1981 XJ650 Maxim High Idle, Smoke.

Alright guys I need a little input please. This is my 1st carb'd anything so please be a little patient. The bike is older than me.

I just bought this bike on Friday under the impression it was running okay, which it does, until it gets hot...

Stuff i know is bad/wrong to start with:
1. Petcock is bad, leaks gas, has no vacuum line attached, only runs set to prime.
2. I believe some gas is leaking from the carbs as well.
3. Has some oil leaking from what I think is the head gasket, doesn't look like much though.
4. No turn signals, lol.
5. Fork seals need to be replaced.
6. Brakes could be better.
7. Needs tires soon.

The bike has 30000 miles on it, I paid $1000 for it. I rode the bike all weekend on short trips, maybe 10 miles max and noticed the hotter the bike got the higher it would idle, after getting home today in lots of traffic it idled at no less than 5k without torque applied, smoke was coming from the front of the engine and out of the exhaust. It still seemed like it was running okay, lots of power, no trouble starting, just had to step on my brakes and apply a little torque to keep the rpms down. The bike takes a little to start when its cold, I let the gas flow for a minute, start it, choke it and it idles at like 1200 for a few minutes and I hit the road, but progressively idles higher the hotter it gets.

I need to know where to start and your opinion on if I got duped or not, I really feel like an idiot for dishing out a $1000 for something I need to be my daily driver, today was the 1st day I rode it for this long in traffic so I guess it wasn't long enough for me to notice any smoke over the weekend.

I owned 2 brand new Bolts before this, but they are out of the picture now and had to get something cheap, so I have little experience working on bikes, plenty working on Jeeps, but nothing carb'd. Thank you for any input, suggestions, comments, concerns, etc. Any help is appreciated.

 

The bad fuel tap is a red flag. How much gas has leaked into the crankcase when the bike is parked? Check oil level and have a sniff in the oil filler cap hole.
And pull the air filter, if it has one and see if it’s oily. All the parts you may need to repair the tap correctly are available from Xj4ever (top right of home page) @chacal

Idling too fast... I suspect an air leak at manifolds or carb throttle shaft seals. They are available but it is a tricky job.
If your not up for it there are a few of us that do it by request. Me, @hogfiddles to name 2. I have friends in Arizona right now for a baseball tournament.

So you have some work ahead,brakes ; front brake line ( steel braided), rear brake shoes, they are prone to delaminate ( wheel lock up and crashing).
Valve adjustment for sure. And the list goes on
Make it run properly
Make it stop properly
New tires
Don’t worry about the pretty yet
Then ride and have fun

 

Avisi0n,

I'd stop riding that thing till you work out the kinks.

Then I'd attack that fuel leak. You'll need a rebuild kit. It's not hard, but you do need quality parts. I recommend buying from Chacal as @Toomanybikes has suggested. You never know what you're going to get from Ebay. The last thing you want is to have to go back in there if inferior parts fail or just don't fit right.

The reason why it only runs on prime is because without the vacuum line to the petcock, the fuel wont flow. This problem becomes two-fold because perhaps the vacuum port on the manifold side is open, causing an air leak... which could lead to a high idle... though my experience has shown an open vacuum port is extremely noticeable and while it will start and run, it doesn't do it well at all!

So...

1- Pull the tank.
2- Fix your petcock problem
3- Make sure fuel didn't get into your crankcase as Toolmanybikes has suggested above. If it has, drain and refill. To not attempt to start again until you do.
4- Continue on the list as posted above.
5- Ask specific questions in this thread. You will get answers. Don't create other threads as I'm sure the problems are connected. This will help others to follow the situation and to help you.

When I got my first XJ, it had similar issues and was really good at only one thing... leaking fuel on the garage floor.

You've come to the right place.