I have been through a lot of this information, but I dont see any tech tips with recomended jet sized or needle settings to start with based on my config. Currently I have a 175 jet in the carb. I gather from what I have read that the original jet was 165. I have no foundation to determine what is a good starting point (or if 175 is good enough).

Thanks in advance.

Huygens

For the BAK and cobra straight slash pipes a good place to start is the Mikuni 170 , pilot 35, clip on 5 and PMS about 3.

Then try the WOT test to see if the main is OK for you situation.

Once you have the main nailed then move the clip to 4 and test ride.

Doc

Forgive me if I am stating this incorrectly.

I have a Barrons jet kit handy. How do the jets in a Barrons kit compare (size/quality/etc) to mikumi or dynojet? Which jet from the Barrons kit should I use? How about the needle settings?

Thanks....

Michael Hansen

huygens wrote:
I have a Barrons jet kit handy. How do the jets in a Barrons kit compare (size/quality/etc) to mikumi or dynojet?

The Baron's jet kit uses Mikuni jets. Mikuni and DJ jets sizes are specified differently.

[quote}Which jet from the Barrons kit should I use? How about the needle settings?[/quote]

The rest of my previous recommendations stand ....

the 170 main, pilot 35, clip on 5 and PMS about 3.

Then try the WOT test to see if the main is OK for your situation.

Once you have the main nailed then move the clip to 4 and test ride.

You can fine tune the PMS by turning it in slowly until the motor 'misses' and then counting the number of tuns, turn it out until it misses. Halfway between these two points is a good starting point.

Doc

I am awaiting some other unrelated parts for my bike before I can try all of this. Unfortunately the Barrons kit I have only has 177.5, 175 (installed up to now), 172.5, and 165 (original).

Realizing that the old saying that 'bigger is always better' is not always true, How does the size of the jet impact the performance of the engine. I can only assume that the larger the hole, the more fuel can get to the engine in a predetermined amount of time, but that the size and configuration of the carb as well as other factors (engine size, exahaust, timing, etc...) impact the ability of the engine to handle higher volumns of fuel. Am I at least somewhat comprehending how this works?

I did do some reading under the Tech Tips and other sources and this is what I am understanding.

Thanks again for your input.

Michael Hansen

Post edited by: huygens, at: 2007/05/15 12:03<br><br>Post edited by: huygens, at: 2007/05/15 12:23

huygens wrote:
How does the size of the jet impact the performance of the engine. I can only assume that the larger the hole, the more fuel can get to the engine in a predetermined amount of time, but that the size and configuration of the carb as well as other factors (engine size, exahaust, timing, etc...) impact the ability of the engine to handle higher volumns of fuel. Am I at least somewhat comprehending how this works?

The cylinder can only accommodate a finite volume composed of a mixture of air and fuel. The optimum air/fuel ratio for unleaded gas is about 14:1, but taking all things into consideration you should be aiming to get 12.5:1 to 13.5:1.

The main jet comes into play at 3/4 to full throttle. As you increase the size of the jet you get more gas into the cylinder; that is the AF ratio decreases or the mix is richer.

A richer mix means less air which results in some unburned fuel. On the R*, this unburned fuel results in carbon deposits on the inside of the engine and seems to result in a risk of sticky valve.

Doc

Based on this, you recomended a 170, but being I dont have a 170, should I consider using the 172.5 or leave in the 175, or even go as high as the 177.5? I cant imagine rolling back to the 165.

Thanks for the 101. I have learned more about carbs on this adventure that I ever would have thought. I can see now the advantage to efi <br><br>Post edited by: huygens, at: 2007/05/15 14:03

You want to go down in size, not up.

For the time being you can use the 172.5 but I think you'll find it still too rich. I've seen some run with the 165 but it usually a bit too lean.

Just go to the dealer and get some large round headed main jets.

Doc

Ready to pull my hair out. I have followed a lot of the advice found here and with great success. One exception though.....I cannot resolve the issue of the carb bowl running out of gas faster than it can get it in the WOT test (or even high-moderate acceleration). I have double, triple and more checked everything I can. I have set the float level as reasonably high as humanly possible without flooding the engine. Before I decide to give up and go with a fuel pump config again (after far too much work), can you or anyone review what I have done, ask me questions, etc... to see what I have possibly missed? I know it is going to be something stupid on my part, but I think it is the forest for the trees thing on my part.

On a side note the mod for the PMS worked well. When this is all done, I will upload the pics. Used a pull choke cable from a local parts store and cut it to length and mounted it to the carb. Just need to make a bracket for the other end thus far. Jetting information worked out very well. Engine has never run so good before. I will know more when I can eventually do a WOT and final adjustments. As well the mod for porting the factory intake worked out extremenly well. Overall the bike has never idled so smoothly, never accelerated so well in first and second. Now if I could only get above second without that out of gas stumble.

BTW DocShadow, I like your site and the work you have done to your bike. Looked it over some. Gives me some desire to look at other mods for mine, but only after I get what I have started finished.

Huygens

Your tank venting might now be working right or you might need to vent the cap. Just a thought as I don't run pumpless.