I have a Beta Jonathan 2003 and I lost the rear sprocket, please help

Axle nut 145 Nm
rear sprocket nuts B and C models 74 Nm
rear sprocket but E and F models 59Nm
front sprocket nut 125 Nm
front caliper mounting bolts 34Nm
Hope this helps - if your wrench isn't in Nm you can get a conversion online.

Look here at Amazon https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=motorcycle+sprocket+and+chain+kit&rh=i%3Aaps%2Ck%3Amotorcycle+sprocket+and+chain+kit

Rear wheel spacer, some bikes have different sizes for each side and they may go only one way so make sure it is the correct side.

Wait until you get new chain and sprockets to do it.

The stock rear sprocket is 41 tooth. The stock front sprocket is 15 tooth. The stock chain is 630 x 96. You can get OEM parts at www.babbittsonline.com/parts/viewbybrand/parts.aspx

Rear sprocket is $52.91. front sprocket is $21.74 and chain is $201.07
Please rate my answer. Thanks.

going to a 42 tooth rear which I'm hoping will fit with a 15 front has anyone managed this without lengthening the chain? i also need the torque settings for the rear wheel axle and sprocket retaining bolts does anyone have them to hand please? TIAI have the 15/42 on mine, it is tight but you should have between 5-10mm of your chain adjustment bolt sticking out of the locknut once it is on and adjusted,,,

going to a 42 tooth rear which I'm hoping will fit with a 15 front has anyone managed this without lengthening the chain? i also need the torque settings for the rear wheel axle and sprocket retaining bolts does anyone have them to hand please? TIAI have the 15/42 on mine, it is tight but you should have between 5-10mm of your chain adjustment bolt sticking out of the locknut once it is on and adjusted,,,