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I have owned four Honda CR 500 two stroke motocrossers, one of which was an aluminium frame conversion. Sold it many years ago, but have been amazed at the rocketing market value. 

I always fancied doing my own conversion and have been looking for a CR 500 two stroke engine for a number of years. They are not commonplace. After all this time, I found three in the last fortnight. The first was, in my opinion, badly welded, and had a crude chain guard hiding one of the welds. The seller was asking a mere £2300, which he has now reduced to £2000, following comments on the state of the welding. 

The second and third engines are now with me. I also bought a Honda CRF 450 bike, with a blown engine. The engine is now out and in bits. I will dispose of the engine parts, radiators and exhaust, plus any other bits I won't need. I will probably start with one engine reconditioned and then get the frame cut and welded to accommodate the CR 500 engine. I will be keeping a photo file, as I go along. Probably starting around Christmas - it will take until then to get rid of the tons of tools I have accumulated and also the redundant bits. With a bit of room, I can work with elbow room. Haven't decided whether to keep the second engine or do a second conversion. I have seen a CR 500 dropped into a KTM SX frame which looked very nice and I have a soft spot for KTMs. 

First photos - the next might be a couple of months later.

CR 500 engines.jpg

1.jpg

2.jpg

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ditchman - the layout on the table was not me - it was the seller. My sons raced CR 500s - youngest had the aluminium frame model. Lot easier to ride than the Husky 610 four stroke - albeit it had been tuned by Steve Clitheroe. However, the real animal to ride was the KTM SX 380 - a lot quicker than any other bike we have owned. 

I had almost given up on getting a Honds 500cc engine and had just made enquiries about a 380 KTM. Only problem was that it was the EXC model not the SX - wider gear ratios and a few less horsepower.

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21 hours ago, Gordon R said:

No power valves on the CR500s, unlike the Kawasaki KX500s.

Years ago my boss's sons both had cr500s ( not for racing just rode them about the farm)  one was three or four years older than the other. And the older one was evil, very flat till it reached its powerband then absolutely mental. But the newer one had bags of power and torque low down and was much easier to ride. I just assumed it was fitted with a powervalve. 

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On 02/11/2019 at 15:30, Gordon R said:

timps - from memory the 86 CR500 was the fastest engine, later models were de-tuned.

From my memory the 85 to 88 were very similar producing 60 + hp with a ridiculous  low end power designed by beelzebub to send you straight to hell. Then from 89 to its end they redesigned the head and exhaust to lower compression which was supposed to aid starting and make it more user friendly.  I think that produced about the 55 ish hp. 
 

I know plenty that raced the 86 put two base gaskets on to help starting and tame it. The jetting was off from standard as Honda jetted it rich on the 86 to aid starting as well. I don’t miss trying to kick the thing up that’s for sure but I did miss racing it.  
 

The later models behaved like an 86 with to gaskets on so I always wondered if Honda had listened to the complaints. 
 

 

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Allegedly 58bhp after a bit of taming by Honda. Never had problems starting them. Petrol on, flood carb, stick in 3rd gear - rock back and forth three times - adjustment of kickstart and wallop. Usually first time starters.

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Got the engines and rolling chassis / blown engine from Facebook Marketplace. The two covers off the bay. Tyres - internet . New radiators, hoses, plastics and graphics are easily available.  New exhaust - again from the bay. Silencer we already have. Kickstart - might have to bite the bullet and buy new - £70. It seems a ridiculous price for a basic part. 

The lad who sold us the engines said a mate had dismantled the engines and might still have some more bits. These arrived today - at his cost. In this day and age, I was surprised at the offer and free postage. Very genuine lad - owns a motocross shop in Middlesbrough. 

 

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On 01/11/2019 at 10:05, ditchman said:

i love it when folk lay everything out nice and tidy.i do excactly the same................:good:

JDog will be watching this as he is facinated with engine stuff.........

Just caught up with this. I am looking forward to the chain saw rebuild.

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Sounds like a genuinely nice chap!:good:

Met him and his other half. They both seemed genuine, but when he said he might have some other bits, I took it with a pinch of salt. Perhaps my former career made me even more cynical. I would have laid money against the parts arriving - my son disagreed. I have had to eat my words.

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14 minutes ago, Gordon R said:

Met him and his other half. They both seemed genuine, but when he said he might have some other bits, I took it with a pinch of salt. Perhaps my former career made me even more cynical. I would have laid money against the parts arriving - my son disagreed. I have had to eat my words.

Nice to be wrong sometimes and not often that human nature is that good.

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