Fast idle

[BooG]

My idle speed has crept up to 1500 from 1100 for no obvious reason. I thought it might be a problem with the advance weights in the beancan, so I sprayed a bit of oil thru the access hole, but that made no difference. I changed out and gapped the contact breakers; no change. Set the mixture/idle/balanced the carbs....still no joy. Not sure what to try next. Any ideas out there?

[fastcataz]

Have you checked your air cleaner?

[Bengt_Phorqs]

At the risk of sounding obvious, have you checked your throttle cables a both ends?

[Ed Miller]

What they said.  

Sometimes my throttle splitter gets a bit sticky and takes some time for the throttles to return back to idle; you can see this by sitting on the bike, looking down at the throttles, and blipping the throttle.  The bike doesn't have to be running to do this.  When that happens I open up the splitter (those things are a pain) and try cleaning it out, and put in some graphite and shake it around.  That usually works for some time.  

Good luck,

[Rob Valdez 79 R65]

Does BooG have a splitter?  We don't know what year it is!

[BooG]

Its a 1980 twin shock with double front discs.

[nhmaf]

I think that this means that you have (2) throttle cables coming out of the right hand throttle grip mechanism, instead of just 1?
If it is just one (which I *think* was first implemented in 1981) then you do have the annoying "splitters" or cable Y-junctions, hidden under your fuel tank
to operate the separate carb cables.  If you've got (2) cables coming out of the throttle mechanism, then you don't have the splitters and 1 cable goes to the left, and 1 cable goes to the right side carbs.

The cables themselves can bind, which could cause your situation, but if you also have the splitter design in there, that is another potential source of friction/stickiness.   They can be a bit like building a ship in a bottle to disassemble/clean, etc, until you get the hang of it.   If you do have them, make a note of where the input (single cable end) adjuster thread and lock nut are so you can put them back to that spot afterwards.   Then, screw the locknut all the way out and screw the threaded adjuster all the way in so that you can have the maximum amount of cable length to play with on the other end of the splitter (which has a cap where the (2) cables come out).   Then, you can unscrew the cap at the other end and try to get the (2) output cables and the little plastic disk that their squared ends are held captive out past the end of the splitter housing so you can inspect for frayed cables, rubbing, dirt/crud, etc..   It is often not as easy as it sounds...

[BooG]

Wow! OK then...I'll be dealing with all that on Thursday, as well as my left hand fork seal which is weeping oil! Gonna have my work cut out! Thanks for the shouts!

[Semper Gumby]

Hey BooG,

One other thing you might check is the exhaust valve clearence.  Take off the covers and see how big a feeler gauge you can get in.  If it's less then that can be a reason for higher idle.  Of course if the exhaust valves are closing up then that is another problem.....

Exhaust clearence should be about .008 inches.  Intake should be .006 inches.

Good luck.

[BooG]

Thanks for that. That is actually next on my list. I've been through all the advice so far and the idle has settled down. One carb was running a bit lean as well. I was reading snowys' article on making sure you've got TDC on the compression stroke on the side you are adjusting by checking the intake valve rising when turning the wheel in gear from the rear of the machine. I took off the rubber timing hole cover to check TDC, and I can't make out any of the symbols on the flywheel. Also, its in a real awkward place to view because of the oil filler hole. Any thoughts on this?

[nhmaf]

You may be able to do this through the inspection hole - I did it when I had the transmission out and was replacing the clutch - take some white paint and dab it on where the timing marks are.  Before it dries all the way, wipe off the area so that the white paint stays in the letters for the timing marks.   Some people even put different color paint
marks on the TDC and full advance marks so that they can easily see with a timing light without having to get close to the hole.    If you've timing marks are full of dirt, etc you'll want to clean them  off before you try to put any paint on them - maybe some swabs or a small brush and some isopropyl alcohol will clean them up without leaving any residue.

[Semper Gumby]

+1 nhmaf said.  I think I used Whiteout on my marks.... 8-)