kz750 twin headers glow red when at high rpms

Through a ring replaced motor with 6000 miles.

Noticed while riding at stop idles high playing with that but also notice it leans out while riding. an oldtimer said i could lift needles a few clips on the slide that would help. any suggestions.

Note pod filters and custom exhaust are on bike.

help
nate

With pods and low restriction exhaust, you will need larger main jets. Stock mains on the BS-38's that go on a 750 twin is 125. You could probably go up to 135 - 140, that's just a guess. If yours is a 1979 KZ750B4 like mine, the needles are adjustable. Stock position is middle slot, you can drop to the bottom slot to go full rich but I don't think that will fix a glowing header problem. What you really should do is put a stock airbox on and a decent set of mufflers. Right now you are cooking more than the exhaust pipes.

nathanhopkins wrote:

Noticed while riding at stop idles high playing with that

That is typically caused by a vacuum leak which would make it run even leaner. The rubber intake manifolds in good shape? Check for leaks.

Would also verify correct ignition timing and that advancer unit is properly functioning.

Good Fortune!

To first reply factory pipes and airbox not option. bike is totally customized its chopped motor is only original part. will try needles first . will check everything else though thanks guy

Nah! Dont listen to these guys, ride it like that!

The glowing is cool at night... :blink:

No seriously, listen up

Get a whole bunch o' jets like 6 richer sets of mains, and 2 richer sets of pilots, and take that bike to a dyno and get to work. (Or use the old butt dyno).

Put in the richest sets and do a run, then decrease the sizes 1 at a time until no further performance is gained then stop, your done. Raise/lower needle as necessary for midrange power.
mains are for full throttle, pilots are cruise and smoothness at small throttle input, screws are for idle.

GL!

The mains are REALLY hard to find. This is one source I found:

www.allensperformance.co.uk/mikjets.html

Main jets are four down from top.

Let me guess... not the double pipe original exhaust, but some single pipe aftermarket deal... yep ride it, the glow is cool at night. and crome looks cool with a nice blue tinge.

Seriously though, if it's a single pipe and if your plugs look in range I'd not fret to much over it... it's why they make the double pipe, so you don't see that pretty red glow and your crome stays nice an purty.

thanks guys

drilled out main jet to 140 bikes running great

Color indicates temperature, so here's a color chart so you can determine how hot your pipes are getting. Keep in mind that aluminum melts between 1100 and 1250 degrees F depending on alloy.





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