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over useing choke


tonyla

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Don't ask me why but I forget to put the choke back down for a bout 4-5 miles in the early morning. Its been very cold in the morning and the choke is needed for start ups.

What damage am I doing?

 

Tony

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Your bike doesn't have a choke!

 

It's a throttle advance so it's just like turning the throttle a little, no problem unless you overheat at a standstill.

 

(Now somebody will tell me that the 1200RT computer checks the position of the lever and changes the mixture based on that...)

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Your bike doesn't have a choke!

 

It's a throttle advance so it's just like turning the throttle a little, no problem unless you overheat at a standstill.

 

 

Yeah! What he said!

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Paul Mihalka
Your bike doesn't have a choke!

 

It's a throttle advance so it's just like turning the throttle a little, no problem unless you overheat at a standstill.

 

(Now somebody will tell me that the 1200RT computer checks the position of the lever and changes the mixture based on that...)

The R1200RT does not have a "choke" lever. It electrically (sp?) adjusts start throttle, idle speed, mixture. No more burned down garages (I hope) because of bike left at fast idle while having breakfast dopeslap.gif
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No problem at all, as Bob says the 'Choke' control is really just a fast idle. The ECU enriches the mixture based on engine temperature and the 'choke' control has no effect on that aspect of engine operation... so it's really not a choke at all.

 

Almost all cars (and some motorcycles) have air-bleed systems under ECU control that automatically provide a 'fast idle' function, but due to cost/complexity issues BMW left this up to the rider on the oilhead (1100/1150) bikes.

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Use of the cold start lever is of no concern. However, a warning, do NOT start your engine and "warm it up".

 

BMW warns against this. Start the engine as usual and ride off after just a moment after you start the engine....no warmups allowed. They are not good for your engine.

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Use of the cold start lever is of no concern. However, a warning, do NOT start your engine and "warm it up".

 

BMW warns against this. Start the engine as usual and ride off after just a moment after you start the engine....no warmups allowed. They are not good for your engine.

...or any engine, for that matter! Best is to do like the man says... Start it and after a few seconds, ride off.

 

Bob.

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This is a slight hijack but while we are on the subject of the fast idle lever.

 

Mine has no effect. During the last tuneup, I got the throttle bodies pretty far out of adjustment, before getting them perfectly balanced again. Since then, the fast idle lever has no effect. There does not appear to be any extra slack in the throttle cables. The engine speed responds immediately to even a very slight twist of the throttle, but not the fast idle lever. Any thoughts?

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Will, both your throttle cable and your fast idle cable run from the handlebars to a junction box under the tank and between the throttle bodies. When either cable is pulled, it turns a wheel in the junction box. Attached to this wheel are two smaller cables, each running from the junction box down to the throttle bodies. When you balance your throttle bodies, you're ensuring that with any turn of the wheel in the box, the short cables have equivalent effects on each TB. So, what does this have to do with the fast idle? Since the fast idle and the throttle use the same mechanical parts downstream of the junction box, knowing that the throttle works isolates the cause upstream of that junction box.

 

It could be a number of things. You might have a broken fast idle cable or it might just be severely out of adjustment. It seems unlikely, but the cable could be disconnected at the junction box (I'm assuming you'd notice if it were disconnected at the bar end). The bad news is that, more than likely, you'll have to pull your tupperware and dig out that junction box to fix it. The good news is that it being out of commission won't do any damage to the bike and you can compensate for it by holding the throttle open slightly.

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This is a slight hijack but while we are on the subject of the fast idle lever.

 

Mine has no effect. During the last tuneup, I got the throttle bodies pretty far out of adjustment, before getting them perfectly balanced again. Since then, the fast idle lever has no effect. There does not appear to be any extra slack in the throttle cables. The engine speed responds immediately to even a very slight twist of the throttle, but not the fast idle lever. Any thoughts?

Sure. Adjust it. If it is anything like the one on my K100, there is an adjustment to set how much effect it has. The adjustment is independent of your TB synch.

 

Bob.

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Apropos of fast idle lever, the other day, I tried using it as crude cruise control; with lever held to max position (left thumb) and no throttle (right wrist on holiday), my R1100RT did a steady 45 mph on level ground. While the idea of my left thumb giving my right wrist a vacation is tempting, travelling at 45 mph is not.

 

Wooster w/o cruise

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Sure. Adjust it. If it is anything like the one on my K100, there is an adjustment to set how much effect it has. The adjustment is independent of your TB synch.

 

Bob.

 

Yes. On the R1100RT the adjustment is at the lever. Just pull back the rubber sleve and get 1mm freeplay in the cable. I tend to ajust mine now as the first step in synch of my throttle bodies, just in case it has an adverse affect on the synch, but you can adjust it now & see. Worst case you have to re-synch the TB's.

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As previously mentioned by a poster, the cold start lever is nothing more that a way to hold the engine at a higher RPM at cold start (or any time, for that matter). However, it is NOT to be used a cruise control. There is danger therein.

 

If your engine no longer increases RPM with use of the cold start lever, your TB sync likely “used up” all the cable slack. Here is what I would do,;

 

1- Re do the TB sync. The RH cable is the only one that should be adjusted. This time, prior to the adjustment, loosen the throttle cable a bit. Then, take up some slack in the cold start cable. The adjustments are near the respective controls at each side of the bar.

2- Check the number of turns to seat the idle air bypass screws. Make sure they are correct for your model. This information can be found in the BMW repair CD.

3- You may have tightened up the throttle cable and the throttle bodies may no longer be on the stops at the respective throttle bodies. Check and make sure each TB bottoms with a nice clack when you release the throttle.

4- The mechanical cables used on the BMWs do stretch with time, especially when new. This is the reason that TB sync must be performed from time to time.

5- After you accumulate miles on your cables, the stretch will all but disappear and the need for TB sync will become infrequent. Mine have not been done for a year and they are still in good adjustment.

6- Finally, clean each throttle cable where it wraps around the spool at the TB (A good dose of WD-40 or carb spray works fine). Dirt and grime accumulate here and can disrupt TB sync. Also, cleaning at these points helps keep the throttle shafts vacuum leak free.

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Bob and Michael. Thanks, that is how I thought it worked. The only mystery to me is why the function changed when I did the throttle body synch. I guess I will have to look into it a little more deeply.

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FWIW, the fast idle control on my '96 RT (pre-junction box 'upgrade') still works perfectly and has never needed an adjustment of any kind in the bike's 70k miles.

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