Motorcycle Repair: digital speedos, gallon tanks, revtech


Question
I have a REVtech based softtail

I have fitted a diamond digital speedo and tach

Everything works - all warning lights etc tach - i have calibrated the speed ok etc but one problem cant seem to work why its doing it - it has jumped several thousand miles on the odometer

i have covered about 1500 miles on it since fitting the speedo and it is registered with 7754 miles on the speedo - i have switched to it when riding and goes up with the correct mileage i have not noticed when it has jumped but the trip meter goes up to the right mileage and does not jump???

any ideas - i am totally lost -other than this problem it works fine

can i ask one other question which again a bit lost on - i have split 6 gallon tanks on the bike
last two trips have notice the bike at one point splutter and run rough can seem to accelerate through it and runs ok - it starts ok and runs ok for a 50 miles etc before doing it - what do you think could be - plugs seem fine - nice healthy spark,color on plugs dead on nice color- could it be petrol from one tank  not coming through or any ideas if it was a coil would it not run rough all the time???

any help really appreciated

Answer
I have never heard of a speedo do what you describe, but I would contact the company and see if they will replace it with a new one.
Do a test on your coil, they can start to fail when they get hot.
Also, check your flow on the fuel from the tank to make sure you have good flow to the carb
Good luck and happy riding
Mike