520 chain

N

na2slow2

Member
Do I need to switch to the 520 gears that is currently on the transmission or switch the transmission to the 35 chain and sprokets. If I do go with the 520 gear what would be close to start with. The bike has a six speed transmission and is a 250 4 stroke. I have not had much luck finding any suppliers for the 520 chain stuff.
 
If you are going to run the transmission it will be easier to run the 520, I lost his number, but Brandon Hetrick out of Pa I think makes really awesome rear 520 gears, a normal four bolt brake hub will mount them. Outlaw karts and parts on Facebook, or Bhetrick on here.

Not sure on gearing, but try to run whatever trans gear gets you close to 1:1 and you will rarely have to change rear gears for most tracks. Unless you have a very big size change.
 
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I make hardened steel 520 rear sprocket. $40-$50 shipped. Your best bet to figure out a good starting ratio is to figure out what the bike had stock and include tire height. You can then go to 4lo.com (4x4 web site) and they have a calculator to change gear ratio with tire size. For instance, you'll have a 29 inch tall "old tire", and a 4.11 " old gear ratio" and you have an 11inch "new tire". It will calculate your new ratio. Then you just need to do the math on what gears to use. In this case, the new ratio is 1.56:1 and a 14/22 puts you pretty darn close at 1.56
 
Thanks guys, when I get my hands on this thing I will figure it up. JIMBO925 I will be getting up with you toward the end of the month. Thanks again Kevin.
 
I run Mr Hetricks parts on my Honda, very nice parts and last much longer than some of the leading brand aluminum sprockets on the market.
 
After doing some math, and using kartsmart I came up with a 21. That seams very small is it even going to be bigger then the hub. Also the front is a 14 so how close will the top and bottom of the chain be. Does anyone have a picture, seams like the chain would be close to slapping itself. Thanks Kevin
 
A 21 is as small as you can go. You will likely need to take a little material off the hub, about .050"-.100" at the tips of theears where the sprocket bolts. There is plenty of room between the chain. Remember, it's not going to be nearly as long as it was on the bike. And, you don't need to worry about swing arm travel. I run my chain pretty tight with only about 1/8-1/4" of slack.
 
chataqua machine makes front drivers and rear sprockets. they have a super nice product. I use there gears and fmi racing gears on my 250f with 520 chain.
 
Since you have to buy gears anyway, you could consider 428 with the 250f, Chataqua makes those gears and gives some handy gear charts and comparison charts. Brandon Hetrick makes 428 rear gears. But not 100% sure on drivers. If it's a Honda 250f the cr250 428 sprockets will fit it, but Chataqua makes the 428 drivers for the cr250.
 
Thanks guys, should of stated its a ninja 250. I have six gears in the transmission so hopefully a 21tooth sproket will work to keep the current ratio that the bike has. Is there a performance advantage with the 428. If not I will have the gentleman from the north make me one. I might get 2 extra front drivers eventually looks like I will be maxed out on the back. I should be good up to 100 mph with that gearing. Thanks Kevin.
 
428 is lighter. Of course any weight savings is a performance advantage. I, personally, stuck with 520 because for my application it is more readily available and cost effective. I'll give up a little weight in favor of durability and reliability. My brother has a beautiful aluminum rear sprocket that no longer has any teeth on it. Lol. Ran it 4 times. Some are better than others but I'll stick with trusty old steel. Lol. Brandon does have quality pieces and Chautauqua machine is second to none if you want aluminum. But again, I like not replacing a sprocket every couple races. I've run the same rear gear going on my 4th season
 
Do you run the o ring chain or an aftermarker regular chain? Guess I need to get a new chain breaker while im at it. Im sure that small sproket on a small hub will weigh less than the floating hub and gear guard. I still have to get up to 330. Thanks
 
Not all 520 is Oring, I wouldn't run Oring chain. A bike chain break will do just the same as the any other chain break.

That is an interesting engine, what's redline on that thing?
 
From what I have read 13500. Trying something out of the ordinary. The motor is 60 lbs heavier than the clone, might get her down to 350 depending on the body and radiator etc.
 
I don't use oring chain, and it for sure is not all oring. I have found with 2 front drivers and 3 or 4 rear gears you got most tracks covered unless you run some "Big" tracks. I have 13,14,15 front and 24-28 rear. I bought the rears from QRC, but am gonna check out the Chataqua machine stuff. I hear good stuff about it. I also run on tracks 700-1100 feet in length. Good Luck!
 
Absolutely Brandons and Chataqua are hands down way better than the QRC. I have some from QRC as that was the widely available gears at the time I built my 450. I got some 428 gears from Brandon and they were great. My brother just put a Cr250 together and had the Chataqua gears and they are very high quality gears, hard anodized and everything.

13.5 should make it an interesting engine. I'd be afraid of gearing, a road bike is probably going to be geared more for the big end. So you'll end up in like 4 maybe, not sure. But, I'd shoot for 1:1 in the trans first and go from there.

Like Phiddy I have 13-15 and never change front drivers. From and 1/8 to 1/4 I ran the same gear. 24-26 rear gears and I might change 1-2 teeth occasionally depending on how well the track is biting. Since the 520 gears change roughly 3-400 Rpm per tooth. For you, with the 250 I know you won't be able to pull the gearing I am, but the 14 sounds close.
 
PBI sprockets should be able to find a suitable 428 front gear. Converting on a 125cc 2 stroke from a 520 to 428 added hp on the dyno pull.....just sayin. :) I'd be looking for a performance cam too....those 250 ninjas are pretty docile.
 
I was thinking that too, smaller chain will free up hp with the smaller motor. Honestly, that heavy of an engine would benefit from a Jackshaft if you can cut the cases down still be able to mount it. Then I would almost go #35. I am running #35 on my Cr125. Biggest reason they went with chain that big on the bikes is the traction on the road and obstacles off-road on dirt bikes. The 35 I think can handle the 250 four stroke power.

I am sure a cam is available for that engine in some form or another.
 
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