rpm's at 55 mph speedo wrong 1982 XJ750

Can any body tell me about what should be RPM's at 55 or 60. Mine at 5000 rpm is reading 45 mph and I know that is wrong in 5th gear feels more like 65 or 70. I need to check cables and speedo gear to make sure it is good. Thanks
Andy

 

Andy,

What bike? The gear ration in 4th gear for the 750 seca is like 9.9xx to 1

*EDIT* I "think" at 5k rpms in 5th should be ~70mph (flat surface). Dont quote me on that though.

"Yes officer, Ass.Fault told me that I would only be going THIS fast at this Rpm. Dont write me a ticket!!!" :lol:

 

According to my GPS, my speedo is always about 5-7 mph slow. At 70, which is really 75, I'm doing around 5.5k

 

another thread said that spiders crawl around inside the gauges, leaving web as they go, interferes sometimes. Just a thought.

 

dang nasty bugs

 

I had a spider build a nest in my neutral light lens. I was much brighter after she was evicted.

GPS is a great way to confirm speedo readings. I have tried this on a few vehicles. Sometimes the mechanical speedo is quite poorly calibrated.

 

Sorry It is a 1982 XJ750 Maxim. With one piece guage set. I just bought it for wife and at 45 mph tach is at 5k rpms. It feels like 65 or 70 mph. Are these guages hard to take apart. Needle does not jump around like cable is bad. Thanks

 

On my '81 XJ650, the tach reads 4250 at 55 Mph. Same on wife's '82 XJ650.

 

Andy,

I think the gear ration is .812:1 for 5th gear. That 45 mph does not sound right unless you ar on a steep incline.
I would verify to make sure an accurate reading(Like riding next to someone else and see if there are any diffrences)
If your truely off then you have a couple of options.
Attempt to repair, search the forums for simmilar topics and you should be able to accoplish the task.
Or just but a known-to-be-well cluster and just change them out.
Ebay is a treasure chest sometimes.