Tach Question

[scott_sinky]

Can anyone tell me where the signal pick up for the tachometer is on an 84 Venture Royale? I'm having "issues" with the engine missing and choking off when operating at low RPMs. It misses at higher speeds as well when I try to "jump on the throttle". The problem seems to coincide with an erratic tach indication at low RPMs.

Thanks,

Scott

P.S. I replaced my Igniter Unit Assembly two weeks ago and everything was working great. Last weekend, while on a 200 mile ride it started acting up.

[Dano]

Scott, you could have a bad ground going onhere. There are 3 main grounds on the bike. THe main ground is right front on the engine (big heavy cable going up the right front frame tube. Second is on the left side of the bike under the fairing for the TCI box. 3rd is behind the light bucket for the instrument cluster, I believe.

Make sure your battery terminals are clean, battery charged up. THese bikes will run like cr*p if the voltage is low.

 

Dan

[mbrood]

The tach "pick-up" for the tach comes from the TCI module. It is triggered by the ignition pick-up for the number 2 cylinder.

 

The output of the TCI for that cyclinder also goes to the number 2 coil AND the fuel pump to act as a tickler trigger to keep the pump active (it's still pressure sensing so it doesn't run ALL the time, just on demand.).

 

If your tach is jumping, this is a CLASSIC sign that the TCI is acting up. Has it seen a heavy rain lately, or a pressure wash that may have got it wet? Have you pulled the two connectors on it and really cleaned and greased them?

[Gearhead]

Yup, I agree but would add the following. I've had the SAME symptom on my 87 Venture and also my 87 Virago (which has 1/2 of the same ignition system). In both cases it was bad connections in the wires from the pickup coils to the TCI box. On the Venture it was the connectors on the TCI itself, corroded from battery acid leakage. On the Virago, the wires coming out of the LH case cover were kinda flaky, bad insulation IIRC. There's another connector on the Venture behind the LH side cover, just aft of the engine. Actually, there are more than one connector, and they all should be cleaned and greased.

 

Jeremy

[scott_sinky]

Thanks for the great responses. I will give you a brief history to bring you up to date.

 

I’ve been trying to figure out a problem with my ‘84 XVZ12DL. Two weeks ago I replaced the ffice:smarttags" />TCI after having a local shop trouble shoot the carbs, generation, spark plugs and tune up before testing it with a different TCI, which we determined to be the problem. The bike ran great for a week then while on a 200 mile ride it started acting up. It would choke off when trying to take off at a low RPM. (under 1200) It is better in the morning when it is cool and gets worse as it warms up.

Today I checked and cleaned fuses and contacts,

cleaned all ignition and charging plug connectors,

tested stator coil leads – 0.9

tested stator coil leads – 0.9

[mbrood]

The pick-up coils get ground through the wiring when connected to the TCI (grounded inside the TCI).

 

Your resistance readings look fine. The ignition coils get 12 volts constantly on the "hot" side when the ignition switch is on and the other end goes to the TCI which temporarly grounds that coil when the pick-up coil triggers the TCI.

 

You also want the check if the pick-up coils (unplugged) show ANY reading from each coil to chassis ground (it should be an open). Any readings on the ignition coils to ground is probably reading through other items also tied to that "hot" line feeding all four.

 

The secondary side of the 3 ohm coils go through solid core ignition wire (basically zero resistance for all purposes) and goes into the stock plug cap which, if you look up inside is a retaining screw. Behind that is a small spring, a small copper thrust plate and then a small 10k resistor ... check these for any corrosion, clean as required. Get rid of ANY oil on the wires and caps. After quite a few years of running, most guys find a bit of "green" copper corrosion on the plug wire where it's screwed into the coils AND the plug caps... just cut 1/8" or so off and screw it back in. That green is NOT our friend.

 

The TCI will heat up a bit as you are running and there's two holes in the upper side of the case which prevents any pressure build up but is also a dandy spot for pressure washers or heavy rain to find a way inside, so a few guys have had to pull the unit and slow bake the unit in an oven at about 200 degrees to "bake out" the moisture. If you ever get yours out... the early units used funky gray and blue "ball shaped" power diodes aoround the finals near the two big connectors that tend to fail (8 total) and should be replaced with 1N4001 series diodes. And as with almost all the electronics on these beasts, if you can get to the circuit board, resolder the main connector pins.

[scott_sinky]

Well, I went through everything one more time. Checking, cleaning, testing. The main fuse (40 A next to the battery) was badly corroded and about half "eaten" through. I cleaned it up and replaced the filament. Thought I had found the problem. However, when I started it up the "dash" High beam indicator light was dim and it acted like their wasn't enough power (electricity) to keep it running. Then suddenly it jumped to idle at about 800 to 900 rpm and the lights were brighter. It ran like that for 20 seconds and dropped to a very low rpm and the lights went dim again. This happened several times. Then I shut it off. Obviously I haven't found the problem. It does still act electrical to me but I'm most definately not an expert. Could it be the voltage regulator?

This "project" is getting pretty disgusting!

Scott

[mbrood]

I would also suspect the fuse clips in the "main" fuse box are also weakened from age and corrosion and brittle... if you can, GENTLY ease each fuse out and "FEEL" how the clips feel as you do, they should have a fairly snug grip, these get a softer and softer grip over time as they get brittle and lose their "springyness". Now the clips need to be cleaned and dialectric grease applied. You also want to clean and grease the larger, white, three pin connector for the stator (behind the left side cover, 3/4 up the frame "up tube", with three white heavier wires). Also check for discolloration of the white housing which would show heat from corroded or loose pin/socket fit. Do the same for the regulator connector.

 

With the engine at about 2200 rpm, you should have 14.5 volts, coming from the regulator. Below about 1800 rpm the stator is putting out less and less voltage and the regulator drops out, causing the voltmeter to show that lower voltage as well.

 

With the side cover and false gas tank cover off as well as the fuse panel cover... turn the bike on and let it idle for a bit... then start gently wiggling/twisting connections looking for a "twitch" on the voltmeter... I would start at the stator connection, then the 6 pin (5 wire) regulator connector, move up to the fuse panel and gently "rock" each fuse in it's mount, then move on to the connections in front of the battery and don't forget the main battery wires. Trying to find a poor connection with this action REALLY likes two people... one to play around and one to just carefully watch the gauge... and yeah, a good digital volymeter makes the detection easier to watch.

[GeorgeS]

Check the Run Stop Switch on the Right Handlebar. Maby corroded Contacts, and high Resistance thru this switch, will lower the Voltage to the TCI and the Ignition Coils.

 

Give the Switch a Bath with electrical contact cleaner. Follow cable from switch, you will come to a Plug. Open plug, and check the Resistance thru the Switch.

 

 

Also, consider the " ON- OFF " Contacts of your Main Ignition Switch .

The contacts, may have gone High Resistance !!

[MasterGuns]

Scott, You never did say why you replaced the TCI in the first place. And was the replacement unit new or used? Common sense, at least to me anyway, dictates that you may still have a faulty TCI especially if you picked one off Ebay or from a parts bike. If it were me, I'd be seriously considering replacing the TCI again with another unit.

[Rocket]

I'd be seriously considering replacing the TCI again with another unit.

 

Check with DonB, he may still be testing / repairing them, as time permits .

[scott_sinky]

It is a used TCI and yes I have considered that it is faulty. I will be taking a look at the one I replaced. Again, thanks for your help. I'll check out these other areas too.

Scott

[mbrood]

For the high speed "hick-up"... I would REALLY check the carb diaphragms... first you would like to get your finger down into each carb throat... as it sits... and push back and release each plunger... they should slide smoothly back and come back with just a slight resistance as the vacuum bleeds but you should be able to hear each make a small "pop" as the slide comes to rest... look for any difference between the four.

 

Then pop them out and, holding them up to sunlight, check the rubber for pinholes or small tears (normally found around the outside, but...) It's a this fabric coated on both sides with a vitron rubber (I believe), very soft and very flexible... in ANY repair you don't want to mess with the flexiblity!

[KingSizer]

Just thought I'd share this bit of interesting info.

My tach DOES NOT MOVE when it's cold, usually on those cold mornings on the way to work. There is no change in the performance of the motor and everything else seems to be working fine, so it's not a major concern for me right now.

Just thought it was different though...

[mbrood]

Todd,

 

Since that signal also feeds the fuel pump and #2... you might just have a mechanical problem with the gauge or a crusty connection from the TCI... but you are right, if everything else is working... smile and twist the throttle.

 

I rebuilt a wrecked H1 Kawasaki and drove it for two years without a tach... nice bike... but then I got a tach and found out I was NEVER approaching it's power curve... yikes, that bike could scoot !

[scott_sinky]

Well, I've done everything I've read in your posts...and more, except for the TCI. Still can't find my problem. I will be sending my original TCI out for inspection and repairs if needed. That way I will be able to eliminate that from the equation. Thanks for your support.

Scott

[scott_sinky]

Just thought I would let you know that I have resolved my problem. After going through every connection and testing everything, I determined that I had two bad, used TCI units. I bought a new one from http://www.cheapcyclepartsonline.com/ (at an excellent price I might add), plugged it in and my '84 Venture is running beautifully. Another good thing about this problem is the other minor problems I discovered and repaired, thanks to the posts I found on VentureRider.com. Thanks to all. This is a great group!

Riding again,

Scott