I finished the wiring on my project, gassed it up and it fired right up but it won't run higher than an idle. It's a 1980 XS650 w/ BS34's, just gone through. I put one size higher pilots and mains, 25 and 135 respectively. I have Uni foam filters, lightly oiled and a MAC 2-into-1. Any body got any ideas?
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Idles fine, but pops back above that
- Thread starter deacon883
- Start date
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- Tags
- carburetors
littlebill31
Smells of Raw Fuel
Stock would be 42.5 pilot and 132.5 mains.
Does it stall when you give it throttle?
Does it stall when you give it throttle?
Ok, got back from my weekend of fun and went to work in the shop. Pulled the carbs, changed the pilots back to the stock 42.5's. Reinstalled the carbs with high hopes and it made no difference. It will start and run at idle, but runs rough if I open the throttle at all and does not increase the rpm's. Sort of pops, not back through the carb though. Do I need to wait til my 45 pilot jets get here?
Should run up with what you, got spray a little carb cleaner around the front of the carbies see if it revs. what does choke do? check your fuel levels yet?
littlebill31
Smells of Raw Fuel
Just spent the last hour rereading the carb guide,
i had my mixture screws out only 2 turns, increased it to 3 turns. gggary, I did do the vacuum leak test with carb cleaner, no change so no intake leaks. I pulled the carbs again and will do a more thorough clean and spray out, special attention to the pilot circuit holes in the top of the venturi. I'll let you know tomorrow night...
i had my mixture screws out only 2 turns, increased it to 3 turns. gggary, I did do the vacuum leak test with carb cleaner, no change so no intake leaks. I pulled the carbs again and will do a more thorough clean and spray out, special attention to the pilot circuit holes in the top of the venturi. I'll let you know tomorrow night...
littlebill31
Smells of Raw Fuel
Are the synched correctly? I would also double check float height too. You have an '80, so the height is 27mm for the brass floats, which is stock. But if you have plastic floats, which some change to, it will be 22mm instead. I would also remove the mix needles. There is, in this order, the needle, spring, washer, then an O-ring. If the washer and O-ring are gone, it will not idle correctly, in my experience. Also check the style of needle. The BS38, non-EPA, is a non-step needle and shorter than the stock BS34 EPA stepped needle. Since it is shorter there is a n adjustment difference. So 2 turns of the short, non-step is about equal to 3 turns of the stock, longer needle.
Well, I got the new pilot jets today, from Jet R Us. Recleaned the carbs, special attention to the three little holes behind the throttle plate, everything is clear. The mix screws have the washer and oring properly installed at three turns out. I set the plastic floats at 21mm from the gasket surface, I'll check level with a piece of clear tubing. Would to high fuel level cause this problem?
crazyazsredneck
XS650 Addict
is u bettery full charged????
littlebill31
Smells of Raw Fuel
Best thing to check your timing is with a timing light. You have a TCI though, not points, so the light will tell you if the TCI is bad, but you really can't adjust the timing like a points system. If it is the timing a diode may have gone bad in the TCI. This has not happened to me, but from what I have been told, and read, if a diode went bad your bike would not run. Although I would still check the timing with a light.
Sounds like it's not getting gas honestly, so...
Does it idle or do you need the choke for it to run??
Everyone will tell you as well, and it's a must. You need to check/adjust your cam chain tensioner, then vavles, then timing (but you have a TCI), then go to the carbs. So check these as well.
Are you petcocks clean? Carbs synched?
How are you getting the "3" turns out? There is a process called the "dead cylinder" method. It's in the carb guide. That's how you adjust the mix screw. There is no set recipe for these carbs. All are different.
Sounds like it's not getting gas honestly, so...
Does it idle or do you need the choke for it to run??
Everyone will tell you as well, and it's a must. You need to check/adjust your cam chain tensioner, then vavles, then timing (but you have a TCI), then go to the carbs. So check these as well.
Are you petcocks clean? Carbs synched?
How are you getting the "3" turns out? There is a process called the "dead cylinder" method. It's in the carb guide. That's how you adjust the mix screw. There is no set recipe for these carbs. All are different.
I checked timing w/ a light, dead on at idle. I'm getting gas, have checked levels w/ clear tube at drain cocks. It starts easily, idles fine. Petcock is brand new Harley item. I guess next step is to build manometer and check sync.
im having the exact same problem, have you figured it out yet? Im running the stock jets on my81, open intake and exhaust. Thing is i had it runnign (kinda) it waas ridable, then after thouroughly cleaning the carbs, it was harder to start, and dnow it will start and idle, albeit rough, but exhaust pops on any try of acceleration. If i can figure this out, id love to get it runnign soon. local shops around here only care about getting paid, and not trying to help out the little guy.
Brilamb2, this probably won't help you, just add to your frustration... I had a bad TCI box. As soon as I located a replacement from E-Bay, it fired right up and has been running great. Is your wiring harness stock? I made my own harness using a simplified diagram I found here, and it's possible that I killed the original TCI by not tightening the ground lead to the frame. My only suggestion would be to clean and tighten all the connections in the ignition system. I know a guy named Rickthefix who can repair TCI's, pm me for his info if you need it. Have a great day in the name of Jesus!
