What tachometer are you dudes using? The manual says to hook up a tach for this, is the one on the dash not sensitive enough for reading increments of 50 RPM?

 

Excellent question that I was about to ask and then found myself coming home with a Velleman DVM205AM multimeter the other week.
Got it for $60 from Fry's Electronics and is the only one that I have found recently that can read two cylinders specifically. However the setup for using this multimeter tachometer requires connecting to the "points" - for the ignition. I don't know about this stuff, but do know that this won't work for our electronic ignition systems. Beyond that, this Velleman does read to an accuracy of 10RPM's.
But I gave it a shot in coming home with it and hope to find a way to get a signal from somewhere in the electrical going to the guage cluster tach' on the bike and getting a reading - hopefully a legitimate one.
Like I said, I don't know about this stuff and I've found it really hard to find a tach' for us twins to use when setting the pilot mixture screws. There's no way I'd spend $350 on a Fluke unit or whatever and only use it a few times in my life.
All in all however, what we're looking for is a clamp on inductor style multimeter tach'. I have yet to get ahold of anyone to see if there is an inductor clamp assessory for my multimeter - but I hope my notes help.
Anyone elses notes are greatly appreciated.

 

I've got the Motogadget, a Tacho made in Berlin. This one can read the increments of 10RPM. It not a matter of Honda, but of the tacho... It's counted by the ignitions of a spark per crankshaft rotation. 2 in our case. Then the tacho switches it into 1240-1270 RPM depending in neutral gear.

Very good one, but for 450€ not too cheap...

Got no pics ready, and my bike is messed up right now...

 

I have hear that you double or half the measurements for a four cylinder reading, but I have a feeling thats a crock o' you-know-what...

 

I'd be surprised if anyone uses the procedure set out at page 5-21 of the manual to adjust the pilot screws. If you're fortunate enough to be able to get an adjustment tool on the screws, you just turn them until you get the highest idle speed on one cylinder, reset the throttle stop screw to 1200 rpms, adjust the other pilot screw until you get the highest idle speed and reset the throttle stop screw to 1200 rpms, check that the carbs are synch'd and go for a ride. If you are concerned about emissions, take it to a shop with an exhaust gas analyzer.

 

This is very hard to do with accuracy, but you've basically described the procedure correctly, except you forgot the part where you richen the mixture a bit (a quarter turn) after establishing the highest RPM.

Anyway, cheap tacs can be had for about 35 bucks at auto parts outlets.
http://base.google.com/base/a/313464...20250138115733

 

supermarto
Senior Member
Back Marker



Join Date: Aug 2007
Location: Tarpon Springs, FL
Posts: 114



"I have hear that you double or half the measurements for a four cylinder reading, but I have a feeling thats a crock o' you-know-what..."


No, it's true. That's why there are manual settings on the multimeter for 2/4/6/8 cylinders. -Was another note that I was going to hand off to you - If you came across a multi'tach' that did four cylinders for example, you'd have do divide the reading by two. But since we're looking for a resolution preferable to 10RPM's so we can get an accurate 50RPM measurement, working with anything other than a true two cylinder multi'tach' is a bit of a pain.
Finally, this link to the analog tach' looks similar to the one Crasftsman puts out. Double check to see that it can read two cylinders and more importantly that what ever you come home with - make sure it's an inductive type multi'tach' (Where a clamp goes over the spark plug wire and detects the pulses of the ignition and then gives you an RPM reading based off of the timing of that signal in the spark plug line.).

 

The number of cylinders IS important for the tach, it's like spaz' said. You must configure your tach to the engine. It's also a matter if you have one spark per cylinder or two. BMW for example. These are even more complicated. So be glad to have a V2...

And if you can't configure the Tach, you'll have some probs fixing it to the hawk...

 

I know it is important, let me clarify: that's why I was saying NOT to use a tach set up for four cylinders, you must use one for a two cylinder. And I am still getting conflicting reports on whether or not the measurement is doubled or halved for a four cyl. tach.

 

4 cyl, 4 signals per engine revolution... 2 cyl, 2 signals... Ie you need to double the signals if you wan't to use a 4 cyl tach on a 2 cyl bike...

Now that's the reason for my problems fitting a CBR tacho... reducing a frequency is easy in electronics... I can do that with my eyes closed... the opposite is hard... and even harder to do without introducing errors...

 

That's what I thought...

 

Heh... just so we don't confuse anyone... double the signals means double the tacho output... If you hook up a 4 cyl tacho to an VTR it's going to read 1000rpm's at 2000...

 

Hmmm - since these are four stroke engines, and only fire every other revolution each cylinder and on opposing cyles; it makes sense to me that a two cylinder engine (other than possibly an older ignition Harley) will fire once per revolution(front, rear, front, rear, repeat). Most late model tachs are calibrated to read 4 strokes, I used to have a handheld tach that had a switch for 2 stroke vs 4 stroke.
Additionally they now make simple tachs that use inductive pickups and there is no number of cylinders config needed - just clip it to a plug wire. It assumes a 4 stroke and counts the number of plug fires per minute and multiplies by two.

 

Well, if you got a tach with this option, you won't have this problem, right. But in case of Tweety with his CBR1000 tacho this one won't help. My Motogadget tacho gets it's signals from the front brake disk bolts. So it doesn't care about cylinders AND gearings. It's always right. And the RPM signal is only one wire...

@ Tweety: If you're so good in electronics, isn't it possible to switch the electronicS of the VTR tach into the dash case of the CBR1000RR? Then you wouldn't have this problem. Just a thought...

 

Well.. I'm good at the stuff yea... but this field isn't really my expertize (I work with GSM stuff mainly radio frequencies)

the reason that won't work is that the CBR1000RR dash has only one circuit board in that box... all integrated... so replacing parts of it won't work, and it needs parts of the circuit to drive the LCD's and such...

If it was the other way... 4 cyl to a 2 cyl tacho it would take me about 2 minutes to solder up the circuit to reduce the signal by two... Unfortunately it's a bit harder to increase the freqency of a signal without garbling the signal...

It possible alright... but I don't know how, unless using rather expensive and sensitive curcuitry... the type that don't like 12V bike electronics... Higgens on the other hand then has obviously found a way to do it that works... (and is about half the price of the circuit I figured out)

 

Hmm, ok then, well it was just a thought. Sometimes it helps to change the point of view, know what I mean... We have a Thread in the german Forum, where the mount and wiring of this dash were described, wait a minute and I'll do some search...

 

Ha! Finally got it!

http://www.vtr1000.de/forum/showthre...ighlight=tacho

The topic was about the SP1, but it soon turned to the Firestorm. And it's in german, of course. If you have any questions about it specifically just PM me...