Challenger chain sizes

[Andy Z]

Hi All,

I was just interested if Challenger owners still used the rather weedy looking 1/2" x 5/16" final drive chain, and how easy it would be to upgrade to a 520-size chain?

Many thanks,

Andrew
#190

[stormer254]

That weeeedy chain was used jap 125s up to the mid80s, which produced more power than a 250 Challenger will ever manage, also its lighter and has more bearing due to more links on the sprocket, buy a decent chain and you will have no problems

[Andy Z]

That weeeedy chain was used jap 125s up to the mid80s, which produced more power than a 250 Challenger will ever manage, also its lighter and has more bearing due to more links on the sprocket, buy a decent chain and you will have no problems

Fair point, the quality of chains these days seems to cover a very wide range!
Do you have any preference?

Can't think of any 125cc jap motocross bike which used a 428 chain in the mid 80's, all the ones I know had 520 by '79, apart from Yamaha, who had them in '76.

Cheers,
Andrew

[John-Boy]

Andy,
I have just converted my Challenger to run a 520 (5/8 x 1/4) chain instead of the original 530 (5/8 x 3/8). The reason being that 530 gearbox sprockets are difficult to get hold of. Both sizes have the same size side-plates so should be of equal strength, but the narrower rollers will probably wear out the sprockets quicker.
Are you sure you mean 1/2 x 5/16? Where do you get a gearbox sprocket to fit?

[johnrunnacles]

250 Challengers definitely had the smaller size chain, John-Boy. Problem I found with trying to "upgrade" to 5/8 x 1/4 was that the replacement gearbox sprocket (presumably intended only for the 360cc) threw the chain alignment out on the 250, so gave up and stuck with the highly-adequate 1/2 x 5/16.
Hope this helps, Andy?
John R

[John-Boy]

250 Challengers definitely had the smaller size chain, John-Boy. Problem I found with trying to "upgrade" to 5/8 x 1/4 was that the replacement gearbox sprocket (presumably intended only for the 360cc) threw the chain alignment out on the 250, so gave up and stuck with the highly-adequate 1/2 x 5/16.
Hope this helps, Andy?
John R

I didn't realise the 250 chain was different from the 360, John. You learn something every day!

[Andy Z]

250 Challengers definitely had the smaller size chain, John-Boy. Problem I found with trying to "upgrade" to 5/8 x 1/4 was that the replacement gearbox sprocket (presumably intended only for the 360cc) threw the chain alignment out on the 250, so gave up and stuck with the highly-adequate 1/2 x 5/16.
Hope this helps, Andy?
John R

Hi John,

That is interesting, and might well be enough of a headache to cause me to stick with the original chain size.

Many thanks,
Andrew

[johnrunnacles]

That might be your best course of action, Andy, although I do have a 5/8" x 1/4" gearbox sprocket going spare (and a new chain to match) if you're interested!

I can't speak for all 250's, John-Boy, but it was certainly the case with my 1965 MX2 with kidney box, that it was fitted with 1/2" x 5/16" chain as standard.

It was good to catch up with you at Marks Tey, by the way!

Best regards,

John R

[stormer254]

The M E that I ride uses the smaller chain and we have never had any strength or wear problems. Any body who has seen the bike go will know it's not slow! However the owner is a much more thorough and competent mechanic than I will ever be