How do you measure RPM's with out a tach?

[busa186]

My dad and I went in on a carbtune and we will need to adjust is idle after we are done but his bike does not have a tach. Now we can do it by ear, or buy a tach and install it, but his friend gave him a tool that you hook to a spark plug and to the coil? However, it does not get that great of reviews, seems to bounce around a lot (up to 400rpms). How would a shop adjust RPM's. (Probably on a dedicated machine).

Anyone adjust the idle with out a tach?

As always thanks for the help!

 

[rusheriv]

1. Bring engine up to operating temp (run about 10 minutes).
2. Turn idle adjustment screw out until engine starts to stumble.
3. Turn idle adjustment screw in 1/8 - 1/4 turn.
4. Engine should be idling smoothly, if not repeat step 3 until smooth idle is reached.

 

[busa186]

1. Bring engine up to operating temp (run about 10 minutes).
2. Turn idle adjustment screw out until engine starts to stumble.
3. Turn idle adjustment screw in 1/8 - 1/4 turn.
4. Engine should be idling smoothly, if not repeat step 3 until smooth idle is reached.

so kinda just by ear... thats what I told him but I think he is looking for a tool. I know he his going to want to set it 1100.25441 rpms

 

[Pardini]

My dad and I went in on a carbtune and we will need to adjust is idle after we are done but his bike does not have a tach. Now we can do it by ear, or buy a tach and install it, but his friend gave him a tool that you hook to a spark plug and to the coil? However, it does not get that great of reviews, seems to bounce around a lot (up to 400rpms). How would a shop adjust RPM's. (Probably on a dedicated machine).

Anyone adjust the idle with out a tach?

As always thanks for the help!

Go with the average of the high and low numbers. I wouldn't completely rule out the possibility the bike is idling rough either. Plugs, filter, fuel etc good? Vacuum leaks?

 

[dadofthree]

Busa's have a nice lope anyway

 

[busa186]

I found that out the hard way when the dealer said "I can fix that with a throttle sync" $140 later, still has pulse of the beast. Just bought the manometer and doing it myself. My dad has a royal star that we are about to sync but he has no tach so finding his rpm is challenging. We found a tool you clamp on but I think he will end up doing by ear.
Posted via Mobile Device

 

[Peregrine Falcon89]

Yut UGGGGGGGGGGGG

soon as it starts the UGG thats around 4k rpm. Ask any squid.

 

[dadofthree]

Tachometer Digital Handheld RPM Meter DTO6234N

 

[Ziggyman]

If you buy a good quality (priceyer) timing light, they come with a RPM display