Dialing the carbs in

So my valves are adjusted and I bench synced my carbs. The bike ran much better, way more power and helped my bad mpg issue as well. Today I rode to work and my bike would barely go 70mph, felt like there was nothing in the throttle past halfway. Not sure what to do now.

 

Did you remove and clean the emulton tubes? Did you check that the slides move freely? Did you inspect the diaphragms for pinholes?

 

+1
Is it cutting out at 70 or just no power at 70.
Also not be personal, are you a large rider like me? Mine gets sluggish around 80 - 90 due to my size (325).

 

Slides move freely, I checked the diaphragams and they were fine. Not sure what the emulton tubes are?

 

Cutting out right at 65-70, I only weigh 160 lbs. I was just flying on it yesterday at 80+ with plenty of power and today it isn't there.

 

That's a problem. If you don't know what they are, can't clean them.

Emulsion tubes have the main jets screwed into one end and have the needles from the slides going into the other. You need to pull the slides, unscrew main jets, and push tubes out towards top of carb.

 

Ah OK, I know what they are now. I had the carbs apart the other day and everything was nice and clean, no clogged jets or anything I could see. It ran flawlessly when I put them back on for a few days then this just started today.

 

Emulsion tube real name is needle jet.
try taking out the bowl drain screws, catch the gas and look for dirt.

 

Will check when I get home today. Is there any reason my butterfly valves would come out of spec after syncing them?

 

after you drain the bowls, turn the tank to prime and rinse the bowls a bit. rather doubtful that one chunk would get in there and plug up the jets.
i don't think that there is a spec for the butterflies other than be centered and tight. recheck your running sync but the problem your describing wouldn't be caused by a sync problem. out of sync is more a idle issue.
what kind of inline fuel filter do you have?

 

No inline filter I will pick one up today, 1/4" right?

 

Or water, but if that's the case it would run bad at all speeds. sounds like your floats are not set properly and the carbs cant keep up withe fuel demand.

 

Yes, but it has to be small to fit under the tank and should have sintered bronze media. Paper filters tend to not flow well enough.

 

Ok so just rode the bike home from work (about 25 miles) it wasnt cutting out this time but past 65 she has basically no power. I will empty my bowls shortly and check for any dirt. Also I forgot to mention earlier, after I bench sync'd the carbs whenever I start the bike after its been sitting at least a few hours it is VERY weak on start up. Once it's warmed up she seems fine idle and all but for the first few minutes after I start it she barely stays idling.

 

What are the pilot screws set at?

 

I'm not sure as I haven't adjusted them since I've had the bike (bear with me, its my first bike and I'm no mechanic) where are the pilot screws?

 

http://xjbikes.com/forums/threads/in-the-church-of-clean.14692/

 

so my pilot screw is the smaller one in the bowl?

 

definitely a lean mix

 

did you adjust your float after putting NEW float needles in. You did replace them right?

 

I haven't replaced the float needles, I have no previous experience with carbeurateors so this is all new to me. If I am running lean how should I set the pilot screws? I'm seeing 2.5 or 2 3/4 turns seems to be a good spot. Also "turns out" means I tighten them all the way them turn them out correct?

 

No. The pilot screws are on top of the carb next to the enrichment plungers. They may be covered by brass plugs, which will have to be carefully drilled and plucked out. Read the Church of Clean thoroughly, as well as The Information Overload Hour (link in my signature). You have a lot of learning to do, but we are here to help.

 

Correct, but you don't so much tighten them as you turn them in until they seat gently against the taper of the hole. If you tighten them as you would a fastening screw you will damage them.

 

so i just got back into the carbs, gave them a THOROUGH cleaning and didn't skimp anywhere. Brass plugs on the mixture screws were already drilled out (lucky me) I set them to 2.5 turns out. Put some seafoam in the tank and the crank case. I need to get ahold of a color tune plug and some carb vaccum sync gauges and I think I can get her running perfect. Also starting to feel pretty comfortable working on the carbs now that I actually know what each piece does. The only thing I'm still not 100% clear or comfortable with is setting the float levels.

 

Did you already bench synch?

Float levels are easiest to set when off the bike. http://xjbikes.com/forums/index.php?threads/6366

 

I did already bench sync(per that method as well) just about 100 miles ago. Trying to get ahold of the vaccum gauges so I can get them spot on.

both links are the bench sync btw.

 

Moe is it possible that floats are upside down?? Have seen that in a set of hitachi carbs and bike will run but not at more than about 1/2 throttle

 

Could be.

 

Floats are in the correct way. Bike didnt want to start run or idle right at 2.5 turns out, I'm at about 3.5 out right now and it starts real strong with no choke. Still seemed to cut out and die if I try to give it any throttle for the first minute or so. Seeing as I dont have a colortune plug right now should I check my plugs next then?

 

I would actualy start by checking for vacuum leaks. 3.5 turns out is a bit much, which tells me that you are needing extra fuel to keep it running. Use an unlit propane torch and work your way around the intake boots, and the throttle shaft seals. You can check the mixture by looking at the plug color, but you might not see anything since you have very little run time.

 

Carb to engine boots are new as of last year so I can't imagine it's those. Not sure what the throttle shaft seals look like. Is there a good picture anywhere?

 

The boots being new dosen't mean that there isn't a leak, it just means that there are no cracks in them. There could be leaks at the o-ring on the engine side, or at the vacuum caps, or even at the carb end if a clamp was too tight, or mounted off center.

In this picture (borrowed) you will see a circlip on the right side of the carb body Under that circlip lies one set of throttle shaft seals. The others are on both sides of each carb. (note that this is a Mikuni; Hitachi are simmilar)


You should also check around the enrichment plungers.

 

Ahh ok, I know what they are now. Guess I need to get a torch and check for some vaccum leaks then. Also its probably worth noting that I have a K&N air filter I never rejetted for.

So if throttle shaft seals do need replacing do you have to break the rack to replace all of them?

 

Then you should just put a paper air filter in. That is probably the reason you are so lean at 2.5 turns out. EMGO makes one that is a direct fit, and is affordable.

Yes. But don't go that far until after you put the correct air filter in.

 

For sure man, I'm not very comfortable with breaking the rack so defiantly not unless I know I have to. I thought you only needed to re jet for exhaust or pods but I've been reading otherwise, seems even the K&N requires it. Going to see if any of the auto parts stores here carry a paper one and see how it runs with that in. I don't have a torch so I'll have to wait until tomorrow to check for vacuum leaks.

 

just rode it around town for a bit, no luck on the air filter. Going to order one online, the exhaust seems to have a slight popping noise now.

 

On deceleration? Another sign of being lean.

 

Only backfiring at idle. Also it died twice on me and now wont start again. Was running great, throttle was crisp feeling again and all the power was back. Rode like 15 miles then I hit 75mph and it totally cut out, slowed down and died. Idk what's going on now, when it did start trying to get it home I had to keep full choke a ton of throttle on it or it would just die and it ran very rough. Also seen some white smoke shoot out a couple times when i was trying to start it, not sure if it was out of the airbox or where. Not sure what to do now, seemed liked it was running really good until it cut out.

 

Check your pilot screws. One may have backed out.

 

Just checked, they were all still the same.

 

Not sure what to try next, bike defiantly isn't wanting to start now though

 

I know I had a real tough time starting mine until I checked and reset the floats. If you haven't done that yet, it's worth at least checking. At higher rpms you may not be maintaining enough fuel in the carb bowls if they are set wrong. I understand setting it wet is the better way, but I had great success with a set of digital calipers (I had calipers, but no secondary tank to use) and setting them to 17.5 mm above carb body rim (less gasket).

 

Don't see it linked anywhere in here, so here is the guide for wet setting the floats:

http://www.xj4ever.com/setting%20fuel%20levels.pdf

And a link to check the enrichment wells, very important for starting a cold bike:

http://www.xjbikes.com/forums/index.php?threads/how-to-clean-the-enrichment-circuit-well.8918/

Also, since some of your issues are at high speed with loss of power:

http://www.xj4ever.com/gas%20cap.pdf