Ty350

[jse]

Wow! Nice explanation! Good job on the motor work. I'm looking for piston and rings for a top end job and my favorite online source doesn't show any availiblility. Are parts availible? Maybe another bikes rings? Also I got some modification info from 1996-1997 about things guys were doing to their TY's to make them "Super TY's". This includes carb mods,swingarm extensions,fork mods,linkage mods and frame mods(!) to reduce rake. I could post some if anyone is interested. Quite a bit of stuff!

Are those Talon brakes pretty rare? They look tempting...

Finding a source for a piston and rings is difficult and I haven't found one yet. I've posted it on this forum and didn't get any good leads and am tempted to convert my 350 to a 250 due to availability of parts. I'd be interested in the 90's mods.

I'm not sure how rare the Talon conversions are here in the U.S. Some riders swap later front ends to the TY for a disc brake.

Jon

[z09]

I just pulled my top end off and I will be taking it to my local guru for his findings as to what pistons or rings might work. His company does all of the local motorcycle shops machining and top-end/crank work. He is a wonderful 73 year old machinist who has decades of motorcycle knowledge upstairs. He is a Wiseco "dealer" and told me that lots of old Wiseco inventory got sold in bulk lots and they don't run those old parts anymore. Yamaha MX 360 parts might be close but not availible either. DT-1 maybe but needing windows cut in the piston? 8o mm Jet-ski??? I'll post my findings...

[jse]

I just pulled my top end off and I will be taking it to my local guru for his findings as to what pistons or rings might work. His company does all of the local motorcycle shops machining and top-end/crank work. He is a wonderful 73 year old machinist who has decades of motorcycle knowledge upstairs. He is a Wiseco "dealer" and told me that lots of old Wiseco inventory got sold in bulk lots and they don't run those old parts anymore. Yamaha MX 360 parts might be close but not availible either. DT-1 maybe but needing windows cut in the piston? 8o mm Jet-ski??? I'll post my findings...

I'd heard about the MX/DT possibilities, but they seem rare also. I had a friend at the local Yamaha parts counter check the Wiseco listing for bore sizes but nothing came up close. There are a lot of the 350's here and I would expect any info you uncover will be helpful, thanks.

Jon

[z09]

O.K. Here it is: DT-1,MX 360 and R1 And R2( all are old Yamaha two strokes) pistons are 80mm as is the TY 350 which has a chrome bore lining. Boring to a bigger size would require re-sleeving and plating(big cost).The DT-1 has a single thick ring which is fine for higher RPM, not the low RPM torque of the TY and the "piston rock"associated with single ring pistons.The MX 360 has a longer skirt(might need shortening) and no rear "port windows"( would need to be cut into the piston).This piston has two thin rings like the TY 350 but the ring locating pins are too close together and would locate the ring ends right over the rear intake port(NOT GOOD).R-1 pistons have the single thick ring. The R-2 piston has the right windows and two rings, the lower is a thin MX 360 ring and the top is a Dykes ring which is "ramped " to the outside and is exposed to the top of the piston/combustion chamber and the compression pressure pushes the ring outward for better sealing.This is the "holy grail" piston/ring replacment for the TY 350. MX 360 stock bore or "one over" rings are a good replacement for the TY 350. Any bigger would dig grooves in the cylinder even when properly gapped. All of the above are discontinued! Maybe someone knows of a source... Jeff

[z09]

I made a mistake above. The MX 360 has a single ring and the R-1 two stroke has the ring pins too close together! Jeff

[kuelmuel]

Wow! Nice explanation! Good job on the motor work. I'm looking for piston and rings for a top end job and my favorite online source doesn't show any availiblility. Are parts availible? Maybe another bikes rings? Also I got some modification info from 1996-1997 about things guys were doing to their TY's to make them "Super TY's". This includes carb mods,swingarm extensions,fork mods,linkage mods and frame mods(!) to reduce rake. I could post some if anyone is interested. Quite a bit of stuff!

Are those Talon brakes pretty rare? They look tempting...

I dunno about everyone else, but I've always found my Talon front disc to be a bit rubbish compared to the Pinky front disc, better to upgrade to one of them if you ask me.

[shane]

hey,

well im new here,so add some lube ok.

ive been reading this post,waiting for Jeff to post some more info about pistons.

i own a TY350 that needed a new piston.weeellll it still needs a new piston.

ok,here is my story,it might be a bit long,so grab a drink and read on.

i bought a 1985 TY350 in november,got a real good deal on it.the kid said it ran out of power and popped in front of his house one day.

ok,im somewhat mecanicaly inclined,ive been around motorcycles a bit,dirt and road,2 and 4 strokes.looking for a winter project that isnt a bicycle,plus ive been looking for trials bike for a while.yes,this one cought my fancy for some reason.

so i get it home,do a quick once over.ever thing checks out,but the fuel is on,no gas in tank.i put fuel in tank,kick it three times,she runs,she run pretty good.come may i go to trails event.10 sections three rounds.i do 9 sections.

no more.bike is making a nasty pinging noise.i park it,b.s,drink beer and watch others have fun.get home and find a broken piston,or the holes in the piston got real big.

my search started.months later,looking everywhere,local bike shops,the net,i find a RT-1 piston at the local yamaha shop.that is after i cant find a TY350 piston ANY WHERE.

it is standard bore,it fits like it should.i have the holes drilled in it,then i find out the skirt DOES need shaved.all the work is done by the local yamaha shop.

i put it in,check for clearence.it looks good.

i fire it up,warm it up,shut it off for it can cool down.start it back up.sounding and running good.decide to check my clutch adjustment,3rd time i let my clutch out hard a nasty sounding pinging sound comes from the motor.

Grandson who is 7 ask how did a rock get inside the motor papa.

yep,the piston broke again,or the holes got real big again.

but i found a spec that shows the holes should be 10mm above the skirt.yes,it was after i got the bike back together.no,i dont know if there was a 10mm space or not.i just know my piston broke.i cant go riding with my Grandson tommrow.

but i will be looking for another 360 piston,probly a R-2.OR WHAT EVER I CAN FIND.

so anyway,

a RT-1 piston will fit.YOU have too have the HOLES DRILLED,SHAVE the SKIRT.but remeber,the holes have to be 10mmabove the bottom of the skirt.at least thats what the spec i seen showed.

i told you it was going to be long,i just hope i didnt bore you to much.im just bummed about not getting to ride with the grandson,he was looking forward to it.but not as much as i was.

oh,try this at your own risk and expence.

later.

shane

[htrdoug]

Jon's TY350 is featured in this month's T&E News

[jse]

Jon's TY350 is featured in this month's T&E News

That's as clean as the TY ever gets.....

Here's a couple of other mod closeups:

Flatslide bell modification/ stock floatbowl drain on flatslide

Extended rear of stock peg to move wieght back without extending complete mount any further

Fabricated caseguard from aluminum

Clutch cable end threaded and nut added to reduce flex in ferrule area to make clutch feel more direct

Cut curve of u-bend tubing added to vunerable part of exhaust bend for better rock protection

Jon

[rosey]

Nice stuff!

I had my footrests modded like that on my Monos... were easier on the boots and feet!

That casing protector may not be as good as it could be (it looks nice though)... the better ones also used the mount on the 'top roller' otherwise a 'big chain off' just moves the whole of the protector and casing lugs off the engine.

Also not sure if you slam a few rocks over there in Tulsa, but I didn't notice you had modded the front bash plate mounting... we used to fit a second bolt in the front mounting (and better to make them with a dowel type fitting so they are a tight fit too) to stop it rocking .. this rocking used to result in cracked flywheel casings!

[jse]

Nice stuff!

I had my footrests modded like that on my Monos... were easier on the boots and feet!

That casing protector may not be as good as it could be (it looks nice though)... the better ones also used the mount on the 'top roller' otherwise a 'big chain off' just moves the whole of the protector and casing lugs off the engine.

Also not sure if you slam a few rocks over there in Tulsa, but I didn't notice you had modded the front bash plate mounting... we used to fit a second bolt in the front mounting (and better to make them with a dowel type fitting so they are a tight fit too) to stop it rocking .. this rocking used to result in cracked flywheel casings!

The stock pegs (and most pegs of that era) are arch killers, as you probably remember!

I thought about a longer top to the case guard but figured (possibly wrong) that the heavy ball-bearing hard roller I made just before it would take some of the hit. I'll take a second look at that, thanks.

Good idea on the front bash plate modification. We have more big rocks in North Eastern Oklahoma than Scotland has bogs (well, maybe not) and that may be my next project.

Cheers for the tips.

Jon

[utahpete]

Hey everyone,

Thought I'd add to this old thread. I bought an 85 TY350 last summer. It was in great condition and I had a blast with it through the fall with widened foot pegs as the only mod.

This winter I found a second flywheel on ebay and had 60% of the band machined off (lightened the flywheel by 1.65 lbs or 25%). I installed Boyesen Reeds and did the recommended mod to the cage and re-jetted the carb. I sent the head off to Bob at BJ Racing for his modification.

And while waiting for it to return I lowered the foot pegs by 1 3/8". I chose not to move them back, just down. I used Sherco's peg mounts as a model and beefed up the bottom of the mounts to add to bash plate area. I did have to lengthen the chain tensioner to clear the new peg mounts.

I purchased new Michelins and successfully mounted the X-11 tubeless radial (with a tube, of course) on the old rims. The first try didn't quite get the bead set ... I stopped at 66 psi and the bead did not quite set. The next day, I used undiluted dish soap on the beads and took the psi up to 70. It was scary, but the beads set uniformly and I backed the pressure down to 55 psi and let it "rest" for 15 minutes of so. Then just kept bringing the pressure down by 10 or 15 psi over the next hour. It held and has held through several severe tests in the big rocks this spring. I ride at 5 psi and the beads have not moved at all.

And the modifications have turned the rather staid machine into quite the performer. With my limited abilities, I'm very happy with the amount I took off the flywheel. It is very noticeable, yet controllable as well.

I replaced the piston pin and small-end bearing (had some wear), and have purchased a new, old-stock piston for '74 DT 360. I'll keep everyone posted as I have the piston modified and give it a try.

Here are a couple of pictures of the bike now.

[lineaway]

Looks like you have the `86 gearing! Next replace the front brake cable mount to the fork with a piece of aluminum block to take up the `flex`. Improves braking quit a bit.

[htrdoug]

Looks fantastic! I think I may be missing my old one...

Put that speedo in a box somewhere where you won't loose it,she'll be bashed in no time otherwise.

I'm having great luck with the Neutech Tubeless system,allows me to run super low pressure in my SWM rear wheel,Highly recommend(2.5psi no issue)

[utahpete]

Yeah. I wanted Talon sprockets and I ordered them from Trial UK, so I figured since I ride in so many rocks, I might as well go with the '86 sprockets. By the way, the two sprockets and the air-freight charge were still cheeper than going with the very-limited supply for these bikes here in the states. I would highly recommend these guys for anything light. The front brake cable mount is next on my list of things to do.

I thought about going with the tubeless system ... maybe next year, I've spent enough that my wife is starting to notice! Speedo is probably safe, as I am self-employed with no disability insurance, and wrecks so far have only resulted in bruises—on me. I am practicing a lot in big rocks and boulder fields though, so it may be better if I take your advice.

Thanks to both of you for your comments.