How do I tell the twist rate on my tachometer

IAMBLAMB

IAMBLAMB

Been Around the Block
I am about to place a fairly comprehensive order with DTT, since I don't want to pay shipping multiple times, I'd like to get it right when I order it now. Can anyone tell me what the twist rate is for the tachometer on a 1982 suzuki gs550L? If not, can anyone tell me how to find out what it has on it. I assume my options are 1:5 or 1:4 but I don't really know what those numbers have a bearing on. Can anyone school me on this? Thanks in advance!
 
You talking about the speedometer or the tachometer? For a tach, I was under the understanding that as long as its run off the same source it will read the same. I was going to use my CB350 tach on my MB5 until I realized that the CB gets its reading from the cam shaft and the MB5 the crank. It would have read double.

At least this is my understanding of a cable actuated gauge, but not sure if its 100% correct or not.
 
Deacon, it depends on the gear ratio of the gear that runs the tach, so it varies.

You can just google your bike with " tach gear ratio" and you should find it somewhere
 
I stand to be corrected but I thought most jap bikes were 1:4 and brit bikes 1:5
 
You can jack the front end up and turn the wheel and see how many times you turn it and how it corresponds to the tach cable turning.
 
SONICJK said:
You can jack the front end up and turn the wheel and see how many times you turn it and how it corresponds to the tach cable turning.
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But then you throw the trans gear reduction ratio into the equation... Would it not be better to remove the timing cover and rotate the engine one revolution and see what the tach drive does?
 
Hoosier Daddy said:
But then you throw the trans gear reduction ratio into the equation... Would it not be better to remove the timing cover and rotate the engine one revolution and see what the tach drive does?
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Yup ;)
I was thinking speedo gear for some stupid reason haha
 
SONICJK said:
Yup ;)
I was thinking speedo gear for some stupid reason haha
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Pffft, and I was thinking you said REAR wheel, otherwise I would have caught on that you were thinking speedometer... we are both whacked :eek:
 
Do the ton has customer service? I just ordered the 1:4 since that's what I thought and it seemed that you guys agree. I asked some city cycles and the guy told me he, "didn't have access to info for that bike.". Which is whatever, I an just going to wing it.
 
put a piece of duct tape on driven end of cable, spin wheel 10 turns and count revolutions of your piece of tape then divide to find ratio
 
650hardtail said:
put a piece of duct tape on driven end of cable, spin wheel 10 turns and count revolutions of your piece of tape then divide to find ratio
Click to expand...

er, i thought the tach was gear driven and had little to no bearing on what the wheels were doing.
 
For that to work you'd need a 1:1 gear in the transmission and you'd need to be in it.

Hoosier's suggestion earlier is the easiest way. Turn the alternator rotor with a. Wrench and count the turns in the tach cAble
 
SONICJK said:
Hoosier's suggestion earlier is the easiest way. Turn the alternator rotor with a. Wrench and count the turns in the tach cAble
Click to expand...

Even a blind squirrel finds a nut once in a while....
 
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