Wtf moment of the day (poor running)

Since ive had my bike from day one I have ridden it everyday at least once and had 0 problems. I left it in the garage for one full day and when I went out ridingthe next day it acted all kinds of funny. When I went through my neighborhood it died on me. Pulled it over and it started right back up so I just went with it. Then I pulled on one street and it was fine then she bogged way down. Up until 3500 rpms it was fine but it acted as though it had a rev limiter on it but when I pull in the clutch it revs over 3500 but slowly. Rode for like 10 minutes at 45 mph tops then it would go to 4500 rpms. It just jumped up randomly and went. Then about 15 minutes of that I was cruising at 4500 and it just pulled like crazy. Like it always used to. Goes all the way to 7800 rpm now but im curious about what caused it and if I have the part in my bin. I did a search but couldnt find anything on here. Also on a side note my headlights dim at idle and when I shut off my bike when I got home the voltage at the batt was 12.79

 

Sounds like you may have had some dirt in the line, are you running an in-line fuel filter? If not, I would install one immediately. You should also put your bike in your signature so we know what we are dealing with. Makes it easier to diagnose if we know exactly what we're dealing with.

As far as the headlight being dim at idle, that's normal. Your charging system doesn't kick in until around 2,000RPMs, so at idle you are drawing off the battery. once the revs go up you are charging the system so there are more volts going in the battery, which translates into more amps to the headlight.

 

Yea it has a clear inline filter from the PO and its an 82-83 motor and my carb boots are needing replaced. I have some but i just need to install them. Would i have to resync the carbs if i just pulled them off and put them back on?

 

If you don't know how old or what shape the fuel filter is in, you might just want to replace it. Also, make sure there isn't a bubble in it, preventing fuel flow.

Installing carb boots won't require any new tuning unless they were leaking air (of course, if they weren't, why would you be replacing them :roll: ). Which boots are they (airbox to carb, or carb to engine)? Be aware, and do a search on the removal of the intake boot screws for the carb to engine head boot. The screws can snap off in the head, requiring engine removal to correct.

A dimming headlight at idle is "normal" but you should measure the voltage across the plug. You might not be getting enough voltage at the headlight with the alternator (less than the 14.5V is should get), and even less when the bike runs off the battery at idle. It's worth a check, resistance can build up in corroded wires and connectors.

 

Measure the Alternator Output.

Above 25-Hundred rpm's ... you need to see +14.2 -to- 14.5 Volts.

No. ???

Inspect Alternator Brushes
Measure
10mm Minimum Service Length
10mm -or- less = R-E-P-L-A-C-E.

And, ...

If you have a STOCK Fuse Panel.
Get rid of it and join the wave of XJ Owners who don't have electrical problems.

 

I had a bubble in the fuel filter but it wouldnt make sense how it reacted for it to be a bubble. Note it ran like always to those rpms and the it acted like a rev limiter. I checked alternator output just now at 2.4k rpm and it was reading 14.5 so thats good but ive been having a problem with intermittent no crank issues and I do believe its the relay(please dont be expensive) because if i stick a screwdriver to it its fine. The carb boots are motor to carb. They're cracked but if theres a chance of breaking stuff off in the head im not gonna touch it until winter.it runs fine it just bothers me knowing theyre basically dry rotted. And fuse box has been taken out and redone with inline fuses.

 

Well It did it yet again.then it just clears up like nothing was wrong after about 25 min of riding

 

With a problem like that - it sure sounds like some water in the gas

 

Its done this even with several different tanks of gas.and even on the same tank of gas it will do this, ride normal, let it sit for a whole day and it does it again but if i ride it daily its fine

 

Intermiitant problems as you describe are the worst and my sympathies go out to you.
Maybe Chacal can perform an X-orcism

 

Sometimes the rubber intake boots "open and close" their little cracks at different heat levels - - maybe - - just a guess.

You might want to schedule surgery a little sooner.

 

Now when to decide to remove the carb boots.Who knows maybe the blessing of the bikes this may will fix it and serve as an X-orcism. Im semi afraid of pulling the boots because I dont want to break a bolt and have to remove the engine at the beginning of riding season in OH. I have replacements that came with the bike.

 

If you have an Inline Filter and it looks clean, ... take it off and do a "Blow Through-It" Test.
Make sure that the Filter isn't made with bogus paper that isn't porous.

<><><>

If you don't know if your Carbs are Cleaned and delivering full-performance; get them done.
Go to a Carb Clinic.
Get a mechanically-orientned friend to help you.
Pay a bright Student at a Regional Technical High School!
Have a fun-filled Summer with a nicely tuned-up Bike.

 

Also what does it do when you run it on prime? This probably isnt the problem when it gives you a hard time next time unlock the cap and try it see if it makes a difference. You might have a vent that is not working right all the time.

 

Use a battery tender

 

It sounds to me like a whole lot of conclusions are being jumped to; and there's a misconception trapped in there too.

First off, your symptoms sound like you need to pull and clean the carbs, pure and simple. While you're at it, record what size jets are in it in case some additional "pod-tuning" becomes necessary later on.

By all means fit an inline fuel filter so the problem doesn't just repeat on you.

Next, if you DO break a manifold stud, pulling the engine isn't necessary; but pulling the head probably would be.

Don't assume the cracks in the boots go all the way through; even the most apparently horribly cracked boots are FINE, and the cracks just need to be dealt with on the outside. The only way to tell for sure is to pull the carbs, hook a finger into the boots, and flex and inspect them from the inside-out.

How many miles on the bike; and how many have you put on it?

Was the rear brake pulled and inspected for delamination BEFORE you started riding it?

 

I did check the back brakes when I had the tires replaced. It had an inline filter on it and it was nasty so I replaced it. It has 209xx miles on it and the last 600 ive put on in the past month since ive owned it. I do agree the carbs probably need cleaned but wouldnt it be more consistent with it being the carbs? I cant do any real testing on the gas tank vent theory until the weather turns better. Although I believe I got it to semi recreate the problem in my garage in neutral and on the center stand and when opened the cap it revved better.

And as a matter of fact I am that kid at the tech school that is best in class as well as going to a state competition for auto tech. I was just curious what you guys thought on what it could be. Previous owner swore he rebuilt the carbs and synced them but cyl 1 is running rich especially with choke. And as ive read on here countless times even if they say they have done it do it yourself so you know youve done it right. Even if it was right its worth the peace of mind and you have a better understanding of how it works.

 

How many times have we heard that one?

And your reply is the best medicine for this remedy.
Go to it and make sure you check out the carb how-to's on the FAQ suggestion forum.
Best of luck with your future success.

 

That was my thinking its not consisant so probably not the carbs. You said, "when I got home the battery voltage was 12.79" is that with the bike not running and key off?

 

yea key off and not running. I think i was just trying help rule out a charging system issue by the bike not being fully charged and running at say 11.5 volts

 

If you just came back from a good ride your battery should have been fully charged 14.1 would be a better reading. Think of it this way these bikes do not start charging untill the rpm gets over say 2200 so if you start out with a weak battery burn up some amps cranking it then the headlight comes on and sucks up some more it will take a while for the charging system to catch the battery back up. If you do not have a motorcycle battery charger /maintainer get one they are available from walmart, harbor freight for around $20 I think. I use the battery tender myself costs more but its lasted me many years without any problems. While conditions do suggest you could have a fuel delivery problem a fully charged battery will help narrow down the possibilities

 

So I got to take it out for about 20 min today and yet again it keeps doing it. After I got back I temped the bikes headers for each cyl and the numbers might help reassure the need for a carb rebuild.from right side of the bike to the left the temps were 427,403,370,330 degrees. Some odd thing tells me these bikes dont like to stay on their sidestands all winter as I have a hunch the previous owner did. Ill have a video of what exactly is going on up on youtube in a few to try to explain what im talking about. Its from my cell so quality wont be the best