tach off by 500 rpm

[grego]

hi all
well after installing the tach about 7 months ago its been driving me crazy that its 500 rpm higher then everybody elses in the world. instead of 1000 rpm per 10 miles an hour its 1500. so at 65 mph it reads 7000 rpm. is 7000 rpm to high for riding down the freeway or am i worried for no reason ?
the questions in my mind are
1. is there a bike mod that would do this ?
2. is the clutch slipping ?
3. is the tach off by 500 rpm ?

was wondering if this tach would work on the gz to answer question #3. could install it to see if the tach is off or if its something else.

http://www.ebay.com/itm/Hour-Meter-Tach ... 561wt_1150 (http://www.ebay.com/itm/Hour-Meter-Tach-Tachometer-for-Harley-Custom-Kawasaki-Suzuki-Motorcycle-Bikes-/230769935749?pt=Motorcycles_Parts_Accessories&hash=item35baf5c585&vxp=mtr#ht_2561wt_1150)

[Water Warrior 2]

Does your bike have stock sprockets? A change in the number of teeth on either sprocket could be the answer.

[grego]

hi all
i purchased the tach in the above thread. to my amazement it is inductive....4 wraps around the spark plug wire. well static test just changing rpm's and comparing the analog tach with this digital one, they read just about the same. the digital tach isn't as fast as the analog one. so i can assume that the tach is not off by 500 rpm... i checked the sprocket and its a 15 tooth sprocket. i didn't check the rear socket.... so now the 500 rpm difference between me and the rest of the world is still a mystery. any idea"s ??? anybody..

safe biking

[jonathan180iq]

It may very well be just the inaccuracy of having the wiring wrapped instead of straight wired into the coil.
All of the tachs that were recommended in the How-To guide involve making a splice into the hot wire of the coil.

I don't really know man. Are you running a non-standard front or rear tire?

[grego]

hi all

i checked the sprockets as water warrior suggested. the front is a 15 and the rear is a 41-250 which are the standard sprockets. the tires are standard , so the mystery continues. if the bike will run all day at 65 which equates to 6500 rpm for the rest of the world , will it in my case hurt it to run at 7000 rpm all day ?

any idea's as to why i'm 500 rpm higher then the rest of the world ??

ride safe

grego

[mrlmd1]

How much do you weigh? Lots of wind? Windshield? A lot of things go into translating engine rpm and speed over the ground.

[grego]

HI MRLMD1

have a windshield and weight about 175 lbs. what bugs me is what would make my bike run 500 rpm higher then the rest of the world......when others have windshields,saddle bags and weight as much as i do.

ride safe

grego

[alantf]

what would make my bike run 500 rpm higher then the rest of the world

Slipping clutch?

[dentheman]

Is it accurate at idle in neutral, but not when riding at speed? This could confirm if the problem is the tach or the clutch.

After reading through your posts it appears you have two tachs that both read high, suggesting the clutch is slipping. I guess one way of checking this is to get to cruising speed, then close the throttle to see if the tach drops to match your coasting speed, or even reads low. This would mean the clutch is slipping. If you can do this on a down-hill so as to maintain a fairly constant coasting speed with the throttle closed it would make the comparison easier.

[mrlmd1]

If the clutch were slipping you would hear that and feel it. Doubtful that's a problem. And your gas mileage and performance would suffer a lot.
You are only looking at about a 7% difference at 65mph from theoretical and what you are measuring. It's not 1500 rpm/10 mph, it's 1070rpm/10mph - your math is incorrect. I would say you are searching for a problem which doesn't exist and is a characteristic of your bike. I'm not sure everyone else in the world gets exaactly 6500rpm at 65 mph.
If your bike rides and runs fine and mileage is OK, performance is OK, leave it alone and disregard or get rid of the tach so you don't look at it. There was nothing wrong with the bike before you had to put that on, and there is nothing wrong with the bike now. You don't like the numbers. don't look at them. Or run some carb cleaner through the gas, check your tires pressures, make sure your brakes aren't slightly grabbing.

[Water Warrior 2]

Brilliant deduction Watson. Your seems to have picked up what everyone else missed. And of course the usual 7% discrepancy most bikes are famous for.

[mrlmd1]

Thanks. Anytime.
No sense in worrying about things that are so insignificant as to be almost useless, except if you like to worry.

[grego]

mrlmd1
thanks for the enlightenment....the root of all of this is my question about being able to run at 7000 rpm for a long period of time without having the engine come apart. the way i understand it 6500 rpm is the sweet spot and running at higher rpm for long periods will shorten the engine life. am i out in left field on this as well ??

thanks

ride safe

grego

[blaine]

You are right,6500 is the sweet spot. :) :cool:

[mrlmd1]

7000 rpm for a while won't kill your engine, but just remember, wear on everything, every type of motor increases with rpm and load and the total revs the engine has done.
With proper maintenance, oil changes, valve adjustments, etc, your bike will be fine, But any bike run at 55 will outlast any other run at 75, all other factors being equal. Go by how your bike feels and sounds, don't try to kill it.