We get quite a few calls at BDT Motorsports asking for assistance when adjusting clutches. It seems their is quite a bit of variance when mixing parts through ATC250R & TRX250R 1985-89 on the amount of 'Arc' Clutch Lever Arm Play in different engine builds leading to clutch assemblies not working properly or wearing out clutch plates prematurely.
The first thing we need to insure is the amount of play the clutch arm (left side top case) has when fully assembled. Ideally we want the least amount of 'Arc' movement or play prior to the plates engaging. The correct amount of 'Arc' play is from .75MM to 3MM or 1/32" to 1/8" when everything is new.
Minimal Arc Play can be accomplished correctly when using a good Clutch Lever Arm (Rod pocket not damaged, worn or burr'ed), a good Rod with clean burr free ends, and the proper Rod Length or amount of washers used. Minimal Arc Play becomes more important to properly adjust when mixing clutch Assembly years, or/and when installing a Honda Heavy Duty Clutch Kit, or an 89 clutch upgrade kit.
To take up excessive Arc Play beyond .75MM to 3MM or 1/32" to 1/8", use the Longest Rod or TIG weld one Rod end and grind down to proper length, or add spacers in .25MM to 1MM increments to eliminate any excessive Arc Play.
With the proper Arc Clutch Arm Play; the Honda Clutch will engage much better, minimal adjustments at Handle Lever & Clutch Cable ends will be needed and your Clutch will last much longer.
Take a look at the Video attached of a BDT engine build with the proper Clutch Lever Arc Arm Play. Note this needs to be checked with Clutch Cable disengaged.