OSSA

Hi just picked up a 1978 tr77 starts lovely and idles nicely BUT after a few minutes it will pick up the revs to almost maximum without any input without sounding dense where do i start?

Hi, Hope someone can help? Ive just purchased a TR77 250 which was sold as a poor runner with the previous owner thinking it needs new points or main seals which were both supplied with the bike. On getting the bike home it starts up very easy but struggles to rev up at all. The bike is fitted with a Dellorto carb which I presume is wrong so maybe causing bike to run bad. Can someone confirm what model of carb this bike needs if current one is incorrect and also where I might be able to get the correct one from? Many thanks, Tom.

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.

This is a problem of my own making and ossa ignorance. I have recently had both the primary case and magneto cases off ; one to free off the clutch and the other to check the points. Whilst the case housing the magneto and gearbox sprocket was off I inadvertently leant the bike over onto its side and the clutch pin fell out which I found a few minutes later. Today when I went to rebuild the bike and sort out the clutch I remembered that the clutch from the engine lever to the cluch housing has a long pin, a ball bearing and then a second pin. I had lost the ball bearing. I had in stock some 1/4" cycle headstock bearings so I used one of them between the two pins. I could …

Hi guys, I have owned a TR 77 for ages, just looked at the engine number and its M-640810 and there is no number on the frame. on all the reference tables the engine numbers start with a "B" can anyone help to confirm my engines identity ? many thanks Rick

Can anyone please tell me the correct amount of oil per leg needed for the OSSA TR77 which has the long leg Betor forks. Presumably these are similar forks to those fitted to the OSSA MAR mk3? Likewise the gearbox/clutch, amount & type.

I am in the process of rebuilding my TR77 and have come across a problem whilst trying to re-fit the front wheel. The hub/spindle assembly is too long to go between the fork legs, please see attached photos. The only thing I can think is that the spacer between the speedo drive and the ns bearing is too long? The spacer I have is 17.5mm long 20mm od and 12.5mm id, Ossa part no 106604 which I think is common to MAR versions as well. Has anybody got their front wheel out at the moment and if so can you please confirm the dimensions of the spacer on your bike. Thanks.

hello i have a oil leak on my ossa TR77 its comming from the crank center gasket near the sump plug its only a slow leak is there any way i can stop it with out splitting the engine? cheers chris.

Hi all I'm restoring a TR77 that I was given as a box of bits (and so have no knowledge of set up...). My Clymer manual tells me that the Ossa has electronic ignition, although the points and condensor set-up on my bike suggest otherwise! I've fitted new points and condensor and now need to set the points gap and timing. The back plate has a clear timing mark that lines up with the crankcasings, so I set it at this position. I then set the points gap to 15 thou, and this opened the points at around 2.2mm BTDC. I searched the internet and found suggestions of anywhere between 2 and 3.5mm BTDC, and a points gap of 40 thou seemed a common theme. So, what works be…

Hello All am going to fit a rear sprocket convert kit to my ossa TR77 350 dose any 1 have any experience in fitting 1 please? It came with the big spacers with a bearing in it and the 4 bolts and a small spacer cheers bond.

Hello can any 1 tell me the silencer on the TR77 250 dose it need the packing? I cant get into it dose it need to be cut open? I just want to make sure because its not my bike as am doing some work on it cheers.

Hi all Anyone know what the correct steering head angle should be on a TR77 MAR? Thanks Adrian

New to the Ossa but after 1 trial on it enjoying it so far. Fitted with a Mk2 Amal Concentric but seems rich on the bottom end. Anyone have recommended jetting or alternative carb recommendations?

Hi there I need some help ,does anyone know where I can get an Ossa tr80 350 oversize piston from,it has already got oversize B in, so looking to get the next size up,any help would be much appreciated Steve

Hi What issues are there with the TRi 125? Starting? Injection? Glued-together frame? They don't seem to wear very well? They seem to be even less common than the bigger Ossa. Thanks

Hello ossa people, I have recently had my 125cc TRI 2013 engine all rebuild because the crankcase was all split open at the air-inlet side below the cilinder. Now I got it back with a new crankshaft in a new case. When testriding I noticed I didn't have power and I can not get the frontwheel of the ground like normaly. I was told by the store that it takes at least 10hours to losen up the new crankshaft so that my horspowers will return to normal. When opening the throttle I notice how the RPM's are slower comming up. Indeed it feels that the engine is so tight that the piston is not running lightly. Mecanicaly the gears and clutch see…

Good evening I have just aquired an Ossa with engine number M 340285 but can not find any sign of a frame number it has a white fibreglass tank and a black frame which is not showing any signs of other colours underneath it would be nice to know what model and size motor cheers

Hi just seeing if anybody can tell me what the tyre and sprocket sizes should be on a Ossa 250 Verde 1979 please. Also am I rite in thinking that the chain tensioner bolts onto the chain guard. Thanks, Martin

I don't think this news has made it to Trials Central yet. Check out the LewisportUSA site for the official announcement: http://www.lewisportusa.com/ I ride a lot with Lewisport Southern Cal Rep, Bill Merritt, about once a week and have gotten to try out the new bikes as they come out. They may yet tempt me off my Raga. Bill rides the OSSA as his daily practice and competition bike. I have nothing but the best to say about Bill's commitment to the bikes he has sold (Gas Gas, OSSA and Beta), to the buyers/riders and to both the practice and competition aspects of the sport. Based on my experience and interactions with Bill I expect that his closer involvement now…

Hi just seeing if anyone can tell me how the air box is bolted to the frame, do the bolts go through the side panel then through the air box cover and then through the air box itself. It’s hard work trying to get this bike back together with no manual lol. Thanks Martin