1. ## sprocket conversion misreading fuel consumption?

So ive read in some forums and ppl saying that a Sprocket conversion can give the wrong readings in speedometer, and total mileage. But does it also give an inaccurate fuel mileage reading? ive been wondering about this becuz my gas light indicator seems to go up fast. On a full tank, after 2 days of daily commuting (within richmond) and one ride back n forth from richmond to vancouver (just went to bayside performance) my light goes up already.
I never really tried running the bike till empty and seeing how far that gas will get me since i dont wanna get stuck in the middle of the street.

I cant exactly tell what conversion my sprockets are (although kevin from bayside said its a mission tuned sprockets, something about a really huge rear sprocket and a really small front sprocket that increases bottom-end)

2.

3. If the sender for your speedometer is driven by the gearbox (or sprocket) then a sprocket/s change will make the speed and fuel consumption figures incorrect. If you know what the original sprockets were (# of teeth) and what the new sprockets are (# of teeth), it's simple math 101 to work out the error.

4. Here's how to calculate the discrepency:
For Example on my TL
OEM combination 17/38 = ratio of 2.235
New combination 17/42 = ratio of 2.470
2.470 divided by 2.235 = 1.105
So your speedo and odometer will be approximately 11&#37; off.
Your speedo speed at 55 is actually 49
speedo at 200 is actually only 178

5. One word: Speedohealer. They work great.

6. Originally Posted by Mechanic
If the sender for your speedometer is driven by the gearbox (or sprocket) then a sprocket/s change will make the speed and fuel consumption figures incorrect. If you know what the original sprockets were (# of teeth) and what the new sprockets are (# of teeth), it's simple math 101 to work out the error.

So technically my gas mileage right now might be saying low when in fact i could still have plenty of gas? my concern is whether my gas is telling me im actually low or not.

7. Originally Posted by Haymura
So technically my gas mileage right now might be saying low when in fact i could still have plenty of gas? my concern is whether my gas is telling me im actually low or not.
Tell me what you did!
Most of the folks on here, who make a change, go to a larger rear sprocket. That means the engine is turning faster than designed for any given road speed.
So in the example given by Shovelhead the onboard “computer” thinks you’ve covered a greater distance than you really have, so it will be showing you better fuel mileage than you’re actually getting.
This is a somewhat simplistic answer and you really need to identify the changes you made.

Just watch your fuel level guage so you don't run out.

8. i wish i could tell u wat conversion i did. unfortunately i dont know. i just bought it from someone and it came like that already I was just told by Kevin from Bayside that my sprockets have been changed to a mission-tuned one. it seems like its killing my sprocket n chains though cuz my chain is making a really loud "chunking" sound and i have a slack and tight spots on my chain. tight ones being really tight with almost less than half an inch of play and the slack ones actually hit the swingarm and this is after i got the chain adjusted at Modernmotorcycling. I know its weird....
I tried to check my chain today and noticed some metal shaving particles which worries me cuz i might be killing my sprockets already or the chain itself. but thats another concern...

9. Mission gearing would probably be up 4 or 5 on the back I guess, and maybe one down on the front? It would suck for highway riding anyway.

10. Originally Posted by SkydiveSonic
One word: Speedohealer. They work great.
I need to get one installed. I'm running -1/+2 right now.

for every 100km my trip adds an extra 10.

11. Even with stock gearing, that statement could be not that far off.

12. Hey,

with my 2003 R6 with -1/+2 gearing my speedo was off by 13.7%. At 85km/h my speedo would be reading 100km/h. Bought a speedo healer and went on the freeway with a GPS to figure out the difference. I took the average over several different speeds to get 13.7%

Programmed it and now the speedo is bang on. At least compared to the GPS unit.

Matt

13. If yer worried about runnin outta gas...open the cap and look...Not that hard

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•