Open Class XR race development and advise

[Mick D]

http://s300.photobucket.com/user/logistics835/media/xr200%202_zpstykrvwsc.jpg.html
http://s300.photobucket.com/user/logistics835/media/xr200%201_zpswv4gstgl.jpg.html
Here is a couple of photos of my xr200 nearly ready for racing
XR class would be good
will be running it the Viper series against all the 250 2 strokes
and the over 45s old man events

That's a great looking build Bruce G. Amazing, well imagined and expedited

Great work!  Hope to see it in action in the dirt (it would make a popular youtube vid!).  How about a feature in VMX magazine?

I thought exactly the same thing too,,,,
I really thought it deserves a professional debut like only the VMX mag can do so well.
Would be a great article, given how many VMX fans have such a soft spot for them.

[Mick D]

Maybe I was just having a bad hair day or not willing to accept anything less than pure optimism.
Specially about the one bike I truly dig above nearly all of my others, my little heavy red darling


Anyhow, apologies Nathan.
I hope what I though of as a great friendship is still as good as I thought,
and strong enough to survive a few mabye unwise and inappropriate words on my part.
Cheers.

[yamaico]

Hey Mick,
I'll do a big fin head for you if want, no problem.
Pete.

[Nathan S]

No drama Mick. As you point out, I've got thicker skin than most.

PS: I forgot to mention top shock mounts breaking...

[LWC82PE]

[Mick D]

Thanks Leith, well done

[Mick D]

Hey Mick,
I'll do a big fin head for you if want, no problem.
Pete.

Its not often that I am lost for words, so why should today be any different

I am humbled at your generous offer Pete.
You are one bloke that has already bent over backwards to help me and I mean gone out of your way.

Now the Head hey. Ummh, I just might take you up on that. Regardless I hope my Maico hoardings may be of assistance when you do your AW  

Leith also sent me this sheet in addition to the one he posted.


You will read where they offer a service for the repair of cracked heads, but they make mention of this fault being on the 250 hondas and TTs not the open class XR.
None of my open class heads are cracked, although some have inferred that they do. So I chose not to believe it unless they vouch of a first hand experience. Maybe just one of rarity or a myth grown on "if the two fiddys do? they all must"

So at this stage I am no longer sure about the trouble and weight addition of a the big fin head. Maybe just cooling the oil would be a more logical path.
I have a few ideas about along that line to pursue first.

[Mick D]

Although, you got to admit that those big fin HRC heads look pretty funky 

Ironic when it comes to cool, they look a hell of a lot cooler than a chrissy tree full of oil coolers.

[redrider1]

I had an 82XR500RC that I did a bit of work to trying to make it a more stable ride and slightly stronger in power.
I did the following;
A complete 82CR250 front end (forks, triples, wheel, brakes) with heavier springs
Had the rear shock rebuilt with a heavier spring made to suit
Special made brake linings for the front and rear (more metallic compound)
Malcolm Smith bigger foot pegs (period pegs)
Higher comp piston
Larger headers
Modified staintune muffler
HRC grind cam (later changed back to std)
Ran the standard reed valves and most other parts were standard.
The bike handled much better in all conditions, braked much better and made stronger and longer power which was very usable.
Great bike you could use almost anywhere.

[80-85 husky]

then ya flogged it....

[Butcher]

i went to classic dirt at lithgow and was looking at a bloke from victoria's C&J replicas.They had XR500 engines with every 2nd fin on the head and barrell milled off. He claimed that they ran cooler than a standard XR. I mentioned about the big fin heads of the 80s. He claimed it was a sales gimmick and did the opposite to their claim, The example he gave me was, the 60s and 70s huskys and ktms had HUGE barrell and head fins , to keep the heat in.

[80-85 husky]

I don't think hrc would go to all the drama of welding big fins on for a gimmick...would they...?

[Mick D]

then ya flogged it....

 

[Mick D]

i went to classic dirt at lithgow and was looking at a bloke from victoria's C&J replicas.They had XR500 engines with every 2nd fin on the head and barrell milled off. He claimed that they ran cooler than a standard XR. I mentioned about the big fin heads of the 80s. He claimed it was a sales gimmick and did the opposite to their claim, The example he gave me was, the 60s and 70s huskys and ktms had HUGE barrell and head fins , to keep the heat in.

Yeah, but the big fins still look pretty funky

Is it the CCM's that they trim as well?

I think maybe a 500tt that Ola Martin has as well?

Yeap, I think I might save Pete the trouble and go for light weight oil cooler approach first

[Mick D]

I had an 82XR500RC that I did a bit of work to trying to make it a more stable ride and slightly stronger in power.
I did the following;
A complete 82CR250 front end (forks, triples, wheel, brakes) with heavier springs
Had the rear shock rebuilt with a heavier spring made to suit
Special made brake linings for the front and rear (more metallic compound)
Malcolm Smith bigger foot pegs (period pegs)
Higher comp piston
Larger headers
Modified staintune muffler
HRC grind cam (later changed back to std)
Ran the standard reed valves and most other parts were standard.
The bike handled much better in all conditions, braked much better and made stronger and longer power which was very usable.
Great bike you could use almost anywhere.

There you go an optimistic common sense approach with a pot of gold result for effort. Cheers Redrider.
Coincidentally a friend just bought one a few hours ago for a project, I think its a 83xl500?

Another friend just sent me this pic of a twin shock evo


How  is that