S to SF wheel conversion. Running POS tires 110/70-17fr 130/70-17r, ~30psi. Bike falls into corners fine and tracks under neutral throttle, heavy throttle, and front braking but wants to stand up when throttle backed off. Ideas?

 

I would venture to say it is the handling characteristics of the bike and possibly the tire profile. Most all bikes will want to stand up and go wide if the throttle is closed mid turn.

 

Thanks. The bike needs new tires so what profile would you tend towards? I read the thread about the KLX liking the 120/140 combo but after a few rides the 110/130 doesn't seem all that bad.

(Here's a link that includes a track-oriented review of the generally panned IRC RX-01 that comes std on the SF. Seems like it's not such a bad tire afterall https://www.youtube.com/watch?v=bHnmukUJ7aQ#t=318.)

 

I agree the IRC is a pretty decent tire when new but they go off/hard in a few months & become very mediocre!

I highly recommend a 140 rear.

 

140 has more choices. A 120 on the front will slow turn in noticeably. Bigger isn't always better.

Do the research going to the manufacturers' web sites to see actual measurement of width and height. Tires can range up to 10mm width difference from manufacturer to manufacturer.

 

So sticking with a 110/70 up front, how would a 140/70 effect handling? So far the 110 130 combo seems pretty good (with the exception of the original issue of the bike standing up when the throttle is cut).

 

Slightly slower heavier steering, the width of the tire is the factor. Think of it as a lever, you have to lean harder to get the same lean angle because it is further off center from the tread. You are, in effect "lifting" the motorcycle to roll across the tread, the wider the harder.

The front tire width has a much greater effect, I would guess because there are more steering factors involved with the front end than just the leverage factor. How the contact patch and size affects it, diameter of the tire, etc.

 

so whilst exploring tire size and handling the issue of rear tire chatter has come up. the rear tends to step out predictably but with a pronounced chatter. Tire or suspension?

 

Possibly tire pressure and weight shift to the front, and/or too much compression damping. Try a few pounds less pressure and see what happens. Maybe a few clicks softer on compression damping on the shock.

A couple of us had front tire patter on slightly rough asphalt in corners. We were running 36 psi, dropped to 32-33 psi and patter was gone.