tony27

Mine came from Sammy Miller Products which is now called Feked Classic Bike Parts. Doesn't come with mounting brackets which are now available from TY Trials https://www.feked.com/yamaha-ty250-twinshock-standard-seat.html https://www.tytrials.co.uk/trailandtrialsuk/cat_88750-Seat.html

Get hold of mid-atlantic trials, they sell ready to go OKO D-slide carbs for a good price. I'd suggest getting the 26mm kit, you need to heat up & stretch the airbox boot to fit over the carb I have seen the kits on eBay from them before but being in the US it would be easier to buy direct http://www.mid-atlantictrials.com/TY-Yamaha.html

YTZ250 is a trike, otherwise known as the TRI-Z Bore diameter looks to be 68mm, wiseco part number 515M06800 for the standard size kit

Some models of Shercos have a different sized shock to other brands, from memory the spring had to be smaller diameter to fit in the space

In the lower half of the north island in NZ we trail ride our trials bikes on harder/tighter tracks than most riders are capable of on enduro bikes. We generally carry 2 or 3 litres petrol in our packs & are gone for 6 - 8 hours

I hate to say it but it sounds like you've gotten things messed up. The bushes on the bottom of the stanchions has to spread slightly to slide into place with the coating on the outside. You slide the stanchion into the fork completely then slide the top bushes down & into position in the top of the fork leg, takes a bit of working around the bush to get it in place as it actually needs to close up the gap. Fork bushes are actually the first part of the seals in reality, it's only when they wear that oil should get to the seals in any great amount The fork rebuild file in the links at the top of the page should show what I have tried explaining about which way to assemble the forks, it's a easy job if you do it right

Depends on which insert you fit, lower compression should tame it down a bit, higher more snappy

Easiest way to make sure the fan motor works is to join the 2 wires to the thermoswitch together, either use a short piece of wire with the correct spade teminals on the ends or just use a paperclip. I have the piece of wire in the bottom of my bag that is always with me on the bike to make sure if something does happen I can always ride back to my car especially when trail riding When the motor is running the fan should work by doing this, if it doesn't then either your fan motor or 1 of the wires is faulty

Ok, from looking at the 75 parts list the shaft you're talking about is 1 of the gearbox shafts, part number 598-17421-00. Fitted to a similar number of bikes https://www.partzilla.com/product/yamaha/598-17421-00-00?ref=e9b9381003ad2d5ac0b735f2a89653adee09ab62 https://www.ebay.co.uk/itm/NOS-YAMAHA-DT80-GT1-GT80-TY80-YZ80-DRIVE-AXLE-PART-598-17421-00-00/263356538646?epid=1923027336andhash=item3d5145df16:g:PsIAAOSwBkRaIV4C

Had the clutch holding nut loosen on a older bike which then lifts the pressure plate. Wasn't something that happened instantly & there was still a certain amount of drive

Looking at Partzilla will give you an idea of what other motors use the same shaft which will help broaden your search results Not really that familiar with what years the TY80 were made but as an example here is the shaft for A & B models & all the other motors that used it. https://www.partzilla.com/product/yamaha/353-15660-01-00?ref=077d15c56588db1d2f2f320eb31147ca11f4a5bc There a couple of brand new shafts using this part number listed on eBay from Canada & the US. They may be the correct part for your bike https://www.ebay.co.uk/itm/Yamaha-Kick-Axle-Assy-Part-353-15660-01-00/153391188038?hash=item23b6d3c846:g:kN4AAOSwdIpcSPqF

Look up pit replica seat covers, made in Thailand & seem to have a good reputation. Listings I've seen on eBay have a cost of $65us with free international shipping

Mine has no flywheel weight on it at all & it works quite well, the flywheel had the band removed before I got hold of the bike so I can't say how it changed things Having a radius on the bottom of the transfer divider is what the top 2 stroke tuners reckon works best, wouldn't be something that would be noticeable on a lightly tuned trials motor The event I got the bike running in time for last year is a 3 day event where twinshocks ride the same sections as the clubman classes but are scored seperately. It's always good to be able to compare the scores & work out how many of the new bikes have lost more marks, first day I lost 1 which was either the same or better than the top clubman, other days I don't remember apart from the scores were higher

Turn a mandrel up with spark plug thread on it then wind the head on without removing the mandrel from the chuck, that gets the head running as true as possible. I altered a YZ490 head using this method & it worked well I had thought about increasing the compression by removing some material from the gasket surface then reinstating the squish band but found having a fresh bore & piston kit improved the compression enough The only work I did to the ports were done to the intake to allow a YZ85 V-Force reed block to fit, no polishing was done. The transfers were already quite well matched, the divider had been knife edged which is now considered to be counterproductive but I didn't bother changing that. You'll be surprised just how good a fresh TY250 motor is

Alternatively throw the dellorto away & fit a oko, much better carbs & cheap to buy

Just like most of the world championships then

I run avgas in my Sherco after having to replace the fuel tank due to ethanol related swelling & it's far better as far as shelf life goes, I had a year or so away from trials & the bike ran fine on the old fuel well shaken up. i wouldn't have even thought about using the leftovers if the fuel was pump gas

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

Wiseco is often referred to as seizeco for good reason, can't say I had any problems running 1 in my YZ465 though. General riding on a trials bike would be considered as a careful break in by most people, I rode some tree root sections that didn't require lots of revs for about an hour to run my 250C in earlier this year when I fully rebuilt the engine

https://www.tytrials.co.uk/trailandtrialsuk/prod_2768676-812-Full-Piston-Kit-TY250-Twinshock.html If you look towards the bottom of the page you'll see a recommendation of 0.002" or 0.05mm clearance

Bearings are C3 clearance so there should be a barely noticeable amount of play, see what happens with the new gasket, unless the motor rumbles the main bearings are probably ok

Heavier flywheel doesn't change the amount of torque a motor has, a 2T should always have more torque due to firing every revolution. When people say 4Ts have more torque they are actually confusing flywheel mass needed to keep the motor turning during the non-firing revolution with torque

It should work but you'll need the head as well, fairly certain the base gasket is the same for both size motors

Have a good talk with the guys when you order the puller, they'll tell you exactly what you need to get things sorted.

Winding the screw in richens the mixture, sounds like you need a bigger pilot jet. The pilot jet in the TY mikuni is different than most other mikunis which means your local shop won't have 1 in stock, with my modified airbox that breathes a lot better I took the advice on TY trials site & ordered a #37.5 which has worked out well B&J racing is closer to you than TY trials so I'd see if they can supply you a couple of different sizes