F115 synchronization

[Hiemester]

Hey guys,
I was synchronizing the throttle intake on my 03' F115 and I am unable to get all the cylinders the same. No matter how I adjust it always leaves the #2 cylinder out of sync. Is this normal? And with only one adjustment screw how do you get them all in sync?

[99yam40]

How are you seeing this sync on the cylinders?
Just curious if the procedure you are using is in the service manual

[TownsendsFJR1300]

A full model # would help but for this 2003 F115 it's similar to my F150(looking at the parts fisch:

2003 F115TJRB Yamaha Outboard INTAKE 1 Diagram and Parts

I gather you have manometer? And there's ports on the plastic runner in-take?

With ONLY two TB's, there's ONE sync screw between them.

Cylinders 1&2 cannot be synced to each other as their on ONE throttle shaft (same for 3&4). You can only sync the butterflys between the TWO TB's

My manual is somewhat confusing on how to set them but as noted, you can't separately set #2 cylinder, it'll be off (or as it is with #1 ALWAYS).

How far out is #2, mm wise at idle?


.

[Hiemester]

I am using an inexpensive manometer. Its a fluid gauge and reads all four cylinders at once. I tried to attach a picture of it but the file was apparently to large. 1,3 and four are in a straight line together with #2 about 3/8 to a 1/2 an inch below. The intake ports are actually in the casted manifold entering the block. The reason I am syncing is to try and cure a stalling at idle problem I have ha since I've owned the engine. It's actually a F115TXRB.

[rodbolt17]

like it has been said.
you cannot sync 1&2 or 3&4.
why not fix the stalling issue?
it is not throttle plate sync.
what is the ISC request at idle??????

[Hiemester]

I would have to reconnect YDS to get that answer for you and I will. But with that said ISC is brand new. Seemed to make no difference.

[rodbolt17]

as the ISC is NOT monitored it or the harness can fail. may show up as an intake air pressure or other code.
can be tested.
last F90 I did a few weeks back the ISC locked and the wire burned in two right at the connector.
so I had to repair a connection as well.
there is n air adjusting screw for bypass air in the inboard side of the front of the shutter.

[Hiemester]

I have been all through the harnesses and saw no issues. With the attempt at syncing I did manage to get the engine to stop stalling but still coughs as if it still wants to. I see two screws accessible from the side of the engine. Its a little confusing as different sources call these different things. I was using the screw deeper in on the shutter to try and sync and the easier one to get to adjust idle. Was I wrong?

[rodbolt17]

I would carefully follow the SM procedure.
then look at the latest tech bulliten for the F150 procedure. they use all the same parts just a different location.
once I had cyl 1&2 syncd to 3&4 you can use the shutter bypass air screw to ;line up #2 to #1.
but do so at your own risk as this is a factory setting and not supposed to be field serviced.
I had a customer some years back that he and a buddy removed all 4 shutter bypass screws and it took me most of a day to make it idle again.

[TownsendsFJR1300]

I have RB's latest F150 sync procedure as a PDF if you want it...

PM me with an e-mail address and I'll send it to you..

Question for RB, is there also a bypass screw for the F150? (And no I'm not messing with it, just curious).

[rodbolt17]

out of memory I cannot remember on the F150.
the only reason I remember the F115 is the issue of the guys that removed all 4 then brought it to me.
what clued me in was when he told me he had removed the A/F mixture screws.

[TownsendsFJR1300]

out of memory I cannot remember on the F150.
the only reason I remember the F115 is the issue of the guys that removed all 4 then brought it to me.
what clued me in was when he told me he had removed the A/F mixture screws.

Thanks.. I didn't see anything in the manual about it..


Syncing the TB's on most Yamaha FI'ed bikes are with ONLY air screws.

My bike does have one butterfly screw(for the two separate , 2 BBL TB's) but your not supposed to mess with it.

On the newer Yamaha 1300's, there's an "un-authorized TB sync". With 4 separate TB's, guys adjust all the shutters closed(with the screw(s) your NOT supposed to touch). Then adjust with air screws (normal sync).

.

[rodbolt17]

yep
but sometimes you must touch the so called tamper proff non-field adjustments.
however ONLY when you isolate that it is the issue.
usually it is a running issue that causes the intake vacuum not to sync.

[Hiemester]

Thanks Townsend, I'll PM you my email address. One more quick question fro you guys, Why is there a shrader valve on the top of the VST? Is this for purging?

[rodbolt17]

ya gotta vent it to drain it.
yep it is that simple.