tony27

Try getting hold of Stephen from eclassicbike over in Motueka, I rode against him at Kaikoura last year & he was riding 1. The way the shocks sit so far above the swingarm may change what maxton need to do to set them up

287g for the 438 piston, 320g for the 311 piston were the numbers I came up with at the time

The used piston with the chamfers by the transfers is the original type 438 TY250 piston, the new piston that has sharp edges & the thicker skirt is the type 311 piston that contacts the crankshaft

Here's the thread on the ozvmx site from when I built the engine, has a few photos showing the differences 311 piston kit, whats it fit? (ozvmx.com)

That is the 311 type piston, notice how the skirt is sharp where it meets the transfer, the 438 piston for a TY tapers in that area. The skirt on the TY piston is thinner as well I'll see if I can find the photos I took at the time showing the differences Try zooming in on the first picture in this listing, the taper is just noticeable & not very big which is why I think you should be able to modify your piston Ty 250 Type 434/516 Yamaha Piston Full Side 0,75 | eBay This is the guy I bought mine from but I don't think it was as expensive back then

Came across this when I rebuilt my 250C, often a type 311 piston is listed as fitting the TY but there are a couple of minor differences. The TY piston is made by ART but the 311 type is made by Izumi, thickness of the skirt is thicker on the 311 piston but the main difference I found was the TY piston has a chamfer from the skirt to the transfer cutout that the 311 doesn't, that seems to be where the piston hits the crank. I assume that the DT2 which is what 311 model code relates to uses either a smaller diameter crank or a longer connecting rod so the piston doesn't make contact If you have your old piston you should be able to see the differences I've mentioned, if you put wrist pin into both pistons at the same time you'll see that the overall height & pin position are the same. I didn't try altering the skirt on the 311 piston but I think copying the chamfer will fix the problem you have

Normal direction ie. anti-clockwise to loosen

Are you sure it's from the gasket & not the weep hole under the waterpump that gives an indication of a failing seal, will leak either oil or coolant depending on which seal has failed

When you order the new shocks remember to get the heavier 50lb springs for angled shocks, I have a set of the adjustable betors on my TY250C with majesty spec shock position & they work really well

You'll be meaning the magical springs, not sure if anyone is selling them in the UK but I think I read France classic trial has them They made a major improvement in my 250 forks along with the damper rods which aren't available for 175s Modifying the top yoke to move the bars forward or buying the billet top yoke makes a big difference to the handling which also opens up the ergonomics a bit

David Lahey aka feetupfun has a 200 in NQ so he should be able to answer your questions A friend has a 175 Majesty & after hoping on my modified 250c did some major mods to his, main changes he made were moved the swingarm pivot in front of the downtubes the same as the 250 & lengthened the swingarm, widened the footpeg mounts to get the same width as on a 250 which helps with balancing - amount was different side to side as the 175 has the motor offset to the right for chain clearance He hasn't gotten to try the changes out yet due to having to rebuild a very noisy motor but I'm sure he'll want to do some back to back tests with my 250 once it's run in

Definitely not HDPE, too flexible. Fairly certain it's nylon

Add a air filter to the list especially if there is water at the venue. I generally only carry a set of folding allen keys with me during the trial, you can generally get back to the start to replace any broken parts

Normally I'd go to partzilla & check the part numbers for the gaskets, the site will tell you all the models that use the same gasket which is normally a good starting point

John Cane at TYtrials.com is great to deal with, just fitted a set of shocks from him to my 250c & have a piston kit on the way for a friends 175 Majesty

That looks more like TY mono than YZ490. Must be another lever that can be modified to fit on the original knuckle

How long are the RD350 levers, I know from experience that the YZ490 levers are really long. Need something a bit shorter than the standard TY250 lever so it doesn't hit the repositioned footpegs as quickly

Looks very Suzuki full floater like in design from what I can see, that front pair of plates would be strange for a upper shock mount with the slotted holes but I think you're right. Definitely needs returning to stock which looks to be a fairly big job

The larger of the 2 measurements is the 1 to use, .02mm of taper is next to nothing which is mainly due to being a watercooled motor. As a comparison I measured a TY175 piston last week that tapered closer to .25mm from the base of the skirt to just under the bottom ring With a good synthetic oil a ratio of 70-80:1 is good, won't clog your exhaust packing & still safe if you do any trail riding between sections You will need to repack the muffler, the packing will be saturated & you'll keep getting oil out the end of the exhaust for quite some time

1 small detail I've noticed & would change is to put the wiring along the back of the downtube instead of along the side to protect it from rocks etc, fairly certain the loop just below the tank is for the clutch cable I've had several bikes that leaked oil at the front exhaust joint, a small bead of high temperature silicon left for 30 minutes or so before assembly seems to work well

Still the same bike you rode in the 90s Roger? Can't say I knew where the TY350 & JT35 I rode in the mid to late 90s ended up after I sold them as they never appeared to come out to trials

Most of the bike is shared with the 2 stroke models, worth looking on splatshop's site to see what is available. Sherco is very good at making improvements to parts & continuing with the same part number if it interchanges 2005 was the first model 320 from memory & it was far from sorted, I can remember the importer at the time here in New Zealand having the engine die a lot when hopping the front wheel. The later carb mods improved that as well as hot starting

If it's like most steel framed bikes the bolt should fit into what is called a nut clip at the back end of the tank, should be easy to get. Sounds like there is something missing in your kickstart assembly https://www.splatshop.co.uk/m6-nut-clip.html

Rev3 Beta & from memory early Jotagas

KX80 carb by chance? A JJH needle available from any trials dealer is a good start