Is a 85 RM disc front end legal on a 84 RM250??

[Tony Two Times]

 

Bought the bike. Got it home. It has a front disk. Checked the VIN thinking it might be an 85 bike and the seller made a mistake. Nope. It's an 84.

Sometimes I'm just not that smart.

T2X

[shelpi]

I would say No, but there were disc's around at the time, so over to some one that has the mom's 

[Andrew L]

Could be an 85 model that was made in 84 the manufactures bring out the next years model half way through the previous year from my experience.

[Tony Two Times]

Being an import hard to tell I guess?

But it will get me out on the paddock either way which was the main goal so no real complaints. Maybe just a lesson learned!

T.

[BAHNZY]

No quick answer here as it depends on what the front end has come from.
If the front end is from an 84 or earlier Kawasaki/Honda then YES you can use it. If the disc front end is from an 85 Suzuki (or other make) then NO you can’t use it even though it’s a 43 mm unit which is almost identical in specification to the Honda and Kawasaki units.  As the Suzuki 84 drum & 85 disc fork diameter was 43mm they interchange easily along with 43mm units as previously noted.

If it’s a Suzuki front end it will more than likely have a gold rim. Other than that check the date stamping on the rims to give you a rough clue as to what year the front end is. Typically anything with a date stamp around August/September 1984 would belong to an 85 specification bike.

The Suzuki 84 TLS 43mm front end has become very rare (& expensive) as owners attempt to return their 84 bikes back to original specification, particularly the 250 & 500’s where a disc front end was used to get better brakes back in the day.

[Krikey]

Being an import hard to tell I guess?

But it will get me out on the paddock either way which was the main goal so no real complaints. Maybe just a lesson learned!

T.

84 model has a 110 mm barrel.  From base to top of barrel (not including the head) will be exactly 110 mm. The 85 model has a different length (can't remember if it's longer or shorter).  That's pretty much the only way to tell quickly as colours mean nothing because they were changed/painted (eg 84 motor was originally black, 85 was silver and 86 was blue).

Aside from checking the VIN, also check the date stamps on the rims if they are original.

[KTM47]

Bought the bike. Got it home. It has a front disk. Checked the VIN thinking it might be an 85 bike and the seller made a mistake. Nope. It's an 84.

Sometimes I'm just not that smart.

T2X

The only answer is NO.

13.14.7.1  Acceptable for Pre 85 class are machines and components built up to and including the 1984 model.

Disc brake front ends from 84 Hondas or Kawasakis are acceptable.

Either just race the bike as a Pre90 or see if you can get another front end.

[LWC82PE]

I thought i had answered this 2 weeks ago in another thread??? The only pre 85 legal suzuki disc brake is a 38mm front end from a 1984 TS250X or disc brake wheel/caliper from a pre 85 GS/GT/GN road bike adapted to a set of 84 or older forks. So like the others have said, a 1985 RM disc brake is not pre 85 legal.

[Tony Two Times]

All good advice. Much appreciated. Will do some checking and come back over the weekend!

T.

[Nathan S]

As it is a race bike, my advice would be to chase an 84 Honda disc front, rather than any drum front.

[Krikey]

As it is a race bike, my advice would be to chase an 84 Honda disc front, rather than any drum front.

I have a spare 84 CR250 front end that I might sell on.

[Tony Two Times]

Barrel is 110mm per Krikeys advice which would make it an 84

Both rims are silver and stamped 985 which i assume indicates 1985 (Interwebs could only cough up earlier code formats for me which didn't help)

So to put the issue to bed I'm gonna say 85/86 front end on and 84 bike.

Just so happens there'd an 84 in poor shape on Gummy for $500. Curse of it is that it's in Tassie and I'm in Brisbane!

Thanks for the help with the detective work. Will keep my eyes peeled for a legit front end, but no real hurry as this bike is just the gateway drug to an Evo RM that will be procured sometime soon hopefully.

T.