i am just about to give up

[shark1979]

i have a 78 xs650.the bike has Pod filters and shorty pipes. i have cleaned to carbs. synced the carbs. adjusted the needle. they seem to be tuned good. but the problem is that i can get above 60mph with out the bike breaking up. i have ordered a rebuild kit so that i can put all new jets in so i know where i am starting. do you have any ideas? i am close to buying new carbs but not sure what ones to get? what one should i look at?

 

[swbill]

Bet I can help here. Your running the small $10 pods off ebay right? The rubber flange blocks the air jet in the mouth of the carb. Pull the filters off and run it down the road. I was able to cut the inside of the flange around the holes and it cleaned mine right up.

 

[Patches]

Have the carbs been rejetted properly for your mods? Also, swbill is right about the crappy pod filters.

 

[shark1979]

Have the carbs been rejetted properly for your mods? Also, swbill is right about the crappy pod filters.

I am not sure if it has been jetted, the guy I bought it from said he put bigger jets in. That is one of the reasons I am trying to start fresh. I have ordered a jet kit and a rebuild kit. I will see what happens. I tried the pod filter thing. Took them off and tried it still the same.
It will run good for about 3 or 4 min , then act like it is not getting enough fuel. Let it sit for a min try again it will do ok for a real short time. Then start breaking up again. I cleaned the tank and petcoks today thinking I was getting trash in there but they were all claen

 

[Patches]

Are you running an in line filter?

Usually the size of the jets is engraved on them.

What do your plugs look like?

Have you gone through everything else like: adjust cam chain, adjust valves, check points, timing, check for air leaks, etc?

 

[alfredo]

subscribed. similar problem.

 

[twinsarehot]

I know I sound like a broken record, but have you read the carbguide?

Does "adjusted the needle" mean the idle screw on the outside? or the needle positioning on the inside? Are you running the bs34s or 38s (ie, are they the original carbs)? What are the current jet sizing? What do you plugs look like? Did you replace the plugs themselves?

Also never take anything the PO says seriously. Look it over.


www.amckayltd.com/carbguide.pdf

 

[bloodthirstysystem]

with your mods you should be 1 jet larger on both pilot and main. needle at 3rd slot (stock setting)

 

[shark1979]

Well, I have the 38s I am pretty sure. They are THe stock carbs. I have changed the plugs. They were a little white looking. The needle is on the 4th notch. When I tried the 3 notch I had the air screw all the way out before it would act right. What size jets were in this bike from factory? Thank you all for your help. Carbs are not a strong point with me .

 

[bloodthirstysystem]

read the carb guide, has the jet sizes in there. you'll know carbs after that..

you set the mix screw at idle (first, have to get this right before moving on) and changing the needle setting will not effect the way the bike runs at idle

 

[shark1979]

well i have 140 main jets. i checked my fuel bowl hight tonight. they were way off after reading i found that they should be set at 24 mm. they were set a 30+ mm . i am thinking that might be most of my problem

 

[5twins]

Yes, it probably was. 30mm is a very, very lean setting for the floats. That's probably why it wouldn't run right after a few minutes and wouldn't go over 60 - lack of fuel. In a '78 carb set with the proper float setting and 140 mains, you will probably need to run the needles in the #2 slot, one step leaner than stock. If you don't, you'll probably get bad stumbling and break-up in the upper midrange (4 to 5K) under heavy throttle applications.