Cleaning throttle bodies -- worth the time?

How tedious and time consuming is it to disassemble the machine and gain access for the cleaning?

I've checked the valve clearances, etc. but I've never removed anything significant behind the engine. I did remove the fuel rail when I installed the cruise control cable.

I can see how a buildup of crud might affect the syncing adjustment of the throttle valves. Otherwise it's probably unimportant. I've not noticed any sticking of the throttle valves coming off idle as I turn the grip.

On one of my cars with a cable actuated throttle I have noticed a sticking of the throttle valve coming off idle. I cleaned the throttle body and valve and the sticking was gone.

Yeah, I did it on my '05 after almost 100k miles. It is both tedious and time consuming. Tank off, tool tray and ECU off, fuel rail off, airbox off, TBs out. This is how far apart you'll need to take it:



The returns are just in the syncronizing, as you surmised. It did make doing a RDCUA TBS a much quicker thing since there was very little difference between the vacuum at idle and at slight open throttle (rolling up to 4k rpm afterward. That was not the case prior to cleaning.

After cleaning, I was able to balance in a nice lull in vibration everywhere but right at 4k rpm. I guess it depends on how much the I-4 engine vibrations bother you and how much spare time you've got to tinker around.

Fred W said:

Yeah, I did it on my '05 after almost 100k miles. It is both tedious and time consuming. Tank off, fuel rail off, airbox off, TBs out.
The returns are just in the syncronizing, as you surmised. It did make doing a RDCUA TBS a much quicker thing since there was very little difference between the vacuum at idle and at slight open throttle (rolling up to 4k rpm afterward. That was not the case prior to cleaning.

After cleaning, I was able to balance in a nice lull in vibration everywhere but right at 4k rpm. I guess it depends on how much the I-4 engine vibrations bother you and how much spare time you've got to tinker around.

Click to expand...

how dirty were they? A little? really bad?

Pretty bad.

Rear (intake) side





And front (engine) side

Excellent pics Fred, thanks.

Since you have experience with this I suppose I can just ride the bike up there and let you clean them for me if the need ever arises.

Sure thing.

And I only charge my customers $250 an hour if they have a service contract. Off contract is $375.

FredW. PAIR block off plates?

Yes. I had them installed since about 40k miles I think.

When I did this throttle clean up I figured out why the plates are getting so crusty. There is a crankcase breather that hooks up to the air filter box on the clean side of the filter. There is a small oil slick on the inner surface of of the box just ahead of that vent. Once some opi mist gets on the throttle plates any dust that happens to get past the filter or carbon solids from the crankcase vent, will stick to the plates.

Here's a shot of the inside of my airbox where that CC vent is.

So, if the air filter is removed, would it be possible to hose the throttle plates with carb cleaner, which does a decent job of flushing off mung..? Meebee with a loong straw?

Tried that. Each of the cylinders have a snorkle dealio that is not a straight shot to the throttle plates.



The above photo also shows the CC breather. It is the Tee shaped thingee that is shiny with oil.

Mine is at 93000 miles.

Sync and valve check is due .... I guess now it's going to be a bit more involved as I may as well remove the PAIR and clen the TBs at the same time.

Will you guys please quit making work for me

Hum, maybe I'll look around for an air/oil separator from something else and plumb it inline with that hose.

Bungie said:

Hum, maybe I'll look around for an air/oil separator from something else and plumb it inline with that hose.

Click to expand...

Now that sounds like a worthwhile mod. You will be posting pics, right?

I was working on the bike yesterday doing the final oil change for the year and noticed that my '13 DOES have a canister inline on this line. Perhaps they saw fit to fit one! This is good news, because it means their is a Yamaha part number for it.

Part #18, the online fiche.

https://partsfinder.onlinemicrofiche.com/yamahagenuineparts/showmodel.asp?Type=13&make=yamahamc&a=742&b=26&c=0&d=-AIR-CLEANER-W/-INTAKE

Bungie said:

I was working on the bike yesterday doing the final oil change for the year and noticed that my '13 DOES have a canister inline on this line. Perhaps they saw fit to fit one! This is good news, because it means their is a Yamaha part number for it.
Part #18, the online fiche.

https://partsfinder.onlinemicrofiche.com/yamahagenuineparts/showmodel.asp?Type=13&make=yamahamc&a=742&b=26&c=0&d=-AIR-CLEANER-W/-INTAKE

Click to expand...

So does my '07. It's in the Gen I as well.

No The time spent isn't worth the reward.

Nothing but peace of mind for a non issue.

Guys, that filter/canister is in the airbox drain hose, #17/#19, not the PCV hose, which is #23 in that fiche.

Yep. #18 is a little filter on the drain line so you don't suck unfiltered air into the airbox. The drain is there in case any liquid gets into the air box, so that (hopefully) won't get ingested in the intake.

Hose #23 comes from the crankcase vent to the Tee fitting #21, which resides inside the clean side of the air box. You'll note that there is no PCV valve to positive pressure, just an open vent from the crankcase. That is unquestionably the source of the black gook that builds up on every FJR's throttle plates over time.

Ah, so it is. I'll make a note to find an air/oil separator that we can plumb into that line.