Expansion chambers - do i need to re-jet?

[buzzer]

I have got these expansions on my GT500... Do I need to increase the jet sizes in the carbs? its standard apart from the pipes

Thanks for all your help guys!

[Zunspec4]

Hi Buzzer,

That is looking sweet. With pipes and intake filter pods you will undoubtedly benefit from some re-jetting. I would recommend that you take the machine (when ready) to a good dyno and get it set up to match your modifications. The air/fuel ratio can be monitored and the appropriate jets selected.

Cheers Geoff

[titan performance]

I run mine in a similar trim, using 115 mains, and 35 pilots. Needle on middle notch. You may be able to go leaner still, but my bike gets used hard and I haven't melted anything, so I'm sticking there ![*][*]

[buzzer]

Thanks for that, Just what I needed to know. Just checked... I have a 1.15mm and a 0.35 drill in my selection. I will check what is in there now and enlarge if needed.

[jabcb]

Thanks for that, Just what I needed to know. Just checked... I have a 1.15mm and a 0.35 drill in my selection. I will check what is in there now and enlarge if needed.

These carbs use standard Mikuni pilot & main jets.
No need to buy them via Suzuki part numbers — they are a lot cheaper if you get them via Mikuni part numbers.

[Zunspec4]

Thanks for that, Just what I needed to know. Just checked... I have a 1.15mm and a 0.35 drill in my selection. I will check what is in there now and enlarge if needed.

Be careful Buzzer. Jet sizes are not compatible with drill sizes. i.e. a 115 Main Jet does not = 1.15mm diameter drill .

Cheers Geoff

[buzzer]

mmm Thanks Geoff... My old weber days a 120 jet had a 1.2mm hole in it, and a 35 had a 0.35mm hole.

I had assumed Mikuni were the same! I will check it out with a drill in the standard jet to check the hole before I go near it with a bigger drill!

[tz375]

Keihin main jets are mm diameter sizes and large Round Mikuni are also, but hex main jets are flow rated in cc/min. Jets are cheap. Buy new ones from a mikuni seller

[Zunspec4]

Hi Buzzer,

I too have taken a drill to a jet to enlarge it . Not a recommended practice though as you will have no calibrated range to enable you to make upwards/downwards size changes. Jet sizes are calibrated in several arcane ways, mostly pertaining to how much fuel they will flow at given a pressure over a set time (or something along those lines lol ). Titan Performance has provided some pretty knowledgeable starting points and as mentioned by jabcb Mikuni jets can be obtained from many sources.

Good luck

Cheers Geoff

[aarron]

I have got these expansions on my GT500... Do I need to increase the jet sizes in the carbs? its standard apart from the pipes

Thanks for all your help guys!

Boy that's a nice looking bike. Any build pics?

[buzzer]

I have got these expansions on my GT500... Do I need to increase the jet sizes in the carbs? its standard apart from the pipes

Thanks for all your help guys!


Boy that's a nice looking bike. Any build pics?

sure, there are lots on my build blog!

https://jtccc.wordpress.com/our-motorbi ... afe-racer/" onclick="window.open(this.href);return false;

[aarron]

Excellent blog. Thanks for posting!