any suggestion on where to get gears

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astronut

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Mar 16, 2008
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I am looking for the gears of a skyfire gearbox from the huashang 4-stroke kit. so far I have tried

1 lawn mover repair
2 transmission repair
3 motorcycle repair
4 motorized bicycle shop

tomorrow I am going to a gear shop :)

what happened was that the bolt that retains the clutch bell, came loose and broke some teeth and a feather key. I got that fixed and the next thing that was wrong was the chain sprocket on the gearbox was a little too thick for the chain and the chain seized against the engine block and sprocket, braeaking another key and some teeth on the the gears. I have never seen broken gears that look like this before. its almost like pot-metal, reminds me of the matarial that the case is made of.

well everything is in perfect conditons now but the gears are ruined. I even fabricated a simple spring loaded chain tensioner. I could get another gearbox with the same quality but I would rather get better quality gears instead.

so if anyone can help please respond

thank you and good luck. :ride2:
 
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cruiser66

cruiser66

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Mar 4, 2008
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Westport, MA
Sorry to hear about all your problems with this gearbox. I think the least expensive way out would be to toss the old gearbox and get a GruBee stage II gearbox. You would have to use a 1 mm shim for the output shaft of the motor if it is a 142-F. I have the same setup as you but nothing has broken - yet... Did your gearbox come with the vented fill plug? If so, there is a newer (improved?) model with no plugs and angle cut gears for the clutch bell and main gear. I have no idea if the gears are any stronger, but they are supposed to be quieter and the box is a direct replacement for the one that came with the Huasheng 142-F. It would cost less than the GruBee, but the GruBee has been around longer and is probably more reliable.

66
 
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astronut

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Mar 16, 2008
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no, the one I got is the "newer" one with the angle cut gears.

the problems are not too bad. had known before hand the whole operation would have been flawless. but as is the case with this hobby al ot of it is experimentation.

I vaguely remember reading something before on that sprocket being too thick though.
 
cruiser66

cruiser66

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Mar 4, 2008
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Westport, MA
I have had no problem with the stock 415 chain hanging on my drive sprocket. I would think that this is the same sprocket as on your box. I think that the chainline is critical and could cause your problem if it's not correct. Using a number 41 chain would give more clearance if it is a thick sprocket. Ref: Azusa Engineering, Inc. Online Catalog - Roller Chain, Motorcycles, etc.
Were you able to do much riding before your problems? If so, did you find that the box was very noisy? The old boxes with the straight cut gears are pretty noisy, but I am enjoying the smooth clutch action, good cruise speed and good hill climbing ability using a 36T sprocket.
 
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astronut

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Mar 16, 2008
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no the box was not as nearly noisy as I had expected it to be, from watching videos of it. it lasted one turn around the block before the clutch came loose. and another before the chain got stuck

actually I should have done more research. the clutch bolt problem is a common one. :D

its ok though the guy at the gear shop said that he could sell/make any gear I need the problem is the price if he needs to make it. if not I'll make my own replacements. :)
 
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astronut

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Mar 16, 2008
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ok heres what happened.

I went to these guys Marples Gears - Precision manufacturing . they could make them but it would be too expensive. some comments from the guy (who gave us a tour of the place)

1. he measured how much carbon was on the gears and commented that it was just a bit too much, making them too brittle. he recommended I buy the gearbox again but place the gears in the oven at 400 degrees for 2-2.5 hours. in order to make them better suited for the task.

2. he also mentioned that these gears where made with an older model machine and that it takes longer to make in those machines, and because of that process its not as strong because its under heat for a longer time.

Note: he showed me his machines and I just found out that the grubee gearbox uses those same machines for their gears.

well, I just could not find these little bastards rotfl

oh and I dont need the new chain, because I ground down the sprocket, had I known I would have loved to try that chain.
 
cruiser66

cruiser66

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Mar 4, 2008
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Westport, MA
Pretty interesting stuff. I wonder if I should be baking my gears. So, are you going to replace with an original or maybe a GruBee?

66
 
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astronut

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Mar 16, 2008
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getting the starfire I think its called. the one with the straight teeth on the gears. the helix geared one I thing is called skyfire. I am baking those gears and putting them on.

I expect everything to go smoothly now :)
 
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astronut

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Mar 16, 2008
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ok in request to more pictures on posts here are some from this ordeal.

this one is the large sprocket. the underside looks the same too.


this one is of the two smaller sprockets


and this one is of the new sprockets fresh out of the oven after 1:45 hrs of baking. they had a really nice blue hue for about 10 min


I ended up getting a new gearbox and baking the gears the new clutch bell, did not fit either of the housings I had. it was too large as was the little rod that holds the large and small cog, so I left the old clutch bell in.

When the other cogs broke the old clutch bell sustained no damage. When I tried using the new gears and the old clutch bell, they did not go well together and this time it was th clutch bell that ground down to the point of not engaging the sprockets. at least the sprockets didnt break.

after some grinding I got the bell and rod to fit and everything ran smoothly like the first time I turned it on.
 
Dan

Dan

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May 25, 2008
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Any updates? I am buying a gear box and building one as well. just wondering if the recipe has changed. Bake at 400 for 2.25 hrs still? LOL, I love this. lil weird home remedies. I am surprised this didn't catch on
 
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astronut

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Mar 16, 2008
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No real updates. The bike has been run for several hours at a time with no problems. It has had many many days of use and abuse, in the name of experimentantion. The metallurgist at the gear place was right.

its almost quiet now. In the beginning it used to make a racket.
 
Dan

Dan

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May 25, 2008
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Very cool. Thanks. That was some great information. Sorry you went threw all that. Think we are all some kind of half saddest not just buying ready made bikes.

When I get my gear box, I am gonna time it so the baby's Momma is home and sees me taking gears out of the oven....rotfl
 
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astronut

New Member
Mar 16, 2008
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Dan said:
Very cool. Thanks. That was some great information. Sorry you went threw all that. Think we are all some kind of half saddest not just buying ready made bikes.

When I get my gear box, I am gonna time it so the baby's Momma is home and sees me taking gears out of the oven....rotfl
Click to expand...
rotfl he he
 
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