CBR_TONY
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| posted on 22/6/04 at 08:10 PM |
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Tacho Problem
Hi,
I've got a CBR1000 powered BEC and have a problem with rev counter (a RacePro Gauge). It only rev's to 3000 before dropping back to idle!!
It is wired to the tacho signal wire from CDI so can't figure it out....any ideas?
Tony
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Jon Ison
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| posted on 22/6/04 at 08:22 PM |
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my 1st thought was have you set the "sparks per engine revolution" but i would guess that would make it read even higher due to wasted
spark system, so no, scratching me head.
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Bob C
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| posted on 22/6/04 at 08:22 PM |
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pure supposition here....... The tacho signal from the CDI box is probably a nice 12V square wave with 2 pulses per crankshaft revolution. Your
aftermarket tacho is expecting the signal from the ignition coil LT (this spoings up to 300V & twangs around a bit). So check the manual for the
tacho, you may need to connect it to the coil LT. Of course when you do this.... the bike engine probably uses wasted spark (or even a coil for each
plug) so the tacho will read 1/2 or 1/4 the real rpm. But the tachos normally have a trimming pot in that might let you adjust it right again (I was
able to make a 4pot tacho read right on a v8 this way) But they normally have the adjustment in the other direction for 6 or 8 cylinder engines.
Or you might have a dodgy connection somewhere........
good luck!
Bob C
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Jon Ison
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| posted on 22/6/04 at 08:24 PM |
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yup, for a car type tacho it would read lower even with wasted spark, good finking that man.
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CBR_TONY
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| posted on 22/6/04 at 08:51 PM |
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Thanks Guys,
will make a few more checks with regards to the coil set up and check with gauge manufacturer if it's compatible with the bike ignition system
although it displays 11,000rpm so you would expect it to!
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locoboy
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| posted on 23/6/04 at 12:30 PM |
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CBR_TONY you have U2U
ATB
Locoboy
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