trialsrfun

I think Tim Britain? may have tested a Kato Yam against a Majesty & std TY175 for the magazine at one time.

I run with the timed engine breather but the small hole is blanked off so as to prevent the intake of any water that gets into the side case from entering the engine. This means that a small amount of oil can build up in the side case. I have been told that if using the open tube breather with a closed end camshaft bush the engine then suffers from pumping losses due to the movement of air from the underside of the piston (the reverse of what happens on top of the piston) as well as pushing oil out down the breather tube where the same forces can pull water and mud back up the pipe into the engine. What are your thoughts on this please Duncan.

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Pleased you got your bike, good luck with her. Should the chrome brake drum surfaces be coming away they can be replaced with a liner without dismantling the wheel. Paul Jackson provides this service, he is based near Huddersfield and has repaired many Bultaco hub's as well as countless other makes where the liner has cracked away due to water ingress between it and the alloy of the hub. Check the carb condition, if it still has the Bing fitted you can get a Mikuni 26mm replacement which is a better bet due to the high cost of Bing parts should it be necessary.

I notice on here http://www.classicoffroadshow.com/ that the above bantam is to be on show at Telford next month, but what is it?

One works bike for at least three years, I wonder how many Raga & Bou get through now?

Do you have any paint details for the Greeves Moorland blue please?

PM on its way to you re; Steve Sell. I do not wish to post his contact details on an open forum but he is in your area.

The dished sprocket is/was an elegant solution that failed to solve the problem of a too narrow but otherwise nicely designed rear hub which self destructs with use due to the flexing & bending of the 12mm dia. spindle. MarliMar OSSA/Steve Sell who should be at the Telford show next month produces a well engineered twin bearing sprocket carrier for the MAR type rear hub which takes the modern 4 bolt sprockets fitted to all the current Beta & GG bikes. He also makes a stainless steel rear spindle that is much stronger than the original and is a direct replacement. The bracket under the seat is for I believe a horn, the silencer ring is so you can pull off the silencer against the spring, re-hang same on middle box tailpipe then run her on open pipe.

I bought my OSSA MAR/TR77 which I am currently restoring with the engine already out of the frame, a friend has been a great help with the engine rebuild & shimming set up. Thank you, I am sure you will read this. Steve Sell MarliMar OSSA stocks all the shims in varying thicknesses to enable crank & gearshafts to be set correctly. Just started a dry build to get everything sorted out before having the frame powder coated and found that the engine does not fit back in the frame at all easily when assembled, the head steady brackets on the frame top tube were catching the fins on the cylinder head. Removed the cylinder head & it fitted easily. Just blank off the two ports & bore first. We used industrial blue paper towel (well worth getting a big roll to keep by your workbench) One thing to be aware of with the OSSA engine, I did not know this, is the cush drive on the crankshaft. It is secured with a taper & impossible to remove without the special puller. I have heard of heat & bars being used but it always ruins the spring & or breaks the flange off the part that goes onto the crank taper. There is a OSSA handbook on the web http://www.custgp.co...l2/Ossa 250.pdf fill the printer with ink & go for it you will need it. The special tool is shown in there & could probably be made on a lathe. The parts pages were also really useful we had these printed A3 http://www.custgp.co... 1972 parts.pdf

Land-Rover exhausts!

Has it been announced yet who it is that is behind the new brand of Vertigo ? If not who are the likely candidates.

I got the M7 1.25mm hex shock mount bolts from Barfast Engineering Newcastle -under-Lyme http://www.barfastltd.co.uk/ not sure if they stock cap screws though.

John Taylor from Stafford rode what was I think a self built Bantam with good success quite a while after the Spanish bikes were winning most everything.

Might it be a plastic frame made using a 3D printer, the RAF are flying Tornado jets using parts made this way so could it be done ?

Yes the end dia. is reduced and drilled at the end for a pin, pin and washer are there but no spring. Thank you all for the info.

Hi Woody, the TR77 & I think maybe the MK3 have this additional round bar from the inside of the swing arm which protrudes about 2" and carries the upper end of a straight expander type spring, the lower end of the spring attaches to one of the bolts holding the chain slipper rubber at the end of the tensioner arm. I have bought a new radial spring for the pivot shaft but the straight spring was missing so I have no idea what the ends were like or how strong the spring was or why they bothered to fit it at all. It is something that can be easily added in the future if deemed necessary though.

Springs...anyone...?

Hi Bondy, what is the black finish you have used to spray/paint? the Bulto engine with please, it looks very well.

Hi Pickle, Superb restoration job a lot of time and effort has gone into that. Do you know the paint code for the Greeves Moorland blue please.

The OSSA TR77 250 that I am restoring to ride has an assister spring (expansion type from round bar which protrudes from inner side of swing arm to end of chain tensioner arm) as well as the radial spring on the chain tensioner/rear brake shaft. I have seen bikes with & without this extra spring so what are you running on your bikes, is the radial spring on its own ok or does it require the other as well, which arrangement works best.

What a right looking trials bike that is, the low slung tank, ample ground clearance & light build I would ride that as it is any day.

Hello Deryk thank you for the information & pictures you are posting on TC. Do you have a picture showing the Comerford silencer please. You are right about the original one, my bike ran very poorly with it fitted so most of the time I left it off, big performance gain but triple the noise. Bill Wilkinson said that the one on his bike fell off when crossing the Forth Road bridge then bounced ??? into the river below.

Someone on a auction website sells a chain slipper that might suit your needs, the one I saw is white in colour and slides down over the pivot tube and attaches using cable ties. look under Pre 65.

Was the TR77 originally fitted with longer shocks than the MAR? Do the inclined shocks lift the ride height of the rear of the bike or because the lower mounting point is at the end of the s/arm does it remain the same.