4th and 5th gear, mid range rpm's??? No pull

[Shifty2932]

So I have found out that I have a set of 78-79 BS38 carbs. I am running stock setting for the carbs, I have crappy kn pod filters, and running drag pipes with thumbscrews for baffles. Trying to wr my head around this small engine stuff. Diesel and jet engines are much simpler. I know I need to change the pods and I'm going to be getting uni pk82 for that. The plugs right now are black! That would be a sign of running to rich, correct? So I would not want to increase jet sizes, right? As this would cause an even richer environment?? Reading other posts I realize drag pipes are not best for mid range rpms. However I feel that when I am in 4th or 5th gear and want to get up go I should just be able to roll on the throttle. Right now this is not the case. I grab a handful of throttle and nothing, until I roll of about 1/8 or so and the r's start to pick up and away I go. But this is not the case all of the time. The grade of the road must be advantageous for this to happen. Any suggestions on what to do to get some power / torque in the mid range?

 

[gggGary]

Have the carbs been disassembled cleaned and overhauled with all needed parts replaced? Floats set, new fuel and vacuum lines, petcocks verified completely functional? You can't throw jets in a donkey and expect it to win the Derby.
Ignition and advance curve tested and set?

 

[Shifty2932]

Carbs have been disassembled, cleaned, and didn't notice any parts that need replacing. Again, all carb settings are stock. Haven't touched the vacuumed lines, petcock does work and is functioning as both carbs are getting the same amount of fuel.

Haven't touched the ignition as I am new to this set up and not sure how it all works yet. How would I go about doing that? I would imagine a timing light? Also heard of using an ohm meter as well.

 

[650Skull]

seems to me you were getting good advice from the right people, (and gggary is one of them), in your other thread, and on the way to getting your problems sorted out. Why start another thread about the same thing???????????

 

[Shifty2932]

650 skull,

Although this thread is similar to the other, I have posed other and more questions regarding lack of power. I took the advice from the other thread and am putting it to use. I've checked the advance rod and spring, all good there, I am getting knew pods, I've corectly ID my carbs all from the help of those members who responded to my thread. I gave kudos to all those who assisted me in that thread. And all that info has helped greatly in figuring out what is going on at that time. This thread although similar is different. I have posed new questions and theories as to why this may be happening, not just limiting myself to focus on the carbs being the problem. As it could be a number of things. Everyone on here so far as been very helpful. But by posting a new thread and throwing a new title on it i have gained insight from a member who did not respond to my initial post about adjusting carbs. And to me that is very valuable. Continuing to reach outside the box and ask for more info is not a bad thing.

 

[650Skull]

Did you read and try any of what the carb guide suggests.
Some links for ignition and timing

http://www.xs650.com/forum/showthread.php?t=28343

http://www.xs650.com/forum/showthread.php?t=25994

http://www.xs650.com/forum/showthread.php?t=26028

A link back to your other thread for some of the answers that will benefit your question here.
http://www.xs650.com/forum/showthread.php?p=292568#post292568

Especially 5twins last 2 posts

 

[Shifty2932]

Well I'm waiting for my pod filters, but in the meantime I lowered the needle and the clip is now in the number 2 slot. I also removed the kn pods and took the bike for a spin. With lots of open road. I did notice a little bit more pull. Between 1 and 3 gears mid range rpm pull was definitely noticeable. Accelerated very quickly through and past mid range rpms. In 4 and 5 gear however improvements were there but not that noticeable. Now there is a little bit of an increase in power through the mid range rpms in 4 and 5 gear. I actually increase speed a bit I instead just getting on the throttle and going nowhere. I will report back once I get the new pods put on and maybe also thinking of just putting new pilot (1 size up) and new main (2 sizes up).

 

[5twins]

Well, with the mods you have and still using stock jets, I would expect the power to be down. Now you've gone ahead and made the midrange even leaner by lowering the needle. What's wrong with this picture? lol. These CV carbs like something on them to help smoothly channel the air in. They don't work very well wide open and bare assed. And they don't work very well with K&N type pods. And they don't work very well when you do mods but don't re-jet to compensate for them.

Yes, go up one on the pilots (from 27.5 stock to a #30) and two up on the mains (from 135 stock to 140). Leave the needles leaned a step once you put the larger jets in. This is something you need to do BUT only after installing larger mains. You don't lean the needle setting on a modified bike running stock jetting. Eventually, to fine tune it and see if the jet sizes you've chosen are right, you will probably want to try 32.5 pilots to see if they improve the low end and 142.5 mains to see if they improve things on top. Do one change at a time so you're better able to see what effect it's having.

 

[Shifty2932]

I have an update. I have put some bigger jets in and switched out my pods. No one in town had a #30 pilot jet on hand as I could only find #32.5 so I picked a pair of those up as well as 140 and 142.5 mains. Well I put in the 32.5 pilot and the bike would not idle...at all. So I took them out and put the 27.5 back in. For the mains I decided to start big. So I put the 142.5 in. Mixture screw is a 2 turns out, pilot at 27.5, main 142.5, and needle clip is in the second slot. I am running uni pod filter now. Couldn't find any pk82 so I am running the up4200st. From what I can tell that are basically the same. Took the bike for a spin, worked through the gears and rpm range. Things seem to have improved. Little back fire here and there when letting of the throttle and back on quickly. 4 and 5 gear mid range has improved. It does not get up and go, but I gradually increase speed. Low end power is good and of course high end is more than enough. I am pleased that things seem to be getting better. Oh, and I also I stalled new plugs, caps, and wires. Attached is a picture of the plugs after my ride. Take a look let me know what you think. They are in position respectively (left and right). I disc not try the 140 mains yet has I did not have time to switch them out and take the bike back out for another spin.