Suspension setting change and tire pressure question after installing taller front tire?

So I installed a new set PR2's in stock sizes on my 1994 VFR and the bike now handles differently. I don't have the same confidence I had the with the old tires and I am very slow on it now.

Background: The bike has a racetech springs, valving in the forks and a fully adjustable penske rear shock. The tires on it before was pilot power 2ct front in 120/65/17 and pr2 rear in the stock 170/60/17 size. The suspension was professionally set up for the previous owner(track riding) who is 10# lighter than me. But his pace was much faster and the springs are correct for my weight and street sport riding. I have been meaning to have the suspension set up for me but kept putting it off. But I have grown very confident on this bike. When I got the bike I was a very slow rider. In the last 1500 miles before the new tires were installed I improved a lot and I am dragging the pegs(feelers removed) every corner (when going canyon carving) and has gotten to the point where moving my upper body around is helpful now and hanging of is necessary(but I don't know how to properly do it yet).

when the front tire wore out I replaced both with a new set. Since the new front tire is taller than the one it replaced I am guessing the front getting raised is what the problem is. I am guessing the quick fix would be to raise the rear a little bit to compensate.

After I installed the new tires I feel like I am back at square one. I am now faster on my 1996 with stock suspension and bt-23 tires.

Do you guys have any suggestions on what approximate changes I need to make to the suspension and tire pressures to account for the new tires? I understand i won't be able to get exact settings over blogs but this is for the interim. I will be getting the suspension set professionally when I get a chance to go to the suspension setup that Dave Moss runs.

btw what tire pressure is everyone running and what brand/model tires?

Thanks

Ricky

 

Ironically, once I put on the PR2's on my '09, my riding confidence improved and so did the handling of the bike. I came form the stock Dunlops and they were crap in comparison. I run the following air pressures, 36f/42r as my standard setup. That being said, if I am not mistaken, the profile on the Pilot Power is more "V" shaped and the Pilot Road2's is more "U" shaped. This gives a slightly different ride, especially when dropping into turns, the V shape tire will have a "faster" turn in as apposed to the more gradual or "slower" U shaped tire. I can say that the PR2's on the more modern VFR is quite popular and do a great job at both commuter duty and sport riding, longer wear with good grip, so it might just be a different feel for you. As far as suspension settings, you can probably set your sag front/rear and see if that helps any.

BTW, if you really want to learn to drag your knee "properly", I just did the Lee Parks ARCs course this past Saturday and it was very fun, educational and well worth checking out.

Cheers!

 

I think you are right. I knew that the profile of the the power and pr2 are different and expected that. I have pr2's on sprint and they work great. I am hoping adjusting the suspension can help a little bit. I thought about the sag. But it wouldn't have changed by the difference in tire height. The sag was already in the ball park before. Thinking about it more I specifically having issues with tighter more technical turns. It's still fine at the sweepers. Going by that train of though I think the turn in got slower due to the front end being higher now.

So I am going to try loosening the front preload a bit and raiding rear ride height to see if that helps. That should help get the turn in faster I think. I don't want to loosen the front too much though as that will change the sag and reduce ground clearance.

 

Well if you do the math, a 120/70 would mean that the side wall is 84mm and that the 120/65 would be 78mm a difference of 6mm, so theoretically you would need to lower the front at least 6mm. Not sure how accurate that is but this is based on how they designate tire sizes. Good luck.

 

That makes sense. I am going to try sliding the forks 5-6 mm and then try raising the rear. I will mess with it a bit and try to find what works best.

BTW thanks for the recommendation on the Lee Parks course. I definitely plan to take a course this year. I was set on doing the Keigwins 2 day Novice school. I will check into the Lee Parks one too. I just ordered the final piece of gear, boots, to start going to the track. The past year I have been acquiring gear and bike for track as funds became available. Now all I need to do is save up for the school itself.