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.
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.
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.
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)
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 ?
lovely bike mate I've just finished building my gripper 350 but having timing issues . there docent seem to be any timing marks could anyone shed any light on the matter
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 ?
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.
MAR 11 tooth sprocket
in OSSA
Posted · Edited by rms
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.