I am having some issues with my carbs. The left carb is hissing when i apply throttle. I changed the float level recently so i went back in a changed it again. At this point it ran at idle very well on the left side and the right started sputtering and backfiring. when i give it throttle the left hisses and the right pops and sounds weak.
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BS38 Carburetor Issues
- Thread starter BCoop
- Start date
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- Tags
- carburetors
How in the world do you know if the float is going up and down?
xskid
xskid
Ok I have cheap pos filters and open headers. I know this isn't the ideal set up for performance but I should be able to get my carbs to the point that the bike is running and responds appropriately to throttle.
My real problem is figuring out why fuel would be spitting back through the carb?
My real problem is figuring out why fuel would be spitting back through the carb?
Got it to run on both sides by adjusting float level. Took it to work and back and then the next day it broke down on the way to work. Left cylinder stopped firing and hissing through carb.
Today I cleaned the pilot curcuit and all other circuits in the hissing carb but when I reinstalled and started her up it was acting the same. The. I adjusted the float level in the hissing carb and it ran on the side and not the other. The other carb hissing like the first!!!!
The problem just switched sides.
Today I cleaned the pilot curcuit and all other circuits in the hissing carb but when I reinstalled and started her up it was acting the same. The. I adjusted the float level in the hissing carb and it ran on the side and not the other. The other carb hissing like the first!!!!
The problem just switched sides.
No offense, I have no idea who you are or what your mechanical level is, and I haven't read your other threads, but your posts in this thread sound crazy. I have worked on lots and lots of BS38s, and I've helped or tried to help lots more with BS38s, but I have never heard of hissing BS38s. Maybe it's time for you to provide a video of what your carbs are doing.
bikefreak69
XS650 Enthusiast
Check them for air leaks by squirting carb cleaner at all the connecting joints and at the pilot screw and throttle shaft seals,if revs pick up you found the cause.
richardthemotorcycle1
XS650 Guru
Do you have everything good and tight? Did you put the carb diaphragms in correct?
I cannot hear hissing over the noise of the engine. Is it running on only one cylinder in your video?
My guess is that the bike dies when you give it throttle because you are flooding the engine. Easy to check by pulling the plug on the running cylinder after you give it throttle and it dies. If you are flooding, the plug will be wet.
If that's the case, we can go on from there.
My guess is that the bike dies when you give it throttle because you are flooding the engine. Easy to check by pulling the plug on the running cylinder after you give it throttle and it dies. If you are flooding, the plug will be wet.
If that's the case, we can go on from there.
Yeah it was running only on the right cylinder. Since then I changed the left carb float
Level and it idles on both sides. I can now give it a small amount of throttle without it dying.
Changing the float seems to be the ticket but I can't seem to find the perfect level.
Level and it idles on both sides. I can now give it a small amount of throttle without it dying.
Changing the float seems to be the ticket but I can't seem to find the perfect level.
You do not tune XS650 carbs by adjusting the float level. There is a correct float level for each carb model, and anything else is incorrect. I'd tell you what your level should be, but you still haven't said what carb set you have, and your fingers were covering the lens in your video so the vid didn't help I.D. your carbs either. You can find the level yourself in the Carb Guide, along with how to set it.
In the carb guide there is a section on "Tuning For Mods" Have you read the carb guide yet? www.amckayltd.com/carbguide.pdf
Leo
Leo
Every 650 from 1970 to 1979 had BS38 carbs so yours is nothing special, lol. To tune them properly, you have to I.D. the year of the carb set, then base your re-jetting on what was stock for that year.
I am pretty sure that they are 1970-75 bs38's. I have to check the size of the main, but the floats are set to 24m. The pilot jet is stock, and the needle clips are in the 4th position (1 step down) so the needle rests higher.
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I tried to switch up my settings. So I checked the float level. I raised the clip to the 2nd position (lowering the needle). Then I started her up. She idled great and was flattening out and dying aroud 1/4 to 2/4 throttle. The left spark plug was wet upon inspection. I noticed that it would idle, and fire on both sides fine but after ten or so seconds the idle gets sputtery on the left and then it goes out completely. It's gradual. I'm left with a pilot curcuit that's sucking air so hard i can hear it make that "hissing" noise i've been talking about.
I want to buy a rebuild kit to rule out any malfunctioning parts. Has anyone dealt with this?
I want to buy a rebuild kit to rule out any malfunctioning parts. Has anyone dealt with this?
