Needed new rear sprocket.

[Carangajeira]

Not quite sure if the Demolition 250 fits in the Dual/Enduro thread, but it sells as "all terrain", though comes with dirt tyres, but now I have mixed use Pirellis fitted.
Before heading out on a trip up the North coast here in Peru I took Oli in for a service at the dealer. No major surprises though the mechanic took it upon himself to change the front 13T sprocket for a 14T - "it will give you a better top speed, and better fuel economy".
Cannot say I noticed much difference, maybe a reduction in RPM a little at cruising speed (100kph/62.5mph), but fuel economy remained pretty much the same. 6 days into my trip I notice the chain seems a bit noisy, especially if I "back" the bike up (out of parking, for example) and realise that the rear sprocket is badly worn, with the teeth all leaning forwards a little!!!
The place I am staying is small but has a bike mechanic, who assures me that all is OK (Mavila mechanic, not Ronco), and squirts a bit of oil on the chain! So I head to Tumbes, a large city about 24 kms (15 miles) away, but they have no Ronco representation there, so I ride around till I find a suitable looking workshop.
The mechanic there agrees that I need a new sprocket, and shows me where the chain has also been damaged (this was a heavy duty replacement last year as the original was weak and stretched a lot) by the sprocket wear. Now in Peru everything is very different - a mechanic does not sell or stock spares, just as spare places will sell tyres, but do not fit them! So we hop in a moto-taxi (3-wheeler!) and head to the part of town where the spares shops are. None of them have a Ronco-suitable sprocket (4 close-spaced holes near the axle, as opposed to the 6 wider-spaced holes on all other makes!), so we buy a 6 hole sprocket and take it to an engineering workshop, and they cut my old sprocket apart and weld the new one round it!!! This actually entailed a further 3 moto-taxi journeys as we had to go back for my rear wheel, and then take it back to the mechanic's workshop as the engineer didn't have the tools to remove the brake disk which was in the way!
6 hours after I arrived I finally get away, with a new chain, and a "fixed" rear sprocket (they couldn't replace the front sprocket, which was after all only 2 weeks old, as the ones there didn't fit!), though this has 42T where my old one was 38T. I head out of town onto the Pan-American Highway, and find that it is closed for a children's procession to the town square - so the only way out of town, and the only way for good's vehicles coming down from Ecuador (only 20 miles away) is closed for 90 minutes while over 1000 kids march through town!
The mechanic charged me US$20 for his labour, and the parts came to about another $50 (including the engineering!), and so far - after 1000kms - I still haven't had to adjust the chain, but have noticed a serious increase in fuel consumption! Amazed what a difference 4 teeth in the rear sprocket make, but I also had a headwind most of the way home!

[alex_in_az]

great story, thanks I really enjoyed it.

[Weldangrind]

The only thing that would have made that a better story would be pictures. I'd love to see your repaired sprocket.

[SpudRider]

A stiff headwind will definitely reduce your fuel mileage.

I also would love to see photographs of your repaired sprocket.

[Carangajeira]

Took some photos, but they don't show it that well as the mechanic painted over the sprocket, so the join is not obvious.

I had to move the chain guard out of the way (rust patch found on guard mounting bracket!) - the bolt is one of the 4 holding the sprocket in place, while the other smaller hole is one of the 6 bolt holes from the new sprocket.

The paint was flaking badly on my swing arm so I did a quick touch up before my trip - I want to try and get an aluminium replacement as Chinese paintwork on metal (maybe just on Ronco's??) is not brilliant!
Edit: OK, I can't count - looks like the new (outer) sprocket has 8 bolt holes, not 6!

[Weldangrind]

I think it's remarkable that he was able to weld two sprockets together like that, and make it functional. I'm surprised that it's not warped.

[Carangajeira]

I decided I wanted to get a "proper" sprocket on the back - also with less teeth!! 42T was hurting my fuel economy big time after a 38T original - but now I have a 37T Honda (made in Japan) sprocket on.
Took a photo of the offending sprocket after the change (sitting on top of the bag the new one came in showing it was genuine Honda!).

The scratched paint was not a thrown chain, but rather caused when the chain was removed.

[Adjuster]

That shop made sprocket is very cool.


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[Weldangrind]

My hat is off to the guy who welded it together.