Sprockets Filing down the drive sprocket?!



Hey guys,

Been putting together my first motored bike using a 48cc kit from www.zbox.com.au. It has gone relatively smooth so far, but now I'm attempting to install the drive chain, and I am finding that it doesn't fit around the small engine drive sprocket properly and gets jammed in there when attempting to wind it on.

The chain fits around the rear sprocket just fine.

In the instruction manual it says to file down the sprocket for 'smoother running'., and also i presume - to make it fit. Has anybody here had to do this? I'm kind of reluctant to just go at it with a file in hand.

Any ideas?
That guy Warren from ZBOX doesn't seem to have much of an idea about chains(or sprockets)...i complained about the stretch in the crappy Chinese chain and he was very defensive saying it was a good chain.......rubbish.
Your chain should fit from new but since it doesn't their are a couple of things u can do:
1.Buy a different sprocket and NOT use that wierd Chinese sized sprocket.I havn't tried this but overseas websites sell updated countershaft sprockets that fit.
2.Buy a different chain that fits both standard Chinese sprockets.....i tested MANY chains and found that the KMC 415H Motorcycle chain fits nearly perfectly...i also understand the YBN 415H Motorcycle chain also fits.
3.Angle-grind the sprocket where u think it's riding-up.I'm afraid i can't help u there because my chain fitted well from new and so does my replacement chain.
4.Email Warren and tell him your problem and let him sort it out....it's rather pathetic that something doesn't work from new.

Also,get yourself a good chain-tensioner...the one Warren supplies doesn't have ball bearing construction and needs constant attention.
Good luck man. :)

See my pic for tensioner:
PS....MBB-Imports in NSW sell countershaft sprockets....dunno if they fit though.
Im glad you guys started this topic as Im at this stage now. I was waiting for my son to go to bed and was planning to pull the cover off to grind down that gear (on Warrens' say so).

I guess thats on hold now to see what everyone else says.

I dont really want to import a new gear at this stage. With it so close to Xmas, the timeframe stretches out. I might check out my local BSC tomorrow to see if they can help.

Keep us informed

Cheers for the info Fetor,

Have emailed Warren to see what he says - which I assume will be "grind it down, she'll be right, mate."

Kind of don't want to do that, but will see what happens. Nice to see someone has the same problem as me though. Looking at you Leigh. :D
Hey guys,

Got an email from warren;

"Dear Mike,

I have had another 4 or 5 similar problems from that batch of 200 units. I shall put a replacement drive sprocket in the mail to you in the morning. It's easy to swap with the black screw tool included in the kit.
sorry for inconvenience - kind regards from Warren Bates
ZBOX Australia
PO Box 113, Bellingen 2454
Tel: (02) 6655 2920
Email: info@zbox.com.au
Website: www.zbox.com.au

So there ya go.
I guess if anyone else if having any issues similar to ours with zbox kits, they should email warren and let him know.

Hopefully this is the end of this problem.

Cheers for the help fellas,
Good to see that Warren is standing by his product.
It is easy to remove the sprocket with the supplied tool(remember to have the chain on or partially on to remove/replace the retaining nut)
The potential problem is when your finished and want to tighten the retaining nut....it's on a tapered spline so it's easy to think that it's tight when it actually isn't.Check it a few times for tightness...........tight...not radicously tight.
:cool:I'm in your same situation, but I'm trying to mate the drive sprocket to bicycle chain and 7-speed cassette.:confused:

The stock bicycle chain meshes correctly on every other link. Every other link is narrower, so rides up on the drive sprocket.

Now I realize why another member's chainsaw engine kept throwing the chain. His drive sprocket was also linked directly to his cassette.:confused:

I ordered a special sprocket from DAX. It's listed as being 1.5mm wide, or less than .060". If this sprocket doesn't work, I'll look for a chain that is more compatible.

Grinding the sprocket's teeth is the last resort for me.

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Hey, MichaelSteve, if you're any good with a digital camera, would you please post close-up pics of both the old and new sprockets?

And who here can suggest which aspect to file from the sprocket? It's thickness, or it's chain teeth? I haven't looked directly at mine, having just fed it onto the bike last night where it did exhibit a slight tendency to jam...


Usually the teeth have to be filed so they are slightly more "triangular" when viewed on edge....mostly towards the tips tho (sprocket teeth facing your nose.....Profile view)