I moved this from another post to clean it up and put the bla bla bla here.
I'll do my best to explain not being an engineer I can not be very accurate. What I can do is explain how I come up with the notations.
First I will look at the coil/ coil assebly. The manual showes different resistance values which tells me the primary and secondary turn ratios are different from the 90. Also the values for the assembly it's self. This can also be conformed since the parts list does still show both 89 and 90 are a different part number. Therers some more related info for this and will share later when time allowes.
Second the
CDI (Capacitor Discharge Ignition): I have both an 89 and a 90 so finding differncent items is pretty easy. The CDI (Capacitor Discharge Ignition) is another matter as it looks the same. The 89 will work on a 90 and 90 on an 89 and the parts fisch show one for both years. However theres a difference. On an 89 you can hook up a harley tack which usally is a two pulse per revolution with out a tach adapter. On the 90 the tach will not work or read the single pulse single even with a tach adapter. I also investaged this with an newer from honda 90 pre and post rev delete. SO (I) conclude two things Number one the 89 had a two pulse per revolutionup untill a certain rpm and number two the out put sine wave is different to which the tach can not read.
Now this is a back yard hacker set up and do not know if true or not however I run it.
I use and 89 set up for the values of the ignition system (CDI (Capacitor Discharge Ignition),coil,plug wire and an after amrket cap) and run a air to fuel ratio that works for that set up as well as
Engine pramitiers around this primese. Agian this is just a hacker thing and can not prove other than with one system(89) it works and whenI change out to the (90) the Engine primatiers do not work. So what I did was set out to find out why. I was told weather true or not form a dealer I trust as he was an Engine guy and his guys in the shop back in the day that the 89 not only had a different head color but the head itself was differnet as well as the cylinder. Some one with greater knowledge then me can confrim that one however as of now I believe it to be true. With difference in sine wave the sparks duration and peak value will vary depending upon the resistave values( assuption based off of ignition theroy).
This leads to the statement of the 89 in stock trim being faster or quicker. From a seat of teh pants and at teh time having froiends with each which consisted of 4 89's and thre 90. no matter who rode what the 89's always was a touch quicker. I can contribute this to only the difference in component and the change from 89 to 90.
I look at the weight, not a big deal. Then I look at the ignition componuts,different. Them the exhaust system, different with the 90 being more restricitive. The intake system, reeds and reed valve and carb setting. You have got to ask your self why not only change the reeds and valve but the carb and its settings. I looked at this as an EPA thing due to the catch bottle leaner jetting and the exhaust restrictions. If you assume for a minute all of that and then factor in the cylinder and head rework it makes since to me. We can explore the two pulse thing for a minute. If its is true a two pulse for 89 and one pulse for a 90 then the 89 is firing at BDC. NOw ask yourself WHY. What effect on cylinder scavaging would this have and if true what cylinder change would be needed for a single pulse to achieve the same result for and EPA certifacation. Again I can not stress enough these are only my conclusions and can not support these with paper work. Only Honda knows and confirm or denia these.
SO I may be all wet and take this with a grain of salt and all one reads on the net is not always true.
As far as the two seater I believe it to be true the fact it had a 500 is new to me. I say A+++ for Lee.
This may spark( no pun intended) great debate however I bet some one will start reading and learn a thing or two about igniton systems and there efect on the cylinder combustion strenght as well as the power strokes duration. Not to mention the effect on the primary CR effectiveness. As I did mentin the intake system as part of the hypothises. The reeds and tip area ratio play a part in this. How you might ask, just like the top end the time the port (valve) is open and closes as well as area has an effect on the compression ratio. Couple this with the angles of the boost and transfers will have an effect on scavageing according to time.
Time for a what if. What if during scavaging the intake charge was clearing the top end the ignition fired and the flame kernal lite off some the clearing change or burn off some of the unspent fuel air mix from the squish. UMM, Just a thought in the process most likly has no merit.
Well that's the best I can doas an explanation. All feel free to jump in or on as an discusision. that's what this board is about.
Adnoh.