CRF Redemption: The 500 Project Part 1

[motoxr377]

2004 CRF250R - Cheap, and still runs well. That only matters for the part-out.

1989 CR500R Engine - Needs a new right case, and inner clutch cover.  The very new Wiseco looks badly scored over the exhaust bridge area, which leads me to believe the relief is incorrect.  Either way, the engine will be completely disassembled, spec'd, and rebuilt to a high standard.


I'll be attending a military school shortly so I'll be breaking ground on this around May.  The meantime will be spent gathering parts.

[citabjockey]

Will be watching this with keen interest!

[vetman]

me want!!!!!

[evo550]

Bit of advise, go with a '93 or later case, the earlier models where made of evil magnesium, '93 onwards where alloy. They have a different part number but fit right up.

[2T Institute]

What does "spec'd" mean exactly?

[scotty dog]

this will be good

[motoxr377]

Bit of advise, go with a '93 or later case, the earlier models where made of evil magnesium, '93 onwards where alloy. They have a different part number but fit right up.

Thanks for that. I definitely wish to remain risk averse. This seems hypocritical considering what I'm building. I'll be on the lookout for a nice used set, or a good deal on new ones.

What does "spec'd" mean exactly?

I will be checking the tolerances of critical wear parts in relation to their factory specifications, and replacing those which don't meet the standard. This is a fairly common practice during a major rebuild. Do forgive my lack of clarity.

[citabjockey]

That is too funny right there!   

I definitely wish to remain risk averse. This seems hypocritical considering what I'm building.

[Stusmoke]

I had a 2005 CRF250R. The suspenders on that thing were the best I've ever ridden on. Although I haven't ridden on much newer since. Anyways good luck, I'll be watching closely.

[jar944]

Bit of advise, go with a '93 or later case, the earlier models where made of evil magnesium, '93 onwards where alloy. They have a different part number but fit right up.

You have a bit of bad info.

Only the clutch side covers were Mg and those changed to Al in 1990. The cases have always been Al since the 500 was introduced.

The only thing they changed in 93 was the cases were no longer painted black.

[moto867]

the gear ratios also changed after 92.  4th and 5th anyway

[evo550]

You have a bit of bad info.

Only the clutch side covers were Mg and those changed to Al in 1990. The cases have always been Al since the 500 was introduced.

The only thing they changed in 93 was the cases were no longer painted black.

Then what caused the waterpump on my '89 CR500 to rot out ?

 
In '93 they change to Al and Honda added another clutch plate, so the clutch basket area is slightly wider.
Check out the pics of the clutch cover in this cr 500 rebuild.
http://forum.2temps.fr/viewtopic.php?f=36&p=105673

[jar944]

You have a bit of bad info.

Only the clutch side covers were Mg and those changed to Al in 1990. The cases have always been Al since the 500 was introduced.

The only thing they changed in 93 was the cases were no longer painted black.

Then what caused the waterpump on my '89 CR500 to rot out ?

 
In '93 they change to Al and Honda added another clutch plate, so the clutch basket area is slightly wider.
Check out the pics of the clutch cover in this cr 500 rebuild.
http://forum.2temps.fr/viewtopic.php?f=36&p=105673

That is not the case, that is the clutch case/side cover. The water pump is not in the case its in the case cover.

The case cover was Mag through 1988/89. There was a 89 only Al cover.  They went wider on the clutch in 1990 when they changed it to Al

1993 was a change to no paint, the cases are the same, the clutch case cover is the same...

don't believe me, look here: http://cr500riders.com/cgi/yabb/YaBB.pl?num=1192743820

[bearorso]

That picture of the broken cases of your 500 - the best advertisement for a decompression system you can find!

The type that Jar944 and others use, is a simple, cheap, no weld / bugger-all effort solution. My solution, is more expensive / involved.

Of course, you could be a 'hard man' and say "I don't need no frigging Decomp" - but your wallet will argue with you (especially if the breakage extends into the main case - if so, hopefully it can be welded / repaired - just pay a lot of attention to the correct alignment of the various shaft / bearing holes  ), and you'll also be ID'ing yourself as a bit of a Drongo. What's not to love about an easier to fire up bike?

Oh, a better KS lever stop on the foot peg, can help, as well.   

As for the WP area rot, Magnesium protected only by a bit of paint (if that) and water, especially under turbulence / cavitation - not a good idea. Yuck!

[Stusmoke]

That picture of the broken cases of your 500 - the best advertisement for a decompression system you can find!

The type that Jar944 and others use, is a simple, cheap, no weld / bugger-all effort solution. My solution, is more expensive / involved.

Of course, you could be a 'hard man' and say "I don't need no frigging Decomp" - but your wallet will argue with you (especially if the breakage extends into the main case - if so, hopefully it can be welded / repaired - just pay a lot of attention to the correct alignment of the various shaft / bearing holes  ), and you'll also be ID'ing yourself as a bit of a Drongo. What's not to love about an easier to fire up bike?

Oh, a better KS lever stop on the foot peg, can help, as well.   

As for the WP area rot, Magnesium protected only by a bit of paint (if that) and water, especially under turbulence / cavitation - not a good idea. Yuck!

I don't understand, why would high compression wreck the crank cases? Not disputing you here I actually don't know.