Carb help??

[catastrophe]

Ok so I have an 81 xs650 with the stock 34 carbs. I put on pod filters and have exhaust the stop right under my carbs with baffles. I read that I should go up one size on the main and pilot jets. Any recommendations from any one who has done this?

 

[ippytattoo]

I'll have to check my notes later but I had Oldskoolcarbs do my carbs and IIRC he went 1 up on the pilots and 2 up on the mains and I am running K&N pods and open exhaust that ends about where you are describing. Aside from a little adjustment on sync and fuel mixture they were spot on. Of course every bike is different so this may not be exactly right for you.

 

[5twins]

Ippy's settings would be a good place to start. The BS34s were very lean right from the factory. Do ANY mods and re-jetting is usually called for. Also make sure your mix screws are set about 3 turns out to start. They can be fine tuned from there but that setting is usually very close to what's needed.

 

[catastrophe]

Yeah thats were I started them at. It just starts popping when I full throttle it. I was looking for the next pilot size but there not on mikes xs. It jumps from 42.5 to 47.5. Any suggestions? Thanks fot the advice

 

[5twins]

A local shop may have them or could get them. Find one that caters to dirt bikes and ATVs. Those guys are modding and re-jetting all the time. Be aware that you require the less common BS30/96 style of pilot, not the more common VM22/210. They are physically identical on the outside but are different and flow differently on the inside. It has to do with which end of the jet that the metering orifice is located on.

 

[catastrophe]

Yeah I know. Thats why I am looking for the #45 pilot. Found them on 650 centrel

 

[5twins]

Don't forget the larger mains as well. You need to do both mains and pilots on these bikes usually.

 

[catastrophe]

Mikexs has the mains but not the pilots. Any recomendation on how many sizes uo on the mains?

 

[5twins]

There's no saying for sure what you need exactly but with your mods, I would recommend starting 2 sizes up on the mains. I would buy 2 and 3 sizes up (137.5 and 140) so I could try both. That's how you select the proper main jet size. You work your way up through consecutive sizes until you get too big, then step back down a size or two.

 

[ippytattoo]

Just checked my notes and I have 45 pilots and 137.5 mains and my mixture screws are at 2 3/4 turns out. I am at sea level or about 20 ft above sea level. It pulls very hard and clean all the way from about 1000 rpms to redline (about 7000 rpms) I am running 17t front and a 30t rear sprockets and it seems to like to cruise around 75-80 mph in 5th with plenty of throttle left.

 

[catastrophe]

Awesome. Thank you tattoo. Apreciate the help

 

[catastrophe]

ok so I went up 2 sizes on the main to a 137.5 and one on the pilot to a 45. Bike got a little bit faster but it still quits at about 80. Any recomendations on sizes for my jets? Its an 81 with the 34s. I am running pods with straight pipes with baffles and the pamco set up