Rear Sprocket (gearing question)
#1
Rear Sprocket (gearing question)
Hey there folks -
I have a 2009 KLX 250 S. It has a Dyonjet fit and FmF slip on.
At 100 km/her (60 mph) - the engine is spinning at 7000 +/-. I am a 200 lb rider.
Red line is 10,500 - not sure when the limiter kicks in.
I just got the bike, not sure of the sprockets (gearing) has ever been altered. Assuming it has not, can any one comment on going down a few teeth in the rear and if that will give any more top end on the highway ? Would that make first gear too tall for trails ?
I do like 70% road riding, 30% trail
rob
I have a 2009 KLX 250 S. It has a Dyonjet fit and FmF slip on.
At 100 km/her (60 mph) - the engine is spinning at 7000 +/-. I am a 200 lb rider.
Red line is 10,500 - not sure when the limiter kicks in.
I just got the bike, not sure of the sprockets (gearing) has ever been altered. Assuming it has not, can any one comment on going down a few teeth in the rear and if that will give any more top end on the highway ? Would that make first gear too tall for trails ?
I do like 70% road riding, 30% trail
rob
#2
Rob,
Stock gears are 14 up front and 42 rear.
The simplest and least expensive method is to change the front. One tooth up front is close to 3 on the rear. So a 15/42 setup would be very similar to a 14/39. This is a good way to experiment.
You may get more top end on the highway with a 15/42. Some riders do, but others say the bike just doesn't have the power needed to overcome wind resistance.
Based on looking at this: Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator
It sounds like your bike may not have stock 14/42 gearing if you're running 7K rpm at 60 mph.
Rev limiter should kick in at about 10.5K rpm.
Stock gears are 14 up front and 42 rear.
The simplest and least expensive method is to change the front. One tooth up front is close to 3 on the rear. So a 15/42 setup would be very similar to a 14/39. This is a good way to experiment.
You may get more top end on the highway with a 15/42. Some riders do, but others say the bike just doesn't have the power needed to overcome wind resistance.
Based on looking at this: Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator
It sounds like your bike may not have stock 14/42 gearing if you're running 7K rpm at 60 mph.
Rev limiter should kick in at about 10.5K rpm.
#4
Hey there folks -
I have a 2009 KLX 250 S. It has a Dyonjet fit and FmF slip on.
At 100 km/her (60 mph) - the engine is spinning at 7000 +/-. I am a 200 lb rider.
Red line is 10,500 - not sure when the limiter kicks in.
I just got the bike, not sure of the sprockets (gearing) has ever been altered. Assuming it has not, can any one comment on going down a few teeth in the rear and if that will give any more top end on the highway ? Would that make first gear too tall for trails ?
I do like 70% road riding, 30% trail
rob
I have a 2009 KLX 250 S. It has a Dyonjet fit and FmF slip on.
At 100 km/her (60 mph) - the engine is spinning at 7000 +/-. I am a 200 lb rider.
Red line is 10,500 - not sure when the limiter kicks in.
I just got the bike, not sure of the sprockets (gearing) has ever been altered. Assuming it has not, can any one comment on going down a few teeth in the rear and if that will give any more top end on the highway ? Would that make first gear too tall for trails ?
I do like 70% road riding, 30% trail
rob
Based on my gearing spreadsheet I made for my 09, the bike has had a gearing change.
Actual peak power is at 8200 rpm (it will rev higher) and with stock 14/42 gearing with a 26" OD tire (probably small to average OD, a Kenda 270 is 26") the speed should be around 67 mph calculated at 7000 rpm.
If you email me I can send you my Excel spreadsheet. You find the tire OD and plug it in along with the rpm and you have the calculated speed. It's a good way to know what is happening when you do changes.
You could go to a 15T front/42 or 43 rear for all your road riding. It should still do okay on mild trails. If you are going to go more off road a quick change to a 13T and a minor chain adjustment and you're ready to go. I ran deep sand with the 13/43 and didn't have any bogging problem.
#5
[QUOTE=robemac;512172
I have a 2009 KLX 250 S.
At 100 km/her (60 mph) - the engine is spinning at 7000 +/-. I am a 200 lb rider.
rob[/QUOTE]
Indicated or actual speed (GPS)? '09s usually show 10% high.
I have a 2009 KLX 250 S.
At 100 km/her (60 mph) - the engine is spinning at 7000 +/-. I am a 200 lb rider.
rob[/QUOTE]
Indicated or actual speed (GPS)? '09s usually show 10% high.
#6
As speedo indicates - tires are Kendas front almost like new, rear center tread getting worn
I see that the rear is 43 tooth. Not sure of front, but after plugging the data into the gearcommander thing, it seems to fit that there is a 13 on the front with the 43 rear - why change both from stock, who knows...that scenario gives 103 at 7 K which is about what speedo says
I see that the rear is 43 tooth. Not sure of front, but after plugging the data into the gearcommander thing, it seems to fit that there is a 13 on the front with the 43 rear - why change both from stock, who knows...that scenario gives 103 at 7 K which is about what speedo says
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