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dirt bike gearbox/reduction drive circlip on sprocket wont stay on

2033 Views 16 Replies 4 Participants Last post by  EPR
As the title says...the circlip on the 14 tooth sprocket wont stay on. Then the gear doesnt sit square and wears out on the inside causing the shaft to also wear. Any one know how to fix this cos ive had to buy a second sprocket now and the circlip wont stay on and i know itll wear again. I was thinking of welding it to the shaft so its square. If i ever want to change sprocket to 11 tooth or 17 tooth ill have to buy a new gearbox complete for $30 but just asking if anyone else has experienced this before.
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There is a slot in the shaft, for the clip, if it is to loose, bend it till its small. The China clips are not very good and your shaft splines could be worn.
Thanks EPR. Yeh i knew the slot was there but the circlip was popping out of there first ride. I bought some more today and made sure it fit snug in there. No more clicking or popping out so far but ill post up here if it eventually pops off.
On another note i cant seem to find a walbro carb around here. I think u guys recommended a walbro wt-603 to me. How much can i pick one up for (a kit to fit to my standard engine) and where i can get one. I already have a pod filter and adaptor. Is thepod filter adaptor to carb called a vstack? These 2 strokes are a bit different than the usual subarus and gm holdens i work on lol but my background helps alot.
Its all good! Took it out for a test run and hit top speed a couple of times. Circlip still on there. For a little dirt bike it flys. So much fun though!! Only wish i could ride it more without the paranoia. I ride in laneways and on the back streets in my area. Big no no but at least i waited till dusk. Anyways, enjoy my fellow mini bikers.
I PMed a website with the carb kit.
Thanks for the info. That site wont ship internationally though. It says no more international orders. Only us and puerto rico address. What a bummwr. Thats the most comprehensive site ive seen for bike parts. Would love to do business with em.
Pocketbikeparts in Florida might ship world wide, but it's atleast $25 min.
Have you tried eBay motors UK. or other countries that ship to you.
Not yet i havent. But ive looked thru their sites. Does the walbro copy carb require a return line plumbed into the fuel tank?
Yes it does. If a 19mm is not to big, you can use a Walbro HDA48D, or HDA223 purge carb, both have no return line. The WT-603 or copy are 16mm carbs, I have all three of them carbs.
On my 603s I run the return line to a fitting on the gas cap, like my avatar Lucky 7 photo.


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Hi just wondering what size circlip it was, i had mine pop off during a ride and i dont know what size to buy
Try your local autoparts store. Same sale a small package that has different sizes in it.
I did this and havent had a drama since..
Take ur gearbox and sprocket to an auto parts store and theyll match up a pack/size. Make sure it fits spot on or it will pop off! There will be about 2mm or so between the 2 ends when its on and it wont turn freely. It will spin only with the shaft/sprocket. If its too loose or too small it will pop off even when u push the bike on the ground. Hope that helps! Any problems just ask again, cheers.
There metric, so becareful, you can get one online, think the 50cc to 125cc are all the same size clip, think it's 17mm on the big bikes, not sure on the smaller ones. SP4Less will have clips, maybe $2. Online store scooterparts
Also it will pop off eventually if the chain tension is too tight. Make sure its a little loose cos when the chain is too tight it causes the sprocket to not spin square due to the tension on the sprocket. As i said it will pop off evenrually so what ive done is put the circlip on and jb weld around the clip to keep it on. When u wanna change the sprocket just use ace tone to weaken the jbweld then lever or crack it off. Another idea that im using now is to put a big washer on top of the shaft and drill a tech screw into the shaft. It holds the washer on there tight and the sprocket has no chance of coming off. U can remove the screw anytime to change the sprocket, just use locktite when u screw it back it. Solved. Havent had a problem.
Great idea, I have never had that problem, yet, but I know what to do now,lol.
EPR, youve helped me out with heaps of info and tips, etc. Im new to pocket bikes and without your advice in the past, id still be new to them lol. Cheers for all your help.
Them clips are suppose to be springs clips, but you can bend them, if they where quality clips,they would break like the piston rings do when you open them to far, Snap,lol.
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