Wanted, Bad Venture Coils

Wanted: Old "Bad" Venture Coils I put a temporary sticky with this message in the General Tech area, but since I haven't heard from anyone, thought I'd give it a try here too. I was hoping some of those coils that folks have recently replaced might still be laying around! If you have one and are willing to part with it, I will happily pay for the shipping, or just ride to your place and pick it up! Thanx.

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I want to get my hands on old coils that anyone has taken off when suspecting them to be bad. Interested in coils from any models, but particularly 2nd gens. I have an old automotive oscilloscope that I want to use to try and identify what the "normal" cause of the failure is, and if there is anything we can do about it. In addition, I would like to see if I can devise some sort of test that anyone can use (without a scope or special tools) to accurately identify a bad coil.

If you have changed one or more and are just going to toss the old coils, will you please send them to me instead? PM me and I'll send you my address.

You can just slip one or more into a free Priority Mail flat-rate envelope (no weight limit) for $4.95. I'll gladly send you the $5 postage.

Thanx,

Goose

Kent, how would you know if you had a bad coil?

Kent, how would you know if you had a bad coil?

That's a good question, and unfortunately, there isn't a real simple answer That's why I would like to get my hands on some that have been replaced as bad, so I can run a variety of tests and try to develop a simple test that might work for whatever is causing those failures. But I'll try to answer your question as best I can now.

The biggest symptom from a bad coil is a major drop in both fuel mileage and power. But many other things can cause both those symptoms too! Even with a bad coil (or a completely disconnected plug wire), this engine runs very nicely up to around 85 miles an hour, where it runs out of steam on only three cylinders.

If you suspect you have a bad coil, the official way to test it is with a special tool that is inserted in the wire between the coil and the spark plug. This tool has a glass tube containing two contacts that can be moved closer or further apart, and the test is to ensure the spark is strong enough to jump across a specified minimum distance. But this test has two big problems - first, few owners have one! And even if you do have it, it cannot effectively diagnose problems that can develop in a coil from heat or load. Oftentimes a coil will test fine in the garage, but break down under hard running.

The other common way to test a coil is by using an ohm meter, but this suffers from the same weakness of being unable to show a problem under heat/load. In addition, it does nothing to test the high-tension wire between the coil and the spark plug.

An automotive scope (oscilloscope) is a MUCH more accurate test of the entire ignition system, but putting an scope on a motorcycle is generally very difficult, if not impossible (depending, of course, on the specific design of the tool and the bike).

Finally, a professional exhaust gas analyzer and a dyno can accurately diagnose the effectiveness of the entire combustion process in each cylinder under any conditions, but it can do nothing to identify the specific cause of any problems that it shows. That means it can easily tell you that you do NOT have a bad coil, but not that you do.

And one more comment on a very common failure that is not technically a bad coil - the plug wires. But it fits in this discussion because our coils and plug wires come together (terrible design, IMHO). Old plug wires break down, all of them. This affects the quality of the spark, even if the coil is still perfect. The most common problem is loss of spark energy through the insulation under high humidity or wet conditions. Generally start worrying about this any time the plug wires are somewhere around 8-10 years old. The obvious symptoms are hard starting and poor idle, especially noticeable if the bike is parked outside and covered with dew. The easiest way to test for this problem is to start your bike outside on a dark and stormy night! Or at least a dark one - you can simulate the storm by just using a spray bottle to mist around the wires. If there is any problem at all, you will see at least a blue aura around the wires, and often an obvious spark jumping from various places on the wire to the engine. This test is best done on a cold engine, since that is when the fuel mixture requires the most energy for the plug to spark.

Hope that helps more than it confuses,

Goose

I have to admit that I'm not familiar with the coils on the Venture. Is there 1 coil per cylinder or 1 coil per pair of cylinders?

Im wondering if there is another setup that will work on the Venture and that is easily serviceable with separate coils and wires.

Time to look at a parts schematic.

I have to admit that I'm not familiar with the coils on the Venture. Is there 1 coil per cylinder or 1 coil per pair of cylinders?

 

Im wondering if there is another setup that will work on the Venture and that is easily serviceable with separate coils and wires.

 

Time to look at a parts schematic.

There is one coil for each cylinder, but for simplicity of design, each coil fires twice during a full cycle of the engine. That second spark provides NO value to the engine, but it is what allows any tach that is designed for a twin cylinder, single coil bike to work on our bike.

I do not know for sure, but any coil with primary and secondary resistance close to the stock coil would probably work fine. The big unknown for me is the electronic ignition (the ignitor), since there could easily be things about that specific circuit that I don't understand. The other unknown for me is the nuances of the igniton system that are critical to correct functioning of a modern "lean-run, quick-fire" engine over the older stoichiometric designs.

Goose

I'm very interested in your results since I'm an old electronics nut from way back. That and I've never been able to figure out why this bike of mine is off just a bit in performance. I'm wondering if Freebird still has the coil he replaced. As you stated there is nothing more accurate than using the o-scope to analyze these to see exactly what is happening. I'd bet you could even control the temp of a coil and slowly heat one up to see if a suspect coil runs good cold then fails as it warms. That would be a neat test.

Next question: Where are the coils located and what does it take to replace them both cost and effort?

Next question: Where are the coils located and what does it take to replace them both cost and effort?

Well, #4 coil is right under the tank on the right side of the frame. Numbers 1&3 are mounted together under the battery - you can see them easily from the right side while the bike is on the side stand, not far in front of the lower shock mount. Never have looked for #2, but I'd bet it is somewhere under the tank, probably hidden by the wires on the left side of the frame. The coils are all different part numbers, but I'm not sure why - maybe different plug wire lengths? They cost about $55 each.

Goose

Kent, Send my your addy and I will

send you my know bad left rear coil

and I will want a full report sir!

That would be for cyl (1) Correct?

I will mail it out before the end of

this week. probably Tuesday.

Jeff

Found out here that they cost $79.00 at Yamaha..

And YES it is because of the wire lengths. the two

rears will be the longest one's. Also, you might want

to try and heat the coil up some how, do to the

fact that they will bench test fine I believe when cold.

The coil I am sending you will have 11,500 miles on it.

wire looks great and the cap looks great. I would like

to keep the cap , so send it back when finished when

you can.. no hurry.

Jeff

Found out here that they cost $79.00 at Yamaha..

 

And YES it is because of the wire lengths. the two

rears will be the longest one's. Also, you might want

to try and heat the coil up some how, do to the

fact that they will bench test fine I believe when cold.

The coil I am sending you will have 11,500 miles on it.

wire looks great and the cap looks great. I would like

to keep the cap , so send it back when finished when

you can.. no hurry.

Jeff

I'm betting South Seattle Yamaha Sports Plaza has them for less. http://www.yamahasportsplaza.com/

SKU: 4XY-82310-00-00

IGNITION COIL ASSY 1 $46.90

SKU: 4XY-82310-10-00

IGNITION COIL ASSY 1 $46.90

SKU: 4XY-82320-10-00

IGNITION COIL ASSY 1 $49.25

SKU: 4XY-82320-00-00

IGNITION COIL ASSY (backordered) 1 $49.25

I have a 99 Venture - I'm guessing it's a good idea to change these out if they have never been changed out?

Looks like you can get the (2) rears for $75.26

??

Not bad. I will be checking my front two coils this week as well!

Jeff

Juggler. My last 4 coils were $24.95 for a set @ Pinwall.

from a 2002... seem to be working fine so far. I would

love to be able to find a higher grade coil (replacement)

one day though.

Found out here that they cost $79.00 at Yamaha..

 

And YES it is because of the wire lengths. the two

rears will be the longest one's. Also, you might want

to try and heat the coil up some how, do to the

fact that they will bench test fine I believe when cold.

The coil I am sending you will have 11,500 miles on it.

wire looks great and the cap looks great. I would like

to keep the cap , so send it back when finished when

you can.. no hurry.

Jeff

PM sent with address Jeff - really appreciate your sending it! I'll be sure to send the cap back along with any good wire as soon as I can test it.

One of my goals is to find a simple way to replace the plug wires on a coil, so that fits right in too!

Goose

Juggler,

Just my opinion but I wouldn't change them unless one goes bad. These coils can last forever or fail at any time. Replacing them won't do a thing to change those odds. I've had one fail but it may never happen again.

coils do fail under high heat ,. on bikes, its the heat soak that kills them or a nice high pressure car wash ,. as a friend found out tonight dont drive them 23miles than go to washing.......the coils spaz and die......at 160 to 170 on the gague after a 49 mile drive stop the bike feel the heat.....with no air movment the coils get a very through baking so why shouldnt they die. if the engine fan could be on a 3min timer that would greatly cooldown under tank temps ! ! Im sure bosh has a relay type switch,. just have to find how to wire them in,. take a laszor temp reading after you ride next time just after shut down than two min later you will be surprized at the diff on a 85 deg day:178:

Kent,

I have a pair of coils from the rear 2 cylinders of my 99 that I replaced. The right rear was intermittent. It worked good until it heated up. I bought a pair on ebay with the bracket, so I installed the set instead of removeing one from the bracket and reinstalling. I would be happy to send them to you. You can keep or destroy them as you wish. Might be a good test to see which one is bad and which is good?

I am at The Hub, so I can't send them until next week, though.

Coil on the way soon Goose!

Jeff

I agree with Freebird, I hope everybody doesn't run

out and buy coils. this will happen once in a while though.

Not the everybody.... only me ! *lol*

How ever there is a high heat problem on the rear coils.

Your bike will run just fine with one bad coil. all that will

happen is that you will notice TOP END power will be gone.

Jeff

Kent, What does the pick-up coil do? and what

and were is it? Somebody had mentioned this

on another site, If that is bad it could be causing

these problems well. Ohhh keep the cap as well

you might want to cross section it for some reason

Thanks,

Jeff

The pickup coil picks up a signal from a magnet on the crankshaft (could be anything that turns with the engine) to trigger the ignitor to generator a spark when the engine is at the correct point is in the compression stroke. If it was bad, all four cylinders would have the same problem, so unless the problem was very intermittent, the bike probably wouldn't run at all. On our bikes, it is mounted in a fixed position, so the exact timing/spark advance is controlled by the computer in the Ignitor.

Goose

Kent, how would you know if you had a bad coil?

It would stay out all night and talk back a lot?

Thanks Kent, Check you PM!

Keep in touch!

Jeff

Jeff, I received your coil - THANX! And good news for you - the coil really had a problem. But the problem was in the cap, not the main coil.

Since I have only received one bad coil so far, I can't make any conclusions if this was a unique failure, or typical, but I do have my suspicions. I'll be doing a detailed writeup on what I found as soon as I can gather a bit more info. I am sure hoping to get more to test.

I was successful in connecting my automotive oscilloscope to the bike, and it immediately identified the problem with this coil. I don't think normal resistance tests would have shown the problem, but I have not finished that part of my analysis. I have not tried to replace the plug wire on the coil yet, but I am certain I can do that. I did find out that the wire is solid stranded copper, not carbon resistor wire - this is a very good thing for us, since carbon core wires break down fairly easily, but copper wires never do (the insulation will break down eventually, but not the copper core). I also found out the plug caps are easily replaceable, and I suspect they are repairable. More to come!

Goose

Kent, That is good news!

Now keep in mind that I had removed that

cap off that wire a couple of times and screwed

it back on.. not sure if that helps you your not.

Is the problem deep inside the cap OR were it screws into

the cap?

Also, is it possible for us to maybe cut off a 1/4 Inch

of the wire on the so called bad coils?

Will you be able to cross section that cap?

Anyways, thanks for what your doing!

Jeff

I will be looking into the front coils today.

I also still think that I might have one in

the front as well. not sure yet. if I (think)

I do , I will send that one to you as well.

Jeff