Need Throttle Body Assembly Expert Advice

[Patent1]

Guys,

I had no problem with my bike's idle until I removed the throttle body assembly (necessary to replace the starter). I took the opportunity to clean the throttle bodies, and have the injectors cleaned by RXInjector in Houston.
However, upon reassembly the bike "idles" at 3500-4000 rpm. Obviously, I screwed something up...I just don't know what. Took the airbox off again to inspect the throttle body assembly. It looks good.

I've taken the bike to a Yamaha dealership. Their mechanic also doesn't know what's causing the problem.

Anyone have any thoughts as to what is causing this really high "idle"?

 

[escapefjrtist]

Retrace everything you've done.

Are you sure the butterflies are fully closed with linkage on the idle screw? Throttle cable slack? Air leak? It's kind of a bitch to get the throttle bodies fully seated into the boots. Any other odd behavior other than high idle?

~G

Edit to add - Are sure the vacuum lines are all reconnected?

 

[Patent1]

Retraced everything before I took the bike to the dealership.

Butterflies were closed, with linkage on the idle screw. Throttle cable slack was within FSM specifications. I agree the throttle bodies are a bitch to get seated. I'm pretty sure mine are at least close to fully seated, if not fully seated. I did not notice anything else riding the bike to the dealership.

The dealership mechanic has removed the airbox and inspected the throttle bodies - Nothing is obviously out of kilter.

I may have to take the bike to a throttle body specialist shop, if such a thing exists...

 

[12tinker]

Perhaps a vacuum leak. A tried and true method is to spray WD around to see if you get an increase in RPM to find the spot.

 

[Mr. BR]

What year is your bike? Perhaps your cold idle circuit is stuck open... it's the "wax motor" thing under the TBs with 2 small coolant lines attached to it. You should be able to see the plungers even with the TBs in place (from the left side). Here's a pic from another TB thread.... the "<--->" arrow in the picture is the actual plunger for each TB... it moves when cold to open an air passage, increasing the idle... once the wax motor is warmed from the coolant, it closes and your idle returns to normal (air passage closed). Any of the real experts out there, feel free to correct me!
Mr. BR

 

[Patent1]

Thanks guys for your thoughts. Here is an update/working theory:

Short version: I screwed up the throttle bodies by mechanically cleaning them.

Long version: the dealership could not find anything mechanically wrong with the throttle body assembly. Their theory is I messed up the throttle body clearances by mechanically cleaning them. If true, only replacement of the throttle bodies will fix the problem. I've obtained a used (2005) throttle body assembly from a forum member. The dealership will install it in my bike sometime in February - it is sitting in a cleaning bath right now.
Hopefully this will fix the high idle problem. If it doesn't, I'm in the market for either a completely new throttle body assembly or a new bike.

Moral of Story - Don't fack around with the damn TBA!

Jim

 

[Mr. BR]

Thanks for the update, Jim!
I'm then curious as to just how far apart you disassembled the TBs.... besides pulling off the injectors, did you separate the TBs?
And what does "mechanically cleaned them" mean?
Btw, I also replaced the starter on my '05 last year and for the first time, had my TBs off and gave them a very basic cleaning around the butterflies plus the passages for the TB balance screws.... but that was it. No issues upon reassembly.
Not pointing fingers here, just curious, maybe learn something for the next time!
Mr. BR

 

[Patent1]

I took disassembly down to removal of the injectors, vacuum hoses and electrical cabling. I did not separate the throttle bodies.

The TBA was pretty filthy; remember its a 2005 bike, I'm the original owner, and I've never had to touch the TBA before now. I started cleaning it with a tooth brush - no real crud removal. Tried emery cloth - again no real improvement. Decided not to play around - used my dremel tool - worked great! The dealership believes the dremel removed very small bits of the edges of the butterflies. I am inclined to agree with them since we've exhausted every other likely culprit.

Basically, I'm posting this as a public service announcement - don't screw with the butterflies!

Jim

 

[BigOgre]

Well . . . might you have any pics you could share of the old assembly? Cleanings of the butterflies come up every now and again, usually in a synch thread. Mostly ideas trying different fluids but I do recall seeing a manual attempt on occasion over the years. Don't remember anyone damaging anything but maybe alignment issues afterwards?

 

[Patent1]

Sorry, didn't take any pictures. Will post again once the "new" TBA is installed. Fingers crossed.

 

[Patent1]

Resurrection Day! Rode the FJR home from the dealership today. She idles at 1000 rpm. So the dremeled butterflies WERE the problem.

I need to mention my dealership: Coleman Powersports, Falls Church, Virginia. The TBA problem was not obvious, and their service guys viewed it as a challenge which we were ultimately able to overcome. They spent significant time on my bike, and discounted the bill. I strongly recommend them if you're in Northern Virginia and need motorcycle service.

Jim

 

[Mr. BR]

Well, a big congrats is in order then! Glad to hear they got it figured out for you... plus some help on the bill $$.
I guess it's a reminder that that those butterflies have a rather precise fit in the throttle body bore... sames goes for CV type carbs.
Best regards and thanks for the update (did you keep the old TBs?)
Mr. BR

 

[Patent1]

You're quite welcome. Wanted to bring some closure to this thread. Anyway, I saw no reason to ask for the old TBA, because the butterfly clearances are shot and thus pretty worthless to anyone. So, for me, winter maintenance is complete, bike is running well, and I'm just waiting on Spring!

 

[BigOgre]

Can't remember where or why but do remember reading something else good about Coleman Powersports recently. They must be doing something right.

 

[Fred W]

For those in need of throttle body cleaning, I successfully clean my ‘05’s TBs. It was at around 75k miles, as I recall. The only things I used was brake cleaner and an old soft toothbrush. Counterintuitively, brake cleaner is gentler on the rubber bits than carburetor cleaner is.

Before

After

Not perfect, but much better.