Any XJ experts in Socal?

I need someone in socal to take a look at my carbs and get my bike running right.

Right now, anytime I get over about 70% on the throttle it starts to sputter out and feels weak (any gear). It is also rather weak even accelerating, weaker than it was before. I don't know if something just needs to be adjusted or if the carbs need to be rebuilt or it needs new jets or what.... I can ride it but it just doesn't feel right.


Any recommendations? A bike mechanic or shop or even someone in their garage that really knows the ins and outs of XJ's?


I don't have tools, patience or space to take it all apart and try to fix it myself. I honestly think that if I tried, I would end up frustrated with a pile of pieces and parts and a motorcycle that would never run again.

 

hey mike

I think your issue is actually pretty easy.
is it popping at all before it sputters? sounds like it is a bit lean... okay, a lot lean. the reason I ask is that you are running straight pipes which will change the dynamics of the air/fuel mixture.

what I would recommend is to do a plug chop as you are getting close to your driveway. get it to sputter and then pull the clutch and kill it at the same time.
have a good look at the plugs. post pics of them and we can help you with it.
if all 4 are white or not showing anything at all, you are lean and a rejet might be in order.

if you are not under load.. sitting in neutral with it idling and give her a lot of throttle, does it respond okay? does it hesitate off-idle to around 2500rpm or so? does it do it under load, too?

once you get the plug chop done, idle it for a few minutes in the drive and check the plugs then too.

do you have the stock airbox? pods? factory recommended air filter?

most of the issues you describe can be fixed with a set of screwdrivers and some patience. all the members here are more than willing to help out with as much as we can.

 

Thanks helmet. I will give it a shot today.

Some more info.

Yesterday I put some shorty mufflers back on the bike and it still responds the same way, which led me to post this thread.

So now, I have mufflers it still feels weak BUT when I am sitting in neutral, it responds FINE no hesitation, it only feels weak when I am riding it. What does this mean, compared to if it responded weak under load or in neutral?

 

just trying to rule out sticking slides as part of the cause. sticking slides will react about the same under load as well in neutral.

it does sound like you are getting very lean as you rip the throttle.

do you have the factory airbox on it?

 

everything other than the mufflers is stock. I did notice the top of the airbox is broken, missing about a 1" piece on the side of the top cover.


The problem is that this wasn't happening before I had the mufflers taken off.


I have a sneaking suspicion that the guy who I left my bike with to weld on the straight pipes screwed around with the carbs trying to make the bike run better. The reasons I am thinking this is what happened are;

1. the guy claimed to know a lot about motorcycles.

2. I told him that I read that if you modify the exhaust it could cause scew up the way the bike runs.

3. My bike would take a LONG time to warm up with the choke on. Once it
was warmed up it ran PERFECT and STRONG, but until then it would run pretty rough.

4. I think that he must have welded on the straigt pipes, started the bike up not knowing that it needed to warm up for a while, figured that the pipes screwed up the way the bike was running, and started fiddling with the carbs trying to get the bike to run right (even though it was just cold)

5. He got the bike to run right without warming up by screwing with the carbs, but now whatever he did to make this happen kills the top end when I am riding. Now instead of having the choke on for 5-10 minutes to warm it upwhen I start, it starts with no choke and runs pretty much ok from the start, maybe 30 seconds of letting it get going. Choke kills it pretty much.

This is like a CSI investigation now.

.....So what could a "motorcycle guy" who knew enough to be dangerous could have done to the carbs that could be causing this? I know he had taken the tank off the bike so he had access to the top of the carbs. And Can I get in there and reverse process? I really don't want to re-jet the carbs or do anything unnecessary. It is a beautiful day and I want to hit the road!


Also, this guy and I had a dispute about the work he did for me so I can't just call the guy and ask him if this is what happened, he probably wouldn't answer my phone call.

 

Dude lesson #1,dont piss off the guy workin on your bike even if u are pissed off. suck it up til u get the goods and remember that even if u dont agree,u hired HIM. whether he was right or not doesnt help u now and the guys here can get u to the first hurdle and probably to the finish line if u ask. Always remember that burning bridges does not allow u to return back the way u came. It is a hard thing for us all even some o us that would rather knock the guy out than look at him twice but again,LIVE and LEARN.

 

at least call to find out if he re-jetted the carbs, etc
the rest of it will be pretty simple once you have that figured out. as for the broken spot on the airbox: as long as the air filter is between the crack and the engine, you should be fine

what I would do if I were is start basic...
check your plugs at idle. are they white, tan, black, clean as a whistle, etc.
if they are anything but TAN do the following: please make note of how many turns it takes to turn them in! just in case you have to reset it the way it was
reset the idle screws to 2.5 turns out... do this by locating the 4 idle mix screws by the intake boots. they are copper, straight head screws
turn them clockwise till they SOFTLY bottom out. turn them each out 2.5 turns.
take the bike out again and get it fully warmed up by riding it. bring it home, idle it for a minute and kill it. check the plugs, make note of how they look.
if they look good (tan/caramel) take it out and see how it runs.
if it still acts up, bring it home and do a plug chop... as you approach your drive, have it running at 4k rpm. pull the clutch and kill switch at the same time. coast in and have a drink. let it cool and pull the plugs. see how they look. make note of it and post here.
pics are helpful too. number the plugs so we can get a better idea.
if they look good, take it back out and get it to sputter as you get close to your house. do another plug chop while it is sputtering.
check the plugs again. once again, let us know how they look.
I realize this is a lot to do, but all it takes is a 13/16 socket, a small straight screwdriver and some patience at this point. I am sure we can get it running good again

 

I know the guy didn't re-jet the carbs, I think he messed with the mix screws and then gave up. Re-jetting meant he would have had to buy new jets and put some actual effort into it.

I kind of did what you described already today (I was bored)

The problem is I pulled a plug out and it the end was black? I have no idea if this recent or old black. What do it do? Replace the plugs so we can start fresh? If it the mix is wrong, how fast will the plugs go black?


I also fooled around with the mix screws, and it actually seems to be running a little stronger now, but it still isn't the way I want it. It is a pain in the butt to do keep playing with those screws, pull the tank, adjust put the tank back on, ride.... repeat. Do the screws on all the carbs need to be adjusted the same amount, or can one carb need 2.5 turns, the next 3 turns, the next 1.5.... and so on? I tried to adjust them all equally. Also, if you bottom the screws out, what does that do to the mix compared to turning them out say 5 times or whatever?

 

if he didnt re-jet, the idle screws is where he did 90% of the work.
black is rich. very rich.
like most things, they require balance to run right. however, what is balanced for one cylinder may not be balanced for another. so, it is possible to have 4 screws all tuned differently. usually, not by much though.

these screws make a HUGE difference in the way they run. one dime or nickel widths turn on the screw can make a lean bike rich and vice versa. that is why I recommended starting at the base of 2.5 out and then fine tune from there. if you have access to a box fan and a vacuum gauge, you can tune them in one shot. the idle circuit actually feeds the bike through the entire rpm range, but it's a small amount when you are turning 8k on the dial. they simply arent designed to flow that much fuel because of the small jet sizes.

also, do you know if he tried to sync the carbs?

 

gee watching this post has told me something. thanks helmet. i got one cylinder tha is rich just like u described and was wondering why. now i know and will make the correction tomorrow. thanks.....its the #3 carb that is rich on mine.

 

glad to help Joshua!

 

helmet thanks.

I am going to try your method tomorrow from 2.5 on all 4 and try to fine tune them. Just playing around today (before your instructions) I got it from say 60% up to about 80% of where it was originally, I think with your last couple of posts I can get it back where it should be.


Can you describe what the procedure is if I have access to the vacuum gauge and box fan? And how will I know if each one is set correct? And what about the black plugs? What should I do with them?

 

you can clean the plugs up and put them back in... if not, pick up some new ones. most places carry them in stock for a couple bucks each. stay with OEM replacements... iridium, etc. take a lot more spark energy to fire than these coils can offer.

as for the vac gauge, pull the vac cap off of one of the cylinders and make fine tuned adjustments to it. after each adjustment, blip the throttle and adjust so that you get the highest reading on your gauge.
do that for each cylinder. if you can leave the tank on, great!
this will get you very close to how it should be.
the fan goes in front of the engine to keep it cool while you are tuning. you dont want to overheat it

 

Mike, I am in socal. Send me a pm anytime

 

Ok, I went and adjusted all 4 carbs to 2.5 turns, rode it around similar results as before. Adjusted to 3 turns and had similar results.

Maybe this isn't the problem?

Here are my observations on how its running maybe this will give anyone reading a clue as to what is wrong with it.

1. I need the choke to start it, and it takes a long time to "warm up" where it will idle and stay idling. I have noticed that before it has ran for a while the idle seems super low like it can barely stay running unless I give it gas or put the choke about halfway on. Then once it has run for a while like if I ride it around for 10-15 minutes, the idle seems too high, almost like the throttle is stuck slightly open.


2. Riding at high RPM/Speed isn't a problem, it is acceleration that is screwed up. If I steadily increase the speed/RPM the bike runs fine, but if I try to gun it from low speed, it accelerates up to about 4-5k (I guess, no tach...) and then starts sputtering like it isn't getting enough gas fast enough. Again, if I slowly accelerate in like 3rd gear it seems to run totally normal, no sputtering.


3. I noticed no real difference between 2.5 turns a 3 turns on the mix screw and where I had it before which must have been around 4 or more turns.


Any clues?

 

sounds like your slides are sticking now.
the slides are vacuum operated and as engine speed is increased and throttle is opened, the slides open to expose the emulsion tubes and allow gas to be pulled in from the bowl.
if you crack the throttle and steadily increase speed, you allow the slides to come up.
when you get on it, you are increasing at a rate faster than the slides can open which will cause sputtering, starving for fuel.

if you decide to clean the slide bores, look up any post by RickCoMatic. he has links to the carb cleaners dream job. step by step with pics and how-to's.
also, he explains emulsion tubes and why they are so, so important.

again, all it takes is a screwdriver and patience. there are many many members here that are always willing to help if they can.
a certain member has even worked with people on webcam to help them out. how cool is that?

 

helmet, I would rather avoid rebuilding, removing or taking apart the carbs if possible.


I bought a can of seafoam, I want to try running it through the engine and see if helps. Any tips on seafoaming an XJ? Do I mix it with a full tank of gas? or??


I am also going to check for any vacuum leaks on the intake.

 

what I usually do with seafoam is remove my tank and fire the bike up.
as it runs, I start to pour SF into my fuel line until it starts to bog down. I throw the "choke" on about halfway and pour a bit more in.
once it starts to smoke a bit, I kill it and let it sit. usually 20 minutes tops.
put the tank back on, put it in PRI and let it sit another couple minutes.
fire it up and watch the clouds roll out of the exhaust.

once that is done, I put some- 1/2 cup or so- into a half tank of gas and run around town.

 

thanks buddy, gonna give it a shot tonight.

 

Mike, I'm in Ventura, I have a colortune and I don't mind tearing carbs apart. Shoot me a PM if you run into a brick wall.