Carb Rejetting

[xs650special]

Hey everyone, my 81 has the mike's xs two into one exhaust system with the headers from that site too. I going to be working on the carbs soon and I was wondering if anyone has done a rejet to get the bike to run the best with this type of exhaust. There are also K & N pod air filters on it.

 

[littlebill31]

There is no set recipe for these carbs. I am assuming you have BS34's on it.
Make sure you read through the "Tech" section carburetor threads and this:
http://www.amckayltd.com/carbguide.pdf
Read until your eyes bleed. Plenty of people will give you advice, but you need to understand how a carb works before you jump into them. Anyone can throw in some jets to get it to run, but you want it to run right.

I used to go up one main size and 2 on the pilot, 3 turns out on the mix. However, because all bikes are different, I now start with the stock jetting and see what the bike tells you. Listening to the bike run tells you a ton of information.

 

[Paulrxs650]

Second that carb guide - best one ive read!

 

[DLD1]

My XS is a 79. I have Mikes 2-1 exhaust, Mikes pod filters, and I run 2 sizes up on mains, 1 size up on pilots, and the needle down 1 groove. It works very well on my bike, and at the very least it's a good starting point.

 

[Scrambled]

I got the same set up on my '78, but I have just sent my carbs down to Oldskool . I will let you know how they work and what he did with the jets. I am switching to Uni pods because so many people that are having carb tuning problems are running with Mike's or K&N s .

 

[littlebill31]

Remember that BS38's and 34's will use different jetting specs, if the pre -'80s discussed above are using 38's.

 

[xs650special]

Little bill after reading the pages on the link above I've decided to postpone on the rejetting for now and just clean them first. That carb info is going to be helpful thanks.

 

[littlebill31]

It is truly best to get it running the way you have it. After you get it running correctly, then you can start to modify. I say this because of what I have seen from others. Some start ripping things apart without even understanding how they work, then chase their tale for weeks on end trying to figure out it was just some debris.
Clean them up, and I mean clean clean. Check every little piece, port, crevasse, everything. Use compressed air to blow out all the little ports.
You will also want to start spraying carb cleaner through ports to see where they come out. This helps explain what they do and how the fuel travels throughout the carbs. Most just spray all over the place and call it good.
The smallest amount of debris can cause havoc.
Have fun with it. Carburetor knowledge is a great thing to have.

And the K&N air cleaners aren't the best. I like the ones from MikesXS.

 

[DLD1]

Very good advice, littlebill31

DLD1

 

[littlebill31]

It is advice that I took seriously from others on this forum. I only have them to thank.

And it's really cool to impress friends with that knowledge. Especially the ones that are "customizers" because they succeeded in bolting on a seat back rest.

 

[DLD1]

Yeah, I've noticed quite a few guys tear into these bikes before they know much about them, and then beg for help. Fortunately for them, there are lots of helpful people here.