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Hello Have a look for JT Sprocket JTF569 or Afam 30300, this is what i use on my Ossa TR80 and i guess that the Mar use the same splines. They come on old Kawasaki KDX and old Yamaha off road, from 10 to 18 teeth and 520 chain. I don't know if there is a shouder on the mar sprocket, i use a bushing behind.

Artein gasket is .035 inch when new

Hi. Have a look for MAR guards, they are the same with different fastenings, but easy to fit to a TR80.

Here is usefull information/specs for TR80 350, translated from a post i've written for a french forum. size/ref quantity crankshaft left bearing 6205 C3 1 crankshaft right bearing 6205 *(NJ205) 1 gearbox bearings 6205 1 6303 1 HK1412 1 BK1616 1 gearbox mainshaft needle bearings 14x18x9,8 2 14x18x12,8 1 crankshaft main seals 25x42x8 FKM 2 gearbox/front sprocket seal 28x40x7 1 clutch pushrod seal 6x16x10 1 gear lever oring 2,5x14 2 clutch needle bearing HK2020 1 kickstarter oring 2,5x18 1 *(May be replaced by a roller bearing, shoulder placed on inner/crank side) Front wheel bearings : 6201 2RS x2 Rear wheel bearings : 6203 2RS x2 Steering tapered roller bearings (same on 350 & 250): 30204 x2 and the seals (SKF) nilos 30204AV ENGINE Exhaust o’ring 4x44mm in FKM material There is no specific engine gasket kit for the TR80. The Artein gasket kit J0000SS000246 (Ossa 350) may be used for the central crankcase and sides, but won’t fit the exhaust or cylinder head. Crankcase gaskets are 0,9mm thick. Cylinder base gasket is 0,5mm thick. Cylinder head gasket is 0,6mm thick, made of copper. Ignition is 1,3mm to 1,8mm BTDC = 14,5° to 17° BTDC Woodruff key is 3x5x13mm. Yamaha 90280-05001 may be used. Rod kit may be found at Nuova Mazzucchelli, (BCO 0438). Can be found at Italkit, ref BC.9438 Primary chain is a duplex euro series 06B2, 9,525mm, 50 pins Crankshaft seals from Yamaha part 93102-25446 should fit. Side clearance for engine shafts (from Ossa 5 speeds manual): crankshaft : 0,1 to 0,2mm (rod big bearing should be centered) gearbox mainshaft : 0,5 to 0 ,9mm gearbox layshaft : 0,25 to 0,4mm gear drum : 0,2 to 0,3mm kickstarter : 1,5 to 2mm FRONT SPROCKET following refs may be used with a spacer behind (520 chain): Afam 30300 JT Sprocket JTF 569 from 10 to 15 teeth, used on Kawasaki KDX 200/250 and Yam YZ250 1983 CARB (original Amal) Fuel petcock is right hand thread, M12x1,5mm, same as Bultaco/Montesa Amal L-2627/408 (MK2 concentrics serie 2600). Choke lever on the left, 27mm venturi. « Spanish » Amal, british Amal have a groove for the rubber manifold, MK1 float needle valve on the spanish MK2… every parts can still be ordered at the Amal company. part Amal ref notes main jet 376/100-130 130 pilot jet 124/026-15 15 fitted on the carb body beneath the air tube choke jet 124/026-40 40 fitted in the bowl under the small tube needle jet 622/079-105 105 two stroke type without side hole needle 2622/063 2B1 fitted on 3rd clip throttle slide 2622/0601 cutaway N°1 air jet 2622/13535 3,5 under the intake adaptator bowl 2622/192 2 stroke type, no threads in the bowl cold start plunger 2622/079 sold as a kit with its spring, plunger, seal... Air screw should be unscrew from 1 turn to 1,5 turn according to Amal. 2 stroke bowl is different from the 4 stroke. FRONT BRAKE (110x25) Ferodo FSB826 Newfren GF.1155 EBC 935G CLUTCH (according to the TR80 yellow notice) Oil is SAE90 for gearbox/axle or engine SAE30 (equal to modern 15w50 or 20w50, depending on the oil brand). For your information, Ipone BOX2 is 10w40 and ATF Dexron III is thinner than engine 10w30) Plate kit is made of 5 friction plates + 5 steel plates. The thicker steel plate (2mm) goes first (on the engine side), stack ends with a friction plate. Surflex 1202 5 friction plates 4 steel plates 1,5mm 1 steel plate 2mm Surflex 1202/B 5 friction plates Barnet 302-63-50001 kit : 5 friction plates Agpa, TJT and CMS seem to make kits for Ossa HEADLIGHT Gonelli 40.103.00 SHOCKS 360mm length 8mm bushing on top 15mm bushing on bottom About Betor, you should choose « hard » springs, 40 lbs can’t be used, and 50 lbs is for really light drivers. BETOR FORK radial shaft seals 35x47x10. This size is common on italian motorcycles mounted with 35mm Marzzochi fork (Aprilia, Moto Guzzi, etc) There is a spacer under the seal, 36x47x4 in aluminium 19,5 cc oil in each fork leg fork springs are 28mm OD 3,6mm wire 57 coils 480mm free length Swingarm bushes are non-standard size 21x25x45mm probably made of nylon, shoulder is 3mm thick feel free to correct me for any mistake.

I took notes when I rebuilt my bike. By the way, talking about bearings: front wheel bearings are 6201 2RS (need 2), rear wheel bearings 6203 2RS (need 2), steering bearings 30204 (need 2, same as TR80 250), steering bearing seals Nilos 30204AV (SKF). As I know, there is no Gripper manual, you should use the Ossa 5 speeds manual, at least for the bottom engine 'cause top engine is different.

if you have trouble finding these seals, go to a Yamaha dealer and ask for part n° 93102-25446

These are the specs i noticed on my 350 gripper while rebuilding my bike. The original seal was 8mm thick, but i only found 6mm seals, but it makes no difference (as for the clutch pushrod seal thickness)

size/ref quantity crankshaft left bearing 6205 C3 1 crankshaft right bearing 6205 *(NJ205) 1 gearbox bearings 6205 1 6303 1 HK1412 1 BK1616 1 gearbox axle needle bearings 14x18x9,8 2 14x18x12,8 1 crankshaft main seals 25x42x8 FKM 2 gearbox/front sprocket seal 28x40x7 1 clutch pushrod seal 6x16x10 1 gear lever oring 2,5x14 2 clutch needle bearing HK2020 1 kickstarter oring 1

It should be 6205 standard on the right (ignition side) and 6205 C3 on the left, without seals (sealed bearings are called RS in SKF code). Radial shaft seals on the outer sides of the engine are 25x42x8 in FKM material, i used Freudenberg BABSL seals in 25x42x6 size which fit perfectly.

This is an O-ring 44x4mm in FKM (Viton®). Or you can fit a length of stove fire rope glued with high-temp engine silicone (Loctite 5920, for example), let it dry, and fit the exhaust, like i did.

The top engine of the TR80 is different from the MAR and TR77 (gaskets for the bottom engine can be used, but not for the top engine), they have a thin head gasket (copper, something like 0,6mm thickness). TR80 is not set up like other Ossa trials, and 1,3 - 1,8mm is the way it should be. Full clockwise is full retarded, this is what I meant ?

It should be set 1,3mm to 1,8mm maximum BTDC. This is 14,5° to 17° BTDC. On my gripper, i have to turn the stator full clockwise (checked with timing lamp). Do you have to original cylinder head gasket ?

Hi We use 2 stroke gear oil for my dad's 250 TY (434, as yours) wich appears to be 10w40 grade, it works perfectly. Any motorcycle oil (with wet clutch) 10w30 or 10w40 will fit in the gearbox. As Yamaha doesn't make bearings or seals themselve, I would go on with any big brand like SKF, Timken, FAG, Koyo, SNR-NTN, SNK, etc. from an official distributor. I think that one or both of them should meet C4 specification. Motorcycle fork seals are particulars, don't fit standard seals as they will leak, use fork seals. Here in Europe we have brands like Athena Seals, i guess that you have the same kind of company is the US. The brand Talon makes sprockets for the TY

Having fun in the garden.. that bike was an absolute wreck. rear frame was cutted by previous owner, and it was all painted in an awfull sh*tty green

According to the numbers it's a Pioneer (US name for the Ossa Enduro). Plonker has a 24mm IRZ, Pioneer is a 29mm double needle.