Shorter dog bones after fitting gixxer rear wheel

[scotiafj]

  Hi  after fitting a gsxr 750 rear on my Fj1200 3xw ,the front feels like it wants to flop into corners as tho its been raked out , the rear tyre Im using is a 150/70/17 profile ,as the ratio is smaller than the standard fj 80 profile Am I right in thinking I would need to fit shorter dog bones to compensate for the reduction on height of the rear tyre/wheel  to put it back to the standard ride height..?? cheers Scotia 

[CutterBill]

Well, for a start...  I think you are using the wrong tire.  Most 150/70-17 tires (that I see) call out a 4.25 inch wide wheel.  Isn't the GSXR wheel 5.5 inches wide?  If so, you have a whopping big mis-match there.  Fit the correct tire before you start modifying the suspension.

Bill

[aviationfred]

Bill makes a good point. 

The minimum tire width should be 170 on a 17"x5.5" wheel. The optimum size is a 180/55/17. Fit a 170 or 180 tire and the handling should improve.



Fred

[scotiafj]

its a 4.5 rear width ..same width as early bandits 600,gsxf 600/750's ,gixxer 750/1100's

[Pat Conlon]

Setting aside the rim width issue for a moment..
Assuming your tire pressures are correct and your steering stem is properly torqued

Checking out the differences in the tire sizes between a 150/80-16 vs 150/70-17 here: https://tiresize.com/tyre-size-calculator/
You will see one tenth of an inch (0.1) difference in height between them.
i.e. 25.4" for the 16" oem and 25.3" for the 17"

So it's doubtful your symptoms are coming from the difference in tire sizes.
A different Tire profile, maybe, but tire size, no.
Try dropping your forks 1/4" and see if that helps.

A shorter back tire will move the weight back (unload the front) and want to make the bike run wide in the corner. Opposite to what you describe

Shorter dog bones (raising the rear) will move the weight forward and make the bike turn in quicker.
That sounds like what you don't want.

I suspect your tire profile is causing you grief. What tire are you using?

[scotiafj]

Setting aside the rim width issue for a moment..
Assuming your tire pressures are correct and your steering stem is properly torqued

Checking out the differences in the tire sizes between a 150/80-16 vs 150/70-17 here: https://tiresize.com/tyre-size-calculator/
You will see one tenth of an inch (0.1) difference in height between them.
i.e. 25.4" for the 16" oem and 25.3" for the 17"

So it's doubtful your symptoms are coming from the difference in tire sizes.
A different Tire profile, maybe, but tire size, no.
Try dropping your forks 1/4" and see if that helps.

A shorter back tire will move the weight back (unload the front) and want to make the bike run wide in the corner. Opposite to what you describe

Shorter dog bones (raising the rear) will move the weight forward and make the bike turn in quicker.
That sounds like what you don't want.

I suspect your tire profile is causing you grief. What tire are you using?

HI thanks for replies .. Im using a pirelli strada front and a avon 3xdm rear ,the rear has a few thousand miles on it .. mibbe your right re tyre profiles .. wasnt happy with front from new n didnt feel as secure cornering (felt as tho it was wanting to wash out )as my previous avon storm

[simi_ed]

I suspect your tire profile is causing you grief.

HI thanks for replies .. Im using a pirelli strada front and a avon 3xdm rear ,the rear has a few thousand miles on it .. mibbe your right re tyre profiles .. wasnt happy with front from new n didnt feel as secure cornering (felt as tho it was wanting to wash out )as my previous avon storm

I think you just found your problem.  I'd bet that tire has a flat center.  It's not a car tire, but I bet it looks like one!
I rode Hayabusa once that a friend had flat spotted rear tire (he had a heavy throttle hand!). It cornered like my F-350 Ford!  As soon as I pointed out the rear tire, he got the message. Problem solved!

[Sabre093]

I'm running a 170 Continental on 4.5 Gixxer rear and it works fine....Sounds like a tire change will help for sure.

[FJmonkey]

On my GSXR rear a Dunlop Q2 180 would rub off about 3/16 of the side of the tire from lack of chain clearance. A 170 cleared. The current Conti Motion is a 180 with the same clearance as the Q2 170.So not all tires are the same.