Basic steps to re-jetting???

Ok, I looked but could not find a topic that gives some detail to the steps required to complete a re-jetting of the carbs. I know that this is basically an "art" / "hit and miss" kind of thing. But beyond finding info on calculating possible jet sizes needed according to mods done to the bike, and where to get the jets (Chacal's XJ4Ever) I really don't know what tools and equipment I will need, what to look and listen for.
I am pretty sure that the first thing to do would be to give the carbs a good cleaning (done). I have them bench synced and it is not running too bad at the moment. I know where to actually screw in the main and pilot fuel jets but now what?

Could someone please write up a "How to re-jet for dummies how-to"? I would really appreciate it

Thanks

 

Screwdrivers, flat type. That's what you need
If you got a sync tool that would help. Of course a colortune plug makes the thing easier but the necessary bits are the screwdrivers. First, do the syncing. 1 and 2 together. 3 and 4 together, then 2 and 3 together. If you do it right the carbs will be synced together what you can prove if you have a 4 gauge sync tool.
Colortune, there is a pretty good description about the things you need to do with the colortune in the box. That manual is pretty good.things

However, the things above aren't necessary. You can make the synching just with your ears but that's damn hard to listen and notice the different noise levels coming out from the carbs as a result of sucking air. It's easier on a flat twin but it's possible on a inline four as well.

The jetting. Again, you don't need to have the colortune because the sparks and the behaviour of the bike tells everything. But writing all those things down it's not an easy thing. It's worthwhile to buy the colortune plug and a sync tool.

Well ... almost forgot but you have to have the YICS tool. You can buy or you can make one (lot's of description on the net with pictures) but it's a must. Without that tool it's impossible to do a proper sync.

 

Thanks for the reply ZsoltK. I have a colortune plug on the way and I have pretty much all of the materials I need to make the four vinyl hose with transmission fluid manometer.
This may be a dumb question but do I need to remove the air/fuel mixture plugs?
Are the air/fuel mixture screws the ones that I need to adjust for the tuning with the carbtune plugs?
How will I know if the jets I have installed are or aren't going to do it for me?
Do I sync with the manometer before or after tuning for the new jets...or both?
Do I need a load on the motor (dyno)? (in gear w/ brakes applied)? when using the carbtune plugs or will a "no load" tuning suffice?

I guess those are some of the questions I have for now.

Carbs have always been a great mystery to me up until now. After reading so much here and actually cleaning, adjusting the floats, and bench syncing them I am beginning to understand how they workso I no longer fear them. I am ready to do this I just need some guidance along the way.

Thanks again

 

Well ... If you bought the right jets based on this page (http://xjbikes.com/Forums/viewtopic/t=14692.html, the calculation instructions are at the end) the jetting wont be a too hard. I was thinking about your question at the morning and find that there is no better guide for jet sizes other than Chacal wrote on the page mentioned above. If you did more changes then it's not easy to write down how can you find the proper jetting and the settings for those jets.


So, the simple answers to your questions.
"This may be a dumb question but do I need to remove the air/fuel mixture plugs? " - If you're talking about the small rubber bits which are preventing you to change the air/fuel mixture yes. If you're talking about something else, I don't know

"Are the air/fuel mixture screws the ones that I need to adjust for the tuning with the carbtune plugs?" - Practically - yes.

"How will I know if the jets I have installed are or aren't going to do it for me?" - That's the art part If you bought the jets based on Chacal's guide, then they should be fine. Other than this ... if the bike not idles around 1000 RPM, backfires a lot during deceleration, smokes white smoke, hesitates during acceleration, not holds a steady RPM during cruising at various speeds then your jets are small or large for your engine. In other words, if the engine behaves nicely the jets are right. If not, your jets are either to small or to large for your engine. You might say I'm not helping you at all, but that's not an easy thing to write down all the possible symptoms. Do the basics and let's see how she behaves.

"Do I sync with the manometer before or after tuning for the new jets...or both?" - doesn't make too much difference. If you do it both, that's the best.

"Do I need a load on the motor (dyno)? (in gear w/ brakes applied)? when using the carbtune plugs or will a "no load" tuning suffice?" - Never. The colortune plug will brake or the plug holes will be covered with carbon deposit and you have to remove the cylinder head to clean them.

Carbs are easy. The problem is that we have some many variables in the equation which is describing the proper setting. But for the basic set-up which should work for general purpose you don't need to know everything. Let's do the changes and report how she behaves.

 

Wow. I think i may have found a big problem with my bike right here. My idle is skrewy, i get pops sometimes with deceleration and the bike does smoke white. I have done a sync on my bike already and it was skrewy afterwards. The throttle on my motorcycle also "Hangs". Seems like all these are the right symptoms to me.

 

If the RPM's "Hang" you want to give the Diaphragm Pistons "The Clunk Test"

Clunk Test:
http://xjbikes.com/Forums/viewtopic/t=1 ... +test.html

 

File not found. Do you have another link?

 

Why exactly do you want to rejet your carbs? If all is original with your airbox you shouldn't need to. If you've removed it, fitted pods and hope to retune it, please don't be offended here, but it doesn't sound like you are yet in a position to take this on?
A rejet is generally never needed if you leave the intake alone, unless a plug cut shows it is. Do you know how to do a plug cut?
I have been around all kinds of engines for 40 odd years, and I would want a wideband lambda, lots of patients, a straight quiet road, lots of fuel and a fair bit of time. If you have binned the airbox, take the advice from Chacal, buy the jets and a pinch of salt, fit both and try it. Will you know where your wrong (ie which jets/needles), and if your rich or lean?

 

before putting hats on you lift the diaphram slide and listed for the clunk when it drops if it does not clunk the bores in the carbs need more cleaning possibly a hone pass. the slides only need cleaning you do not want to remove the finish so chemical only

video of clunk test can be found in this link way down
https://www.xjbikes.com/forums/threads/in-the-church-of-clean.14692/

 

clunk

 

If you've cleaned your carbs you won't have to hone anything. In fact I would recommend against it.

 

That’s what I was looking for. Thank you bunches. I remembered reading about this, a couple years ago, when I rebuilt and benchset them. I just couldn’t remember the details. I thought maybe it was reaching in the venturi and lifting it with the finger. But at that point, it’s got the resistance via the diaphragm.

 

Looks like you replied to my comment, by accident. I’m not rejetting. I’ve been turning a wrench for over 40 years as well. But thx for trying.