high ratio gears

[FLEA]

looking for info on high ratio gears.on the new motor im putting together now (750,rephased,shell 1 cam,worked head,2-1 with single lectron carb) with a set of high ratio gears,,,,,,was after practical info from someone running these gears on the road (not track) about what front and rear sprocket combinations you are using and where you get the sprockets as the xs650 rear sprocket wont be big enough and really don't wont to get a set made up and please I know 17/32 is a good combination for a non high ratio gear set up but im after info on the high ratio gearing

 

[Newagerocker]

looking for info on high ratio gears.on the new motor im putting together now (750,rephased,shell 1 cam,worked head,2-1 with single lectron carb) with a set of high ratio gears,,,,,,was after practical info from someone running these gears on the road (not track) about what front and rear sprocket combinations you are using and where you get the sprockets as the xs650 rear sprocket wont be big enough and really don't wont to get a set made up and please I know 17/32 is a good combination for a non high ratio gear set up but im after info on the high ratio gearing

I ran 16T countershaft and 36T rear on my sidecar outfit. You'll will have to really shop-around for anything not within a tooth of stock as those kind of numbers are not readily available.

OOPS! I read that meaning high nunber low ratio.

 

[fredintoon]

looking for info on high ratio gears.on the new motor im putting together now (750,rephased,shell 1 cam,worked head,2-1 with single lectron carb) with a set of high ratio gears,,,,,,was after practical info from someone running these gears on the road (not track) about what front and rear sprocket combinations you are using and where you get the sprockets as the xs650 rear sprocket wont be big enough and really don't wont to get a set made up and please I know 17/32 is a good combination for a non high ratio gear set up but im after info on the high ratio gearing

Hi FLEA,
First, those new primary ratio gears aren't HIGH ratio they are LOW ratio, as in the new engine gear has more than 27 teeth and the new clutch gear has less than 72?
Nitpick over.
Now you have to do some arithmetic.
Count the new teeth and work out the new ratio.
Compare it to the original (2.666) ratio.
To get the same overall gearing the rear sprocket will need more teeth.
You can get a 42T from (I forget which) catalog.
Need more than 42T and you are into cutting the tooth ring off a dead XS650 sprocket and welding on a bigger one.

 

[650Skull]

When i was speaking to Ivan about this he said most of the street guys were running 17/36. Could go 18/36. Mikes sells a 38 rear as well, 17/38=18/36 or 18/38. if you want really want to be sure by the sprockets and work it out for your self.

Give Ivan a ring. He is the man who knows.

 

[FLEA]

thanks skull,ivan replied on fb page (xs650) was supprised to learn he runs 17/34 on his road bike which would have thought would have made it a bit doughy on acceleration but as you said hes the man with these gears.might try 17/36 as a safe bet also means only have to buy back sprocket...hadn't realised mikes sold the larger sprockets.will make things easier hopefully

 

[650Skull]

Hi FLEA,
First, those new primary ratio gears aren't HIGH ratio they are LOW ratio, as in the new engine gear has more than 27 teeth and the new clutch gear has less than 72?
Nitpick over.

Got me confused. Ivan Hoey, (Makes replica sets of Halco High Ratio Primary gears), Calls his Gear set High Ratio Primary gears.

Link Here.

 

[fredintoon]

Got me confused. Ivan Hoey, (Makes replica sets of Halco High Ratio Primary gears), Calls his Gear set High Ratio Primary gears.

Hi Skull,
yeah, I know, I know.
And it's not only Ivan, everyone who makes low ratio back axle gearsets does it too!
And they are all technically incorrect and it drives me bloody crazy!
It's almost as bad as my wife saying she's taking something out of the freezer to unthaw it!
(I've given up on correcting her grammar but you guys are fair game.)
BTW, thanks for posting the link, no matter what he calls them, that's beautiful work.

 

[mrriggs]

Maybe it's a regional thing but I've always heard lower numeric gear ratios referred to as "high" or "tall" gears, and higher numeric ratios referred to as "low" gears.

First gear has a higher numeric ratio and is referred to as low gear. Fifth gear has a lower numeric ratio and is referred to as high gear or top gear.

Think output shaft speed, not reduction ratio. A 4:1 gear set will turn the output shaft 25% the speed of the input shaft. A 2:1 gear set will turn the output shaft 50% the speed of the input shaft. Fifty percent is faster than twenty-five percent so a 2:1 ratio is "higher" than a 4:1 ratio.

 

[fredintoon]

Hi mrrigs,
a lower ratio gives a higher speed* so it's called a higher gear even though it ain't.
Makes perfect sense in English but I wonder how it's said in French?

*Although if it's too high it'll go faster in 4th than in high, eh?

 

[650Skull]

Hi mrrigs,
a lower ratio gives a higher speed* so it's called a higher gear even though it ain't.
Makes perfect sense in English but I wonder how it's said in French?

*Although if it's too high it'll go faster in 4th than in high, eh?

Yes this is what XSjohn done to his bike. He reduced the compression ratio to 8:1.1 and geared it 18/29, (although i think he went to 18/30 later on). Said to have no vibration and would cruise on the highway in 5th but all the twisties were done in 4th and around town was 2nd gear

He would swear by this mod............but then he was a republican....................lol

 

[mrriggs]

Hi mrrigs,
a lower ratio gives a higher speed* so it's called a higher gear even though it ain't.
Makes perfect sense in English but I wonder how it's said in French?

*Although if it's too high it'll go faster in 4th than in high, eh?

Yes, a ratio with a lower number in front of the ":1" gives a higher output shaft speed.

I think the confusion comes from the backwards syntax of ratios. It's just an inverted fraction; 2:1 = 1/2, 4:1 = 1/4. The number ahead of the ":1" represents the denominator.

You say that 2:1 is a lower ratio than 4:1 because 2 is less than 4. Maybe that is correct when talking about ratios? I don't know. The damn things are already backwards so it kind of makes sense that you reverse the language along with the numbers.

The more conventional use of "high" and "low" is a little easier to understand. You use a low gear at low speeds and you use a high gear at high speeds. It would be kind of confusing if you shifted into fifth [high] gear to start out and shifted down to a lower gear as you accelerate.

 

[FLEA]

intresting,mikes must have put their min shipping price up.36 tooth rear sprocket au$33 shipping au$49 is there any suppliers in aust.damm just waiting on a order from mikes never thought to look up larger sprockets on their site (to busy wondering if once again they will send me 2 left side petcocks instead of left and right.their photos look odd and when sent email just got some waffle back) but weather hi or lo ratio terminology by all accounts well worth the investment looking forward to finishing

 

[650Skull]

Keep an eye on these guys. They don't have a 36 tooth but stock moves quite fast. Have a 33 tooth XS650 sprocket

650Direct has them in Canada. Price is $4.40US, cheaper than MikesXS.

Freight should be $23/24 for a sprocket from the states

 

[webbrs]

Can someone post the equation to match chain link count to sprocket size? I want to run a 18/32 sprocket and I swore I found it on here but can't find how long of a chain i will need. Thanks

 

[TwoManyXS1Bs]

Webbrs, bigger front with smaller rear will probably need no chain length changes.
Try the forum's google search of 'sprocket chain length', and enjoy the reads...

 

[mrriggs]

Here you go.

www.gofastforless.com/junk/SprocketChainCalculator.xls

It'll calculate chain length and hunting percent. It also factors in tire size when determining drive ratio.

 

[webbrs]

Thanks Gents, I found much on rpms not much definitive about lengths tho. I am still searching. The calc only opens in read only format and then I found the "measure count and divide" method, so... that is a recipe for death with me. I feel if could have done that I would have become an engineer not a truck driver slash weapons techspurt. I feel that peanut has it right with the smaller rear only swap, that way I can fit the chain by dropping links if needed.
BTW, Has anyone used red grease (we call it 5th wheel grease ) or any grease on an o-ring chain? I want to use a light smearing inside the loop so it gets slung outward and into the links. I have no guard (thanks mr p/o) and don't want to wear motor oil or lube etc. Sorry if its a hijack.