ty 250 mono aftermarket parts

Got a technical question? Ask it in here.

Moderator: Moderators

FM350
Expert participant
Expert participant
Posts: 488
Joined: Thu Apr 14, 2011 7:04 pm
Bike: Fantic
Club: Otter Vale

Re: ty 250 mono aftermarket parts

Postby FM350 » Tue Jul 26, 2011 5:28 pm

I wonder bearing in mind the cost of things like Pro Monty exhausts, and works type air boxes from Japan, what rear suspension unit are you using?



Ferretflasher
A grade participant
A grade participant
Posts: 102
Joined: Fri Nov 24, 2006 7:45 am
Location: grimethorpe, UK

Re: ty 250 mono aftermarket parts

Postby Ferretflasher » Wed Jul 27, 2011 7:11 am

I have 3 rear shocks to choose from, a standard DeCarbon Yamaha unit, a standard that has been rebuilt & lengthened by 20mm and a Fox Air Shox unit that is quite literally an air unit from the 90's like a Mountain bike that can be pumped up with a shock pump. All 3 are used for different trials with the +20 mm unit giving the best results as it never bottoms out, unlike the standard unit when you hit a hollow at speed and bottom out the tyre on radius arm/rear fender on full compression.
Go onto eBay France and type in YAMAHA TY 250 and you will find a new Dutch unit to fit but it retails at 499 euro !! It is fully adjustable and probably quite good but its worth nearly as much as the bike !! The Fox Shox needs rebuilding as it dont hold air after 5 hours so I dont use it much ! It was quite trick in its day but dont know who could rebuild it today.

The standard unit with remote canister is still very good so long as it has not leaked but the rubber bump stops tend to perish and the top rose joint needs changing after 25 years .... but otherwise not a problem to my level of riding ... just dont expect to do bunny hops or side swings as easy as a modern bike, it is best suited to no-stop and can do most things ... it did after all herald the dawn of the mono shock era !!



FM350
Expert participant
Expert participant
Posts: 488
Joined: Thu Apr 14, 2011 7:04 pm
Bike: Fantic
Club: Otter Vale

Re: ty 250 mono aftermarket parts

Postby FM350 » Thu Jul 28, 2011 6:18 am

Cheap and easy way to get good rear suspension on the TY, is to modify the linkage and fit unit from a modern bike, which are very often changed when bikes are new, by riders who upgrade to Ohlins.



Ferretflasher
A grade participant
A grade participant
Posts: 102
Joined: Fri Nov 24, 2006 7:45 am
Location: grimethorpe, UK

Re: ty 250 mono aftermarket parts

Postby Ferretflasher » Thu Jul 28, 2011 9:38 pm

If only it were that easy ........... that Yam rear shock has a forked lower end which means big problems to over come ..... but I too am on with that!! The suspension crank will need 2 large alloy lugs welding onto it where the bearing would normally sit, these need positioning so as to give a shock length of about 280mm centres. I shall post pic once I've got something worked out.



FM350
Expert participant
Expert participant
Posts: 488
Joined: Thu Apr 14, 2011 7:04 pm
Bike: Fantic
Club: Otter Vale

Re: ty 250 mono aftermarket parts

Postby FM350 » Fri Jul 29, 2011 5:51 pm

Plenty of non runner Gas Gas Pros around, so the easy way to modify the TY is to use the linkage parts from one of those, rather than attempting to use the TY parts, which wont work well with a modern shock anyway.



Ferretflasher
A grade participant
A grade participant
Posts: 102
Joined: Fri Nov 24, 2006 7:45 am
Location: grimethorpe, UK

Re: ty 250 mono aftermarket parts

Postby Ferretflasher » Sat Jul 30, 2011 6:09 am

Far too much work involved,and it wouldn't be a TY after wards. May as well ride an old GG Pro. No, IMHO the TY does NOT need radical changes, just small tweeks and improvements to the old bike and its plenty good enough. Just fitted a Boyesen reed valve and chopped the old cage out, well worth the money for the smooth clean response ... along with everything else I have done. Piston & rebore is most expensive thing I have done to it !!



FM350
Expert participant
Expert participant
Posts: 488
Joined: Thu Apr 14, 2011 7:04 pm
Bike: Fantic
Club: Otter Vale

Re: ty 250 mono aftermarket parts

Postby FM350 » Sat Jul 30, 2011 4:42 pm

Cant quite see how fitting a cheap rear unit and linkage that worked properly would mean your bike wouldnt be a TY any longer?



Ferretflasher
A grade participant
A grade participant
Posts: 102
Joined: Fri Nov 24, 2006 7:45 am
Location: grimethorpe, UK

Re: ty 250 mono aftermarket parts

Postby Ferretflasher » Sat Jul 30, 2011 9:42 pm

Yam mono swing arm is totally different to that found on a GG, the linkage and shock sit inside the recess AND the shock is practically vertical. The Yam has a solid swing arm with the shock angled above it via the relay arm. Therefore it would need the swing arm, linkages and shock ..... and brakes and wheel ..... and the chain is on wrong side .... and the brake would need to be hydraulic etc
Just not worth the time & effort etc. although Dans Hamilton Yam also has a GG rear wheel and master cylinder just welded on like with the GG Aire has !! Simple but works very well, cost about 2 GBP / 5 A$!!
My extended shock is nothing special, all I did was lengthen the U shaped fork job at the end with a bit a 4mm strip and welded it on, cost about 2p ...0.5 cent!! Sure does make a difference though.

Keep it pure .... keep it Yam ... keep it cheap !!



FM350
Expert participant
Expert participant
Posts: 488
Joined: Thu Apr 14, 2011 7:04 pm
Bike: Fantic
Club: Otter Vale

Re: ty 250 mono aftermarket parts

Postby FM350 » Sun Jul 31, 2011 2:55 am

I have a couple of TY swinging arms and to be honest cant see much of a problem modifying one to accept a Gas Gas shock and linkages? Main advantage of a more modern shock is obviously improved suspension performance, but on the TY this would also allow a bigger air box. However for use in easier events the stock bike is perfectly ok, and only really needs alteration if its going to be used in air-cooled mono championship events, against bikes like 245 and 305 Fantic's.



Ferretflasher
A grade participant
A grade participant
Posts: 102
Joined: Fri Nov 24, 2006 7:45 am
Location: grimethorpe, UK

Re: ty 250 mono aftermarket parts

Postby Ferretflasher » Tue Aug 02, 2011 4:47 am

Anyone seen anything like this in times gone by?? Made by Fox Shox, USA sometime in the late 80's I believe. It holds 110 psi now OK. What pressure did it work best with?
Attachments
IMG_2844.JPG




Return to “Technical help”

Who is online

Users browsing this forum: No registered users and 7 guests