Pipes and Jetting

[tomithy]

Sorry if this has been done to death, but I couldn't find anything relevant with a quick search.

I'm currently refreshing an L1 ZXR 750 that has an aftermarket pipe on it (Tingate). I'll be checking the jetting at some stage, and was wondering if there's a general rule of thumb when jetting for a new pipe? I know I should just take it to a shop and let them jet it right, but that would be against the povo principle of this bike

Cheers guys.

Tom.

[swearbear9r]

dont know about the jetting but i took my 9 to nevel lush racing in victor habour told him wot i had on the he just did the jets to suit and got just over 10hp and thats with a slop on yoshi k&n filter.. think he did a to job........ let us know wot u get out your 750 like to know........

[adge82]

Your plugs will tell you.
The colour should be a browny/caramel type colour.

White = lean
Black = rich

Im sure their is much more to it than that, but if you want better answers and results i reckon give the boys at High Octane in Thomo a call.
They have a dyno and are very familiar with the L model 750's.

[tomithy]

Thanks

[Ticketyman]

Just get a factory pro kit from the states while our dollars good and slot it straight in with there recommendations and get the ignition advancer as well. You can purchase all this delivered to your door for around $300 Aud.

[tomithy]

$300?!

That's almost a quarter of the purchase price!!

[z900/zx9]

Your plugs will tell you.
The colour should be a browny/caramel type colour.

White = lean
Black = rich

Im sure their is much more to it than that, but if you want better answers and results i reckon give the boys at High Octane in Thomo a call.
They have a dyno and are very familiar with the L model 750's.

Plus 1

[oldman]

Jetting can be tricky as there is a lot involved. The main thing I would suggest is take good notes because float level and metering jet settings, (all carbs do not have metering jets), can get messed up to the point where you will not know how to fix it. I would go one step at a time probably starting with the main jets. Go up about .002 thousanths at a time and as previously mentioned check the plug color. Unfortunatley if you have metering jets it could give you a false reading. I would start with a couple of runs to red line then shut it off before doing any more riding and check plug colour. If it is not right add or remove a couple of thousanths depending on color, (white insulator= too lean, black insulator too rich, and a nice Jim Beam brown just right). What I did was bought a machinists drill bit set and found the bit that went tightest through the existing hole and drilled one size larger until it was right, If you screw up just soldier the hole shut and drill it to the original size. Once you get the main jet right you need to adjust the metering jets. This is not always necessary however, as sometimes the main jets take care of it all. A sign of mal-adjusted metering jets would be low speed surging or an extreme lean condition at low speeds indicated by white or pitted insulators. Once again the key is taking good notes, count the number of turns you crank out or in the metering jets, or the number of shims etc. and be sure to note the float level. It is a long process if you do it yourself but I always loved the personal involvement. Good luck.

[tomithy]

As an update, I bought the Factory Pro v1 kit for roughly $130 delivered.

Fit it all in, 180 mains, put the needle on the suggested setting and it ran sweet. Reset the pilots to two turns out, synched the carbs and it ran even better. Thanks for the tips guys

On a side note, gave High Octane a call, and they quoted me a 'max' of $700 to do valve shims and carb tune. John went on a spiel about how valve shims should be done to give a baseline (to which I agreed) then, when I said I heard about the shop through ksrc he said 'well what would I know then, you forum boys know pretty much everything there is to know, right?' Great way to make a sale I thought...

Given the good reviews they've had on this forum I might give them a go another time, but not right now with those prices and with that kind of attitude