Loss Of Engine Braking After Valve Job

[motochick]

Greetings Fellow FJRer's,

I wanted to pick your techies brain on a strange problem I'm having after taking my bike in for the 26k valve check. Before the service I've always had some engine braking when I'm cruising in 2nd or 3rd gear and I let go of the throttle. Every bike I've owned has had this characteristic when I let go of the throttle in lower gears (some to the point of tossing me).

Well since I got the bike back, when I release the throttle I feel like I'm in neutral, I keep rolling and am forced to use more front brake. The revs slowly go down but something ain't right. I talked to the mechanic who is Yamaha certified and who I trust, and he thought it could be the throttle cable since he said he had to adjust it to "the limit" on both ends just to get the grip play right. Well there is no binding in the throttle switch it snaps back promptly when I release it, so I'm not sure what this could be. The engine runs great and idle is fine. I even lifted the tank and looked at the operation of the cable and it appears to be opening and closing the throttle bodies with no binding.

Any advice or things to check would be appreciated.

 

[RossKean]

Greetings Fellow FJRer's,

I wanted to pick your techies brain on a strange problem I'm having after taking my bike in for the 26k valve check. Before the service I've always had some engine braking when I'm cruising in 2nd or 3rd gear and I let go of the throttle. Every bike I've owned has had this characteristic when I let go of the throttle in lower gears (some to the point of tossing me).

Well since I got the bike back, when I release the throttle I feel like I'm in neutral, I keep rolling and am forced to use more front brake. The revs slowly go down but something ain't right. I talked to the mechanic who is Yamaha certified and who I trust, and he thought it could be the throttle cable since he said he had to adjust it to "the limit" on both ends just to get the grip play right. Well there is no binding in the throttle switch it snaps back promptly when I release it, so I'm not sure what this could be. The engine runs great and idle is fine. I even lifted the tank and looked at the operation of the cable and it appears to be opening and closing the throttle bodies with no binding.

Any advice or things to check would be appreciated.

I'm guessing he slipped a tooth on the cam chain...

 

[RaYzerman19]

If you've had the throttle spring unwind, and now this adjustment, that might be the cause. I did the throttle spring unwind back when I got it and noticed this too. At idle, or stopped, this is no issue. At higher rpms, the air rushing past the throttle bodies might hold them open a bit more until rpms drop down. It's second nature to me, no issue.

OTOH, if the mechanic had to adjust the cables to the max, something may be wrong with his method. This bike isn't very old so no way the cables are stretched that much. I would try a readjustment.

 

[ionbeam]

...since I got the bike back, when I release the throttle I feel like I'm in neutral...The revs slowly go down but something ain't right...

Those symptoms are in keeping with a significant vacuum leak or a throttle that has some friction keeping the grip from returning to the closed position. Check the throttle return first. I don't know what's up with the throttle cable adjustment, that's not right. If the throttle is indeed snapping back and the throttle tab between the throttle bodies is indeed going down completely on the throttle stop then vacuum leaks are the primary cause of a 'floating' throttle response when the grip is in the idle position.

I wonder if the tech put the rubber caps back on the sync ports or if the rubber boots that connect the throttle bodies to the intake ports on the engine have loose band clamps. First do or have done for you, a thorough visual inspection and a mechanical confirmation that the band clamps are tight. Where are the synch screws? Are they all the way out or all the way in? Can you adjust the idle speed up and down with the idle adjust screw?

If you still haven't found the problem, a clean way to check for a vacuum leak is to use a propane bottle with a very slightly open valve. With the engine running, wave the propane nozzle around the intake area, it there is a leak there will be a change in rpm. A messy way to achieve the same thing is to do the same process, only spraying WD-40.

 

[FJRay]

If the valves were just checked and none needed adjustment then it should not have lost cam timing. Unless the tech messed with the CCT for the hell of it. I would make sure on the cable adjusment. I have only done mine once in over a 100k.

 

[Bungie]

I believe once again Ion has it nailed. Classic symptom.

 

[motochick]

If you've had the throttle spring unwind, and now this adjustment, that might be the cause. I did the throttle spring unwind back when I got it and noticed this too. At idle, or stopped, this is no issue. At higher rpms, the air rushing past the throttle bodies might hold them open a bit more until rpms drop down. It's second nature to me, no issue.

OTOH, if the mechanic had to adjust the cables to the max, something may be wrong with his method. This bike isn't very old so no way the cables are stretched that much. I would try a readjustment.

I think this might be the case, I did the "unwind" trick when I first got the bike to relieve some tension on the wrist, but for some reason now the throttle bodies are held open a bit upon release of the throttle. I ran the engine with the tank up and notice the slow settling of the throttle bodies when I let go of the throttle. When the engine is off, it snaps open and shut like its supposed to.

hmmm...now to figure out how to undo this "mod" I made. I guess that's what the search is for !

Thanks for your help guys!

hmmm....can find many threads on releasing the throttle spring but none on pulling it back....am I screwed on this one?

 

[HaulinAshe]

If the mechanic adjusted the throttle cables at/near the throttle tube/grip to the "max", then he adjusted at the wrong spot. The slack he was trying to eliminate MUST be adjusted-away at the throttle body end of the cables.

Removing all the slack from up top, will cause excessive binding of the throttle cables themselves and could very well be the root cause of your symptoms.

Unwinding the 3rd throttle return spring is a great modification and much needed on a 2007. BUT... the throttle cables must be properly adjusted, well maintained/lubricated, the throttle tube and bar end must be kept cleaned and properly lubricated, and the throttle bodies themselves must be kept clean... Or the whole system fails to close properly when throttle is released.

Take the time to clean, lube and properly adjust it all. IMO It's time well spent, especially on a 2007!

 

[wfooshee]

+1 on Jeff's post. Early on I did the same thing on my own bike, just because I was too lazy to go under the tank. Noticed the grip had a LOT of play, and it took almost all the adjustment at the handlebar end to take the slack out. After doing that, though, the throttle would not return fully under spring pressure alone, if the handlebars were pointed straight.

I could turn the bars all the way right and the throttle would return just fine.

As for differences between engine off and engine on, I can only speculate, but there's no way on God's Green Earth that airflow can hold the throttle plates open against their springs. Even if they weren't on springs and just floating, you will observe that only half of each throttle plate is on the side being opened by suction. The other half would be closed by suction. Now I wonder . . . . could that be why they pivot in the center in the first place???!?!?!?

And if the airflow would open the throttle, why wouldn't every car in the universe (not having return cables to restrain the throttles) instantly go to full throttle as soon as you bring it off idle?

So I would suggest that maybe the bars were in a slightly different position with engine running, then engine off, without being noticed. Like I said, my cables would bind when nearly straight, i.e. 99.9995% of actual riding, but were free when turned full right (not likely at 65 MPH!)

 

[RossKean]

So I would suggest that maybe the bars were in a slightly different position with engine running, then engine off, without being noticed. Like I said, my cables would bind when nearly straight, i.e. 99.9995% of actual riding, but were free when turned full right (not likely at 65 MPH!)

+2 I had the same thing happen once on a Roadstar. Tightened up the cables (too much) to remove the slack and throttle return became very sluggish.

In my response to the original post, I was looking for something that might have been directly related to a mistake made in the valve adjustment i.e. mis-timing due to the cam chain skipping a tooth . I admit that I am not enough of a mechanic to know whether this might be noticed under engine braking conditions.

Seems that we have cable service (loosen, clean, lube), too loose throttle spring and vacuum leaks to consider (so far).

Let us know what turns up!

 

[charismaticmegafauna]

I wanted to pick your techies brain on a strange problem I'm having after taking my bike in for the 26k valve check. ...engine braking ...Well since I got the bike back, when I release the throttle I feel like I'm in neutral

...mechanic who is Yamaha certified and who I trust, and he thought it could be the throttle cable since he said he had to adjust it to "the limit" on both ends just to get the grip play right.

Well there is no binding in the throttle switch it snaps back promptly when I release it, so I'm not sure what this could be.

The engine runs great and idle is fine. I even lifted the tank and looked at the operation of the cable and it appears to be opening and closing the throttle bodies with no binding.

Any advice or things to check would be appreciated.

...for some reason now the throttle bodies are held open a bit upon release of the throttle. I ran the engine with the tank up and notice the slow settling of the throttle bodies when I let go of the throttle.

When the engine is off, it snaps open and shut like its supposed to.

...the throttle cables must be properly adjusted...! (and..., properly routed.)

On the center-stand, with the engine at idle (in neutral), turn the h/bars full-lock L.& R. -- if the engine speed changes, there's something not right with either/both the throttle cables adjustment and/or routing.

...And if the airflow would open the throttle, why wouldn't every car in the universe (not having return cables to restrain the throttles) instantly go to full throttle as soon as you bring it off idle?

(off-topic)

Diesel powered cars will -- if you apply enough carbon-based fuel. No intake restrictions to the air supply for diesels, WFO all-the-time, the fuel is controlled.

(look out if you've got a fuel leak...)

 

[motochick]

thanks for all the tips guys!

I'm just gonna get a new throttle cable installed. Even though the bike only has 27k on it, I think the cable got stretched out. It's adjusted to the max on both ends and I had it running today with the tank up and could see the slow closing of the throttle bodies even though the throttle switch snaps all the way back freely. Something ain't right that it's adjusted to the max at both ends.

It's probably unrelated to the valves and just got worse when he tried to readjust the cable after the work.

 

[carlson_mn]

Sounds very fishy. Sub'd for info.

 

[allrider]

thanks for all the tips guys!

I'm just gonna get a new throttle cable installed. Even though the bike only has 27k on it, I think the cable got stretched out. It's adjusted to the max on both ends and I had it running today with the tank up and could see the slow closing of the throttle bodies even though the throttle switch snaps all the way back freely. Something ain't right that it's adjusted to the max at both ends.

It's probably unrelated to the valves and just got worse when he tried to readjust the cable after the work.

You don't need a new throttle cable. Those don't typically wear out even on bikes with 100k+mi. I'll bet getting it adjusted by someone that knows what they are doing, and being more concious about closing the throttle manually should get your engine braking back.

When I unwound the throttle spring on my 07 I noticed it doesn't snap back like it used to and adapted. You will too.

There must be a forum member in your neck of the woods that could do that adjustment for you. I would but it might be a bit out of my way.

Cheers,

 

[motochick]

Just a follow-up, got a new throttle cable and that was the problem. Don't ask me how a cable got stretched out after 30k, but that did the trick

Thanks for all your tips

 

[HaulinAshe]

Just a follow-up, got a new throttle cable and that was the problem. Don't ask me how a cable got stretched out after 30k, but that did the trick

Thanks for all your tips

It wasn't the throttle cable. It was getting a throttle cable properly adjusted. I've got $50 that says so.



Glad your bike is fixed, because that's by far the most important thing.

 

[dcarver]

It wasn't the throttle cable. It was getting a throttle cable properly adjusted. I've got $50 that says so.

I am NOT giving you another 50 bucks! :lol:

 

[DailyCommuter]

If you've had the throttle spring unwind, and now this adjustment, that might be the cause. I did the throttle spring unwind back when I got it and noticed this too. At idle, or stopped, this is no issue. At higher rpms, the air rushing past the throttle bodies might hold them open a bit more until rpms drop down. It's second nature to me, no issue.

OTOH, if the mechanic had to adjust the cables to the max, something may be wrong with his method. This bike isn't very old so no way the cables are stretched that much. I would try a readjustment.

I think this might be the case, I did the "unwind" trick when I first got the bike to relieve some tension on the wrist, but for some reason now the throttle bodies are held open a bit upon release of the throttle. I ran the engine with the tank up and notice the slow settling of the throttle bodies when I let go of the throttle. When the engine is off, it snaps open and shut like its supposed to.

hmmm...now to figure out how to undo this "mod" I made. I guess that's what the search is for !

Thanks for your help guys!

hmmm....can find many threads on releasing the throttle spring but none on pulling it back....am I screwed on this one?

I did it once, because I couldn't decide if I liked it unwound or not, The trick to it is pretty easy actually. I took a wire leader from my fishing tackle box, a very small one, then I fed it under the spring coil, and used tweezers to grab it when it poked out the other side of the bottom. Then pulled it up to the hook end of the throttle spring, and hooked it on the loop of the wire leader, pulled around one revolution and hooked the spring back on again. obviously you need to do it in the right direction, but if you've done the unwind, I'm sure you can handle the re-wind. On a side note, after I wound mine back up tight, I went for one ride and decided I liked the unwound tension alot better- I'm only throwing this out there, because you asked if there were a way to do it.