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What company makes chain/sprocket conversions?

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I don't blast around, I just casually trail ride, so, I am sure I don't need anything bigger than my TTR125 sized chain, which I actually think is a 428.  I would like to reduce reciprocating weight by going from a 520 chain to a 480/428 or ????.  I have looked for threads for the past 45 minutes to see if there was anything about going from 520 chain to a smaller chain on my 2001 rm125 but found nada.  Is there a manufacture that specialized in conversions? Would be nice to find a backwards conversion to free up some low end chugging power.

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Now why didnt "I" think of sitting down for 4 hours during work and calling 20 companies instead of asking a quick question here thinking someone might have been down that path before?

Silly me! 

Thanks for the awesome advice!  👍

Edited by sikpupy

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There is no point in going to a smaller chain, "back in the day" when most OEM's were converting everything to 520 weight and power loss was some of the reasons given for not going with a 520.  But the difference is so small that it just wasn't worth the effort in staying with the smaller 428's.  Most riders will never notice a performance difference of any kind.

In short, don't bother ~ it's not worth the effort.

 

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Yup, going from a 520 to a 428 chain/sprockets might gain you 1/10 hp. It's like the people who worry about the loss of power from the added drag of an o-ring chain, keep your $$, increase your skills... 👍

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Hey all, well, HP, weight reduction yada, yada................  I was just thinking if there was something out there for $20 more, I would do it, but, not really interested in spending goofy amounts of money on it.  Now, if I could find a front sprocket that would fit without modes, I would not mind modding a back sprocket just for a "can he do it" project for fun when I am bored, lol.

TTTYL

 

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On 27/05/2017 at 4:41 AM, sikpupy said:

I don't blast around, I just casually trail ride, so, I am sure I don't need anything bigger than my TTR125 sized chain, which I actually think is a 428.  I would like to reduce reciprocating weight by going from a 520 chain to a 480/428 or ????.  I have looked for threads for the past 45 minutes to see if there was anything about going from 520 chain to a smaller chain on my 2001 rm125 but found nada.  Is there a manufacture that specialized in conversions? Would be nice to find a backwards conversion to free up some low end chugging power.

Is the carb tuning right ?

imo this will make more difference to the low end chugging power then the chain and sprockets 

i do see your point of lighter components tho

 I run a none o ring (cheap ) chain on the wifes ktm 200 and it works well

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Hi kxrob, to be honest, the engine is in pieces, so, i have not got to tuning yet.  This is all bench racing ideas and talk for now so that end of the build up is complete and out of the way.

I am pretty anal about lubing up the chain every run, before or after, so the chain should  (and i could be wrong) live as long as an o-ring chain.

 

Thanks  :cheers: 

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Okay, so, you all are going to kick e in my nuts, but, I am still on the 428 quest.  Ask me why and I will just say I am a stubborn bull dog when I get locked into an idea.  My sprockets and chain need to be changed, so, might as well.  I am also posting this here for others to read if they come up with the same hair brained scheme as me, as I could not find any info on it.

Anyways, for those looking to do the same, the front sprocket JTF426 has the (for lack of better description) 18 inner inside tooth dimension / inner outside tooth dimension 20 / pitch(?) Z-18  .  Basically, in a nutshell, its the same for the RM125 but in a 420 chain pitch.

Rear Sprocket - Looks like I am looking at a 78 rm125 rear sprocket.  Sadly, it looks like the inner circle is too small to fit the rear hubs raised location ring, but, that can be grinded down like a back yard redneck, or, done by a machine shop.  Almost too easy if you have, or have access to a lathe.  You will also have to drill new holes as the 78 sprocket is 84mm diagonal bolt hole spacing, as opposed to the 146mm 01 sprocket.

Is it all worth it when said and done?  Debatable.  Is it easily feasible?  For the most part.  Should one do it?  If you run out of projects and you would really like another challenge, yes, its not that big of a deal.

I will still putt around the internet and trol some conversion links to see if I can scrounge up any more info.  And dont sweat it ohiodrz400sm, now that I spent ANOTHER 3+ hours just surfing, and know what I am looking for, I will call JT at minimum and see what they say.

 

Thanks to all those with positive reply's, even if they are not what I want to hear.  Its always good to see what reality is, even if I am on an off tangent course.

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Seeing as though the factory recommended service life for a 125 piston is only 2 hours, do you really think they unnecessarily used an oversized chain? In a class where horsepower is everything?

The 1978 125 has the output of a modern 85cc class bike, hence the reason they both use a 428 chain.

 

If you want to free up as much power as possible, use a good quality conventional chain. If you want to replace your chain every other ride, by all means, put the mini-cycle chain on.

 

 

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I will assume those recommendations are for a bike on a BMX track pinned to the balls and back.

Did I say it was an "oversized chain"?  I dont think do. 

Under your guise and theory, if a 78 output of a modern 85cc uses a 428 chain, then, you need to get online with Honda and bash them for using a 420 chain on my 2001 cr80.  It looks like they were not listening to you when you were in the engineer's drawing room. 

Just to smooth your ruffled feathers out a little, I was thinking which is beneficial now that I think of it.  Heavy chain for .001% inertia, or, smaller chain for that .001% hp. 

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ohiodrz400sm, I owe you a humble and sincere apology.  I read your first post at work hastily and incorrectly.  I thought you meant call "A" sprocket specialist.  I was like, how do I know who the f*k is a specialist?  I did not realize it was a specific company you were referring too.  Since you commented again, I was like "uhm, wait, is this a company?".  I did an internet search, and, sure enough....  Please accept my sincerest apologies to everyone reading this post and especially you.  I give you full permission to run over me with your bike...............a few times.

Edited by sikpupy
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