Need Help Bad idle after warming up

[nishy213]

Hey guys posting again, So after the first tb sync i took to a regular shop i go to and theysaid it was all out of wack, nothing was synced and we kinda assumed that was the reason why the idle was so bad. Even after the 2nd sync the bike will drop down to 1000rpm even tho idle is set at high. when the bike is cold it’s fine, but the hotter it gets the shitter the idle is. I’ve had spark plugs changed ans cam chain looked at but i’m out of options at this point.

https://imgur.com/a/SogZ34x

 

[Gary in NJ]

Have the throttle bodies been cleaned? If the bores get gummed up it creates a restriction at the throttle plates.

BTW, your shop sucks. How does a mechanic sync the throttle bodies with such a poor idle? Find a new shop. With such an erratic idle I very much doubt that the TB’s are properly sync’ed.

 

[nishy213]

Have the throttle bodies been cleaned? If the bores get gummed up it creates a restriction at the throttle plates.

BTW, your shop sucks. How does a mechanic sync the throttle bodies with such a poor idle? Find a new shop. With such an erratic idle I very much doubt that the TB’s are properly sync’ed.

the other shop i took it to get it checked said the same, he sent me a video of how bad the syncing was done. He adjusted them properly but i’m still having those issues. I plan to confront the first shop about it, i was blinded by the indie homey vibe of a small shop but they suck. Anywho are there other things i can check? The 2bd mechanic said that it could be because of my exhaust which is sc project w/o baffles. A bit of air also leaks around where the slip on clamp meets the cat pipe but is this normal? I still don’t understand it, i wasn’t having these issues until after the spark and tb sync. And why does it idle like normal when it’s cold but thr warmer it gets the more the idle will drop

 

[Gary in NJ]

I was trying to think of typical reasons for a low idle. A vacuum leak is out, because that usually results in a high idle. A fuel restriction is not likely because the engine would shut-down upon application of throttle.

The Air Cut-Off Valve could be the cause of the idle problems. Below is clip from the FSM that gives the CONOPS for this circuit:

AIR CUT-OFF VALVE
The air cut-off valve is controlled by the signals
from the ECU in accordance with the combus-
tion conditions. Ordinarily, the air cut-off valve
opens to allow the air to flow during idle and
closes to cut-off the flow when the motorcycle is
being driven. However, if the coolant tempera-
ture is below the specified value, the air cut-off
valve remains open and allows the air to flow
into the exhaust pipe until the temperature be-
comes higher than the specified value.

 

[TownsendsFJR1300]

I'm trying to remember if was a low idle or high idle issue that the main set screw
(star screw accessible from the left side, under the tank-tank DOWN) wouldn't work.

To fix that issue, open up the BASE air screw to 7/8 -1 turn out and re-sync to that cylinder.

It gave you more adjustability.

Also, do not try to sync to what Yamaha posts for sea level. I'm at sea level and you
cannot get that # / setting to THAT spec. Just get them all within 10 MMs of the base and your good
to go. To help with low speed vibs re-sync at 4K. In your case, just get it running correct for now.

My last sync, at sea level, years ago, (well within 2m's):

 

[nishy213]

I was trying to think of typical reasons for a low idle. A vacuum leak is out, because that usually results in a high idle. A fuel restriction is not likely because the engine would shut-down upon application of throttle.

The Air Cut-Off Valve could be the cause of the idle problems. Below is clip from the FSM that gives the CONOPS for this circuit:

AIR CUT-OFF VALVE
The air cut-off valve is controlled by the signals
from the ECU in accordance with the combus-
tion conditions. Ordinarily, the air cut-off valve
opens to allow the air to flow during idle and
closes to cut-off the flow when the motorcycle is
being driven. However, if the coolant tempera-
ture is below the specified value, the air cut-off
valve remains open and allows the air to flow
into the exhaust pipe until the temperature be-
comes higher than the specified value.

how hard is this to do by one’s self. I’m good to taking stuff apart and putting it together but the space to fit my hands under this bike is hell

 

[Gary in NJ]

The Air Cut-Off Valve can be found directly above the cylinder head - there are two large ~1-inch hoses that lead directly to the valve. Check the assembly for a loose or cracked hose(s). If one of these hoses is out of place or cracked...you probably found the issue.

On the cylinder head cover you will find the the two (one for cylinders 1&2 and another for 3&4) Reed Valve assembly. Remove the reeds and inspect the reeds for cracks or wear. There is a bending tolerance on the reeds of 0.016" that needs to be verified.

There is also a Air Induction solenoid that needs to be checked at 18 to 22 Ω at room temperature. In order to check this the positive tester probe goes on the Brown/Red wire and the negative probe goes on the Red/White wire.

 

[nishy213]

the airbox rubber where it meets the throttle body under the airbox there’s cracks and rust. I also found that the airbox when you look in i can see a gap between where the rubber is secured to the tbs. could this be why ?

 

[nishy213]

I'm trying to remember if was a low idle or high idle issue that the main set screw
(star screw accessible from the left side, under the tank-tank DOWN) wouldn't work.

To fix that issue, open up the BASE air screw to 7/8 -1 turn out and re-sync to that cylinder.

It gave you more adjustability.

Also, do not try to sync to what Yamaha posts for sea level. I'm at sea level and you
cannot get that # / setting to THAT spec. Just get them all within 10 MMs of the base and your good
to go. To help with low speed vibs re-sync at 4K. In your case, just get it running correct for now.

My last sync, at sea level, years ago, (well within 2m's):

could you attach an image of where this nut would be located ? Thank you

 

[Gary in NJ]

the airbox rubber where it meets the throttle body under the airbox there’s cracks and rust. I also found that the airbox when you look in i can see a gap between where the rubber is secured to the tbs. could this be why ?

Air leaks between the airbox and throttle bodies will not cause idle issues, but they will cause the TBs to be very dirty - which will cause idle problems. Air leaks between the TBs and the cylinders will cause idle problems - but it is usually a run away high idle.

 

[TownsendsFJR1300]

could you attach an image of where this nut would be located ? Thank you

The "idle adjustment screw"? It's a star shaped screw on the port side of the bike right under the
tank.

It'd show in your owners manual.

The syncing procedure is in the shop manual, in detail...




.

 

[nishy213]

that last big hole when i turned the bike on like this it was blowing smoke up. and when i revved the bike with the airbox top off the brass tb were smoking as well. Is this normal ??

 

[nishy213]

here’s the video:

https://imgur.com/a/ynQD1eP

 

[Gary in NJ]

That’s not smoke, that’s unused combustion gases. Normal.

 

[nishy213]

That’s not smoke, that’s unused combustion gases. Normal.

Thanks, how about the tps sensor it keeps dancing between 15-16

 

[nishy213]

replaced the fuel pump today, cleaned throttle bodies and refit air box. yet no change. I just don’t know what it could be. I’m going to try changing one coil into another and see if that works.

 

[nishy213]

i Fixed it if anyone’s watching. Dirty coils were the problem. lol