Runs great for a short ride....then won't start!!

Ok, First to Sno, Rick, Robert, and Woot. If this is already on here a dozen times from the past I appologize I looked through several forum pages from the past but didn't find it.

Well my 1982 Xj550, that I just purchased 3 weeks ago today, (that I have spent endless hours on in the that time frame), I got it running good finally. Keep in mind that it sit for almost 4 years without starting before I bought it. ANYWAY, I've went through and done everything I know to do to it and finally got it starting and running good......at least until it gets warm and then it won't start for nothing. I don't have it tagged or insured because I wanted to make sure I could get it running good first and didn't have to spend a long extended time working on it while paying needless insurance. So, I take it on really short rides around my subdivison, probably usually five miles or less, and it runs FANTASTIC, doesn't cut out or miss, or anything, not so much as a simple cough. BUT......when I get back home and kill it......it ain't starting till tommorow. I'm sure someting is getting to hot and causing this but I'm not sure what. Does anyone know what this might be????? I'm past my level of machanical diagnosis abilities on this one!!

 

Have you disassembled the carbs and cleaned them? Sounds like the pilot jets are ok but the mains may be plugged.....

 

Yea, I've clean the heck out of them, honestly, probably been in the carbs 75-100 times in the last 3 weeks. Like I said it's running fine when I kill it, but it won't start back up again for nothing, I can try it till the battery goes dead!

 

What is your starting sequence like? I was having the same problem recently with my XJ650J, I was just kind of trying too hard to start it. Turns out it starts with less than half choke all the time and when its warm it takes none. For me it was just a matter of getting the starting sequence down, so that I was giving it the opportunity to start.

 

WELL....just an update, not really any different from the last few. BUT, I went out this mornign, choked the bike, and it fired right up and sit and idled like new. I let it sit about 5 minutes and killed it. Hit the started button and it fired up almost instantly, sounded like the starter didn't even make a full revolution. I let the bike sit about a minute and again same thing, started up just as nice and easy as a dream. I repeated this process about 5 times. Took the bike for about a five to 10 minute spin and brought it back......well if you've been reading any of my post you know what I'm about to say. It wouldn't start to save my life. Like I've been saying I know it has to be something getting to hot, but I have no clue what. Anybody......I mean Anybody got a clue, because I would sure love to be able to start riding this bike and know where ever I'm going......I'll be able to get it started and back home!!!

 

dawsoner, it honestly doesn't seem to matter what I do. Once it's good and hot, it just won't start back up for nothing. I can not choke it, choke it, halfway choke it......I'm not a fan of this at all because I've been told it can cause "A denpendency disorder", BUT I can even squirt a bit of starting fluid and at this point it won't start at all, what I really mean by at this point is (when it's hot). Once I let it sit and cool completely for several hours it will start right back up again. But if I go back out there and try it in anything less than.....oh......2 to 3 hours, I'm just wasting time and the bikes battery!!

 

Ok, I got a buddy of mine that used to be a Motorcycle machanic....unfortunetly he's a super busy guy so I try not to bother him, BUT he said my problem sounds like my valves are out of adjustment and when the bike gets hot the clearence isn't enough. I ordered the XJCD, but I probably won't get it for about a week or so. So I got 3 questions for you guys.

1. Does that sound right to ya'll?
2. If so why is the bike still running good until I kill it?
3. If that's the problem does anyone have the correct valce clearence specs you can give me for that? The bike is a 1982 Xj550 seca

 

Spec valve clearances are:

Intake: 0.11~0.15mm
Exhaust: 0.16~0.20mm

To be measured when the engine is cold.

I am absolutely not a motorcycle mechanic, but mine was running shockingly well when the clearances were all tighter than spec and a few were as small as 0.00~0.04.

 

Kind of sounds like vapor lock. Did you put the bottom carb shield back on?

 

No I didn't install the bottom carb shield back on when I put the carbs back on. If it is vapor locked, what do I need to do to keep it from happening/

 

Yeah that used to happen with mine come to think of it,I did the valve adjustment and balanced the carbs and its running much better.....

 

put the shield back on, see if it helps.

 

ok, I'll try that. That would be great if that was all it was (the shield). I got a guy who said he could adjust the valves for me but he won't be able to get to it for atleast a few days......hopefully, he's a busy guy. Do I need to get shims? If so anyone know what size?

 

BlackMax, what do you mean by "balance the carbs"?

 

with a vacuum gauge,you attach it to the vacuum port on the intake manifold.But i think your prob is valves for sure,I took mne for a drive and if I stopped anywhere it had a very hard time to start

 

http://xjbikes.com/Forums/viewtopic/t=14827/

It's even on a 550...just like yours! You will first you measure the shims, then if you need any new ones you order them and replace so get the proper clearance. Chacal is a good source.

 

OK, we need a lot more info here; this isn't an uncommon problem but it can have many different causes.

-when you say "it won't start" what DOES it do? Turn over, briskly, but not fire?

-Is it acting as though it's not getting gas, or is it turning over somewhat sluggishly?

-"I've done all I know how to do to get it running right"-- elaborate, please.

-How many miles on the bike?

-How old is the battery?

-Have you checked and adjusted the valve clearances?

-Did you do the "basic carb cleaning" procedure? Not breaking the rack, but at least the basics?

-While the carbs were off, did you check the float heights (using fuel) and at the very least, bench-sync them?

-Have you checked the fusebox yet?

-What condition are the battery connections, the starter solenoid connections, and the starter connections in?

-Have you checked the wiring from the RH switch pod (OFF/RUN/OFF) where it plugs in, inside the headlight shell?

-Are you sure it's not simply a plugged gas cap vent? Try opening the cap next time.

This is an OLD motorcycle; there are not going to be a lot of "quick fixes" as you delve into it. This particular issue is most likely a compound problem, not a simple "turn this screw" kind of fix.

You're going to have to approach it methodically; you can do it now or after you beat your head against the wall for a while.

READ: http://xjbikes.com/Forums/viewtopic/t=24010.html
READ: http://xjbikes.com/Forums/viewtopic/t=14581.html

Get on eBay and get a manual (or two,) read the above, and then answer my questions. We'll figure it out.

 

When it get's hot and it won't start, please check if there is spark, If no or very weak spark then it could be the pulse sensors that are on the left hand of the crank. They can and do get bad. When it gets hot it will not put out a spark. I lost a championship due to that one. Wound up with 4th overall


Sean

 

Ok....Well, I'm back to square one AGAIN,,,,square one being it won't even start now. BUT, for the sake of this post I will try to cover as much info as I can. The problem I was having was that the bike would start and run great if it was cool, and hadn't been ran in awhile but once you rode it, and parked it, it wouldn't start back up. Ok so here goes everything I can think of.

When I say "it won't start"- It's turns over briskly. It has a somewhat weak spark at times and then at other times I've checked it, it has no spark. and then at other times it has good spark.....

It's seems to be turning over fine until the battery starts getting low. Sometimes it kinda has a cut out sound in the starter.....I don't know if that make sense but it just about halfway stops turning over.

The Bike has approx 36,500 miles on it.

I cleaned the carbs as good as I could. AND benchsynced them. No, I didn't check the float hieghts....your going to have to inlighten me on that one.

The battery is new, and I've been keeping it charged with a battery maintainer.

I have checked the wiring for the on/off switch, it seems fine all connections are time and I volt metered it and got voltage.

I think the last time I tried to start it back up after I was having this issue, I did try opening the gas tank cap, BUT I will definetly try that next time if this happens again.

To Bigfitz52- I read both of the post you wrote. I'm not a person to take short cuts, I'm just looking for direction. When I face a problem such as this that goes beyond my very little knowledge of motorcycles, then I just need to be pointed in the right direction. I don't mind being "methodical" I just have to know the steps. I don't have much $ to spend on parts so I can't always try swapping everything, but I can do what I need to do or try without part swapping. It just frustrating when it runs so great and smooth on somedays and then on the next day it won't even start.

I want to thank you and all the others for giving me direction. It's advice well heard and will be well taken.

Thanks Again!

 

Cool. Now go back to my most RECENT post, with all the questions in it.

Answer ALL my questions (the ones you didn't just answer anyway.)

That will give us more to go on.