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?

 

[Traumahawk]

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?

I do run 155 on all 4. Now, one of those things that I learned years ago, the back cylinders do run just a bit hotter at idle, and that's why I suspect in the early yamaha literature that yamaha said they put 150s in the front, and 152's in the rear.
Years ago, at idle and the bike level, the rear cylinders were a couple of hundred degrees hotter coming out of the cylinder heads, than the front. I used a temp gun to see the temp of the exhaust, on a kerker 4 to 1. (You probably won't be successful on the stock double walled exhaust) I got the temperature to within about 75 degree of each other by richening up the rear A/F screws 1/2 a turn. If I am running 4 turns out on the front, then I will turn the rears 4.5 turns out.

17 mm on the floats and 1 clip on the needles. I am also running shims on the needles. I can't remember now if I am running a 20 thou or 30 thou shim. Fyi 20 thou is equal to a 1/2 clip. Where the clips are is what gives you really good gas mileage.

 

[crosserchad72]

Thanks for your input. I am gonna play with mine. I seem to be starving for fuel at low rpms. I have to get on it before it starts running normal. Just under load. Then back to spitting and sputtering. Im gonna try your setup and see where it goes Thanks again. Yes carbs are clean . Purchased my own ultra sonic. I am gonna dig into the clips for mileage. Cause I get like 28 to 30. No matter how I ride it. Anyway, when in doubt, gas it out..

 

[crosserchad72]

Oh I have a UFO exhaust 4 into 2...

 

[Traumahawk]

Thanks for your input. I am gonna play with mine. I seem to be starving for fuel at low rpms. I have to get on it before it starts running normal. Just under load. Then back to spitting and sputtering. Im gonna try your setup and see where it goes Thanks again. Yes carbs are clean . Purchased my own ultra sonic. I am gonna dig into the clips for mileage. Cause I get like 28 to 30. No matter how I ride it. Anyway, when in doubt, gas it out..

What are your A/F screws set at? That's what covers 0 to about 4000 rpm at about 1/8 of the throttle. So exactly what your cruising on going around town. With my needles on the leaner side, I would get between 40 and 45 mpg. Average around 42. That was fueling up, driving about 25% around town and the other on the highway at 75.

 

[crosserchad72]

2.75 turns out....thats my AF .. I just checked fluid hieghth and I must have done it wrong. It barley even reached bottom of the bowl.....I'll have go revisit that thread.

 

[crosserchad72]

2.75 turns out....thats my AF .. I just checked fluid hieghth and I must have done it wrong. It barley even reached bottom of the bowl.....I'll have go revisit that thread.

 

[Traumahawk]

2.75 turns out....thats my AF .. I just checked fluid hieghth and I must have done it wrong. It barley even reached bottom of the bowl.....I'll have go revisit that thread.

My A/F screws are 4 turns out in the front, and 4.5 in the rear.

 

[crosserchad72]

Thanks .. I'm on it.

 

[wilks]

Hold up hold up…..let’s revisit this 42-45 mpg statement…..how in thee hell are you doing that???

 

[Traumahawk]

Hold up hold up…..let’s revisit this 42-45 mpg statement…..how in thee hell are you doing that???

Ok, fair enough. Lets start with the basics......have you ever played around with carbs for cars, something like a carter or an edelbrock? Do you know the theory on how they work? And if not, thats ok.

 

[wilks]

Played with a lot of Holleys …..no Carters or Edelbrocks

 

[Ryce]

My bike has the Morley kit, I was never able to get it to run right with the shorter DJ stage 7 spring.
I changed to the stock spring and was able to get it to run better. I have a Kerker 4 into 1. I also went to slides that I drilled to .125 in, on the lift hole. I use a Motion Pro needle and stock idle jets.. The PAJ 1 and 2 air jets are one size bigger. The bike will take throttle in 5 th gear at 1500 rpm with out issue. I usually get high 30's to low 40's mpg on the road,; I would like to hear of anyones experiences on how they determined how big to drill the slide lift holes and what there experiences were with changing from the short slide springs (DH stage 7) vs the longer stock springs. Regards

 

[Traumahawk]

Played with a lot of Holleys …..no Carters or Edelbrocks

So on carters or edelbrocks, or holleys, the amount of fuel that flows is determined by the size of the jet. Smaller jets flow less fuel, larger jets flow more fuel. On edelbrocks and carters, the needle will go down into the jet, and take up space. This happens at part throttle, so you get better fuel mileage.

CV carbs are very similar. The needle doesnt go into the main jet, but it does interfere, take up space, and not allow as much fuel to enter the carb throat. On the needles you have clips. A clip that is closer to the blunt end, makes the needle sit further down, takes up more space, allows less fuel to enter the carb throat. If the clip is closer to the pointy end, then the needle sits higher, allowing more fuel to enter the carb throat. More fuel/more power.....LESS mileage. So your looking for a main jet that gives you the most HP, and you want the needles to sit as far down as possible, so that will make you leaner going down the road, and thats where the gas mileage comes into play. If you get too lean on the needles, the bike will buck, etc, and NOT be happy, but you wont hurt the bike. The gen 1 WONT allow you to get too lean on the needles. Make sense?

On my set up I am at 1.5 clips from the blunt end. So the needles sit down into the carb, not allow as much fuel into the carb throat, and gives me very good mileage.