low idle 1982 xj 650

i recently purchased a Yamaha Maxim xj 650. The bike was running perfect for the first couple days and today i went on about a one hundred mile ride. After this it began to have a low idle (under 1000 rpms) and dies out after a few seconds depending on how shes feeling.

I have read things about oil pressure, throtle body leaks ect but i am not sure what mine could be. The shop i purchased it from installed pod filters and my carbs are newly synced and cleaned.

I have not tried adjusting the idle knob yet because i wanted to see what other people had to say first.

Thanks for the help

- cheers

 

Adjust the idle knob.

We need lots more info on the bike; like the miles and what you may or not know about it.

Do you have an inline fuel filter?

Don't worry about "oil pressure" or "throttle body leaks" those items don't really apply here.

And as much as I hate to say it, unless the shop really knew their stuff, there are probably a lot of things you're still going to need to attend to.

 

the miles i am not sure because it had needed an engine swap from another maxim xj, i am guessing around 35000.

I am not sure how to tell what kind of fuel filter i have but if you can tell me what to look for ill take some photos.

As far as i know the oil had been changed carbs cleaned/ synced, new battery, new front brake, new back tire, all new lines, new pod filters, ect.

I had been thinking about it since the last post and i was wondering if it is possible that from riding it for an extended period could have caused the idle knob to move into a different position from the vibrations?

I appreciate the help

 

Dude, if you have a fuel filter it would be in the line coming from your tank down to behind the carbs. You would be able to see it if you have one just look under your tank. No the vibration isn't going to change your idle. Get it warmed up by riding it for at least 5 mile or so then set the idle speed to 1050 rpm. As Fitz mentioned, shop mechanics these days really don't know what they are doing on these 30 year old bikes so you can't really go by what they told you they did. You still may need to properly clean the carbs, vac sync the motor and colortune to get it where it is suppose to be.

 

The XJ650 should idle at 1050rpm; the 550s idle at 1200rpm.

 

if adjusting the knob fixes the problem should i worry about anything bigger? would this only hide the problem? I just dont know what would of made the idle go down in the first place

 

A: Yes; lots of stuff.

B: Maybe; but don't fret, your bike will be serving up all sorts of surprises the longer you keep trying to ride it without properly "recommissioning" it.

Many, many different things could have contributed. It actually depends on what the shop did or more importantly didn't do before they turned you loose on the bike.

You've got two basic choices: Trust the shop you got it from, and see what sort of wonderful surprises crop up;

or properly "recommission" it yourself-- get a service manual, and go through the entire "maintenance" section item by item and step by step, leaving nothing out, taking no shortcuts, and doing it right. Then and only then will you be able to be 100% sure of the condition of the bike; and only then will it begin to be reliable enough to ride regularly without the "surprises."

 

i fixed the idle without adjusting the knob and it is at a proper 1050. i have been searching for a manual, any ideas on where i can purchase or download one?

 

Yes, the idle adjuster CAN move with vibration - mine did before I fixed it.

Anyway, what was it that was causing the problem, and how did you fix it?

 

Check with Len at XJ4Ever. He has some manuals in stock.

 

it seems that there are 4 grey tubes that stick up just before the carbs, one of them connected to the tank, the other two clogged with bolts. As i was checking for leaks i noticed on did not have a bolt anymore (must have broken off at one point), as i put my finger over the hole in the tube the bike seemed to go back to its normal idle so i plugged it and now the bike seems fine.

I figured that it was a possibility that the idle could vibrate out of place, mine doesnt seem that hard to turn

- Thanks for the help guys this forum is awesome.

 

Yes, they're the vacuum take-offs for each carb.
The long one to the fuel tap creates the vacuum that holds the diaphragm open to allow fuel flow.
The others should be sealed off (apart from when you use them with vac gauges) and an open one would weaken the mixture - thus the higher revs.

Nige