bitzz

Start with the basics. You've got a 36 year old bike with a fair amount of mileage. Start with a compression test and a leak down test... if the rings or valves are sacked you wasting valuable beer drinkin time and monies. Check the oil pressure. If that all checks out, tune the motor and leave it alone. You might want to get rid of the CV carbs. Your time and money are better spent on suspension. You can get all the adjustment that a modern fork has by dropping in a cartridge kit from someone like Maxton. It is probably the cheapest, easiest way. Might not LOOK as spiffy, but it WORKS.

Chain sizes are easy to figure out The first number is the pitch, the distance from pin to pin in 1/8"... so a 520 or 530 chain is 5/8" pitch, a 630 is 3/4" pitch and a 428 is 1/2" pitch The next two numbers is the sprocket thickness... a 530 is 3/8", 520 is 1/4, a 525 is 5/16 ... but nothing governs the OUTSIDE dimensions... a 530 chain could be 1 1/8" wide (outside) for a cheapo Oring or as narrow as 0.8" for a DID HD Non Oring. Modern 520 chains can be as strong as 630 chains of 1980. If I am changing chains I usually use a 520. My GS1000 has a 520, and I just converted the neighbor's kid's 90cc ATV to 520... had the chain and sprockets on the shelf