power boost vacuum advance unit

[FJ111200]

I was not aware that the 1990 FJ's used a vacuum advance. I thought they were a DCI ignition.

It could be that a previous owner converted the 1990 bike to run on 1100 or 1TX 1200 electrics.

That's what i did on my 1989 3CV and have continued with the application on my XJR1200's.

Just a thought.

[Pat Conlon]

The digital box alters the timing, but it uses sensors to determine the adjustments needed, (e.g. pick up coil and pressure switch.)

Hey Travis, help me out...Bob W seems disinclined to respond, yet he is very good at snarky comments.
Below are 2 timing tables. The top is for the early FJ's and shows 2 different curves based on vacuum, and the bottom table is for the late model '91+ DCI ignitions. The 2 dashed line different curves in the bottom table are for the different detuned FJs sold in the JDM and Swiss markets. The solid line curve is the full power FJ sold in the US, Uk, etc, markets.

What I see in looking at this bottom table for the '91+ FJ's  is only 1 timing curve based on engine rpm.


So, my question remains: On my '92 how is my DCI ignition altered and where is the alternate timing curve shown on this table?

And if it indeed has only 1 advance curve programmed into the DCI, what is the vacuum line coming off my #2 manifold used for?

I do agree with Andy that proper carb syncing will probably cure the OP's issues.    Thanks amigo!

[SlowOldGuy]

Pat,
I see 3 curves on that second plot.  The hose should be going to something called the Boost (vacuum) Sensor.  I always assumed it changed the timing, but I have no proof.   What else would it be used for?

I also "assumed" Yamaha went to a separate "vacuum" sensor for the ignition system so that when it went bad you could just replace the (relatively inexpensive) sensor instead of the whole ignition box.

I may be giving them too much credit, though.  :-)

DavidR.

[Pat Conlon]

David, as I understand it, without having the footnotes, the top solid line is the full power DCI's, the second dashed line is the JDM and the third dash-dot line is the Swiss version which was detuned the worst.

Our Scot friend Stuart posted this info:

Here are the ignition advance curves from my factory manual for Euro markets. The top is for the early FJ1200. The lower is '91+ models. The solid line is the full power model we got in the UK. The middle line is slightly retarded possibly to meet 100bhp limit in some countries. The lower line is for Switzerland who had severe power restrictions.

I *think* I remember reading somewhere on this forum about the '92's vacuum line going to a pressure switch and having something to do with the DCI controlling the fuel pump functions and the reserve switch.... I'm sure Bob knows...
[edit] The 92's wiring diagram does show 3 wires going from the "pressure sensor" into the DCI ignitor unit.

[FJ111200]

  The hose should be going to something called the Boost (vacuum) Sensor. 

DavidR.

The Boost sensor or boost pressure unit or other thing, is something that was used on the XJ1100 and XJ650 Turbo only.
This was just prior to the FJ1100 being introduced, which they, Yamaha, then incorporated into the TCI or black box whatever you want to call it. I know 'cos i'm experimenting with the XJ1100 system on one of my XS1100's.

[Travis398]

ohh we're posting graphs now eh?  I am not sure what that was supposed to prove, but they are different grafts comparing different things on different bikes.

I would guess comparing ignition curves of bikes from different countries assumes your not going to ride your bike with the booster disconnected.

Do tell...........how does this reserve switch booster work? 

[Pat Conlon]

ohh we're posting graphs now eh?  I am not sure what that was supposed to prove, but they are different grafts comparing different things on different bikes.

Easy, the point of the ignition timing graphs was to show that only one advance curve was shown on '91's  not two like the vacuum bikes show.

I would guess comparing ignition curves of bikes from different countries assumes your not going to ride your bike with the booster disconnected.  

No, I wouldn't do that....Tell me, where  does this word "booster" come from? You assume the '91+ vacuum pressure switches are some kind of booster? I know the term booster is used on the vacuum ignitions but I'm not aware this term is used on the '91's... Is it in the shop manual?

Do tell...........how does this reserve switch booster work?  

There is that word again...Travis, I don't mean to irritate you, that's why I asked the question..... So, I assume your answer is....
On the '91+'s the vacuum hose off the #2 manifold goes to a "booster" switch which alters the advance curve on the DCI ignition....?

[Pat Conlon]

Travis, here is a detailed timing graph for the 1100's which have a vacuum (boost) advance...see the 2 different lines?

[weymouth399]

Snarky huh.

I don't know how exactly the cdi box works, as it's sealed and I can't fix it if I did know how. But I do know that my race car has that very ignition system on it. But the race car DOES NOT HAVE RESERVE so what does it do there.    You want f-ing snarky I'll give ya snarky.

Bob F-ing snarky W

[Travis398]

Tell me, where  does this word "booster" come from?

Pat I'm sorry I use the word boost loosely. If you check my original post I believe I gave the technical name.

I just use the word Boost because it is in the thread title.  "Power boost vacuum advance unit"

Although that may not be the official name of the part, I still know the part he is asking about.

[Pat Conlon]

No worries Travis, thanks Bob, I stand corrected. Just because I can't find a second advance curve on the '91's table does not mean that a second advance curve does not exist.
I put a aftermarket DCI unit on my '84 and it has no provisions for vacuum, so only one advance curve is used. I was thinking the same existed on the late DCI's but a vacuum switch wired into the DCI would do the same thing and as David points out, when the switch fails you don't have to replace the entire DCI module.

[Dan Filetti]

As much love as I have for the FJ, and I really do have a soft spot in my heart for it, I really like the fact that, fuel injected bikes can be fitted with a sophisticated power commander.

I decided I wanted to smooth out a slightly rough idle in the Gixxer the other day.  All I had to do was plug my bike into my laptop, and adjust the fueling at 1000 RPM with 0% throttle to a value of '-15', hit upload, and it was fixed.  Within a second of hitting upload, the bike responds the new programming and runs differently -better in this case.  Making such changes to a carbureted bike takes much longer.  It is really rewarding to do it all in 10 mins and make the bike run better with the push of a button.

The version of the PC I have is actually made by PC for Yoshimura and has a few extra whistles and bells.  It allows for three different maps to be loaded into it, and if I had the handle bar switch, (which I don't) I could switch between them at will.  I have toyed with the idea of buying the switch and creating a 'rain map' and possible a 'fuel economy map'...

Also, it allows me to adjust timing values for specific throttle position and engine RPM.  Pretty cool.

I know this is off topic, sorry for the hijack, but I wanted to pass this on...

Dan

[Travis398]

[edit] The 92's wiring diagram does show 3 wires going from the "pressure sensor" into the DCI ignitor unit.

Pat It's not really a fair debate if one of us has the power to go back and change previous posts.
We all know changing just a word or two can change the meaning of a post, and change the context of each following post.

I'm not saying that happened in this case but it would be nice if you would leave the original post and reply to it with your updated info.
Then everyone can read and understand both the before and after.

Putting that advance tube in the ignition box is a bad design, it can corrode, get bent or even break off.
Looking inside the box I would say you would have a hard time fixing this if it did happen.

In 88 when they moved this pressure switch external (for whatever reason) it used 3 wires. One was the +12volt DC from the key switch and the other 2 are the send/return from the ignition box. I would have guessed they are all like that But if your 92 is not like this than it would be possible that something is different on the 92.

I don't own a 92 so I can't confirm or deny this.

I know this is off topic, sorry for the hijack, but I wanted to pass this on...
Dan

Dan this whole thread is a hijack so we all should be apologizing

[Pat Conlon]

A couple of points:
1) If I wanted to hide it from you Travis, I would have not identified the new info. with [edit]
2) The new info. did not change the course of the discussion, if anything it supported what you were saying.
3) My edit was done at 2:26 and your next post was not until almost a hour and a half later, at 3:53.

Yet, you wanted me to do a new post with this late info?  Geeeze.

You saw my edit before you posted, if not too bad...

[fj11.5]

hey pat, just wondering what ignition unit your using, and if it changed the way your Fj runs, , asking as I'm using a unit made in new Zealand , , easier starting it seems, and has a very smooth power delivery , dousnt have the turbo like kick from 7000 rpm like a standard unit but pullls better right through the rev range from idle to 8500