2002 GSXR 750 sprocket question.

[gixxerboy70]

Hey all, Im new to the web site and thought id throw out a question that im looking into. Im building a custom 02 GSXR 750 from the ground up and am trying to figure out a sprocket combo (front and rear) that will give me better acceleration without losing a ton of top end speed. Stock is 17 tooth front and 42 rear. Im planning on doing the 520 conversion so whats the best sprocket combo size to go with? Any help would be awesome. THanks
Lance

[Jake]

I went up two on the rear. Seems to be the best to me. I went down one on the front along with going up two on the rear, and it just seemed to go through the rpm's too quick.

[gixxerboy70]

Thanks for the reply. So just changing the rear sprocket and leaving the front one works best? Is it easier to wheelie? Just curious. Thanks again

[Jake]

Originally Posted by gixxerboy70

Thanks for the reply. So just changing the rear sprocket and leaving the front one works best? Is it easier to wheelie? Just curious. Thanks again

If you want, you can save some money and just go down one tooth on the front sprocket. It's about the same as going up two or three teeth on the rear, just harder on the chain. As for wheelies, it does come up easier.

[MROCK]

o.k. i will try to explain this the best way i can about the going down in front. and probably will recieve some slack for it but it just makes sense.
my advise only go up in the rear. my suggestion is up 4. yes easier to wheelie and you won't loose but maybe 5 to 10 mph on top end.
reason for not going down in front. although -1 in front is = to 3 in back it is different. you drop 1 in front what that will do is make your internal components spin faster than stock. which in turn yes it is = to 3 up in back and will make it roughly the same torque. but it will make your motor work harder than just going up in back. and rpm's will climb quicker. hope that makes sense, if it doesn't i will try to find an article on it.
hope this helps,
marc

[gixxerboy70]

Hey thanks for all the great help guys, i really do appreciate it. Ive heard so many different ways to do it, just wanted some other opinions. So marc, if i go from a 42 rear up to 46 its less torque on the engine? Im a pilot so im trying to understand the physics behind it. I understand what your saying somewhat and it does make sense. Does changing the sprocket throw off the speedo as well? Merely curious

[MROCK]

Originally Posted by gixxerboy70

Hey thanks for all the great help guys, i really do appreciate it. Ive heard so many different ways to do it, just wanted some other opinions. So marc, if i go from a 42 rear up to 46 its less torque on the engine? Im a pilot so im trying to understand the physics behind it. I understand what your saying somewhat and it does make sense. Does changing the sprocket throw off the speedo as well? Merely curious

if you go up to 46 you will create more torque at the back wheel. pretty much the same thing as a car, they say the most bang for your buck in a car is gearing. which is what you are doing with the bike, gearing it. i personally think you will be pleased with +4 in back. and yes your speedo will be off. the faster you go the more it throws it off . and with the 520 conversion since the the chain is slightly thinner that will also effect your performance cause it produces unsprung wight. which the chain will spin easier. i think i worded that right. i wish i new a good analogy for you, but unfortunately i don't. sorry. i will try and find the article and post it for you. it is a lot easier to understand than what i'm trying to say.
check back.
thanks,
marc

[gixxerboy70]

Hey marc, thanks for all all the addt'l info. Do they make anything to correct for the speedo or is that the price you pay? And not to sound completely stupid, but is this whats technically called the "520 conversion"? Id really like to read this article you speak of. If you find it, email it to me at homerunnutt52670@aol.com . Thanks again for the great info and sorry to sound so stupid.

[MROCK]

Originally Posted by gixxerboy70

Hey marc, thanks for all all the addt'l info. Do they make anything to correct for the speedo or is that the price you pay? And not to sound completely stupid, but is this whats technically called the "520 conversion"? Id really like to read this article you speak of. If you find it, email it to me at homerunnutt52670@aol.com . Thanks again for the great info and sorry to sound so stupid.

you're not sounding stupid at all, don't know if you don't ask. i just posted a thread on how to adjust my headlight. lol
technically a 520 conversion consist off stock gearing, same size spockets front and back, just thinner and thinner chain. and i think it's extra for addition teeth. but they do give you more than enough chain.
honestly i just bought my gsxr 600 01' and it hase the 520 conv. and i wish i had the 525. 525 will last longer and is more durable. but that is completely up to you. if you ever plan on doing stunts (wheelies) a lot i would stick with 525. to me it's safer, but then again i've never heard of ahyone snapping a 520. another thing if you decide to keep the 525 the most you can go up is +2 with the factory chain. but you can add links to the chain but instead of one master link you will have 2. sorry , don't mean to babble, but i try to cover every aspect just in case to question comes up or someone else needs help.
and i looked and looked for that article with no outcome. but i will keep checking.
marc

[old newbie]

Although I'm new to motorcyles, as a mechanical engineer, math is my game. No one can decide what's a best gear for you. Depends on what you're doing with the bike. If you're racing a particular track regularly, then the track dictates your gearing needs.

The factory will usually select a gear ratio that produces the highest top speed not too far from the engines peak power RPM. Lower gearing will raise the rpm at which top speed occurs. If you spend a lot of time cruising at high speed, lower gears will increase the engine rpm, probably increase fuel consumption and reduce engine life.

One of the reasons that a front cog is often changed rather than the rear is to avoid a change in chain length. Increasing the rear sprocket by 3-4 teeth requires one more link of chain, while dropping the front by 1 tooth would not. For a new setup, you'll get better chain life with a 17 tooth front sprocket and a larger rear.

If you change from a 42T tooth rear to a 44T, the engine rpm will increase by 44/42 = 1.048. Instead of 8000 rpm, it will require 8380 to achieve the same speed. It would require an engine speed of 12,576 to achieve the same speed as previously attained at 12,000.

A 46T rear will increase the engine rpm by 46/42 = 1.095. Instead of 8000 rpm, it will require 8760 rpm at a given speed. At higher engine speeds, it would require 13,140 rpm instead of 12,000 to achieve the same speed.

[MROCK]

gixxerboy70 alright the guy pm'd me and when he get's back from vegas he said he would e-mail me the diagram. when i get it i can forward it to you if you would like. but this is the message he sent.


"I dont know where the thread is so Ill just try and explain it. Anytime you go down in the front it puts more stress on the counter shaft sprocket since it is spinning so much faster. The faster it spins the more violent and touchy the throttle becomes. If you just run all your gear in the back the power is smoother due to less stress on the counter shaft sprocket. I have a diagram on my comp that explains it but Im in Vegas right now. As soon as I get back though I can email you the diagram. It explains it better. Hope this helps. Ill talk to you soon. "

EDUB
__________________

[MROCK]

Originally Posted by old newbie

Although I'm new to motorcyles, as a mechanical engineer, math is my game. No one can decide what's a best gear for you. Depends on what you're doing with the bike. If you're racing a particular track regularly, then the track dictates your gearing needs.

The factory will usually select a gear ratio that produces the highest top speed not too far from the engines peak power RPM. Lower gearing will raise the rpm at which top speed occurs. If you spend a lot of time cruising at high speed, lower gears will increase the engine rpm, probably increase fuel consumption and reduce engine life.

One of the reasons that a front cog is often changed rather than the rear is to avoid a change in chain length. Increasing the rear sprocket by 3-4 teeth requires one more link of chain, while dropping the front by 1 tooth would not. For a new setup, you'll get better chain life with a 17 tooth front sprocket and a larger rear.

If you change from a 42T tooth rear to a 44T, the engine rpm will increase by 44/42 = 1.048. Instead of 8000 rpm, it will require 8380 to achieve the same speed. It would require an engine speed of 12,576 to achieve the same speed as previously attained at 12,000.

A 46T rear will increase the engine rpm by 46/42 = 1.095. Instead of 8000 rpm, it will require 8760 rpm at a given speed. At higher engine speeds, it would require 13,140 rpm instead of 12,000 to achieve the same speed.

yeah math IS definately you thing. pretty impressive. hopefully gixxerboy70 can benefit from both.
thanks,
marc

oldnewbie can you calculate that out if i went +7 in the rear. i have a 16/45 so i would be going up to 52 teeth in rear. oh i'm on a 01' gixxer 600. if that matters.
thanks,
marc

[old newbie]

Changing just the rear sprocket from a 45 to a 52 would increase engine rpm at a given speed by 52/45 = 1.156. Basically it's a large 15% increase.

For instance, instead of 12,000 rpm, the engine would be spinning nearly 13,900 at the same speed. That's a big jump.

You would also need two full links of additional chain, since 4 teeth equals one link (1-1/4 inch, the minimum increment of change).

[gixxerboy70]

Hey thanks for ALL the super info! You all have been a tremendous help. Id also be very interested in seeing that diagram, if you get it DEFINATELY let me know! You can email it to me at homerunnutt52670@aol.com

[MROCK]

Originally Posted by gixxerboy70

Hey thanks for ALL the super info! You all have been a tremendous help. Id also be very interested in seeing that diagram, if you get it DEFINATELY let me know! You can email it to me at homerunnutt52670@aol.com

i will definately forward that diagram to you when i get. glad i can help.
marc