Throttle adjustment question

[morrie]

My choke works but the fast-idle position doesn't. There is a little more slack in the cable on one side and I would like to snug it up. I think that would fix it and also remove some lag from the throttle, but I'm worried if that could get the throttle bodies out of synch.
Can anyone advise?.

[Boxer]

Your question is puzzling. The high idle cable goes into the junction box on the left side and rotates the cable pulley slightly, which should pull both TB cables simultaneously. If one is looser when you activate the high idle switch, then it sounds like something may be loose in the junction box. If one TB cable is noticeably looser than the other at idle, your up throttle synch will be really off.

[iowabeakster]

This statement is puzzling also...

My choke works but the fast-idle position doesn't.

Technically speaking, this bike does not really have a "choke". It has a fast idle adjustment lever that has 2 positions (plus its standard "off" position). You can think of the lever effectively doing the same thing as the throttle (right hand grip)... it just is limited by how much it can open the throttle (just a tad).

The topmost position... the lever must be manually held up. If it is not held, a spring will pull it down into the the middle position. That is the way it is supposed to work. This is a safety design. That way, the lever can never be left in the top position. This topmost position should only be needed for a couple seconds during a cold start-up. Once it is started, this position should not be needed.

The middle position... should be be a used for only the first minute or two after starting. I usually push the fast idle lever all the way down into its "off" position, when I get to the first stop sign (3-4 blocks from my house). My bike idles at about 1300 RPM at that stop sign. When I push the lever all the way down into the "off" position... the bike idles at 1000 RPM.

The "off" position...when it is fully warm, it should idle at 1100 RPM.

...There is a little more slack in the cable on one side...

...but I'm worried if that could get the throttle bodies out of synch...

What Boxer said...If there really is more slack on one side... your throttle bodies are already way out of synch. A synch job's purpose is to ensure that both sides have precisely the same amount of slack.

Yes, you can make an adjustment to the cable for the fast idle lever. It is done the same way that the adjustment is done on all the other cables.

[morrie]

OK,

Thanks guys. I'll adjust the slack side so that it's just taught and see if it matches the other side. Then I assume that I can play with it until I get fast idle in the first up position.

Just FYI, I have found that riding the twisties with the lever in the first (fast idle) position eliminates drive lash and makes for smoother transitions into and out of corners.

[Boxer]

First of all,neither side should be taut when throttle is closed. Both should have a small amount of slack. If not the butterfly valves in the TB is being held slightly open even at idle.
Once you have both sides slightly loose at throttle closed position, you adjust idle synch with the big brass screw on the right side usually, but in this case you can play with them a little each to get your idle to 1100 RPMs with both synchronized using a synch tool of some kind. Once they are synched at idle, using the same synch tool, you have to adjust one side (usually the right side) at the TB cable adjuster ferrule while the bike is revved to about 3K RPMs. This will get your cables synchronized so they pull exactly the same when you turn the throttle.

The high idle switch is totally independent of the cable and idle adjustments I just described. The high idle has 2 positions as Iowabeakster explained above but they are essentially the same action on both, one just pulls the cable farther than the first one. And that high idle cable rotates the cable pulley inside the junction box to pull both TB cables the same amount. Thus, when the high idle is activated, (unless my memory has faded on the subject) you should have no slack at all on either TB cable.

[boxermania]

Both Boxer and iowabeakster are correct

The throttle cable (with the appropriate slack) comes to a pulley that acts upon the TB's. The "choke" lever (really a hand accelerator) acts upon a slide that pulls both TB cables the same amount.

Suggest doing an iddle adjustment and TB sync, before attempting anything else, then go ahead and verify the operation of the "choke". In the middle position the engine rpm shoulb be in the 1300 to 1400 range, un the u"up" position (hand held) the rpms shoulf be in the 2200 to 2400 rpm once the bike warms up a bit.

Users that have difficulties modulating the clutch have improved their technique by either increasing the idle speed via the Big Brass Screws or by simply moving the "choke" lever to the detent or middle position as the increased engine speed makes getting going easier.

[CycleRob]

To get the RPM's Boxermania listed you must have, or very nearly have, the minimum TB throttle cable free plays. Turn the steering lock-2-lock with the hot engine idling to ensure the freeplay is not to tight. ANY RPM increase means you need to resynchronize the TB cables with a ~ half turn additional freeplay.

If you're in Canada or a really cold climate, you need all the start lever cold start RPM's you can get! To accomplish this you actually tighten the fast idle cable adjustment so there is less than zero play. When the freeplay goes away, continue loosening the left handlebar cable adjuster (exposing more threads) with the hot engine idling and the bars fully steered to the left. When the RPM's increase, turn the bars fully the other way to see if that steering lock position has a higher or lower RPM, then leave it at the higher RPM side. Lastly, turn the adjuster the other way (cover exposed threads) 2 turns past the point where the idle is normal. Now check the hot low idle RPM. Pretty cool, huh?

These thumbnails below take you to pics of what is inside the throttle junction box that applies the throttle when you pull on the start lever. Click on the thumbs, then the pic that appears to enlarge it to full size.



Following that start lever hyper adjustment, note the Hi and Low RPM's the new negative freeplay adjustment provides and post your results below.

[riceburner]

OK,

Thanks guys. I'll adjust the slack side so that it's just taught and see if it matches the other side. Then I assume that I can play with it until I get fast idle in the first up position.

Just FYI, I have found that riding the twisties with the lever in the first (fast idle) position eliminates drive lash and makes for smoother transitions into and out of corners.

sounds like your tick over is a bit low.