I have a 1985 Yamaha Tri-Z with 20X11X9 Rear Razor Tires. The machine stock came with 22X11X8 tires and the sprocket size were 13 front and 44 back. Now it has 14 front and 44 back but I feel it tops on fifth gear too fast. I am thinking about changing the rear sprocket to 42 or 41. What do you thing is that too high of a gearing? The trike only has an OEM 0.10 piston, jetted card, boyesen reed, stock stripped pipe and an Answer Hot Tip silencer. What Tri-Z guys are running?

 

As far as gearing goes, I'm running 14-44 right now, but I have the 86 model YTZ250S which is a 6-speed. I have, at the moment, 20x11x9 Holeshots on the rear, but I don't believe they're truely 20". Compared to every other 20' tire I come across, they seem taller. Current modifications to this Z include being bored 40-over(not really a modification for power), ported/polished, and DG exhaust. Future modifications: Possibly a different port job(a BIG maybe), installing the 38mm carb that I have w/twist throttle, installing a high(under-the-stock airbox cover) fuel tank and removing the under seat tank assembly/fuel pump, clamp on air filter, extended axle(which I trying to buy right now), either Duncan Racing's Pyramid Reed cage assembly or a set of Boyesen Pro Series(P-53)reeds(the ones listed for the 88-92 YZ 125 dirt bike are the same as TRI-Z), and an extra set of 10" wheels to run (18&quotHoosier TRI-TRACs on. Back in the "day", an 86 TRI-Z modified by Klemm Racing, running this almost identical set-up at a TT or flat track, were set up with 15-40 sprockets. I'll have to do some testing to find the right combo, though I believe 15-40 is where I'll end up to for the racetrack. I'd probably put the 13 or 14 tooth back on for playing around on the powerline fire roads and such.

 

Next time you take the motor apart,put in 5th gear out of a 83 YZ250.It`s an overdrive for the 5 speeds.Its the same ratio as 6th in the 86 TRI-Z.