Sun Super Tach II

Now I know there is a whole section on connecting up a Tach but bear with me. I purchased a Sun Super Tach II (2 1/8 diameter for $15.00) and want to use it on my 2006 RSV. Now my question is this, I believe the Tach as it is will not work correctly on the bike as it will only read from the 1 coil it is connected to there by when it says 1,000 RPM the motor is really doing 4,000 RPM. What I need to know is the RSV considered a single fire setup because of the 4 individual coils?

Now I found this info on building an adapter for mutli coil setup (picture attached). I priced out the diodes and they are around .02 cents each (in a lot of 100) and the resistors I figure can't be much more and a small box to put them in less then $5.00. My question here is will this work on the bike as a single fire adapter if there are 4 setups made and each connected as shown in the picture to the coils with the Tach set to the 4 cylinders setting.

I have water proofed the Tach to the point of it floats but would be better off saying it's more water resistant not water proof. When I get this done I'll upload a PDF on how I made the Tach water resistant (a few O rings), fixed the mounting, and got it all to work.

It seems to me that even though we have 4 coils, there is a waste spark on every revolution. I say this because I expected the same problem you describe when I first tested a tach, but one designed for a twin engine works fine when connected to one of our coils. Because of this, I suspect that if you make the shown adapter and just bridge two coils instead of all four it may work fine. That assumes, of course, that your tach has a setting for a 4-cyl engine.

Goose

BTW - where did you find the info on the adapter? Picture looks like it is on paper instead of electronic file (unless you just printed it out). Can you post a more detailed scan? Never mind, I found the pdf here:

http://www.gadgetjq.com/Tach_Adapter.pdf

I found the info here after a bunch of Google searches

http://www.motorcycle-journal.com/forum/marauder-m50-secret-hideaway/36171-tachometer-solutions.html

I looked at the wiring diagram for the RSV and there is 1 lead comming from the crank trigger to the control box and from the box there is 1 lead to each coil. So I guess my next question would be if there is a wasted spark do they wasted on all coils at once (I wouldn't think so) or would it be something like fire on 1 waste on 2, fire on 3 waste 4, fire on 2 waste on 1, fire on 4 waste on 3. If this is true then the connections that "should" work would be on coils 1 and 2 or 3 and 4.

Thing do get confusing.....

The engine fires at top of Compression stroke. The waste fire is 180 degrees camshaft (360 crankshaft degrees) off at the top of the exhaust stroke. It is because motorcycle ignitions are crank mounted versus cam driven as most cars. On my old CM400 twin, I believe one cylinders fires hot and other cylinder fires waste at same time (only one coil)

Ok I have all good new on this. To recap I bought a Sunpro Sun Super Tach II CP7906 from EBay for around $15.00. Now I looked around asked questions even sent an email to Sun asking if this could be used on my bike (06 RSV) they said no. Well I went ahead and found what I thought I would need to get it working and well to keep it short,

1) Purchased the tach and set the tach to the 4 cyl setting.

2) Cut the foot off the tachs mounting bracket (hacksaw).

3) Home Depot bought a piece of 1½ x 1½ angle aluminum and cut a piece as wide as the tach mount about 1½” wide (hacksaw).

4) Cut one side of the alum (hacksaw) to match the lower portion of the tach mount and using 2 8-32 stainless screws and nylon locking nuts attached them together.

5) Check all screws and nuts for proper clearance before or as doing this part because a mistake here you will have to purchase another reservoir cover. Mount the aluminum to the front brake reservoir cover with 2 10-32 stainless screws and nuts, do not use nylon locking nuts but use standard nuts with washers (I put a "O" ring around each screw unnder the washer but found it was not necessary) with locktite you will see why when you go to mount it. Check all for proper clearance by doing a dry fit.

6) Take it all apart and paint the aluminum and the tach bracket semi glossy black, 2 coats. Now with the wires you will need to buy some wire wrap because the piece supplied is not long enough to hide the wires from where you mount the tach to the coils.

7) Go to the auto parts store and buy some black RTV silicone and use it to fill / seal all openings on the back of the tach then put a small bead around the mounting plate before you attach it. Now after you have everything set the way you want it fill the back of the attachment screw with the RTV, I went slowly here first making a flat washer plug out of a thin piece of cardboard and putting it in the hole then filling the hole with RTV. I also put an "O" ring (2.5”) around the back of the bezel of the tach and super glued it in place. I also removed the redline marker and put an "O" ring (2.5”) in there between the bezel and the lens and when I was done it floated in a bucket of water, I would call that water resistant.

8) Now for the hookups, all the wires are long enough to reach from the mount down through the current holders on the handlebar through the frame cover back towards the coil on the right hand side. The beauty here, connect both the red and the white (night light) wires from the tack to the lead on the coil that has the larger lug (on mine it is the bottom lug) the green wire goes to the smaller lug (on mine the top lug) the black I attached it to one of the mounting screws for the coil. Now as far as how I connected it I made a few small “Y” connectors which allowed me to leave the original wires intact and still get my connections. These were straight up connections nothing other then just set the tach to 4 cyl and your set.

So for a total cost of around $25.00 and a little work I have a working tach. Now I have yet to “road test” it but letting the bike run for around 20 minutes revving the engine now and then it was rock solid no bouncing around and when I made small idle adjustments they were reflected in that tach as such. I also noticed that Sun has a chrome version of this tach for a few extra bucks but the way I look at it for the cost of the tach and $10.00 you can’t go wrong. I did find one place on line that sells the black tubing for running the wires through http://www.davebarton.com/blackvinyl.html

Did you have to make a connection to Both coil #1 and #2 to get the correct RPM reading

I didn't BUT (there is always a "but") I have noticed that it will after a while "bounce" the needle on the tach and it's not all the time. The needle will bounce around +-300 rpm when this happens, it's not so bad as to make it impossible to read but more an annoyance then anything else. Driving around town staying under 55 and even under acceleration it will remain steady with no fluctuations but once on the highway and up to cruising speed it will fluctuate and not all the time. It's something I can live with for now but will more then likely fix by next season by adding the wasted spark type of connection. I would recommend that if you're going to do this connect the wasted spark method and save yourself the trouble of having to take it all apart to do it anyways. BTW it works great and I have not had one issue with it yet and this is after around 1200 miles and it has gone though the pressure washer at the car wash a few times already. Now if only the rain would stop and I could get out and do some more riding....

I was out this past weekend and I paid close attention to the tach. I noticed that the "bounce" is not from the wasted spark but from vibration / bumps in the road. The bouncing of the needle is like I said no more than +- 300 rpm when it does do it and it stops in a reasonable amount of time say a few seconds.

if i understand - you installed the tach, set to 4 cyl, without building the adapter you mentioned in your first post - if so - it seems like such a simple solution :-)

if i understand - you installed the tach, set to 4 cyl, without building the adapter you mentioned in your first post - if so - it seems like such a simple solution :-)

Something is still wrong here - a four cylinder engine has to turn two full revolutions to fire all four spark plugs once (so it fires an average of two times per revolution). Our bike has four coils, so each one would ordinarily act like a single cylinder engine, meaning that the engine would have to turn two full revolution to fire one time (an average of 1/2 time per revolution). However, all indications are that our bike has a waste spark, meaning it fires each coil once every time the piston reaches TDC, but that would STILL only be one fire per revolution, or half that of a 4-cyl car with a distributor.

Motorcycle tachs that work correctly on the RSV are designed for bikes that fire an average of one time per revolution (such as a Harley with a stock dual-fire ignition), so there is no way a car tach set on 4-cyl should read the correct RPM if it is connected to just one coil.

The only point to this post is just to warn others to not go jumping to the conclusion that a car tach set on 4-cyl is going to work on an RSV - there is still something missing here. I actually have an old shop tach that has both a 2-cyl and 4-cyl setting - I'll see if I can hook that up to the RSV and compare the reading with my Drag Specialties tach.

Goose

OK, now I am certain, you CANNOT take a normal car tach for a four cylinder engine and get correct reading on an RSV if it is simply connected to one coil.

I just took my shop tach and clipped it on the coil for #3: set to 4 cylinders, the reading is just 1/2 of reality. Set to 2 cylinders it read the same as my Drag Specialties tach. I have NO doubts the Drag Specialties tach is correct; because, I have compared it with my computer, AND I have watched as my rev limiter hit right on que at 6,500.

Goose

Ok just to show this does work with this tach if someone(s) wants to come over to my house and I'll supply the beers and dogs take the tank off and have anyone check it out. I'm not upset by this just want to show that this does work with this tach and even I was suprised because after sending an email to SUN asking about an adapter for the wasted spark issue and was told by them the tach won't work without one. The only issue I am having with it is at highway speed sometimes and I mean sometimes the needle will bounce around 300 rpm on rough roads and I attribute this to the sensitivity of the needle on the tach itself. I have done nothing other than connect the tach to 1 coil (the one on the right side under the tank) as discribed here and I also used the power side of the coil to power the tach and ground is to the frame using one of the bolts that mount the coil. I live in Holbrook MA so let me know I will be around all weekend if you any of guys want to make a ride over. The following weekend weather willing I'll be riding to Medina NY for a 4 day weekend.

So, just out of curiosity, what does your tach read at the point your rev limiter kicks in? That would pretty much tell us whether it is accurate or not.

Joe

I'll check tonight and let you know.

Ok I pulled the gas tank and made a short video which I uploaded to you tube. Now at the start of the video I show the connections with the green wire from the tach harness to the white OEM coil wire and back to the trigger connection on the coil with the green wire. The power for the tach and the back light for the tach attach to the hot or + side and then is connected to the coil + terminal and the ground connected to a bolt that holds the coil in place. All the engine revving is done in natural and when the tach hits around 3200 rpm you can see the interrupter hitting and once at that point the tach does go nuts but before that it does hold fairly steady and I will admint this shows it to be a lot worse then when it is under load on the road. All connections to the coil were done using "Y" harness setups and yes the fuse is in the worst place it can be and I will be switching it around later this year.

[ame=http://www.youtube.com/watch?v=W_JFxtFy66o]YouTube - Yamaha Venture 06 Sun Super Tach II[/ame]

Gee, I hate to tell you this, but your tach is reading 1/2 the real RPM, just like I said.

If you were really idling at 500, it would be barely running. And that bouncing around 3,200? It is the rev limiter at 6,500. You are lucky that bike has a rev limiter, or you would have smoked that engine trying to see some decent RPMs.

Goose

Ok I am now begining to see what your saying. The tach is reading 50% of the true RPM and if I connect it up using the wasted spark method it will read correctly? Now on another note why don't I see the needle bounce I keep hearing about?

Ok I am now begining to see what your saying. The tach is reading 50% of the true RPM and if I connect it up using the wasted spark method it will read correctly? Now on another note why don't I see the needle bounce I keep hearing about?

I really have no idea what you are talking about. YOU are the one that said you had a needle bounce at 3,200, right? What else are you hearing about?

As for the correct connection, the "wasted spark method" does not make any sense. Let me try to explain from the beginning, again.

On our bike, with four coils, each coil only NEEDS to fire one time in TWO revolutions. But if that was what it was doing, your tach would only be reading 1/4 of the real RPM. But through some quirk of design, they have it putting out an unneeded spark at TDC on the exhaust stroke - that is the "waste spark". But because it does have this waste spark, your tach is reading 1/2 real RPM instead of 1/4. But to get it to read REAL RPM, you need to either be able to feed the tach the spark pulses from TWO coils at once, or double the number of pulses from one coil.

Your options for this are to make the adapter we talked about in the first two posts of this thread, or buy a commercial single-fire adapter.

Goose

Ok I have a set made up and I'll try to get then in this weekend and go from there. I am sorry I came across wrong and I do appreciate the help.

Ok here is the corrected install

[ame=http://www.youtube.com/watch?v=swCsJd9x6Qk]YouTube - Yamaha Venture 06 Sun Super Tach II Part 2[/ame]

I used the diode and resistor medthod and it works just as V7Goose said it should be and I do thank him for the assistance in correcting this. I ended up connecting the Tach to both of the front coils on the righ side of the bike.

You got it now Brother! Makes ya feel good dont it?

Went out for a ride for around 3 hours today no issues and I honestly do not know why I thought it was right to start with, I won't go into how many motors I have rebuilt (bored, blueprinted, balance, decked, hand ported and polished) setup and installed. Anyways thanks for the help and pointing me in the right direction and yes a good slap in the back of the head is needed now and then.