Am I on the right track? bs34's

section8joe

section8joe

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Ok, I running long pipes with no baffles 1 3/4 and Mike's XS pods. 45 and 137.5 jets. Mixture screw is 3 turns out. I understand that 1 and 3/4 pipes aren't really ideal for these bikes. Anyway, the bike is running waaayyy better then stock jetting. I do have some issues and I just wanted to see if I'm on the right track. Idle is set at 1200. Bike idles great. After the bike runs for a bit idle slightly hangs when coming to a stop. The pipes pop on decel. 2 or 3 times on a 15 mile ride the bike seems to loose power for a quick set. It even stalled at a light while idling. When I give it full on gas it will cut out for a sec then picks back up.
I'm thinking the bike is still running kinda lean. I think I'm pretty close on the pilots and and maybe need to go up a size on the mains. Should I use the mixture screws to richen the pilot and see what happens? One other thing I wanted to note. I was using the dead cylinder method to get the correct mixture setting. I had the screws 3 turns out. When I moved the screw 1/4(carb guide guidelines) in and out not much happened. Should I do some thing different?
Sorry for the long post. I just wanted to be descriptive.
 
Are the carbs synched? Most of the performance guys recommend a restriction cone in the exhaust port when running 1 3/4" pipes.

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The haven't synced the carb with a manometer. I don't have torque inserts but I did but off the first few inches of the stock exhaust and weld the larger diameter pipes to the original pipes. Should I be trying to adjust the mixture screw a different way? I set my idle at 1500. I then kept the original plug in the cylinder. I grounded the plugcap using a grounded spark plug. I then tried to move the screw in and our 1/4 turn. Very little change in idle.

I just noticed this... I have my bike setup to run with the lights on or off. I noticed that my bike will idle slightly higher with the lights on. Not sure if it matters.
 
your stock pipe inserts should help.
I'd synch the carbs there are plans for ahome made manometer on the site. I don't (haven't) use the dead cylinder method so can't comment.
 
Ok, I make a manometer. I used the dead cylinder method to set the mixture screw. I believe that once I unplugged one spark plug my idle was around 300 or 500. So when I mess with jets I need to set mixture screw then sync right? I just want to make sure I'm doing things in the correct order.
 
It does not matter really which you set first.

I would do the sync at 1200 rpm (use the screw between the carbs), then go to one cylinder running at about 300 to 500 rpm to adjust the mixture screw. Adjust the other cylinders mixture screw. Lastly, re-chack the sync.
 
If you change the pilot (low speed) jets, you will probably need to re-set the mix screws. The mix screw and pilot jet go hand in hand and work together. They are part of the same carb circuit (idle or low speed) so if you change one, it influences the other. Changing the main shouldn't affect the mix screw setting unless you did a radical change of like 5 or 6 sizes. Then it might.
 
Ok, I set the idle between 3 and 500 and tried to reset the mixture screw. I really didn't see or hear any difference. I think my carbs are really out of sync too. I tried using the manometer and I have to yank the tube off the carb holder to stop it from sucking oil into the carb. I'm trying to sync by putting my hand on the ends of the exhaust and the bike seems to be run a bit better. If I tighten the sync screw it opens the right carb and closes the left. True?? The bike seems to be dying around 3500 rpm for a sec then again at 7/8 throttle. I'm assuming I need a larger main. Right?
 
The answer is false on the sync screw and Wrong on the larger jet the 137.5 should be just about right for the straight pipes set your mixture screws 2 and 1/2 turns sync the carbs!!! I don't care how mutch oil you suck in the motor if you don't sync the carbs I can't help anymore. On the false answer the center screw adjusts the right carb only even though they are linked. Ride it tell how it runs. And 5 twins I know this is going to be a real :banghead: someone is probably out buying 5 or 6 over jets now since you brought them up in your piolet jet mixture screw example. :laugh:
 
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Carbs are synced up perfectly now. I'm working on a charging system issue. Once that's taken fixed i'll have to revisit my carbs. Thanks Scabber.
 
Yes your not stock now you have changed the piolet to a 45 correct. Reread 5 TWINS EXPLANATION again lowspeed circuit. How is it running after the sync. not driving at idle it will idle or not?
 
section8joe,
The low speed, pilot, idle circuit are all the same. Different names but all referencing the same action. The first 1/4 of the throttle. The carb guide has the illustration of three over lapping circles to give a visual. All the names apply to the first circle.
 
I understand that, he suggested that I have my mixture screws at 2 or 2 1/2. Curb guide recommends 3 out on the 34's. He recommends rereading 5twins low speed circuit explanation. I'm just trying to find it.
 
Sorry guys I'm rushing around at work trying to read and post from my phone. I apologize for that. I'm making myself look like an idiot! I red 5twins post and I did reset my mixture screw. I cannot find any reference to 2 or 2 1/2 turns out for 34's. Post 5c of the carb guide lists all the carbs and screw settings:

XS1, XS1B: 1 turn
XS2, TX650, TX650A: 0.75 turns, XS650B: 0.75 turns
XS650 C, D: 1.5 turns
XS650E, F: 2.25 turns
BS34, all: 3 turns

I also used the carb guide advice on how to adjust the mixture by moving the screws in and out 1/4 turn. Did I miss something somewhere?

I appreciate the help and everyone's patience with this issue.
 
When you install larger pilot jets, you've added more fuel to the mix so the mix screws may not need to turned out as much as they were before. That's why you need to re-set them any time you change pilot jet size. Where they were may not be ideal anymore with a new jet size.
 
The 2 and 1/2 turns was a good base line setting since you got hung up on mixture screw settings and not sync your carbs. Any advice I can give you from here on is in the guide and from talking to XS John. With his needles with straight pipes he recommended a 49 piolet 135 or 137.5 main his needles no longer exist. His needles looked like the canadian needles in the picture in a thread on this forum.. John and I didn't always agree I run my carbs leaner for performace and he liked to run ritcher cooler running what we did agree on was main jet selection. How you run your bike ritch or lean is up to you. Your pipe selection makes the perfect tune impossible on a street bike in my opinion. Since You have got you carbs in sync now take it out and run it and see were you are at now. So far you are the right track. I don't recommend 49 the 45 is a better choice you can up to 3 and 1/2 turns mixture screw it might clear up
 
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