Just my perspective on jetting carbs for the 1st time

[Hammer-N-Anvil]

Hi All,
Long time lurker first time poster. well I've made comments here and there in the past, but this will be my first thread. I think I'm just looking to document some of what I've done to the bike and see if anyone has any suggestions or similar issues going on, as opposed to asking directly for help. I think if someone where to directly tell me or show me how to fix a problem then this wouldn't be as fun as it already is. I enjoy learning and trying new things and figuring out why what I just did made things worse...

Okay, enough with the eHarmony application.

I bought a 1975 xs650B in good running condition. The engine and frame have been given more than enough love and have had plenty of identity changes in the past. I finally had the dream vision of how the bike was suppose to look after 2 years... in an actual dream.

The engine has had all the necessary love without pulling it completely apart. I did the cam chain, valve lapping, timing... read the carb guide, the carb manual... All things I really enjoyed learning and doing myself. I've been working on the carbs for some time now, not rushing anything. Sometimes going a week without fudging with it. It's suppose to be enjoyable, right? Well, I want to fucking ride now!
I've gone up and down the list of pilots and mains, now having bought damn near every size on it. Just working on fine tuning the bike now.

I am currently running VM34's with 42.5 pilot, 150 main, and with the needle jet up 1 from center (which I believe is the #4 slot, but I can't remember if it counts up or down at the moment ) UNI pods, straight pipes.... yada yada yadda all the things listed below. The bike now fires up great, needs a little love with the mixture screws, but can be dialed in no problem. I've played a bit with different pilots and mains and it seems to me that I am getting closer to where I need to be. I just need to take some tools and the jets with me to a parking lot one weekend and tool around to see what works best. Because I have found that what sounds good in the garage doesn't mean shit on the road.

My main reason for posting this is, when I first started this process some of what I read on here was extremely intimidating and down right confusing, but after taking the time to do things right and do my HOMEWORK, which I always hated, it really has become quite enjoyable. I may be doing things that most experienced bikers would scratch their heads at but I'm learning how to do things myself... Which has always consisted of breaking it first then figuring it out....

Feel free to point out any major flaws in my methods, or post your own experiences, favorite links, horror stories, ect... These bikes have now become the garage builders cherry popper I believe and I'd like to get to the point where I can help out more of my buddies when they have their owns issues... Thankfully there haven't been any carb issues yet.

Cheers

 

[TwoManyXS1Bs]

Hey, Hammer, sounds like you have a grip on things, doin' good so far.

Your first biggest flaw is NO PICS!

Glad you're enjoying the learning process...

 

[5twins]

Are you sure you have VM carbs? I ask because 42.5 pilots are huge for them and 150 mains are small. I never heard of anyone running jetting like that in VMs.

 

[TwoManyXS1Bs]

Those do sound like BS34 numbers, but if you're really running VM's, this could be an interesting read:

http://www.xs650.com/forum/showthread.php?t=6570

 

[Hammer-N-Anvil]

Ah well there you go... BS34 are most likely what I have, I couldn't quite make sure 100% what is was I had other than the 34B 168 stamp on my carbs, but as a visual trial/error type I was not able to find any sort of identification chart that spelled out what exactly it was that I have. I have 100s and 100s of pics from start to finish that just need to be sorted through. I almost documented every freakin' pains-taking step

 

[5twins]

You have 2 left side VM34s there. That's why the idle speed adjustment screw on the right carb is buried between the two carbs. They make a specific right side version that has the idle screw on the right for easy access. 42.5 pilots, my God, it must smell like you're standing in a puddle of gas, lol.

 

[grizld1]

Looks like you didn't find the link to the VM 34/36 section of the XS650 Garage Carb Guide while you were doing all that reading. I'm not going to play "Write it again just for me," but I'll tell you right now that you're not even close to a viable baseline.

 

[Hammer-N-Anvil]

Thanks 5twins and TwoManyXS1Bs I really appreciate clearing it up. Now that I know 100% what it is that I have in front of me I will do the necessary research. But the reason for using the 42.5 pilots was that the bike ran like shit with anything lower and would hang big time with a blip of the throttle. Upping the pilot made that go away completely (which I pulled from the carb guide). No fuel smell, runs great at idle and decent at mid range, i need to work on the mains, which will in fact effect the pilots, but nothing seems to be really obviously wrong with the bike. I may be solving a simple problem with a complicated solution, but like I said, it's my first go round. I plan on making plenty of mistakes and in doing so, I will i the future be able to say why one can't do something for that specific reason...

I by no means am saying that what I have done and am doing is the way to go, nor have I asked for help. I know you guys are constantly repeating yourself thread after thread grizld1 and I appreciate that. I don't want anyone to get burned out by helping others. I was raised with the "Hello McFly" method as my old man would knock on my head... I don't mind people pointing out the obvious, I just don't always get it after the first knock.

 

[grizld1]

Some guys will never learn it, but there's more to a carburetor than mains, pilots, and needle clips. I'm not gonna screw around with a bunch of long-distance diagnostics--been there and done that a few times too many. You can strip those carburetors, find out all of what's in there, check float level, and do it right, or you can take short cuts and post a bunch of drama.

 

[5twins]

The thing with the VMs is there are so many tuning parts (jets, needles, etc.) available that you could spend the rest of your life trying to sort them. That's why an established baseline (jetting specs that work for your particular bike) is what you look for. There is a good baseline for the VM34s on a 650. Find it, use it, and you'll be golden.

 

[Hammer-N-Anvil]

5twins Much appreciated! and thanks for the moral support grizld1