Bouncing Front End After New Tire Installationi

[knoppixguru]

Hey everyone,

First of all, love the forum and I come here for all my mechanical questions, and many of you have been a significant help to me in the past two months (how long I've had the bike). This is my first post, and first bike, so forgive me if I'm doing something wrong (I read the FAQ section, but I still worry about breaking a rule or being a noob).

I have a 1982 GS450L with 9200 miles on it, give or take, in good condition. I bought new IRC Durotour tires (100/90-19 front, 120/90-16 rear), and I had a local Suzuki/Honda shop put them on the rims and balance them for me. I installed the front tire and back tire back after cleaning up and greasing some parts here and there, and I took it for a ride today to test everything out. Everything seemed normal until I hit about 20-25 MPH, and that's when the front end started to bounce. The bounce isn't violent and doesn't feel like a vibration, it's just an up-and-down bouncy feeling. The front tire was low on air anyway, so I filled it up to 25 PSI (as recommended for "Normal Riding" on the chart located on the stock chain guard). I had to get the bike up to about 50 MPH to get to the gas station I was headed, and the bouncy wasn't nearly as prominent at that speed, but something was still off.

Some more facts to help diagnose the problem:

• The forks have always felt like they could use oil or something, they're not super responsive, and sometimes get slightly stuck down after coming to a stop. Starting from the stop un-sticks them, but this may be helpful.
• Also, after I put the front tire back on, I can hear the faint noise of the front brake pad rubbing against the disk. The disk itself was warm to the touch after riding to the gas station (about 5 minutes of riding), but not too hot to touch. Maybe this has something to do with the bounce as well. The disk looks fine though, and has never caused me issue.
• The PSI was at 20, and after filling it to 25 PSI there was practically no difference.
• The rim before balancing had no weights on it, and there was a tiny bit of vibration when riding (nothing I thought abnormal for a twin). But after balancing, the mechanic at the shop put just one weight on the rim, maybe this is throwing the balance off?

Before the new tires, the bike was really smooth other than the seemingly normal buzziness of the twin engine. The ride felt really smooth. I haven't really checked anything yet, but I've read up a lot on here about similar problems happening to other people. So far I have a few ideas of what it could possibly be, but I wanted the experts' opinions , thanks!!

 

[chuck hahn]

Beads seated fully? Any gaps at the edges of the rim that are noticeable? What PSI does the tire say on it. Its usually best to go with the tires info at first and adjust per your "feel" . Some tires will like a lesser pressure than on the tire itself and some will be close to the stated pressures. And maybe have them rebalance them.


Take the pads off the rotor and clean up the pins and associated parts that allow the rotor to float.

 

[knoppixguru]

Thanks for the reply. I inspected the tire more thoroughly this time, and it looks like the tire is maybe too seated. There is a guide-line like line going around the rim on the tire. The line kind of bulges out. It looks like on one portion of the tire on one side that line is under/inside the rim. It seems like the person who mounted the tire put that part too far into the rim. Could that be the culprit? Also, the tire only says that the PSI maximum load is 41 PSI. It's a tubeless tire, but the mechanic put a tube in it since he didn't have valve stems that properly fit.

 

[Stuarth]

Odds are the forks are binding- they were pulled inward when you replaced the wheel/axle. Raise the front wheel off the ground, loosen the axle nut and the axle clamp nuts and see if the forks move in/out when they're not clamped in. You should be able to tighten things back up, tightening the axle nut first, then the axle clamp nuts.

Also sounds like you've never checked/changed the fork oil which is something that you should do, but it's not likely the cause of the bouncing since it was fine before you changed the tires. It's also likely not the brakes. Good luck!

 

[chuck hahn]

All that isnt the cause..the tube is just insurance from leakage. If its ballanced well the tube is of no meaning.

 

[knoppixguru]

That's good to hear the tube in the tubeless tire is okay, I was a little skeptical. Here is a photo of the part of the tire I was telling you about. Notice how the groove on the tire kind of sinks into the rim more than it should. It's only like this on this side on this part of the tire, for about 6 inches around the rim. Sorry the picture is sideways!

 

[Weapon]

ya that's not supposed be like that, and is probably causing the bounce. your tire hasn't seated itself on the rim properly so its essentially egg shaped with that being the low spot.

 

[knoppixguru]

Even though it's only on that side? I think you're right though; that may be what's causing it. Should I take it back to the same mechanic to have him fix it (if he will do it for free of course)? Or should i go some place else?

 

[Guest]

Seem to me that the valve stem reinforcement area is wedged between the tire bead and the rim. Let all the air out and push the valve stem in as far as it will go to get it past the tire bead. I've seen this many times at the bike shop I worked at years ago

 

[Sandy]

Which Dunlop is that? I use the GT501s and the bead on the front tire on those is an absolute pig to get seated properly. The rear seats fine, the front not so great. After a few tries and probably more air than one would normally use it will seat. Tire lube and lots of swearing kinda helps it along. Maybe your bead is the same and they didn't double check their work before they released the bike to you. I'd take it back and show them.

 

[knoppixguru]

These are actually IRC Durotour RS-310's. I bought these because they were the only brand I could find matching exact sizes for this bike, beisdes Kenda, and I have heard not so good things about Kenda's. From the short ride I did earlier, they felt great so far!! I'm going to take the wheel back tomorrow, and have them remount it or something. I'll update tomorrow, thanks for the help everyone.

 

[Sandy]

These are actually IRC Durotour RS-310's. I bought these because they were the only brand I could find matching exact sizes for this bike, beisdes Kenda, and I have heard not so good things about Kenda's. From the short ride I did earlier, they felt great so far!! I'm going to take the wheel back tomorrow, and have them remount it or something. I'll update tomorrow, thanks for the help everyone.

Too funny. The D partially visible in your photo sure looked like a Dunlop D to me.

 

[knoppixguru]

Too funny. The D partially visible in your photo sure looked like a Dunlop D to me.

Looking back at the picture, it totally looks like the Dunlop "D". Lawsuit! lol

 

[knoppixguru]

Update: I took the front tire back down to the shop where they mounted it. They instantly saw what was wrong, remounted, and re-balanced it. They were really nice about it too, apologetic and whatnot. I slapped the corrected tire back on the bike, and it rides just fine. In fact, I didn't realize how out of balance/old the other tires were; the bike rides so much smoother than I thought it ever could! Thanks for the help everyone. Where I'm at, it's supposed to be sunny and in the 80s all day, so I'm glad I got the tire fixed in time for this weather.

 

[eil]

Good to hear that they fixed it without any complaint, but honestly I have to wonder about the kind of shop that doesn't at least visually inspect their work before handing it back over to the customer. Especially something as critical as a wheel. Let this be a cautionary tale about having other people work on your bike.

 

[knoppixguru]

Good to hear that they fixed it without any complaint, but honestly I have to wonder about the kind of shop that doesn't at least visually inspect their work before handing it back over to the customer. Especially something as critical as a wheel. Let this be a cautionary tale about having other people work on your bike.

I'll definitely be skeptical in the future. I bought a Clymer manual for this bike, so I typically do my own work. But mounting the tires required equipment I didn't have unfortunately. I'm looking forward to doing some future brake work and valve adjustments, those will be my next projects!