tony27

That'd have to be a first, must be feeling his age now . You'd know our rocks aren't that big even in limestone quarries

Throw Peter B in the mix & that makes 3 of us

Yep I'm that 1 Tim

Pretty cheap really, if the motor was quiet apart from the mains then your piston should be fine. I'm not sure whether the 01 still used the same piston supplier as the 99 which had a very heavy/solid piston compared to the 290s & later motors but if they did it will be good. Unfortunately if it does need doing my guess will be around 300 pounds all up for a motor that will give years more troublefree use

They were the older open 6206 ETN9 C3s, the sealed type hadn't come out as a fix when I last replaced them Like you say they aren't exactly overcooled in the cases but I'd expect to see wear in other places in the engine & quite a bit of carbon on the piston crown & head but they're fairly clean. Seem to remember the blackness as being something mentioned in earlier postings with bultacos suffering particularly badly in the 70s, thought back then was carbon comtamination so you could be on to something with oil film breakdown I run motorex powercross at roughly 70:1, is meant to be a very good oil

It was suggested to me a couple of years ago that the bronze bush idea is probably the best thing for both the brake & linkage as needle rollers aren't really suited to the minimal movement they're doing in both places. They prefer to have full rotation ie a turning shaft rather than the maybe 45deg forward & back they get in these 2 places. I agree that the seals aren't the best but after owning a gasser in the 90s before with the separate seals outboard of the narrow bearings which always tried turning inside out when you worked on them that the intergrated seals are ok as last as you keep the maintenence up

Nope Tim not a copper just a toolmaker

Chris is great to deal with, has supplied me with a few engine pieces & always replies to emails quickly. Make sure you look after the linkage bearings with constant regreasing to prolong their life, still think the sleeves are the weak point

I don't think its anything to do with being grease filled but more to do thermal expansion & the possibilty thats what is leading to the short life span they can have I've got my engine apart at the moment & found the transfer ports have a black film in them the same as the bearings often do when they fail, wish I knew the reason for that

With the length of time the TYZ motor has been around the moulds for the engine are possibly nearing the end of their life, the amount of engine cases etc needed for 1 year of scorpa production would probably be less than a days production. There is the very real possibility that yamaha only produced the motors every few years as ecomony of scale says that the change over time of 1-2 hours for each of the moulds plus changing set ups on the CNC mills for the bearing holes & mating surfaces would not be worth it for the numbers required The reason sherco etc have been successful is that they have the cylinders done by the same company as each other or at least sherco & beta do anyway. They use a specialist piston manufacturer, in beta & sherco's case vertex who do replacement parts for japanese bikes as well & are used to doing lots of small runs. The sherco 290 & beta 270 have the same piston with a swapable name insert in the mould. The same manufacturer does both beta's & montesa's frames. Most use the same forks, everyone uses ajp brakes. Basically they all design the parts & have them made then assemble them at their own factories with a lot of shared components that are all made relatively locally rather than buying a ready built motor from half way across the world

I'm about to order the allballs kit from the local KTM dealer to be brought in by the importer with their next order, it contains the spherical bearing as well. Sherco doesn't harden their sleeves & so they wear quickly, I made some toolsteel sleeves & got them nitrided about a year ago which are still going strong. Biggest issue with replacing the spherical bearing is that the spacers are a tight fit in the bearing & easily damaged during removal. From memory the bearing code is GE12 but I'm not 100% sure on that. Part number for a shock bearing kit is R217 I think but the allballs kit would work out cheaper if you're doing the linkage at the same time http://www.goallballs.com/SHOP/shopexd.asp...Ret&id=3354

Neo I've got the SKF catalogue at work as well, in their codes RS1 is single NBR seal & 2RS1 is seal both sides. Some of the other manufacturers have their own coding for this such as l for NSK from memory. SKF use Z to denote steel shields which is fine for electric motors or skateboard wheels. I seem to remember reading somewhere that beta use these in their motors Quick explaination of the full code for the bearing is 6206 = bearing size 2RS1 = 2 steel backed rubber seals ETN9 = polyamide cage C4 = greater internal clearance- higher number is more clearance GJN = polyurea thickened grease In general the codes can be added together to give the specs of bearing you need The older type bearing code was 6206 ETN9 C3 from memory which will give you an example of how this works Trialsnutterman this is who I got the bearings from, they've been very helpful & parts get here quicker than they would from Australia which is where our bikes now come in via. When I asked SKF about the bearings they confirmed the specs matched what is on the page but said they aren't stocked in New Zealand & they didn't have a price although they would have investigated further if I wanted to wait

Brought my telescopic gauges home & just realised the piston should be 76mm so I've got the wrong micrometer in my bag, lucky measuring 1mm past is still on the scale I have the sealed bearings from sherco to fit, they have a poly urea thickened grease in them according to SKF's catalogue. The specs give a 7500rpm limit due to the seals which would be as a constant speed rather than a peak so everything stacks up Bike wasn't rattly but there are a couple of lines on the piston, only slightly discoloured rather than scuffed. I'm just thinking while its apart I might as well replace it & the beta importer owns me a favour, pistons are exactly the same as in the 270 beta

They say confession is good for the soul so here goes ..... Turns out when I did the mains & seals about 2 years ago I put 1 of the washers for the kickstart idler gears(#M163) on the wrong side of the casing, there was 1 of them plus the #M071 washer at the end of the output shaft meaning the 1ER pinion was 1mm closer to the 4EME pinion than it should have been, when I first split the cases & turned the shaft I could stop the problem by lifting the right fork slightly Putting washers back in correct positions removed most of the play in the kickstart idler & stopped the gears trying to select by themselves The gearbox shims look okay with not much wear only polishing where meet, the bushes in the gears have some play but not excessive. Forks are polished & selector drums still has the hard anodising in the slots so shims & washers will only be a precaution The main bearings are black as normal & noisy but already have them, transfer ports are also black- both in the cases & cylinder almost as though some burning charge is entering them(not logical just a theory). Haven't measured piston yet as I didn't bring correct micrometer home but I'm thinking it may as well be replaced after 5 years, bore looks good All in all the motor has very little wear & the amount a full freshen up is costing in parts is tiny compared with how much enjoyment I've gotten out of the bike so far

I'm guessing that yamaha is playing the GFC card & saying it's not economically viable to be building such a small volume engine with only 1 application & no use for it elsewhere, that & like the other japanese manufacturers are looking to stop 2 stroke production

Have engine out & everything apart from cylinder off, some end play in mainshaft 0.5-1mm max but none on output. Will take cylinder off & split cases at work tomorrow & do some measuring What should I be looking for kickstart gear wise, all looks good at first glance. Idler gear has a bit of play, 1-2mm at the most so will do bearing in that. No rounding or chips evident so far

Just started the pull down & only happens if leant to clutch side, turning hub by hand if leant away nothing happens but leaning towards me can feel gear trying to engage & then start to drive bike forward. My guess is that 1 of the shims has worn & lets a gear move just enough to catch the dogs on the gear next to it, they're only about 60p each so I'll probably just replace them anyway to be safe. Hopefully the bushes in the gears are okay & not letting them tilt. When I did the first set of main bearings the selector forks were good & so was the drum so I'm not anticipating problems there, would add greatly to the cost as forks are 40 odd pounds each & drum 80 odd. Will let you know findings once its apart & measured

Does anybody(Cope) know the thickness of the shims in the gearbox, about to strip mine to find some play & freshen up the motor & would help to have reference sizing to compare with Symptom is that if I lean bike to right(clutch side) on my workstand & rotate wheel or front sprocket if chain is off that it will lock as though in gear while in neutral, putting bike upright again disengages it, not sure about what happens if leant to the left as normally when oiling chain

Another remote possibity is you got 1 loose sprocket bolt, hope not as that'll eat a groove into swingarm

What condition is your chain guide plate(plastic piece on top of swingarm) because sooner or later your chain starts to hit the mounting screws, not convinced thats the reason though

I want 1 just not in a little french s**tbox

I'm beginning to wonder if its not chain at all & maybe something like pinking/pinging as you say it only happens under load in the higher gears & pulling the clutch in which unloads motor gets rid of it. Have you changed the type of fuel you're using lately?

Good to here they're still going strong Neo, I ended up ordering the standard late model 1's from the UK, SKF # 6206 2RS1 ETN9 C4/GJN Specs say normal NBR seals & a polyurea thickened grease rated -30 to +150C so hopefully they'll last, heat not so much the problem as water because I ride a lot in creeks esp when trail riding & we all know that shercos are completely waterproof

By my adding that wouldn't include parts, costs below Main bearings 18.29 x2 Crank seals 5.92 x2 Clutch gasket 4.85 Centre gasket 5.92 Reed gasket 1.13 Base gasket 5.69 Total 66.01 Then add Piston rings 21.46 x2 Little end bearing 30.13 Grand total 139.06 GBP Not an excessive price for a full engine rebuild after 8 years really, if you where talking mx change that to 6 months I'm pretty much spending that on my Jarvis which has plenty of hours(be into 4-5 figures) & the piston & barrel are both still fine, engine rebuild is easy for me so no labour cost involved.

Bearings,seals & gaskets are on their way 1 other little thing I'd like some advise on. When I lean the bike to the right on a workstand & turn the rear wheel it feels like it's trying to select a gear which goes away when put back flat so I'm expecting to have some wear in the gearbox somewhere. Does anyone have an idea of the correct amount of clearance between the selector forks & selector ie how much sideplay is acceptable. Otherwise my other thought on possible cause is the bronze bushes/bearings in 1 of the gears has excessive clearance/wear allowing it to tip Any thoughts?