Only runs on Choke. Why?

Just got a 1981 650 Maxim. Great condition but it had sat for about a year indoors.

I drained all the carbs and flushed them out with clean fuel. There were two drain screws for each carb, but I can only get to one each. Hope that's OK? I figured they do the same thing.

Anyway, drained it... Greeny / yellow fuel came out then nice and clear. Added sea foam to another gallan of fuel and put it in the tank.

Here's the problem. The bike will only run when the choke is ON. The more I decrease the choke, the lower the RPM's get and finally it stalls. The more I increase the choke, the higher the RPM's get. Any throttle and it dies.

I also noticed that one exahust header is not nearly as hot as others. If I'm sitting on the bike, it is the first cylinder on the left. Either 1 or 4 I guess.

I ask, for the first and definitely not the last time, for help!

Dan

 

It sounds like some or all of the pilot jets are plugged or really dirty. The pilot tubes have some very small holes in it and they are very easy to get plugged when the bike sits for a while with fuel in the carbs.

The choke (enricher) is supplying fuel at the idle and low transition level instead of the fuel being supplied by the pilot circuits.

If the engine will still rev up off the choke then the main jets are still flowing, at least somewhat.

The real solution here is to pull and clean the carbs. It sounds like they were full of gunk and there are likely other parts that are cruddied up from that. You MAY have some success by pulling all the pilot jets and spraying carb cleaner down the holes. Let it sit for a while and repeat a couple of times. Pay particular attention to getting the O-ring and washer out of the holes before trying to do this as you don't want to loose them.

Once again, the real solution is to pull and clean, adjust, and sync the carbs. You will be much happier with the results if you do, and the engine will run much better overall, AND you wont be fighting some elusive carb problem until you end up doing it anyway.......

 

Yeah, good advice I think. Well the sea foam is doing well. I just tried starting it now and I can actually rev the motor as long as the choke holds the rpm's over 2000. anything less and she quits.

Looks like the carbs are coming off tomorrow!!

 

I also pulled the plugs. They are all running pretty rich I think. All are black.

 

Probably from running mostly on the choke. No way to get a decent reading without the carbs mixing right. You are making a good choice pulling the carbs at this point, rather then dinking around with it for a month and then pulling the carbs anyway to make it right! Pay particular attention to the little holes in the sides of the pilot tubes when you clean the carbs.

 

The SeaFoam dissolved the hard "Varnish-like crap" that forms in the bottom of the bowls.

That stuff clogs the Pilot Jets immediately.
You need to Clean your Carbs.

SeaFoam is a nice product; but it can't dissolve some of the stuff that forms when gas evaporates, leaving behind a hard coating of varnish thats in the tiny fuel metering ports.

You got all your low-speed Jets and metering ports to clean.
You always check and clean the Emulsion tubes; too.
Since you have to go-in through the Top to pull the Emulsion Tubes out of there ... you're basically doing a "Whole 9 Yards"

If you had pulled-out the Drain Screws when the bike got parked ...
maybe pulling the rack and knocking them down could have been avoided.

 

I'm pretty good with tools and instructions, on a scale of one to ten, how hard will it be to do the carbs right?

Will I need the color tune plugs and the YICS tool? How do I know?

 

It's not difficult. It's time consuming and meticulous work.

I once wrote what is close to the definitive article. Some of the tools and substitutions for special tooling and fabrication of things needed it included in my test.

Good luck.
If there's something you don't understand ... I'll try to explain it!

http://xjbikes.com/Forums/viewtopic/t=2 ... whole.html

 

What a great article! (link to old-fasioned carb cleaning) I'm still waiting for the XJ-cd but have been making a list of things to do with this bike. I've copied a couple of your excellent posts to file away for future reference.

Rick I really appreciate your excellent posts and the help you provide.

 

Hey Rick,

Thanks for the info. Is your post on the XJ CD? I just got them.

 

I don't think my Carb Cleaning Article appears anywhere but here, in archive.
I didn't intend for a wide distribution, in that the article is a "work in progress" needing another smoothing-out and the addition of accompanying photographs.

In its present form, it has served everyone willing to attempt their own carb cleaning quite well.

I've been overwhelmed with family issues, household chores and distracted by a 750 Maxim I salvaged, got running, cleaned-up, restored and now customized with a really comfortable remodeled seat and fine-tuned so well I make-up ridiculous excuses to go-out riding it around just for the pure enjoyment of it.

"I'll be right back. I'm just going to ride over to a neighboring State and pick-up a pack of matches." The excuses are wearing thin.

I wish I could magically get everyone dialed-in so they could enjoy the feeling of being fine-tuned and custom-seated, and able to do a little carefree zooming-around for the fun of it.

I know having squeaky-clean carbs is a generous part of high-performance. I hope my instructions help get everyone get closer to
"All tweaked and Pimped" for showing-off. At least well enough to lie about running-out to go and pick-up nothing; someplace!