is pretty obvious.

Later 90's CR250's claim 58bhp, and will be alot more than 5bhp more than a CRM all day long! Look at the number of differences between them, and the size of the carb etc!

CR500's did become more detuned as the years went on,and especially after the open class ended, making them less relevant and the need to develop them any further. Early water-cooled versions and the fire engine red Elinsore era air heads are savage animals though! Even so at the end Honda still claimed 64bhp/6000rpm, which isn't that much compared to a works racer from in the day.

You often won't get sensible dyno readings for MX bikes as fools run them with full knobblies on the rolling road.

Big capacity two stroke cylinders don't actually work all that well compared to smaller cylinders, and it's very hard to get good cylinder scavenging at both low and high engine speeds. No bottom end, no top end and a comparative huge midrange hit is the norm, though it's all relative as a 500 will have much more torque than a 250 even outside its efficient rev range.

[Sean.S]

[stevo as b4]

Mate your talking rear wheel numbers not crank?
As yes your miles off if your comparing claimed figures?

For a start a typical CRM won't better 34-35 r/w bhp at best. By your reckoning a CR250 would be high 30's at the back wheel. If they were that low, I guarantee CR250's would have been so far behind all the other 250's they wouldn't be able stay within a lap of an MX circuit, and consequently no one would have bought one either.

All the bikes from any era are generally within spit of each other anyway. And like I said you can pull all sorts of very weird and inconsistent r/w bhp figures off the net, as many jokers run them with knobblies on the dyno, with all the issues that brings.

If you think there is 4-5bhp between the CRM and the CR then how do you explain the reason why a CRM uses a 31mm carb and yet a much bigger 38mm unit is fitted to the CR.

You can put some CR engine parts on some compatible year CRM's, even cylinders and heads, but you still won't see the same power.

[lllN30lll]

Only an idiot would put a 500 2 stroke on the road.

That's why I own one. Service Honda cr500. 2008 crf 250 frame/2001 motor. Lots of trick bits.

26t rear sprocket for the road and it still wheelies everywhere. I really can't fault it at all.
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Turbo R1
CRF450R

[P.]

Fucking christ 26 teeth and its still hairy. Dem balls.

[Fizzer Thou]

[Cdb1991]

Id say defo do it mate , youll love it, as people said changing from mx to super moto wheels youd havto change the chain to but thats only a 10 minute job anyway, making a road legal mx bike aint as hard as it seems anyway theres a few threads on here where people have done them already, i personally would rather a 4stroke as a supermoto bike but aslong as you keep ontop of maintanance hopfully youll be fine, i had a kx250 2stroke road legal just to get from my house to some local woods green laning etc and it was fine , ive now changed to a ktm450 and again its fine so yeah easily done mate, if you got the funds to go buy a cr500 go do it mate and enjoy the summer