Liquifire: 80-81 VS. 82-84?

[JDGuy]

Below are some ignition advance plots scanned from the Kawasaki service manual for the standard Invader (same/similar to 80/81LF?) and the LTD 4/6 HSR ignition (same/similar to the 82/84LF?). The degree increments on the Kawasaki HSR ignition curve are not labeled, but would appear to be in 1 degree increments with the RPM at the mid point of the vertical axis divisions. It is my guess that the HSR ignition was a Kawasaki development which may have applied directly to the 82/84 LF? The last attachment is my rough plot comparison of the two ignition curves, assuming that I have interpolated them correctly?

EDIT: AS PETER POINTED OUT IN A POST BELOW, I DID NOT INTERPRET THE LTD 4/6 GRAPH CORRECTLY FROM THE SERVICE MANUAL. THERE ARE NO UNITS ON THE ADVANCE PORTION OF THAT CHART, I ASSUMED 1 DEGREE UNITS, SHOULD HAVE BEEN 2 DEGREE UNITS. TO AVOID CONFUSION I HAVE DELETED THE COMPARISON GRAPH THAT I MADE ON THIS POST. THE COMPARISON GRAPH POSTED DOWN A WAYS IS CORRECT AND PETER HAS CONCURRED.

[That Girl Racing]

Pretty standard ignition curve. They retarded the ignition about 12degrees from 3000 to 8000. Bear in mind the module does not know the static timing of the motor. It only knows to take 12 degrees of timing out. Notice the Invader curve is flat from 3000 on. We do this same curve on tracks with poor traction to stop the track from spinning. Peter

[Norton]

JDGuy & Peter,

These last two posts remind me of a saying "I did not even know, what I didn't know". Thank you very much for the effort! I consider this very valuable information. Unless specific Deere/Kaw HSR information shows, this will have to be my starting points.

Changing the timing curve to control track spin is probably old news to a experienced racer but for me it was an epiphany!

keith

[ICCSF 108]

JDGuy / Peter, Great posts this is now in my saved section

Kenny

[That Girl Racing]

JD Guy. I think you misinterpreted the HSR curve in relation to the Invaders. The HSR advances to about 25degrees at 3000 then retards to about 16. The Invader curve rises to 16-18 and stays flat from there. The earlier ignition timing at lower RPMS gives the HSR more power coming off idle and at engagement. However once at 7000-8000 both are timed similairly. That is why the HSR makes no more power than the early ignition. Peter

[JDGuy]

Peter, I bet you are correct. I was struggling with it after I put it on line, and wondering about a power loss with the HSR at only some 8 degrees advance at 8000 RPM, per the comparison graph in the above post. EDIT: THAT GRAPH WAS INCORRECT AND I DELETED IT. I made the assumption that each vertical division was one degree on the service manual graph for the LTD 4/6 HSR. If you make the assumption that each division is 2 degrees, the graph looks something like the one below, which is the point I believe you made. I had previously looked at 2 degree divisions which results in some 30 degrees advance at about 3000 RPM. That seems huge? The 4/6 service manual graph also leaves some RPM up to interpretation. Probably the best we can make from all of this is an indication of what the Liquifire curves may have looked like (note next paragraph).

Keith / Norton: There may be other factors in relating the Kawasaki advance curves to the Liquifires. The Gordon Jennings Two Stroke Tuners Handbook lists several engine parameters that effect the determination of an optimum advance curve, such as combustion chamber shape, spark plug location, distance from plug to remote area of combustion chamber, etc., some of which are different Kawasaki vs. Liquifire. The question is were the Liquifire curves unique (?),……or were the engine differences not sufficient to warrant Liquifire specific advance curves? Peter, your thoughts would be appreciated. I think I am finished with this before I do any more damage!

Guy

HSR using 2 degree increments from service manual graph

[That Girl Racing]

Guy. Now you got it! My guess is that both curves would work just fine in an Liquifire. Also, fuel will be the major player when it comes to preventing burndowns. Bear in mind that when you mash the throttle how little time you spend with the timing advanced. Where the trouble shows up is when you are cruising at part throttle (lets say 6500) with an extra 6 degrees of advance in the motor. This is where needle and tubes come into play. This is a very good post. Got anything else for us? Peter

[Norton]

JDGuy & Peter,

I give you guys an A+ on your assigment! And that is considering the small chart correction made today! As often times is the case no one person knows all the answers but put some heads working on a question and things can come together.

I understand that all this info is for a Kawasaki in a Kawasaki, not the Kawasaki in a Deere. Rich has shared info about the "somewhat detuned nature" of the 440 liquid Kawasaki version that Deere tested and approved for it's use in the LF. He stated Deere was looking for longer engine life and of course gave up some h.p. to reach that goal. If the two different engines were timed differently with the HSR is a question yet to be answered I guess but right now I am very happy with what I have. As a start point now, I plan on setting the timing of my 82 LF at 16 degrees @ 6500 and then go backwards and "find the curve" the installed CD box provides. If and when a CD box is found that works, and meets the curve you have shared with us, I will share the application ASAP.

Peter and JDGuy I have lots more questions on this subject but they are more on the electronics side. Like dip switches for different fuels and pipe temp and timing relationships. Course this is getting away from vintage era....

keith

[hotrodcr250]

so is the 1980 invader 4/6and 1981-82 ltd the same ignition as the 82 -84 liqifire or different due to the dual plug set-up?

[AirborneX4Special]

Roughly, yes. I am still efforting the picture enlargement scheme so you guys can see the ignition curve comparison and decide for yourselves. It is a tiny picture in Deere's bulletin and of little use as is. If nothing else, I will reproduce it by hand, scan it and upload it for you.

[hotrodcr250]

do you have a pic of the jd hsr cdi boxor part #

[AirborneX4Special]

Yes, but they are no longer available. There is an effort in the works to reproduce them but nothing concrete as of yet.

[JDGuy]

RE: 80/81 LF vs. Invader....Ignition timing curve difference?:

Was there a different Ignition timing curve due to cylinder head and compression differences between LF and Invader? No answer here, but the Kawasaki CDI part numbers are different LF vs. Invader, and the external wiring connections and color codes appear to be identical....suggesting internal electronic differences?

80/81 LF CDI AM54840 = Kawasaki 21119-3001, See photos (2) below of NOS JD part in Kawasaki box.
Invader CDI = Kawasaki 21119-3002 via Kawasaki parts manual

[AirborneX4Special]

I'll bet there is no difference in those two parts. Dennis Kirk lists the same external coil for the LF and Invader.

[AirborneX4Special]

This is the Liquifire ignition curve chart from Deere's 1981 Changes and Improvements bulletin.

LF Curve Comparo.jpg (5.94 KiB) Viewed 5797 times