Jetting with Morley's Muscle Kit

[Iowa_VMAX177]

Hey guys. I have had Morleys kit on the bike for a while now and I am very happy with it. I have a VooDoo 4-1 exhaust and I've read numerous times that with aftermarket exhaust, usually you jet leaner then stock for best results. I have my bike jetted with 155s and it runs really good. Any reason behind that? Why do other people run leaner jets and have good results but I run richer jets and it runs really good? Is there something I'm missing? Yes, I do have everything installed that the kit came with (air restrictors, slide springs etc.) My A/F screws are turned out 1.5 turns also. Thanks.

 

[Fire-medic]

I bet you would be even more-happy with 150 or 147.5 Mikuni jets in it. and that your A/F screws will end up being turned-out further. Synch the carbs after replacing them, of course.

 

[MaxMidnight]

Hey guys. I have had Morleys kit on the bike for a while now and I am very happy with it. I have a VooDoo 4-1 exhaust and I've read numerous times that with aftermarket exhaust, usually you jet leaner then stock for best results. I have my bike jetted with 155s and it runs really good. Any reason behind that? Why do other people run leaner jets and have good results but I run richer jets and it runs really good? Is there something I'm missing? Yes, I do have everything installed that the kit came with (air restrictors, slide springs etc.) My A/F screws are turned out 1.5 turns also. Thanks.

I'll offer my standard answer #1: Base any changes of factual data.
By that I mean establish what the current air/ fuel ratio's are and make changes from there. If possible get a baseline run on a dyno or if not conduct some plug chops at various revs.
That way you will know where where (or if) you need to make adjustments.

The alternative is to change the jetting which will cost in time and money (if you don't have the replacement parts) with no guarantee of an improvement or the potential to make it worse.

 

[dannymax]

The Morley kit usually includes air correctors. If so you will need to factor that into your calculations.

 

[Traumahawk]

There are a lot of variables when determining jetting. It doesn't seem to matter as much on a stock bike, because you are only changing 1 or 2 variables. With Sean's kit, your changing more. Altitude and float height, and aftermarket exhaust are the 3 main ones to look at. The higher the altitude the leaner the jetting you will need. The richer the float level, the leaner the jetting you will need, and aftermarket exhaust, the leaner your jetting will need to be.

I run 155s with Sean's kit. My float level is 17 mm, very lean, so I have to go richer on the jetting. 1 mm in float height equates to 1 jetting size difference. I am also at 1100 ft above sea level, so kind of a wash. I also have a kerker 4 to 1, so have to go leaner on the jetting. I know that at full throttle, my A/F is 13.6 to 1. Not bad. I run factory pro needles, and get over 40 mpg at 75 mph. My A/F screws are set 4 turns out in the front, and 4.5 turns out in the rear. Once the bike is warmed up, at idle My A/F is 13.2. I also use an innovate LM2 to get these numbers.

Think of it like this.....balance. If your leaner here, you have to go richer there, to balance things out. Make sense?

 

[Traumahawk]

Here is the link to the factory pro website. Good information. I followed their advice for determining main jet, and needle settings. I did not readjust float level height. Why mess with 2 variables, when you can make the same adjustment with one. I did follow their advice on needle position. I can be 5th gear, 2000 rpm, and go full throttle. No popping, no bogging, I am intentionally lugging the engine to see how it responds, and it works well.

http://www.factorypro.com/tech/carbtun.html

 

[crosserchad72]

Hey when you say 155. Is that in all 4 ? I run 155 on 1 and 3. 150, 2 and 4. What do you have floats at? Needle position?