Question and Possible answer to my problems By damin69 (Read 990 times)

[damin69]

Ok so last night and today. We changed out carb and Variator no diff. I put Electric Fuel pump on. Wow huge diff on starting.

So now on to the question and possible answer to my problem.

I come back and I put scooter up on Center stand and I twist thottle it goes up to like 6000 then I let off and it then goes up to 8000 just as I let off. I can smell burning rubber. I look sure enough the tire as I am hitting High RPMs is rubbing agains the Case.

So I look at the tire size it is a 140/60 -13

So I look up online the Stock sizes says it should be 130/60 -13

So I am thinking that my issue with not being able to hold speed or pick up speed is because I have this huge Drag issue with the tire.

What do you all think?

[Jeff]

You said it wouldn't go past 55mph, that would be an awful lot of tire drag to hold it back. I would think that tire would be *smoking* and showing major signs of damage if it was rubbing enough to keep you from going past 55. Now I know not to go with the larger size though, heh.

[Cruiser]

The 140/60 tire is only .4" wider overall than the 130/60. This means .2" less clearance on either side of the tire. I think most scoots would have enough initial clearance to accommodate the larger tire with no rubbing. I would check the mounting of the wheel to see if there is an alignment problem. Hopefully there are no damaged components which could mess up the wheel alignment. It would also be a good idea to check side to side wheel play. As far as I know there should be none.

[damin69]

Well that is the thing. The drag is not on the sides. as the tire spins it balloons and there is a strip that is about 1 inch wide right at the center of the tire all the way around you can see has been rubbing and I could see it hitting the motor when it was on the stand. I believe this is causing drag. Being wider gives it more tire to balloon. Maybe I am wrong in that thinking but there just is not much room between tire and the motor.

Now I know when my tire went flat on my other scoot it rubbed really bad on the side wall as these low profiles mushroom out when the go flat and that is the way this drag feels when I go down the road on this one.

[damin69]

There is definitly something wrong in this area. The part of the tire that is rubbing is all the way around the tire dead center about 1 inch. It is an avon tire not sure if the tire is just out of round or what but between the tire and the motor there is less than 1/2" of clearance so I am not sure how much the tire balloons out as it spins but on this bike it is fast enough to rub against the motor. As long as I am going less than 40 there does not seem to be any problem but over that and it causes drag. I think once I figure this issue out I may have a decent scooter to ride..... Man why do these things have to happen. If they had a BAD Luck Lottery I would Win every Time....

[damin69]

Ok Things are getting becoming clear. So with the 140/60 on the scooter I have about 3/8" clearance between tire and motor.

So here are the results from JR on tire sizes

130/60/13 : 5.1"W x 19.1"T

140/60/13 : 5.5"W x 19.6"T

With this that means that there is .5" diameter difference.

So why does it not rub all the time.

Ok Early morning has been like 40 degrees rubber is HARD. it does not expand so never had any issues riding in to work and was able to hold good hi-way speed.

Warm up in afternoon tires warm up rubber gets soft start riding and tire starts rubbing against motor causing drag. No issue driving through town or starting out but the tire is not spinning fast enough to balloon out to hit........ :-)

[Jeff]

I was looking at the clearance on mine yesterday since I have everything off it and have a very clear view of the clearance between tire and engine. I didn't measure it but the old carpenter in me said it was about 3/4", no less, maybe a hair more. I took a picture too if you want to see it. I can also get an actual measurement if you want. Mine has the 130/60/13 tire, though it is getting worn now, at 5k. I'll need to replace it soon.

[damin69]

May 23, 2011 10:30:30 GMT -6 Jeff said:

I was looking at the clearance on mine yesterday since I have everything off it and have a very clear view of the clearance between tire and engine. I didn't measure it but the old carpenter in me said it was about 3/4", no less, maybe a hair more. I took a picture too if you want to see it. I can also get an actual measurement if you want. Mine has the 130/60/13 tire, though it is getting worn now, at 5k. I'll need to replace it soon.

Jeff. I can not even stick my Pinky between the tire and motor and I have small hands.

[damin69]

May 23, 2011 11:50:42 GMT -6 Cruiser said:

May 21, 2011 17:38:45 GMT -6 Cruiser said:

The 140/60 tire is only .4" wider overall than the 130/60. This means .2" less clearance on either side of the tire. I think most scoots would have enough initial clearance to accommodate the larger tire with no rubbing. I would check the mounting of the wheel to see if there is an alignment problem. Hopefully there are no damaged components which could mess up the wheel alignment. It would also be a good idea to check side to side wheel play. As far as I know there should be none.

OK....... Alignment then???

the tire doe not have wobble back and forth... The stock mounting bracket on muffler side is on. So guys you have to help me out here. What is going to cause an alignment issue? I can only tell you what I have for clearance.

I realize there is a serious problem as there should be more clearance which my scooter does not have. I just have no Idea where to start if there is no Obvious signs of missalignment? There are no adjustment screws on the Mounting bracket with the bearing in it. And the CVT Housing has no adjustments that I am aware of.

So where do I start?

[Cruiser]

I wouldn't think that there would be enough centrifugal force on the tire at 50 or 60 mph to really change it's diameter that much, but it certainly is something to take into consideration. Jr's specs say that you will have 1/4" less clearance with the larger tire. The tire should still have plenty of clearance. What brand of tire is this? I think Dr. JR runs Avons. Some brands will have a slightly larger diameter than others. Maybe you have a really stretchy tire? Can you feel any play front to back on the rear wheel?

If nothing is obviously wrong, I would go back to the original size tire.

[damin69]

May 23, 2011 12:19:02 GMT -6 Cruiser said:

I wouldn't think that there would be enough centrifugal force on the tire at 50 or 60 mph to really change it's diameter that much, but it certainly is something to take into consideration. Jr's specs say that you will have 1/4" less clearance with the larger tire. The tire should still have plenty of clearance. What brand of tire is this? Some brands will have a slightly larger diameter than others. Maybe you have a really stretchy tire? Can you feel any play front to back on the rear wheel?

If nothing is obviously wrong, I would go back to the original size tire.

The tire is an Avon Not sure of the model. Like I said There is not noticeable wobble so not seeing any signs in that aspect of alignment. The scuff that the rub causes on the tire is directly in the center all the way around so no signs of aligment issue that way. (why can nothing be OBVIOUS on these things :-()

And as far as going back to the original tire size that is the next try. Which is why I am wondering about the Wheels. If the 13" on Jonway is the same as the 13" on the roketta. I have not taken them both off yet to try and swap but I think I am going to try. Since my Jonway is not running yet.

[genest11]

damin69,

I put the 140/60-13 on my 250b just as Dr. JR suggested. It was close but I have had no problems. Are you sure the tire is rubbing on the motor? When I fired up my scoot to be sure everything was operating properly it did rub against the air intake box but I corrected that when I put the scooter back together.

I still have the 130/60-13 rear as well as the front tire with less than 300 miles on them. If you want my old Kendra (sp?) tires they are yours (or anyone else that may want them) for the shipping cost. I live just outside Boston, MA.

[damin69]

Ok this will tell you exactly how close the tire is to the motor case.

This is a piece of 1/4" ply that I cut a 1/2" wide x about 6" long piece off of.


Couple of Pics just showing the relation of tire to case.



Now with the piece of ply that I can not even get between tire and motor. So my Clearance is actually less than 1/4 Inch...... :-(

[damin69]

Ok well Got new tire put on today. And well it 100% took care of of the Rubbing issue. It did not get me my RPMs back. I am able to still only hold 5000 rpms.

Free wheeling it will give me 8000 but get it out on the main hiway and it just has no topend. In town is great and low end power is great. Top end is just dead. So guess I will be pulling the plug and checking engine compression.......... :-(