In the bike week my bike has dropped 5mph at 6100-6200 rpm. I used tp be able to run 61-62 at those rpms and now it runs around 55 56, any ideas on what it could be or where to look?

 

A slipping clutch?

 

i changed the oil and its still doing it. The bike has 9400 miles with heavy clutch usage

 

You should be able to tell your clutch is slipping. Take off in 1st and speed shift to 2nd, if the engine revs and you don't get thrown off the back, then your clutch is toast.

If you used non-motorcycle oil, drain it and throw the filter away, try motorcycle oil. Take it easy for a while to get the previous oil on the clutch diluted.

 

It's hotter out now? Less o2 molecules?

 

Shift from 5th to 6th gear?

But seriously, if you haven't changed any hardware (sprockets, tires), it would have to be a slipping clutch. Or an issue with the pickup for the speedometer?

 

If it ain't yer clutch, or the speedo, could it be yer tach?

 

When clutch is engaged the drive line is mechanically fixed from crank to back wheel. The speed, created by the rpm of the rear wheel, cannot drop unless the engine rpm drops. There has to be either slippage in the drive line or the rear wheel diameter is different. Mechanically speaking, the only way that registered speed can drop while rpm remains the same is if...

• The clutch is slipping, as others have said, and very likely.
• The back tire is really low on air pressure making the rolling tire diameter effectively smaller, so it has to spin faster to show the same speed on the speedo which is driven by the front tire. I don't know if it could get low enough to cause a 10% error.
• something in the speedo drive is failing. 06-07 have cable drive, 09-up have electronic drive. Not likely, but possible.

Easy to check the tire, and how to test the clutch has been given.

 

Speedo is fine per the gps. Shifting from 1 to 2 feels like blahhhhhhh

 

ive been using the same oil for over a year now