Chinese Scooter Club

Philzee · Wed Jul 02, 2008 12:42 pm Speedo problem, help needed!

As you know from previous posts, we bought a Yiben 50cc scooter for our son's 16th birthday, we bought it second hand just in case it wasn't what he wanted and we wouldn't lose much cash on it.

Firstly, We were told by the owner that it needed a new speedo cable as the speedo wasn't working. But upon closer inspection I had my doubts.

When I spin the front wheel fast the speedo thingy in the wheel (sorry for the lack of technical terms lol) doesn't turn so I figured this was the problem and not the cable...so:

1. Does this part turn freely normaly?
2. Is this part supposed to turn freely because just now it doesn't.

I have spayed copious ammounts of WD40 in there to clean it as it was very gunky and I couldn't see well.

3. Also the screw that holds the speedo cable in place has seized and rounded....any way to get that out?

Any help on this is greatly appreciated ;)

jpmacd733 · Wed Jul 02, 2008 12:59 pm

For #3, you can cut a slot in the head of that screw so a blade screwdriver will work. Cut the slot nice and clean so the screwdriver gets a good bite. It looks like you may have to cut a little of the casting on each side but that should be OK. When you try to remove the screw, if it seems too tight, heat it up and try again rather than mess up the new head.

Joe

Philzee · Wed Jul 02, 2008 1:02 pm

jpmacd733 wrote: For #3, you can cut a slot in the head of that screw so a blade screwdriver will work. Cut the slot nice and clean so the screwdriver gets a good bite. It looks like you may have to cut a little of the casting on each side but that should be OK. When you try to remove the screw, if it seems too tight, heat it up and try again rather than mess up the new head.

Joe

cheers, I'll give that a try ;)

Fox · Wed Jul 02, 2008 2:53 pm

They have this new screw extractor called a Grabit, that is perfect for that.

See here:

http://www.4grabit.com/Default.asp?bhcp=1

Philzee · Wed Jul 02, 2008 7:03 pm

thanks for the replies so far, but the screw just aint moving no matter what I do...I may need to just drill it out as a last resort :(

As for the speedo problem..

I think I have figured out the mechanics of what MOVES the speedo, in number 2 that I circled yellow, you can see that it has 2 "wings" on the circular washer type thing, these match up with cut-outs on the wheel which turns so I guess this must turn to rotate the speedo drive I marked as number 1. Now the problem is it doesn't turn, so I assume the washer with the wings is seized as I can't move it at all.

Now, my next question is... How do I remove it to free it off?. I see there is a darker ring on top which has 2 cut-outs which would give access with an open ended spanner, But can anyone confirm I'm on the right track before I do some damage to the mechanism by accident?.

I hope this makes sense to anyone reading this...descriptions aren't my forte lol

DaveS · Wed Jul 02, 2008 8:30 pm Re: Speedo problem, help needed!

Philzee wrote:
1. Does this part turn freely normaly?

That is the worm gear that drives your speedometer cable. You should see it turn when the wheel is rotated. If it does not turn it is either out of position or you may have some stripped gear teeth, either on the worm gear or the gear that drives it. Most likely, the stripped gear teeth are on the worm gear itself.

macker71165 · Wed Jul 02, 2008 8:57 pm

hey fox you always come up with the good stuff! I was wondering if there was such a thing? and now you found it, I gotta ave it! :lol: ave a k!

Philzee · Wed Jul 02, 2008 10:52 pm Re: Speedo problem, help needed!

DaveS wrote: Philzee wrote:
1. Does this part turn freely normaly?

That is the worm gear that drives your speedometer cable. You should see it turn when the wheel is rotated. If it does not turn it is either out of position or you may have some stripped gear teeth, either on the worm gear or the gear that drives it. Most likely, the stripped gear teeth are on the worm gear itself.

the gear that drives it is seized, Do you know how I would go about either fixing it or replacing it?

Fox · Thu Jul 03, 2008 1:25 am

macker71165 wrote: hey fox you always come up with the good stuff! I was wondering if there was such a thing? and now you found it, I gotta ave it! :lol: ave a k!

thanks for the K+... I gave you one back. I found a site that sells the GRABIT's in UK:
http://www.dm-tools.co.uk/product.php/site/froogle/sn/BOAGBSET

DaveS · Thu Jul 03, 2008 8:52 am Re: Speedo problem, help needed!

Philzee wrote:
the gear that drives it is seized, Do you know how I would go about either fixing it or replacing it?

The gear that drives the worm gear turns with the wheel, so if that gear is "seized" then your wheel does not turn and you have bigger problems than just the speedometer. In other words you should NOT be able to turn the drive gear independent of the wheel itself turning, and if the worm gear is in mesh with the drive gear it will only move when the whole wheel turns. I have not ever actually had to repair the speedometer drive on a scooter, but the photo that you showed looks a lot like the speedometer drive arrangement on the left front wheel of old Volkswagens that I have worked on. IMHO, I think that you need to carefully look at the worm gear where it meshes with the drive gear on the axle hub, and verify that it is in mesh with NO stripped teeth. My bet is that you will find that the problem exists in the worm gear itself.

macker71165 · Thu Jul 03, 2008 2:40 pm

nice 1 fox!

Philzee · Wed Jul 09, 2008 6:01 pm

Just thought I'd post an update to this thread.

Rather than bash away at it and possibly cause some damage, I took the part to a local dealer who specialises in 50cc and 125cc chinese bikes/mopeds. He has an inhouse repair service which charges only £10 per hour for servicing (which I thought was good value). So he had the part over the weekend and when I picked it up on Tuesday I found to my surprise that it only cost me £10!. I am well impressed and the service this guy gives is second to none.

Anyway it turns out that the part I numbered as 2 in the pic can be pushed out (with a bit of persuasion) from the opposite side of the picture. this was the part that was sticking and it had caused the 2 wings on the washer part to get flattened by the rotation of the wheel which is why the speedo wasn't working. This was sorted with a pair of pliers and just bending the wings back up slighly to catch with the wheel.

So the speedo problem is fixed yippee!! lol

.....on the downside, I forgot to mention to the guy that fixed it that the screw was rounded and I have tried everything...I even bought a set of screw extractors and tried them on it....it snapped in the hole that was drilled and now I have a stuck screw and a hardened screw extractor which I can't drill out lol.

Can't win 'em all I suppose :)

macbert · Thu Jul 10, 2008 1:47 pm Re: Speedo Problem

Philzee,

I just want to thank you for your post. I used it to fix a friends scooter speedometer last night, and it was very helpful. I had the same problem with the bent tangs. I think that whoever put it together didn't have the tangs in the driver slot on the brake drum when they assembled it, and the tangs bent when they put it together to install the wheel on the scooter. After that, the tangs just rode over the top of the driver slots, and would work intermittently, or not at all. I used a socket to drive the tangs off of the gear to straighten them and flipped it over because it had worn badly on one side. Now it works perfectly.

I would give you some karma if I had enough posts to do so.
:D

Philzee · Fri Jul 11, 2008 10:10 am

I'm glad I could help out someone ;)

That is the main reason why I put the update on here, because when I was searching the net at first, I couldn't find anything about it at all.