tony27

The backfire as it died would suggest timing has moved to me, pull the flywheel & check the woodruff key

250 takes less technique than a 125 due to having a broader powerspread, either would be a big step up on the Scorpa 4 stroke. Can't comment on the difference between the ST & factory

The 250c I ride occasionally had the steering head angle modified around 99 to the same angle as the Beta of the same year by the New Zealand Beta importer's son, we stood both bikes side by side last year which confirmed what we suspected. Even with the newly lengthened swingarm this bike steers really well, as a bonus ground clearance is slightly increased without going to the extent of lifting the motor in the frame like Majesty did Weight is more of a problem on the more common A models than the later bikes with their steel tanks & bulbous aluminium clutch & ignition covers, I haven't looked for the claimed weight difference between an A & C or later bike but the aluminium tank & narrower magnesium sidecovers I would think there would have to be 2kg saved Like everything not every bike suits everyone, what works for me could be totally wrong for you. Once you've decided on how important parts supply is to you it's best to try as many of the remaining options as possible, it's no good buying a bike that is easy to get parts for if you don't get on with it

It's a feel thing adjusting taper roller bearings. Adjust them so there is a slight amount of drag with the top yoke off, when everything is tightened back up the wheel should stay pointing straight until given a light push but shouldn't take any real effort to move

Double check the numbers, I suspect they will actually be ST25. Without looking at my bike I don't think there are any numbers on the cylinder & head to give you the engine size, the 250 & 290 share everything but the piston, cylinder & head so the engine number isn't the only a sure indicator of actual size

I use those on my CZ vmx bike, only the brake is drilled for span adjustment

To use the DLS brake plate you really need to be using a 80/81 465 brake plate with mono forks otherwise the cable will be at a strange angle to the forks

I have ARC folding levers on my sherco & the span is adjustable independent of the other adjustments using the bolt & locknut near the folding pivot point in visible in this photo. Some of the other folding levers may have the same feature

I've just done the opening up of a TY175 intake to take the original reed block out of my TY250, took a while with a dremel but less metal needed to come out than was needed to get the v-force reed block into the 250 What number reeds fit TY250 twinshocks? Boyesen's website show quite different numbers for 74 & 75 which is incorrect as they should be the same part, I suspect what they have for 75 is actually the mono but I can't confirm that

From what I can see the connection for the killswitch is the type that can be opened & the wire removed without needing to cut anything, just remove the wire & clip the cover back together while you check for spark, you don't need a killswitch fitted until you try starting the bike Another thing to check is that the crimped connections on the wires are actually working which will involve a multimeter when you have the flywheel off, it could be a good time to replace the wires while you're relocating the condenser which will make sure the connections are all good & there isn't a break in a wire Shortening the plug wire isn't a silly idea, looks like you'll have enough left over to have a spare for the future, replace the cap while you're doing that

Going off the number on the piston I would assume it is a wiseco piston, the UK expert in TYs uses wossner which may be lighter. Either way they are lighter than the #311 pistons often listed as fitting TY250s which crash into the crank due to being thicker walled & not tapering up at the edges TY motors don't require any special tools to assemble apart from a clutch basket holder Have you looked at getting another crankshaft off eBay if your's is bent? You're definitely having a bad time with this motor, I didn't even need to do the crank in mine which had sat for years, was still on standard piston & cleaned up to 70.25mm no problem

Theirs was 1 of the locally assembled ones called a NZeta, I seem to remember when they picked it up at a fundraising auction that they used a car battery to get it running & take it for a ride. They were quite a different bike with petrol tank over the front wheel, a spare wheel that fitted either end & the 12v electrics I spent a lot of time on Jawa & CZ bikes when I was younger, they were really well made with a lot of parts sharing between the brands & engine sizes

My parents CZ scooter had that in the early 60s maybe even late 50s but it was quite a bit bigger than the normal generators fitted to their road bikes with the same motor. Electrics have improved hugely since then

I would assume the rusty coil was the 1 at the bottom? That shouldn't be the cause & neither will the dirt at the bottom of the cases. By all means clean everything but I doubt that is your problem Scroll down this link to the readings you should have from the stator, usually 1 of them is a long way out if there is a problem https://www.splatshop.co.uk/stator-repair-exchange-new-style.html

The wasn't a standard airbox fitted when I first got the bike to work on, the A model I could rob parts off if needed had a shrunken, rock hard connection. Once I got a C model airbox I needed a connection & I found the seller on eBay was making them. Their website is www.claussstudios.com well worth a look for rubber parts for other model bikes

I did quite a bit of work with JB Weld to fill in all external signs of the oil pump system on the clutch cover which is why it looks different, needing to repaint the magnesium covers on the C model made it easy to hide. I haven't looked at the part numbers for the oil pumps but I wouldn't be surprised if they are the same with only the drive in the cover being different, the gasket for the pump is same so any of the kits should fit

In effect they have changed the gearing the same as if they had fitted a 42tooth rear sprocket, not sure I would have done it the way the have. As said before the 9tooth front sprocket wears the chain quicker & has a shorter lifespan due to the tighter radius the chain goes around

No real damage but you are missing out on bottom end power if it needs repacking

From what I see in your photo the drive fits into the end of the crankshaft unlike my C model which means no extra parts inside the clutch cover, get the blanking plate kit from B&J Racing or TY Trials & block the other end of the oil line which should be into the side of the intake port on the A model - a short 6mm bolt & fibre washer will do that Run a good oil at 40-50:1 & you should be fine with no other changes needed. http://www.bjracing.com/id115.html https://www.tytrials.co.uk/trailandtrialsuk/prod_179120-Oil-Pump-Hole-Cover-Kit-TY250-Twinshock.html

E=3/4 reach, H=1/2 reach. S is standard electrode ie. the fat type, different last letter refers to shape of the electrode tip

When you ride for the venues owner there is no honour system, the rules don't apply the same as they would for a lower ranked rider

I have that ignition in my 250c, you'll need to mark the cases & flywheel at the correct firing point before strobing it. Chances are centre of the slot will be pretty close, I didn't manage to strobe mine before using it & it was pretty good, some slight pinking under heavy load hill climbing between sections but fine in the sections

I bought I of those for my TY, perfect fit on the bike & well worth the money

Have heard that about their 250 engines as well

My TY250 is fitted with an x-lite from memory & didn't have any problems at the multi day event I did last year. Still want to get a set of spokes to fit a flanged Akront rim so I can go tubeless at some stage but struggling to find somewhere that can roll 4mm threads