1985 XJ700n High Idle Issues

So I've been working with Hogfiddles restoring my XJ700n (this is the air-cooled model) and we got it running perfectly well. The carbs were cleaned and restored by Hogfiddles and it's got the correct airbox, filter, airbox to carb boots (and in proper orientation) and it ran perfectly well this spring but then all of a sudden I got this weird high idle (3,000+) after it warmed up. However, if I squeezed either the front or rear brake (in an gear including neutral) the high idle would come down to around 1700 (electrical issue connected to the carbs?). I almost never had to start the bike with choke. Now, the temp dropped to the mid 50s and 60s and it has a high idle almost immediately after starting the bike (don't have to use choke or "fuel enrichener") so it'd be awesome if I can get this fixed because if I sit at a light or stop sign the bike just wants to race and it has automatic cruise control because I don't have to be on the throttle and it wants to rev so it just cruises.

 

@hogfiddles

 

Spray some ether or propane around them methodically and see if you can hear a change in idle

 

Basically, try to figure out of its a leak? Okay I'll try this possibly tomorrow and get back with you. Also, is it dangerous or will it hurt the bike to race at idle like that when I'm spraying it?

 

Yes, that's you're trying to find....

You can turn the idle speed down....

 

The idle speed is around 1200 when I first start the bike up, but after it warms up it climbs quickly. So should I start the bike up and then turn the idle down after it's running or should I turn it down before I start the bike?

 

I would bring it down a little bit after its warmed up, and then see how it is on the next cold start up.....see what it does.

 

So I brought down the idle and apparently I went down too far with it, but with a little throttle it ran well, I brought the idle to 1100ish after it had run for a few minutes and I'm not getting the racing like I was. I'm going to take it for a longer ride and see if it does the same thing and I'll also test for leaks. Something told me to check the idle adjustment, but it ran perfectly well at the beginning of the summer without spiking so I don't know what changed.

I'm still curious why the idle would come down to around 1500-1700 when I would apply the brakes, that still makes no sense to me...

 

Unless there's a short somewhere where it bleeds from the TCI or coils somehow?

 

Maybe when if I can come to your clinic next spring we can put a multimeter all over the bike and figure out what's wrong. I'm more mechanically inclined over electrical...the relationship between ohms, amps, and volts just doesn't work in my brain

 

We can try!

 

I had a high idle on mine when the throttle cable had no play in it , turning the handlebars slightly raised the idle as the cable become tight,
Just check your cable and slacken off at the adjuster near the throttle a slight bit and see if it makes a difference