Monday, June 20, 2005

Good conversation

There's been some good newbie discussion going on the "r5yamaha" Yahoo! Group lately. Mel from Seattle wrote in with these good questions:

Hi, I recently purchased a 1972 R5, until my owner's manual arrives I have some basic questions:

1. What do most of you have for tire air pressure on stock size tires?
2. What fuel do you run? Is there a need for premium (92 octane) with compression only being 6.9:1? (forgive me but I am new in 2-stroke world).
3. Shop manual, any recommnedations?
4. Basic setup, where do I learn about air/fuel mixture setup, carb sync, idle speed, etc?

1. Engine runs strong, it has less than 8,000 miles. It accelerates really well (at least that is how it feels to me) however at coasting or compression braking (throttle closed) I get a lot of bucking and surging. Any ideas?

There have been some responses, this latest one from Ed:

Hey Mel,

Run premium fuel ALWAYS! You are running too lean and that's what you are hearing when you are cruising along at speed at part throttle.

The way to tune these is to make it rich to the point where it 4 strokes and then back it down to the point where it no longer does this. You want it as rich as possible to keep it cool. Never run anything less than a 120 main(I run 130)

keep the needles near the middle, set the float height at exactly (this is critical) 15mm, use a 30 or 40 pilot jet and play with the air screw some (start at about 1 3/4 turns out and go in from there till it runs smooth but doesn't make any clicking noises at about 60 mph for about 10 minutes). Run a STOCK air filter and baffles in the exhaust. Using a dial indicator and volt ohm meter (this is a must) set the timing at 2mm before TDC. At this point the points should just begin to open. You can tell this by the needle just starting to flutter on the vom. The points need to be set first. Do this at TDC and set them at 13 thou.

R5s are bullet proof, but until you get them set up right they can be difficult. It is extremely important that everything be correct for them to run right and be dependable. Once there they stay there with little work so take the time and set it up right now.

Hmmm... I have a bit of that bucking, so perhaps my timing is off... It's been about a year so I'm sure things need to be checked and reset.

No comments:

Post a Comment