New tires..bad wobble..on my non KZ bike

I have a question here. I bought a new Fat Bob in early May. Just hit 10k miles on the bike and had the 10k service and new tires put on. I went with Metzeler 880's instead of the stock Dunlops. I also put a 200 rear tire on instead of the stock 180. I know for sure this has been done on many of these bikes without problems.

On my ride back from the shop when I hit 70-80mph I started getting a pretty bad wobble. Sometimes in the past with this bike I get a small wobble going over seams or something but nothing scary. This is different.

The shop that did the work told me tires balanced up fine..no problems. I said something is definitely wrong man, I've ridden the bike 10k miles in 6 months and this is not how it rides. Then I told him this will save me money on engine mods cause the bike is plenty exciting now. His response....I don't know what to tell you, bud.

I know this isn't a Harley forum but there are a lot of you with many years of experience and I thought someone might have an idea. I am taking the bike to a different shop to be looked at. Hopefully tomorrow.

Perhaps with your former tire set up the conditions were not there to notice, now with new rubber on the wheels several things need to be checked:

1.Steering stem bearings(too tight/loose?)

2.Front fork action(not binding).

3.Swing arm lubrication.

4.Rear shock preload settings the same for both sides?

5.Tires inflated to manufacturers pressure?

Have you tried taking your hands off the bars and see if the bike want's to track right or left?

Splandman wrote:

I also put a 200 rear tire on instead of the stock 180..

WHAT SIZE IS THE RIM?
How Wide?

also, how much weight did they use to balance it?

John T wrote:

Splandman wrote:

I also put a 200 rear tire on instead of the stock 180..

WHAT SIZE IS THE RIM?
How Wide?

also, how much weight did they use to balance it?

5 inch width on the rim. 1 ounce in the back. No weights on the front. When I got back from my first ride I noticed this..see pic. So I thought the weight came off. Called the guy and he said the front tire didn't need a weight, that it balanced right without one.

Pic wouldn't post, but there's some of that sticky stuff on the rim. He said it's where the old weight was. He didn't clean it off.

MFolks wrote:

Have you tried taking your hands off the bars and see if the bike want's to track right or left?

No I haven't. When I was doing about 60 I would give the bars a little push to see if I could make the wobble happen and the bike felt like a snake. It's really strange cause this bike has always felt really solid to me.

IMO a 200 rear is too wide on a 5" rim. Heck that 180 should be on a 5.5" rim. I think that a 200 goes on a 6" IIRC. I second all of the checks that Mfolks gave you. Also, I would verify that the rear axle adjusters are spaced evenly so that the rear wheel is straight.

Splandman wrote:

I know this isn't a Harley forum but

1) new tires will act up until they have been thru a couple of heat cycles

2) they can go that fast? must of been a BIG hill:laugh:

testarossa wrote:

IMO a 200 rear is too wide on a 5" rim. Heck that 180 should be on a 5.5" rim. I think that a 200 goes on a 6" IIRC. I second all of the checks that Mfolks gave you. Also, I would verify that the rear axle adjusters are spaced evenly so that the rear wheel is straight.

I'm certainly not saying you're wrong, because I honestly don't know. I do know that there are several people that have put the 200 tires on stock Fat Bob rims. What I do not know is if they are guys that ride to the local bar or guys that actually get out and ride their bikes. I'm not sure you would notice just in town.

Nebr_Rex wrote:

Splandman wrote:

I know this isn't a Harley forum but

1) new tires will act up until they have been thru a couple of heat cycles

2) they can go that fast? must of been a BIG hill:laugh:

Guess I should expect that here. My KZ will do things my Harley won't. My Harley will do things my KZ won't.

Splandman wrote:

testarossa wrote:

IMO a 200 rear is too wide on a 5" rim. Heck that 180 should be on a 5.5" rim. I think that a 200 goes on a 6" IIRC. I second all of the checks that Mfolks gave you. Also, I would verify that the rear axle adjusters are spaced evenly so that the rear wheel is straight.

I'm certainly not saying you're wrong, because I honestly don't know. I do know that there are several people that have put the 200 tires on stock Fat Bob rims. What I do not know is if they are guys that ride to the local bar or guys that actually get out and ride their bikes. I'm not sure you would notice just in town.

No harm, no foul. I agree that it can work. Let's be honest, you're not exactly getting your knee down on the Fat Bob are you? So ultimate tire performance isn't necessary. I also understand the desire to have a fat tire back there. Lord knows I have spent enough money and time to get a 180 on my KZ. However, my point is that you have a problem that cropped up after you introduced a bunch of variables into a mechanical system that was previously stable, no?

So we need to eliminate variables to get back to where we were. I'm guessing that you are stuck with the tire at this point. I would start by checking all of the things that Mfolks pointed out, and I really suspect that your rear may be mis-aligned. Verify those things, and then see how it rides. I doubt that a balance issue would cause a wobble unless it were a gross imbalance. Maybe have another shop check the balance just to eliminate that possibility.

Now if none of that stuff works, then you may have to try a different rear tire. The one thing that putting too wide of a tire on a rim is that it causes the tire to adopt a un-natural profile. In effect, it becomes a taller tire. Taller rear tire = steeper front fork angle and quicker steering. The quicker steering could be part of what you are experiencing. I know that my zx-10r wants to follow grooves more than any Harley that I have ridden. It has pretty quick steering.

Hope this helps.

Yeah, I see what you're saying. It seems nuts that a weight would cause this much instability. Also seems like I would feel some kind of problem at a lower speed.

I'm not dragging knees but I have scraped up the heel of my boot while it sits on the forwards. Does that count?
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That's about as close as you'll get. You will get your knee down eventually... and your shoulder! :side: :side: