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Junglejeff

Twin shock project

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I am rebuilding a ty250a.I have only been riding trials since spring of 2018 but figured I would share my rebuild for all to injoy (or laugh at).I ride a 2015 GG txt pro but like vintage bikes.The ty250 was my 1st motorcycle I had in 1976 when my father purchased it for me.The deal was I would work in woods taking down tree's to pay him back.I had no idea it was a trials bike but rode the hell out of it.

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Edited by Junglejeff
Wrong date

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Engine ran but barely when I got it.Found broken piston and slightly loose rod and right main bearing. I purchased a rod kit from B&J performance and a clutch carrier bearing and a front fender.Picked up a oko 26mm carb for it also.Ordered some falcon 13.4" shocks for it today from Europe.My performance shop informed me today my crank was done and my cylinder is fit to new wossner piston so looking forward to picking that up next week.

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The man at the performance shop was real surprised at the quality of the crankshaft.He does not get to work on bike stuff alot as he mainly does snowmobile and marine performance engines. He was amazed at how yamaha built such a nice crank for this application. He was able to true crank to within. 0005" with ease. 

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3 hours ago, Junglejeff said:

 He was able to true crank to within. 0005" with ease. 

Thats probably because Japanese bikes have relatively loose big end pins in comparison to European manufacturers

PS id be careful with your swingarm angle, don't over do it

Edited by faussy
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20190210_162923.thumb.jpg.d1be7fb8e57d6d73637cb0a663090945.jpghave most of welding and repairs done.Installed a new rear right motor mount to replace the broken one.frame and swingarm will go to powdercoat shop next week for a coat of yellow.

On 1/4/2019 at 6:45 AM, faussy said:

Thats probably because Japanese bikes have relatively loose big end pins in comparison to European manufacturers

PS id be careful with your swingarm angle, don't over do 

 

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That gusset in front of the rear upright must be pretty close to the rear end of the main chamber of the exhaust

Edited by feetupfun

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Also, why put gusset behind the upright ? I did not, and I never had any problem.

Guy

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On 2/14/2019 at 2:57 AM, feetupfun said:

That gusset in front of the rear upright must be pretty close to the rear end of the main chamber of the exhaust

About 5 mm away.I bolted on exaust to make sure there was not going to be interference before I put them on.

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On 2/14/2019 at 4:53 AM, guy53 said:

Also, why put gusset behind the upright ? I did not, and I never had any problem.

Guy

Overkill lol.Going to shave it down because I really didn't need it.

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I added the gusset behind the tubes as well but didn't add 1 in front, rode it a few tmes before adding it as insurance against bent tubes.

Are your shock mounts drilled through the tubes & welded both sides like Majesty did?

I also ended up adding swingarm extender plates to help with keeping the front down on climbs, haven't come across any negatives to doing this as I'm pretty certain the steering head angle had been altered

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On my bike, I welded the shock mount on the tube, I have no problem, but I'm not an expert rider so I don't ride as hard as one.

Guy

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8 hours ago, tony27 said:

I added the gusset behind the tubes as well but didn't add 1 in front, rode it a few tmes before adding it as insurance against bent tubes.

Are your shock mounts drilled through the tubes & welded both sides like Majesty did?

I also ended up adding swingarm extender plates to help with keeping the front down on climbs, haven't come across any negatives to doing this as I'm pretty certain the steering head angle had been altered

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I made 2 jig plates out of some scrap aluminum t-bar I had laying around.Drilled them a 340mm.I have read that just just putting the longer shocks in the stock holes makes bike real nice handling.I then left one on standard shock mount and used the one on other side of bike to mark frame.I then drilled through the tubes and slid a cold rolled shaft thrue.I marked the shaft and put it in my old harbor freight lathe and machined ends down to 12mm then tacked in place.Using the straight shaft kept everything perfectly in line.

Edited by Junglejeff
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After I had it fit up I did all the welding on the outside to lock shaft in(no pic of that).The frame bows out some as it goes down so I have the upper shock eyes fit as close to frame as feasible. I cut the shaft off on the inside then went deep and filled with weld.My concern was after drilling frame there was not alot of frame left and I wanted 100% weld contact with shaft and weld to frame.I may have to shim lower shock mounts out a little to make shocks perfectly parallel.

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I had to shim the lower end of the shock on mine, ao I think you will also have to.

Guy

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