Sprocket/tire/chain changes and effects on speed.

[DeadLastRacing]

where whould a smert move be. I roll 22 on the rear. I run a full DMC exhaust, jetted and unifilter. Its a stocker engine wise, For now.

 

[justrandy]

where whould a smert move be. I roll 22 on the rear. I run a full DMC exhaust, jetted and unifilter. Its a stocker engine wise, For now.

What gears do you have now??? Stock? How do you like it??? Geared too low? Too high?

 

[DeadLastRacing]

I believe Im running stock? first and second and a little in third are really quack shifts.......I just looking for a little more speed. This winter im gunna get into the engine.

 

[justrandy]

I would drop the back down to 38 then. You'll pick up some speed, but not as much as just raising the front to 14. Close though.

13/40=.325 (stock)
13/38=.342
14/40=.350
14/38=.368

 

[DeadLastRacing]

Thanks.......14 tooth front here i come! I'm retarded but what does the .350 a reference to?

 

[justrandy]

14 divided by 40. 14/40

It really doesn't matter, but it makes better sense to say 40/14 or 2.857... Because it takes 2.857 revolutions of the front sprocket to equal 1 revolution of the rear sprocket.

Its harder to visualize .35 revolutions of the rear sprocket being equal to 1 rev of the front.

 

[DeadLastRacing]

Dude....killa graph......+1 exalt point. I change my mind. 14-38 combo......here i come.

 

[tiimbo]

I posted this tutorials and I'll post it here too. You should find this very easy to understand, I think I got all the ratios and grear changes in there.


I'll post some ratios with different tire sizes.
The lower the number the higher the revs will be and the more top end you lose. Remember you can't go to high numbers because your motor may not have the torque and you'll actually lose power.

dave, how did you come about on those ratio's?

 

[dave76]

I posted this tutorials and I'll post it here too. You should find this very easy to understand, I think I got all the ratios and grear changes in there.


I'll post some ratios with different tire sizes.
The lower the number the higher the revs will be and the more top end you lose. Remember you can't go to high numbers because your motor may not have the torque and you'll actually lose power.

dave, how did you come about on those ratio's?

I divided in the tire size by the gear ratio. I actually gave overall ratio.

 

[justrandy]

Dude....killa graph......+1 exalt point. I change my mind. 14-38 combo......here i come.

Thanks! Now you'll have 4 sprockets to play with in case you don't like the 14/38.

If you have a 1986-1988 model, you can go down to a 37 instead of only a 38. Just pointing that out... I just said 38 because I didn't know what year you had.

http://www.sprocketspecialists.com/ProductSearch2.aspx

 

[sandracer99]

it would be cool if we could make a chart in excel with all the ratios listed and both tire sizes.
I did not see a 15/39 on 20's in the list. Could a stocker pull it?

 

[blackburn]

Great chart justrandy, been runnin 14/40 and I think I'll try a 38 rear. I run 20" rears and I have a stock motor with a Pro Circiut pipe Stage 2 jetting(outerwears airbox cover) with a clamp on K&N. You guys think my motor will pull the higher gearing in the woods?

 

[dave76]

it would be cool if we could make a chart in excel with all the ratios listed and both tire sizes.
I did not see a 15/39 on 20's in the list. Could a stocker pull it?

It's gonna be sluggish.

 

[yamarider]

eh, i think it'll be ok, these things have enough touque stock to lug around taller gears. It's probably going to be most noticable taking off uphill, it'll take a little more clutch to get it going.

 

[justrandy]

I'll edit the chart with the other gears and post it as soon as my ISP gets back online. There's just no way I can move pics around with a dial up connection.

The excel chart is already made, I just have to change the numbers and copy n paste. Uploading is what's hard to do right now and photobucket takes a lot of bandwidth.

 

[justrandy]

 

[DeadLastRacing]

What the negative of bumping your sprockets up this high. Say if one were to run an 22 rear and have the 17/38 combo.......what is that going to do to the engines performance and clutch wear. Why wouldn't everyone run a 17/38 combo? Its all about speed right? will a 17 front even fit?

 

[yamarider]

You'll never achieve those speeds unless the engine has enough power to hit those rpms in high gear. A stock engine would not be able to come close to winding out with gears that high. A 15/40 with 22's is actually way too much for the stock motor unless you're downhill with a tail wind. The speeds in that chart are just theoretical numbers, it doesn't take into consideration anything about wind resistance, the weight of the machine or rider, or any of that stuff. It's just simply how fast the wheels would be able to spin at said rpm with said gearing, with no load on the engine. So yeah, with 17/38 and 22's you could get your rear tires spinning almost 90 mph with no load, but u sure as hell ain't going anywhere that fast unless you have one hell of a wicked engine build going on.

Aside from the fact that you would never be able to get out of 4th gear with a stock engine and gearing that high, you would also take a lot more time to get up to speed, and you would really work your clutch over in the process. The taller 1st gear is, the more you will need to use the clutch to pull out, and the more spaced out the gears are between each other, again you'll put more stress on the clutch.

Generally the ideal gearing setup when top speed is concerned, is to gear it just high enough that it can wind the rpms all the way out in high gear. If it's so tall that it can't wind out high gear, often you can achieve higher speeds in 5th than 6th... and that's definitely not beneficial in any way, all that will do is slow you down.

 

[DeadLastRacing]

So with a stocker of a power plant, what is the best gearing for a bit more speed yet still able to gain all the benefits with out doing clutch or any other damage?

 

[yamarider]

Depending on your tire size, stock i'd say stick with the 13/40 with 22's, and 14/40 with 20's. With a few basic power mods like you have, i'd say you could bump the sprocket up one more tooth and be fine. I ran mine with 14/40 and 22's when i had exhaust, intake, edelbrock carb, ported head, and a high compression piston and i could wind it out all the way with a little power to spare, but i kept the gearing that way because much taller would have made the technical riding at paragon more difficult. Some of the jeep trails there are nothing but rocks and boulders, so it was a lot of slow riding and clutch work in those sections. I still did pretty well in those with the taller gearing without having to kill my clutch.