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Discussion Starter #1
So my dl650 hasn't felt quite as "smooth" as it should. I chalked it up to a slightly loose chain and the touchy fuel injection. I no longer think this is the case after putting about 6k miles on the bike.

I am coming up on my 7.5k mile service, and throttle body sync is one of the scheduled maintenance items. Most people seem to say they are unnecessary or that their bike hasn't needed one. Based on other posts I have read, it seems like I definitely do.

At low throttle inputs, the bike seems to slightly surge. At highway speeds, the issue seems to go away. I held the throttle slightly open at idle the other day and noticed that the RPM's would go up and down within a couple hundred RPM. This seems to explain exactly what I have been feeling at low speeds and coming off idle.

Am I accurate in my reasoning here? I wouldn't question it normally, as it is a scheduled item for maintenance anyway, but most people seem to say they don't need it.
 

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My '07 Wee didn't surge when it needed a TB synch, but it did feel raspy. Some multi-cylinder carbureted bikes I had in the past, though, did exhibit a pronounced surge when the carbs were in need of synch.

Sounds like you might need it, or at least a check.
 

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I was able to make this and sync my wee with good results. I had a couple friends over when I did it,and they thought it was kind of crazy, but it worked like a charm.
How can I make my own throttle body sync tool?
Later model bikes are different, I think. I don't think a TBS on later model bikes has the effect it did on earlier models, nor is it performed in the same manner, but I could be wrong.
 

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The only effect a TBS has on a 2007 or later DL650 is on the idle mixture. A need for a TBS will show itself as an inability to run under 3000rpm without lugging. A good TBS will get down to about 2500rpm with fair smoothness. It will have no effect above 3000rpm. Extreme need cases may show a lumpy idle.

Pre 2007 Wees can benefit from a TBS at higher rpms as they get a throttle linkage adjustment.
 

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Discussion Starter #6
The only effect a TBS has on a 2007 or later DL650 is on the idle mixture. A need for a TBS will show itself as an inability to run under 3000rpm without lugging. A good TBS will get down to about 2500rpm with fair smoothness. It will have no effect above 3000rpm. Extreme need cases may show a lumpy idle.

Pre 2007 Wees can benefit from a TBS at higher rpms as they get a throttle linkage adjustment.
This sounds like my issue. RPM's seem to hold steady and have no issue in the upper ranges. It is only coming off idle and at low speeds/low RPM's.

I have a 2008, so I guess I will let the dealer do it with their computer.
 

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If you haven't had a fuel injected bike before, the problem may be with your expectations. Do not expect the engine to be smooth under load below 2500-3000rpm. Speeds below that rpm range are accomplished by keeping the revs up and feathering the clutch. The bike will never chug along smoothly at idle speed with the clutch lever out.
 

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Discussion Starter #8
My previous bike was fuel injected. I was accustomed to the somewhat abrupt on/off throttle response that comes with most FI bikes. I've never had an issue of RPM's varying by a few hundred while holding the throttle at a constant position though. I've tried to write it off as normal for a while now, but something seems like it's slightly off.
 

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Discussion Starter #9
And because I've read too many posts and am now paranoid... does a faulty TPS cause jerkyness/RPM variation at low RPM/low throttle?
 

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A bad TPS will cause a bike to die at idle after a long ride, especially on a hot day. Below 2500-3000rpm your bike should not be given a load. Are you trying to run low speeds under that rpm range? That won't work. Speeds below those supported by 2500-3000rpm need to be controlled by reaching at least those revs and using the clutch to modulate speed. This fuel injected twin doesn't have enough power pulses to pull smoothly below those revs.
 

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Discussion Starter #12
A bad TPS will cause a bike to die at idle after a long ride, especially on a hot day. Below 2500-3000rpm your bike should not be given a load. Are you trying to run low speeds under that rpm range? That won't work. Speeds below those supported by 2500-3000rpm need to be controlled by reaching at least those revs and using the clutch to modulate speed. This fuel injected twin doesn't have enough power pulses to pull smoothly below those revs.
Yeah, I figured TPS mainly causes the dying at idle issue, but saw a bunch of different things posted as well.

Nah, we're talking in the 3k RPM range here. I wouldn't try to ride along under 2500 RPM, that's why I wasn't sure what you meant by riding along at idle speed.

Check the TB hose clamps for tightness and the vacuum nipple rubbers, could be an air leak.
Yeah, I should probably check that. That seems to be a big issue with the DL1000's, but I didn't think it was for the 650's. Never know, good thing to check though.


Thanks for the feedback guys. Appreciate it. :thumbup:
 

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I just performed a throttle body sync last weekend. WOW! My home-made manometer was about a foot and a half off, using oil. After adjusting the set screw to equalize vacuums, and buttoning up the bike, the difference was absolutely astonishing. The bike operated much smoother through all RPM ranges, and the little bit of "chudder" I experienced at low RPMs is completely gone. Highly recommend this preventative maintenance!
 

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Might be a fluke but my first tank of gas after TPS & TBS adjustments lost a few MPG. :confused:
The bike runs noticeably better but I really liked 55MPG+, time will tell, but Fall's coming and that makes for a bit less fuel economy anyway.
 

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This is a very helpful thread. Now I know to keep my RPM's up about 3.5k when riding along at 35mph to prevent that slight surging.
 

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Surging in 4th only; tight chain, tire balance or TB?

Hoping to get some insight on my 06 Wee. I recently put on a new Shinko 705 and noticed the wheel weights looked similar to when I brought it in for the tire change (off the bike). I shrugged it off thinking, certainly they balanced it.

I hadn't noticed or felt anything strange with way the bike was running prior to the new tire, but the old tire had worn out noticeably out-of-round. Now that the new tire is on the bike, the bike seems to kind of surge a bit, only in 4th gear, and only on decleration and maintaining around 4,000 RPM. As soon as I pick up the revs in 4th, the surging feel goes away, and it seems like it's only in 4th.

I think the chain is probably on the loose side and adjusted similarly to before. What is the likely culprit here? Tight spots in the chain, tire not balanced, or something else. The tire itself seems smooth as glass at all speeds. Or is it possible something else was off before that I did not notice which caused the first tire to wear out-of-round? Any thoughts would be appreciated.
 

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I just performed a throttle body sync last weekend. WOW! My home-made manometer was about a foot and a half off, using oil. After adjusting the set screw to equalize vacuums, and buttoning up the bike, the difference was absolutely astonishing. The bike operated much smoother through all RPM ranges, and the little bit of "chudder" I experienced at low RPMs is completely gone. Highly recommend this preventative maintenance!
I do a TB sync on my DL1000 every time that I change the oil. Using my home-made manometer, a MotionPro 90 Degree Carb Tool (#08-0229) and a flashlight I can get the throttle bodies sync'd in 1/2 an hour or less with only needing to remove the right side angled lower panel. At that point the oil is hot, ready to drain and I'm good to go until the next oil change. And the bike stays happy and purring. :thumbup:
 
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