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jeepwm69

1985 TRX125(s) for the kid

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This is going to be a looong term project, but figured I'd start a thread on it.  I have other projects before this one, but I would like to disassemble the better of the two that I have to get the engine etc in the shop and out of the weather.

 

So, this is my first chain drive project.  Looks like it should be....interesting, especially given the lack of availability of a lot of parts for bikes this old.

 

Machine on the top is now missing front bumper, and rear rack (BASFNB took those for his kid's 125, split the $100 purchase price of the machine with me), and the top end has been off for no telling how long.  Tank has been lined and looks iffy.  It only cost me $50. 

 

Machine on the bottom has a good tank, engine is complete, and has decent tires and a front rack to replace the missing one on the other bike.  This one cost me $100 (funny how I had to pay more for the worse looking one, huh?).

 

This will be for the newest addition to the family, so not in a rush to do it, but don't want to leave stuff out exposed to the elements in the meantime, so plastics are in storage from the machine on the left, along with the good gas tank.   Going to pull the motors and carbs and put them inside too. 

 

Looks like I have to pull the engine cover and subtransmission to get the chain off, and that has to be done before I can pull the motor.  Will update and try to take some pics as I go.

 

125.jpg

125 front rack.jpg

Edited by jeepwm69
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1 hour ago, toodeep said:

The drive chain doesn't have a master link in it?

 

I assume it does.  Haven't looked yet.   I haven't ever worked on a chain drive but saw that in the FSM.  How does the clip come off to take that master link apart? 

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usually a master on a bike chain is a sliding clip, if it doesn't have a master , make one , grind a link , I would think you can get a master link if not from a dealer then from Motion Industries or maybe McMaster Carr , I have seen chains on equipment that don't have a master 

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Yep, a pair of pliers and slide the clip loose to take it apart. If that part of the motor doesn't have to come apart keep the chain in the motor side and pull it from the rear axle. They are kind of a pain to fish through once they are pulled out of the motor unless it needs to come apart. A 428 master link should be easy to find if it is a continuous chain so break it if it doesn't have one.

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Good to know. 

 

I think I'll take the one off of the bike with the incomplete motor first, see how it goes. 

 

Looks like the subtransmission on these is prone to breaking.  That and worn sprockets. 

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I don't know much about chains.  What's the difference in a roller drive chain and an Oring chain?

 

http://www.ghdiscountatvsupply.com/1985-1986-honda-trx125-428-x-92-drive-chain-front-rear-sprocket-kit-13t-50t-free-u-s-shipping/

 

Edited to add, looks like I'm better off with the oring chain, but given the age, wouldn't these orings have deteriorated quite a bit?

 

https://www.fixyourdirtbike.com/tips/o-ring-chain-vs-roller-chain/

Edited by jeepwm69

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Oring will last longer but the roller is cheaper. A good chain lube and light use the cheaper chain will last a long time. If your going to try to ride it like @SlammedRanger then oring and knee braces will be needed. 

 

For your use any good chain is going to treat you good. Do not buy baler/bulk chain from a parts store though. That stuff breaks cases.

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O-ring, X-ring, and Z-ring chains are good for keeping mud and grit out of them. The Z-ring is designed specifically for sand dunes and desert racing. The standard roller chain is good for mx style racing and everyday riding. If you spray a regular chain with lube often eveeything will be fine. The o-ring is for the less maintainance oriented person. Spray it every few rides. Or never and it will hold up for quite a while.

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