If my clutch sticks, drags or makes noise then I know there is water in the transmission fluid which in my case is ISO 46 hydraulic oil. It means time to change it.
SAE 10-30 is a multi-grade engine oil and transmissions don't need multi-grade oil, transmission oil is never subjected to combustion chamber temperatures, all it lubricates is spur gears, shift forks and a wet clutch.
If your engine is left standing for a long period without use and there is any water from condensation or fuel in contact with the clutch then your friction plates will swell. That is what causes the stick and drag. Take all the friction plates out, clean them well and dry them completely before reassembly with fresh oil. Examine the dry plates for consistent thickness in the friction material, sand them flat and even if necessary or replaced damaged plates as required.
ATF is Automatic Transmission Fluid and perfect if your motorcycle had an auto transmission with a torque converter and everything is virtually fluid driven. Trials bikes have no auto transmission, no torque converters, what they do have is the same things inside as a farm tractor or heavy construction equipment like an excavator. Hydraulic fluids have a higher operating temperature range and maintain viscosity better than ATF in a broader temperature range.
If the small gaps between the clutch friction pads becomes clogged with dirty oil and burnt pad material, then fluid can not escape from inside the clutch pack causing the clutch to slip. Lot of people miss that one.
SAE 10-30W is what Yamaha recommended, when all other oils you mentioned were already available....
Is the atf just a good alternative to 10w30 it says to use? Or just better for old bike? I was planning on full fluid flush and renew anyway but good to know that’s normal for the clutch to stick.
i found an online manual for the ty350 but it would be dead handy to have a book in the workshop- I’ll give steve a try👍🏻
The old boy i got it off said to run it 40:1 not synthetic - sound ok? What’s the general opinion on mix?
40:1 non synthetic is what i use in my ty250 monos.
10/30 is what i run in the gearbox, ATF is fine too. They all stick if stood for more than a week or two.
Got my workshop manual from Trail and Trials UK, 3 languages, not cheap, even pricier now.
I believe there is a ty350 mono manual available online somewhere FOC to download, i have this too and printed out, most of it is useable for the 250 bar bore/piston info.
Apart from Carlos Casas and many others in the ssdt, and Javier Cruz, Javier Gil, Carlos Bosch and at least another ten in the pre 65 and highland 2 day ....?
Ok ok, apart from ...
7 hours ago, b40rt said:
Carlos Casas and many others in the ssdt, and Javier Cruz, Javier Gil, Carlos Bosch and at least another ten
Hi Everybody. I am thinking about getting a new bike. I am 50 and have no experience with motorcycles but I am a decent mountain biker. I also ussually excelled in other agility sports like snowboarding and kitesurfing. What would you recommend as a first trial bike? I am also wondering whether I could share the bike with my wife. She would only ride it off road without really getting too agressive. I have much more ambitious plans I weight around 162lbs and my wife is about 105lbs.
I have a Clymer Vintage Spanish off road manual, comprising the Big 3 - Bul, Mont, Ossa from the years mid 60-s to late 70's all models trials thru motocross, 125-350.
May still be available, some pretty useful stuff in there.
Another thing that can help with this sort of work is to modify the ID or OD of the old main bearings enough so that after fitting the new conrod, you can do any test-fitting of the crankshaft with ease at room temperature
Hi Dickie, I use the SKF bearings you mention in all the motors I build, and to date not one has failed. It is interesting to note when a main bearing does fail, it is nearly always on the ignition flywheel side. A roller bearing such as this has far more strength than an ordinary ball bearing of a similar size. One thing that is a benefit, no need to heat up that case when you are ready for assembly, just pop it straight on. Hope this helps..........
Concur with ease of assembly/dis-assembly using a pair of roller bearings as opposed to 2 x ball bearings or 1 x ball and 1 x roller brg.
Back in a previous life i built Brit parallel twins for a living in my own workshops.
Norton came out with a fix on their Combat Commandos in the early 70's which were a pair of FAG bronze caged 3 piece rollers, set up and run with end float.
No more bottom ends and crankcases exploding, and comfortably able to handle much more torque and bhp.
We fitted these with machining of crank or cases wherever possible on various bikes, mainly Meriden Triumphs, and a big benefit was ........... ease of assembly/dis-assembly...
I have my current bikes - both 84 ty250 mono's - because where i live there are no Bultaco and Montesa twinshocks, nor Yamaha twin shock ty's nor anything remotely pre 65 Brit project bike ish. the nearest being Indian made 350 - 500 Bullets c/w front disc brakes and indicators......
I love my Forma Boulders enough to have two pairs, but holy hell they get hot! Is there anything on the market that's reasonably priced and has big holes in it?
I might ask a shoe repair place to add some holes to my rough pair or something
I wear Boulders too.
Try riding out here!
I'm outta the house and togged up ready to go by 7 at the latest. Done by 9.00 am, 9.30 the very latest.
Forget summer time which is Mar-May here as its already 30C by breakfast and 38-40C by lunchtime.
I wear thick army socks, and thin camo cargo trousers tucked in, can't wear shorts - had too many burns, cuts and unneccessary scabs.
The last crank that I rebuilt needed a hydraulic press rated at 40 tons! This started the crankpin moving with the usual and expected load clang...scattering two onlookers... and from then on in until pin release the pressure was showing at 25 tons. Crankshaft realignment using vee blocks and dial gauges on a surface table, but some get a good compromise using eye and copper (dead blow) hammer to nudge one flywheel half a tad or more on the crankpin.
Reasons for flywheel half misalignment can be down to sudden shock being transmitted to the drive side of the crank. Air gun/ rattle gun tightening of crank nut. Excessive leverage against either side of the crank when tightening either the flywheel or drive nuts, over-torquing without using the correct flywheel locking method. A good reason to not lock the engine by the con-rod.
Bouncing or smacking one half of the crank assembly to bring it into tolerance is a standard practice, its quicker than setting up on a press which could cause too much movement. Welding the crankpin in place is a belt and braces protection against high engine rpm sudden seizures spinning one flywheel half on the pin.
Concur with all the above, but especially, puleeze, please please, inexperienced people - a rattle/air gun HAS NO PLACE NEAR A CRANKSHAFT.
In fact i don't like them on any engine/clutch/gearbox internals.
You Tube can be a great source of education, it also has a fair few numpties who should not be let anywhere near a set of spanners.
I have only ever taken a BSA C15 crank apart, to install a new bearing. I entrusted the work to a local heavy engineering company. I got the flywheels back, installed them in the crankcases, and they were as stiff as ever. Took it all apart again and had the engineering company re-true them, as they said they were 5 thou out. They need to be way under 1/2 thou, only possible with precision measurements.
.
On 5/28/2020 at 1:24 AM, phiggs said:
way under 1/2 thou,
Really?
If you've got everything to within half a thou i reckon you've done pretty well, deserve a pat on the back, and the beers on me down the pub.
A thou is perfectly acceptable, obviously half a thou is better, way under - nigh on impossible.
Seat unit itself with plastic or the red seat alone?
If its just the seat i have a vgc red one spare. 3rd one on the right.
I sold my decent freshly painted steel tanks and plastic seat units in the UK and went smaller plastic tank with Paul's Shedworks one piece tank/seat unit shelters.
In 76-77 i was still 16 and riding first a gold metal flake FS1E, followed by a fairly rapid Fantic GT. Our market town's only new m/c dealer was Suzuki.
I used to drool over those 70's two stroke trail bikes like the TS185 and 250.
Was'nt there a 350 or 400 or was that Yamaha?
Yamaha was in our nearest city and i loved those DT175, 250, 360's too.
I checked the date stamps on the bike, the bike is a '13 and tyres are 2011 and 2012, I guess they should be replaced with new rubber, although they have virtually no wear, thoughts???
Thoughts?
Its not a road bike, you are not travelling along tarmac at 60mph, save some money and give them a go.
as you can see from the photo is in lovely condition.
On 5/8/2020 at 5:27 PM, Mikey349 said:
. BUT I can only select 1st, 2nd and neutral gears..The clutch cable had been adjusted to maximum so thought maybe replacing this might help matters bearing in mind I couldn’t select neutral when the engine was running. The new clutch cable was fitted and neutral could now be selected with engine running and also 3rd gear was available if you lifted the lever hard enough ( not ideal ) 4th and 5th are nowhere to be found...
What you mean is someone has made it pretty externally to sell on.
Lovely condition i would describe as pretty AND mechanically all working well, and at least as good as the factory intended.
Having a box of missing gears, no neutral, an iffy clutch is not part of that description, IMO.
I ran a m/c shop in the UK for 15 years, and if i let a m/c go out in that condition mechanically, yet cosmetically clean & pretty, i would be the first to admit to being a scoundrel and deserved of a good ear bashing.
I weight around 162lbs and my wife is about 105lbs. 
Old new guy
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SAE 10-30W is what Yamaha recommended, when all other oils you mentioned were already available....