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idle/throttle sync help please


Mulepick

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I've read all the help, I believe, but still need answers.

 

My new (to me) bike has no idle stop on the left TB. I know these are not to be adjusted, just wondering if others had one or two.

 

I've slackened up the throttle cable at the grip. It is very slack at each throttle body. In fact I'm out of adjustment screw and I can still pull the cable out of the adjusting knob on the right (less so on the left). What's more, even with everything this lose, the right butterfly turns very quickly after grabbing the grip with the left following later. Easy pull on the right, you can feel it harder when the left kicks in.

 

This making any sense?

 

I've got the brass at 1.5 turns out and the electric throttle sync'r but it doesn't make sense to start with them when the cables are clearly not in sync, right?

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The left side should have a stop screw. And a lock nut too for that matter. If the TB butterfly on that side is going fully closed inside the throat, among other things it will damage it.

 

Sounds like there are some issues. Is the bracket with the threaded hole for the stop screw there?

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Sounds like there are some issues. Is the bracket with the threaded hole for the stop screw there?

 

Yes, the mount is there but no screw or lock nut.

 

I played around with the TB cable knobs and can get them pretty close if I slack the heck out of rhs and take in just about all I've got on the lhs.

 

Helpful hint:

After you've spent a month tearing your new bike down, replacing the clutch, fabricating new frame parts, aligning, peaking, and tweaking...

 

don't forget to put the trans fluid back in lest you hear noises on the way back from the local gas station that sound like your new clutch is going to explode. dopeslap.gif

 

Bob

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Sorry, but you're never going to get this right without the stop screw. Not only is it needed for idle sync, but it sets the correct closure gap inside the throttle body and also the TPS voltage is dependent upon the TB being in a fixed very precise position. Hanging off the end of the cable won't get it.

 

Suggest it's time to start shopping for a used throttle body in the salvage places.

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I'm pulling the TBs. I'll measure the gap in the TB with the stop and try to reproduce it in the other TB if I can find the right nut/bolt.

 

I used to get a headstart sync'ing the old Goldwing carbs by measuring butterfly gaps with feeler gauges. Made sync'ing much faster.

 

BTW, anyone smell something acrid near the breather hole in the clutch compartment after replacing same? I'm going to give the clutch a little more slack but wonder if this is natural for a new clutch.

 

Tks for all, as usual,

 

Bob

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Good. That's a good approach on the TBs. After you get the butterfly gap set, then go through the zero-zero procedure to set the TPS position. From there, on to a sync. Set the left cable to where it just doesn't lift the left TB butterfly off its (now new) stop screw.

 

Personally I like to sync idle with the RIGHT stop screw, the above idle with the right cable. But there is some differences of opinion on that approach vs. using the brass screws. PM me if you want my whole step-by-step.

 

Yes I think some smell on a brand new clutch plate is perfectly normal.

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Tks for good news Ken. Seems I'm on the right track. I'm a little shy about messing with the TBS as the paint is not cracked and lined up perfectly. Don't think anyone has changed it.

 

Anyway, no chunks in the trans fluid after a 20 min sputtery ride so I don't think I queered the gearbox too bad. Already got the Redline and that should take care of that.

 

I'll keep you posted.

 

Tks,

 

Bob

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Presuming you meant to type TPS instead of TBS, here's the thing. The Motronic expects to see a baseline TPS voltage (approx. 380mv) when the left TB is on its stop screw to set the correct fuel map curve. In your case at the moment, no stop screw = no correct baseline TPS voltage.

 

But if the TPS is truly still in it's factory position, this might luck out to your advantage. Once you get the stop screw and lock nut themselves figured out. Leave the TPS position alone and hook up to measure the voltage. Now, instead of the standard method of adjusting the TPS's position to adjust the voltage, adjust the idle stop screw instead. Remember the TPS is just a big potentiometer, variable resistor. When you change the position of the butterfly (with the stop screw) you change its output voltage.

 

By looking at it and adjusting it the other way around this should get you very close back to a factory positioned stop screw and butterfly position.

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ShovelStrokeEd

A minor niggle here. 380 mV is more an optimum setting once idle speed is set. Most stock bikes that I have measured, tend to be in the 320 to 340mV range and I would use that as a starting point.

 

Replace stop screw and locknut. Adjust for say, 335 mV. Perform and idle synch using the big brass screws, starting at say 1.5 turns out. Get the bike in synch at 1100 RPM and then work on the cables. Considering the age of the bike, replacement of the throttle cables might not be a bad idea.

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The gaps between the L and R TB idle bolt plate and the moving cable holder are within 0.05mm of ea other now (at about 8.88mm). Visibly, the butterflys are open the same.

 

Tomorrow I'll start reverse engineering the proper settings using what I'm almost positive now is an undisturbed TPS.

 

Tks for the idea, I'll let you know what the values turn out to be.

 

Bob

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Attached everything today; TPS is coming in at 332mV DC right off the bat. That from an eyeball/caliper match to the RHS. 'Bout time I had a little luck as the riding to fixing ratio is approaching a singularity.

 

From here I'll follow the regular warm engine sync procedures.

 

Prayers are appreciated.

 

Tks,

 

Bob

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Attached everything today; TPS is coming in at 332mV DC right off the bat. That from an eyeball/caliper match to the RHS. 'Bout time I had a little luck as the riding to fixing ratio is approaching a singularity.

 

From here I'll follow the regular warm engine sync procedures.

 

Prayers are appreciated.

 

Tks,

 

Bob

 

Bob,

Just make sure when you finish that the TPS voltage is .360-.385 (pins 1-4) or it will run like crap. smile.gif

 

Mick

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ShovelStrokeEd

Just make sure when you finish that the TPS voltage is .360-.385 (pins 1-4) or it will run like crap.

 

Mick, not necessarily so. I would certainly do the full synch procedure first and see how the bike runs from there. Actually, I would set the big brass screws at 1.25 turns out and set the idle synch using the right throttle body stop screw and, afterwards, should it be necessary, trim the idle speed with the big brass screws. I would next attack the transition synch by watching which side drops first and adjust the cable sockets on the throttle body to suit. A final trim at say 4K RPM just to be sure.

 

Then go and ride the bike. If you are unhappy with the off idle throttle response you might wish to adjust the TPS once the synch is perfect to get the range up to slightly richen the mixture. It sometimes will result in an improvement. Many bikes run well with the factory setting which is right around 330 to 340 mV.

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Just make sure when you finish that the TPS voltage is .360-.385 (pins 1-4) or it will run like crap.

 

Mick, not necessarily so. I would certainly do the full synch procedure first and see how the bike runs from there. Actually, I would set the big brass screws at 1.25 turns out and set the idle synch using the right throttle body stop screw and, afterwards, should it be necessary, trim the idle speed with the big brass screws. I would next attack the transition synch by watching which side drops first and adjust the cable sockets on the throttle body to suit. A final trim at say 4K RPM just to be sure.

 

Then go and ride the bike. If you are unhappy with the off idle throttle response you might wish to adjust the TPS once the synch is perfect to get the range up to slightly richen the mixture. It sometimes will result in an improvement. Many bikes run well with the factory setting which is right around 330 to 340 mV.

 

Hmm. This is the first I can remember reading where someone integrated the rhs TB stop screw (idle synch), brass screws (idle set), and cable tension (off idle synch). This makes sense to me.

AFter reading all the different procedures I opened the brass screws 1.5 turns. Warmed the engine, cal'd and hooked up the twin meter, and adjusted idle synch using the r TB stop screw. That done I adjusted brass screws for idle speed. Not knowing how to handle the synch off idle, I just tightened up the cable linkage. Now I'll go back, try it again using the linkage for off idle synch.

 

After all I've done, I'm listening for any little disturbance. I may have to tighten the R tappet clearance a little more. I get a little drivetrain whine that I don't remember. Maybe this is due to the Redline "tomato soup" I just put in or maybe I didn't align the driveshaft right?

 

Is anal retentive hyphenated?

 

Got the pipes/muffler ceramic coated and, no, I don't want to hear how I need to alter all adjustments for this. tongue.gif

 

I want to get this sweetie buttoned up and ride it for about 5k before I get dirty again. Not too soon to start thinking about which color to "pimp" it with though...

 

Bob

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