82' XJ750 Low Miles - Strange Problems

First post here and also my first bike - excited to tap into the amazing community on this forum!

Got the bike 10 months ago from my father - it has been in a garage since '95 with only 8k on it. Got a brand new battery for it and put in new spark plugs - took it to a shop who gave me the go ahead after cleaning "the most gummed up carbs he's ever seen." It ran like a dream. I rode it into November and then stored it in my parking garage - put stabilizer in it but didn't run it through until it was dry (left about 1/4 tank of gas in it). You'd think I would learn from the previous issue... Kept the battery indoors over the winter on a tender.

Fast forward to April and it won't start (surprise!). When I hit the start button (from a stop) it does nothing until I pump the throttle a little. It will slowly ramp up to full starter repetition but won't catch. I can get it to start whit a roll start (2nd gear). Even then it takes at least 3 tries at 15mph for it to catch. Gotta give it full choke for about 3 minutes otherwise it sputters out. It starts just fine after running for more than 20 minutes and will catch if it is warm (usually ~1hr after running).

Things to note: battery is tested and good and I do not have the mufflers on it (but I do have them). Put 3k miles on it last year so it is now at 11k. Every part is OEM.

- thanks in advance for your help.

 

Welcome aboard. It's a very good looking bike. You need to check the valves clearance. Read the Information Overload Hour and get a manual if you don't have one.

Gary H.

 

Sounds like a little bit of clogging in your pilot (low speed) circuit, and the choke circuit (those pesky passages in the bowls). You may get lucky by running some carb cleaner additive and a full tank of fresh gas through it.

Why on earth did you pull the mufflers off? That will affect how the bike runs. I understand you may have rode it all season last year like that...but that doesn't make it right haha.

 

Thanks for the advice here - I'll read up.

 

Hmm interesting...I've got carb cleaner going through it now so hopefully that helps a bit. If not I'll check the areas you specified. Thanks!

Took the mufflers off because one of em had some cosmetic damage that I'm working on. Heard that only running one was worse than running none at all - is that true?

 

Yes and no having no "back pressure" actually robs power . This also can cause jetting problems in carbs ...

 

Certainly running only one is bad, and arguably worse than running none at all. But running none at all is far from ok.

 

The carbs can get clogged up again because you need to run the bike long enough to get stabilized fuel in the carbs. I put two cycle gas in mine and the oil keeps the carbs from drying out and the tank won't rust. Springtime drain the two cycle gas and fill it up with non oxy fuel and run the bike till the oil/gas mix is gone and it's ready for summer. (I know I will get some heat for admitting this, but it works for me)
You may need to pull the carbs again and clean the lower ends out. Enrichment jets in the float bowls are the first to clog then the pilots. The mains will restrict some but that would not be a starting issue but a lean condition on higher RPM's. In any case XJ engines need ultra clean carbs to perform well. Lots of reading material on this subject if you want to tackle the job yourself.

 

i had starting problems similar if i took the fuel hose off and blew into the carbs it would start straight up .. i took the top carb lids off to clean the air jet under the diaphram and one of the diaphrams was stuck to the lid must of popped out of its seat just as i was closing it the last time i had them off ..its worth taking the tops off and checking the air jets because shops do a quick job and might of just cleaned bowls and jets at the bottom

 

perhaps even just try a fresh lot of fuel and taking the fuel hose off and blowing on it to get it started or however you can and then just ride around for a bit would be the simple thing to do

 

The gas here is bad stuff. There is so much ethanol in it moisture is attracted and the gas goes bad in no time. That's why you see Green jets when you open these carbs up. The brass jets start to turn green from the moisture. Then the gas turns into a brown goo that resembles maple syrup. It does clean up with carb cleaner and some scrubbing.