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valve adj/TB synch question


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'04 1150RT

Just did my first tune up. Adjusted valves, new air filter, plugs, TB synch with Twinmax...


I took a long time to do the valves and TB synch because I'm obessive about that stuff. TBs at max setting reading zero from idle to 4,000rpms. So, I'm pretty sure everything was set correctly. Here's my issue: When I start the bike now it runs a little rough and takes a little longer to warm up. Once it hits operating temp, it runs great - it idles right around 1,100rpms and runs smoothly. Why the difference in start-up after the tune up? Did I miss something? Should I look at the valves again? Should I do something else? Or, should I not worry about it and just ride the damn thing?


Thanks for your help


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Just a note, mine 02 RT is doing exactly the same thing. My problem is that I did a TB sync first and it ran great but decided to check and adjust the valves after dopeslap.gif and it ran greater, and now I'm comptiplating whether or not to do a sync again.(It's sort of a hassle and I had help).

Mine runs rough when cold then runs fine(a little surging) when it's warm

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Just an additional note: The left brass screw is turned out 1.5 turns and the right is just a little under 1.75 turns out.

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From a throttle body sync prospective, all you’re doing is adjusting the cable length so that the butterflies open and create a uniform vacuum between them off idle. Once they are set correctly the bike will run fine. The immediate difference that you see when you adjust the valves is how it affects the idle. If the bike is idling fine at the correct RPM, and a good blip of the throttle doesn’t cause any coughs then there is little to be gained by a re-sync. However…. one never knows for sure until they do it again!

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OK, serioulsy...


Getting everything in sync at a single engine speed is easy... but getting things in sync at a multitude of speeds, plus idle, can be rather challenging. It's mostly a matter of experience and it takes a bit of time to gather that. I found one technique that can be effective is to note how vacuum readings change dynamically as you open the throttle and tweak for overall consistency vs. trying to target perfection at a specific speed.

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OK, Temps have been up there, you could spend all your time in tinkering with your bike or riding it, if it is smooth at temp, ride it and keep it at temp.. The miles will come up very quick that will say that it is time for your next tune up and oil change..

Ride the D**N Thing..

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Seth is making a lot of sense here.


I usually follow the same method. Get the idle synch right and then adjust the cable tops for equal drop when cracking the throttle rather than trying for a synch at some steady RPM. I might look at that from a couple of different places, say, just off idle, 3K and then 5K revs.


Truth is, unless you have locked the throttle, you'll spend far more time making subtle modulations to your throttle than you think. You also gain the benefit of having the engine slightly under load this way and it will more reflect real world riding.

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