Hard Starter with starting fluid

Alright so, its an 81 xj650, Carbs cleaned and bench synched professionally, valves in spec. Took it to the dealer when it was not starting and they got it fired up by putting in 60 pilot jets. shes runnin pods and straight piped. they recommended that i put size 50 pilots in her to fix the idle problem. I did that So now she sits, wont start unless i use starting fluid and even then its tough. Could the timing be off horribly? what else would cause it not starting. good spark and compression. Help me out xj wizards

 

Floats are set correct and all bowls are getting fuel.

 

i think we need to know more of the symptoms. what happens after you get it started with starter fluid? does it run at that point? if so, *how* does it run?

 

Runs strong but wont idle

 

Try adjusting the idle screw. After cleaning my carbs I had the opposite problem, idling at 4k, it was just out of adjustment.

 

And the enrichement circuit? Does choke help it out?

Those are some HUGE pilot jets. I bumped mine up from 40 to 41 for some exhaust mods. Not that it affects your starting problems, but what size main jets did they put in? Really seems like they were just throwing darts at your carb settings...unless they really have a VAST experience with XJs/intake/exhaust mods/jetting (like someone with a lot of 80s racing experience). Did the "wet set" the floats?

Gonna be honest, likely, the dealer is just taking your money. How much has all this carb cleaning/rebuilding cost you (I ask because members on the forum who do REAL XJ CV carb cleaning charge between $250 and $300 for LABOR alone...because that's really what it takes). This is why we usually rebuild these ourselves.

The BEST course of action would be to take some of your mods closer to stock. Airbox would be the first one. That way, you might get something running, and can further make adjustments from a good starting point.

Also, you're going to need A LOT of jets to figure out what jetting is going to work with your set-up (x4). No one will be able to give you a specific number unless they've got the EXACT same set-up, and they or someone else with the EXACT same set-up tested and verified the set-up.

 

the starting issue could be caused by a weak battery, or by clogged enrichment ports in the carbs. a "professional" cleaning doesn't necessarily mean a "good" cleaning.

the easiest thing is to check the battery at an auto parts store. if it checks out, you've likely got carb issues that are unresolved.

 

Battery is good, starter is strong. carbs cost me 250 to be cleaned. i went through them again and blew air threw all the ports. Cant go back to an airbox because of some frame modifications. i bumbed the main jets up to 118

 

idle adj screws set to 2.5, i tried it at 2 and 3. still nothing. im thinking i need to double check the valve specs. Im just confused. Motor needs spark, compression, correct fuel/airmix, and correct timing to run. its got good spark compression so either the air/fuel mix is off or its not getting in and out of the combustion chamber correctly

 

choke helps with idle but not a whole lot in starting it

 

You might need to back off the pilot screws further. Try 1/8 of a turn at a time. This is just to get it to START...not run RIGHT. But seeing as it doesn't idle (have you tried the idle adjustment knob?) you likely still have a clogged pilot circuit. Was it cleaned out? Pilot mixture screw removed for cleaning?

I can tell you it's the air/fuel mix. Likely LEAN (no surprises there w/ pods). Those huge pilot jets + pods, along with questionalbly clean carbs, are not metering fuel at the right ratio for combustion.

Timing is unlikely because it CAN run. If your valves weren't opening or closing at the right time they'd crash into the piston crown...so it's not option 2.

I've seen some of your previous posts, where you had issues last fall and people gave you advice, but you didn't respond that it was fixed. Did you ever have the bike running? Did you have the carbs cleaned again? Or are you referring to the cleaning done last year?

 

exactly. so, we have to eliminate each variable one at a time, to troubleshoot.

you say it has good compression across all four cylinders. great. do you know the readings? if so, post them. having all the information helps.

also, you say your valves are in spec. again, what are the readings?

the engine runs fine at high RPMs once you've started it, right? so timing's out.

you've tested the battery under load? even *new* batteries can be fickle. save yourself a headache -- take the battery to an auto parts store and have it load tested.

if the battery is ok, that leaves fuel/air mixture.

you have pods, putting you at an immediate disadvantage in getting a correct fuel/air mixture. the stock airboxes restrict the airflow, which is by design. pods let much more air in, giving you a lean mixture. you also have aftermarket exhaust, which adds yet another variable.

my understanding of the re-jetting process is that it's an interminable guess-and-check ordeal.

but that won't even get you there unless the carbs are fully clean. i'm sorry you spend so much money having someone else clean and sync your carbs. i did that once also. many of us have. most of us have had to do the work ourselves after wasting that money, to get them *fully* clean and appropriately synced.

 

Looking back at some of chacal's recommendations for jetting (which he freely admits are just best guess starting points), I think your pilot jets are FAR too big. You might want to go back to a 40, maybe 41 or 42. But 50 or 60 seems like too big of a jump. Jetting changes must be made incrementally.

 

Alright so, compreesion in all cylinders is between 120 and 128. i didnt write them down, as for valves i did that a while ago, wrote them down somewhere and lost that sh*t. i do remember checking them and the were in spec. The battery will spin that starter all day and give good spark so im pretty sure its good. so basically that leaves me with the carbs, my least learned subject. So when starting what happens? is it all pilot jet squirting in conjuction with the choke. what im confused about is absolutly no starting at 40 pilot jets and hard starting at 60 pilot jets. right now they are 52.5 and still hard starting and sh*tty/no idle. Im guessing that i need to go somewhere between 45-50 pilot jets, but where the heck am i gonna find those that fit lol. Also if the air/fuel mix is good but the valves are way outta wack(maybe i screwed up reading them or something stupid). Would that cause no start?

 

waiting for chacal to chime in on this one

 

The only way the valves can be "out of wack" is to not seat, or not be in spec. They are seating if your compression is in spec.

You could always check the valve clearances again and post them (you didn't do that the last time). Members can verify that your clearances are set properly.

The pilot mixture screw meters the air flow from the pilot air jet. That air flow picks up fuel from the pilot FUEL jet. This circuit is responsible for the correct fuel delivery on idle and off idle.

The emulsion tube/needle/main jet/slide meter fuel for the rest of the RPM range.

Your butterflys will "just" barely cover the pilot circuit opening when bench synced. If it completely covers them, then you won't get any fuel at idle.

The enrichement circuit delivers even more fuel, for starting. If it helps your running condition, then you are running too lean.

Of course, if any of these passages aren't clean, you won't meter any fuel through them.

How far out did you adjust your pilot mixture screw with the 40 pilot jets installed? At least 5 turns out? 2-3 isn't going to cut it with your mods.

You can get all of these jets from chacal. PM him. However, you probably won't like how much this is going to add up to.

I ask again, have you gotten it running and idling since the fall? or are we still dealing with the same issues that you were dealing with then?

 

Alright manbot thanks for the carb lesson that helps a lot. Ive gotten it running but not idling last week after the dude put 60 pilot jets in her. when i get her runnin with the choke it will idle but when i give less choke it bogs down, sounds like its getting too much fuel but i think im wrong. Im inclined to think its running rich because it has 118 mains and 52.5 pilots(sounds crazy but it ran with 60s)

So....wat im gonna try is messing with the pilot screws with the 52.5 pilots in and if thats a no go i will go back to 40s and try that again. i only went out 3 turn with the 40s. then i will check the valve clearances again and verify.