Fuel starvation...I think

Ok so I finally got around to giving the XJ some of the attention it needs. I pulled the carburetors off and gave em a good cleaning. Didn't split the rack at all so they should still be synched at least fairly close. And when it runs it seems the synch is fine because it runs like a b**** slapped badger.

However it seems that after just two or three minutes it doesn't want to run. starts to stumble and eventually dies and then doesn't want to start. Let it sit for 15 minutes or so and it fires up, sputters a bit and runs like the dickens again...for about two or three minutes.

Almost seems like it just goes to hell once it warms up.

I'm thinking fuel starvation because the plugs read lean. Any ideas?

When I did the cleaning I did nothing in the way of float valve adjustment (don't really know how that's done anyway). A friend suggested it could be the floats but...what do I know?

I guess I should make it clear that I'm pretty unfamiliar with the bike. And pretty much know just enough about working on bikes in general to get me in trouble.

So any thoughts or suggestions would be greatly appreciated.

***Mind the language! Thanks, Robert.

 

I guess I should have included that it's an 85 XJ700 Maxim. It sat for a little over a year with a healthy dose of SeaFoam in the tank. Most of the gas ended up in the motor. Yes I changes the oil before running it.

 

My guess is you did not clean the carbs good enough. They should be totally dissambled and cleaned. Try again, this time take them all the way apart paying attention to all the little passages ab be sure they are clean. Set the floats to proper specs and they will run if everything is done carefully.

 

I have no clue how to set the floats, nor a clue as to what the specs ont hem should be.

So there are passages in the carbs that can only be gotten to with them split off the rack? I was pretty sure I got everything cleaned out.

Thinking maybe I'd be better of taking it to a shop.

 

Good luck finding a shop that will spend the time on your carbs that they REALLY deserve.

I would hold off on splitting the carbs off the rack.
I think he meant to get the carb spray nozzle in all the holes including the bowl passage. Do not forget to take some 1500 grit sand paper to the throttle shafts / slide bores. "clunk test" drop the slides into the bores. They should slide easily and stop abruptly in the bottom of the bore. This adds engine brakes among other things.
As for the floats, google search xjbikes clear tube method. The google engine is way better than this sites.

 

Post your location , maybe there is someone near you who can help. BillB is right you don't really have to split the rack apart to clean enough to have running carbs. It all depends on their condition. I always will split them to get all the carbs apart before cleaning, it is harder to get all the passages when leaving them together but possible. Do some searches here there is lots of good "how to" articles to clean and adjust carbs.

 

Milwaukee, WI.

 

How did you set the fuel mixture screws? That's exactly what mine does when it's running lean, turning the screws out a quarter or an eighth of a turn at a time will make it run longer and longer until it suddenly just keeps running.

But your choke (fuel enrichment) should keep it running while it's cold...does the choke have any effect?

 

There are several articles on carb cleaning. Chacal has one posted... "In the church of clean" You can't do half the job and expect good results. Having said that start with valve adjustment and then follow one of the threads on cleaning carbs. Follow step by step, no shortcuts. RickOMatic also has good posts on the topic and I understand that he will clean and bench sync, set all the floats and rough set the mixture screws. Don't know what he charges, but if he does it you know its done right. You could contact him through PM.

 

Thanks everyone for the replies. I really do appreciate it. However I found and corrected the problem. It was indeed fuel starvation. Cracked the drains and the bowls were empty. So I pulled the tank off and checked the petcock by putting a hose on the vacuum nipple and pulling with my mouth...No fuel would flow from the petcock. Removed and dismantled the petcock and gave her a good cleaning. Put it back together and she is running good. Well a little lean but I'll adjust that tomorrow. It's raining here now and I don't have a garage to work in.

Thanks again for all the advice.