kz750 twin performance upgrades

my 78 has 4 more HP :pinch:

Would the introduction of unleaded gas have been a factor?

KZJOE900 wrote: Would the introduction of unleaded gas have been a factor?

Don't think that has anything to do with spark plug heat range.

reference



Influences to spark plug temperature
Any of the following situations can increase spark plug temperature:

-Lean air/fuel mixtures
-Increasing compression
-Forced induction (Supercharging, turbocharging or Nitrous)
-Camshaft change
-Advancing ignition timing
-Higher engine speed
-Higher engine load
-Lower air temperature (more dense air resulting in leaner air/fuel mixture)
-Lower humidity (more dense air resulting in leaner air/fuel mixture)

www.totalmotorcycle.com/maintenance/sparkplugs.htm

gumby prichard wrote: my 78 has 4 more HP :pinch:

But the service manuals for the 750 twins in that series (B3) and my '79 (B4) call out the hotter B6ES plug. If the engine is tweaked up for more power, that would imply colder plug if anything. If the later years make less power (probably from the smaller 34 mm carbs) they could run a hotter plug.


According to the OEM part drawings, it calls out B6ES for the B3/B4 models (see below) and the B8ES is listed as optional.

but my 78 specs noted the bike at 55 hp so if your bike is a 79, stting that they have more power would be incorrect because the specs you posted showed 51 hp, NO? :huh: :huh: :huh: :huh: :huh: :S

gumby prichard wrote: but my 78 specs noted the bike at 55 hp so if your bike is a 79, stting that they have more power would be incorrect because the specs you posted showed 51 hp, NO? :huh: :huh: :huh: :huh: :huh: :S

My '79 printed manual showed 55 HP and B6ES plugs.

This manual I got on a CD ROM also shows 55 HP for US models, the 51 HP is the "G" which is the German model. They have to make all the German vehicles less powerful so they can't be used to invade Poland. :laugh:

Since WW2 the japs have been kissing butt giving us the fast models over germany so we don't bomb them agsin, hahaha, that's what it is.

No but honestly me and my friend always blame ever stripped bolt or rusted shut piece on any bike we buy on ww2, "ever since then they are seeking vengence by screwing us over with their designs and selling them too us" lol :lol: :lol:

the ironic part is we both own bmw's and buy jap bikes

Worked on my 750 again tonight, and i feel slightly stupid, maybe its a false alarm, but i was moving the coil around today since currently it isnt mounted because i recently changed my shims and noticed one of the plug wires was labled 2. looked at the other one and it is labled 4. this means the coils on my bike came from a 4 cyl bike..... the coils are white and read NIPPONDENSO 12V 10T AND LABELED NUMBER 129770.

CAN ANYONE TELL ME WHAT THIS IS OFF OF MAYBE AND WOULD THIS CAUSE ANY SORT OF IGNITION TIMING OR SPARK PROBLEM CAUSING MY TIMING TO BE INCORRECT?!

on a side note i ordered the dyna s ignition today along with my right side calipers to complete my dual disc setup :laugh:

Use your Ohm Meter to measure the Primary coil resistance. Thats the small wires, not the plug wires.

should the bike be running or just turn the ignition on? and how many ohms should it have for a stock points ignition?

Ignition off and wires disconnected from coil. 2 - 6 ohms resistance, hopefully 4 ohms.

Maybe you have four cylinder plug wires, A four cylinder coil will fire 1 & 4 or 2 & 3.

Measure between the two spark plug wires and look for 17k - 23k ohms with plug caps removed.
If you have the hard plastic plug caps they're probably 5k ohms each.