can't sync the throttle bodies

mattster31 · Mar 18, 2008

Hey there,

So I decide to change my plugs. I figure while I am there, I might as well pull the valve cover and check the clearances...........they were OK

Then I thought.............."hey, why don't I clean the throttle bodies and sync them"

Well I followed a members post as to how to make your own manometer, and it looked great!

When I run the engine with the lines plugged in, the levels initially change slightly. Well I think it's going great until cylinder 2 and 3 seem to be wanting to suck the fluid right out of the lines!!!! There is also so much turbulence in the fluid it would make it impossible to read anyways!!!! I am quite sure there are no air leaks. Perhaps I am using tubing that's too small??

The throttle bodies can't be that far out of sync as is seems to run fairly smooth, so I don't know what the deal is. I think I might just have to buy a pro unit or pay a shop to do it.

Any suggestions anyone??????

teerex51 · Mar 18, 2008

mattster31 said:
(...) I think I might just have to buy a pro unit (...)

Mattster, I think you hit the nail on the head right there

I've had a Morgan CarbTune for a couple of years and it makes the TBS a cakewalk.

Stef

Checkswrecks · Mar 18, 2008

mattster31 said:
Hey there,
So I decide to change my plugs. I figure while I am there, I might as well pull the valve cover and check the clearances...........they were OK

Then I thought.............."hey, why don't I clean the throttle bodies and sync them"

Well I followed a members post as to how to make your own manometer, and it looked great!

When I run the engine with the lines plugged in, the levels initially change slightly. Well I think it's going great until cylinder 2 and 3 seem to be wanting to suck the fluid right out of the lines!!!! There is also so much turbulence in the fluid it would make it impossible to read anyways!!!! I am quite sure there are no air leaks. Perhaps I am using tubing that's too small??

The throttle bodies can't be that far out of sync as is seems to run fairly smooth, so I don't know what the deal is. I think I might just have to buy a pro unit or pay a shop to do it.

Any suggestions anyone??????

You have two problems, one is the amount of vacuum you're drawing and the second is lack of snubbing. Snubbing can be fixed by folding the lines to kink them and then playing with small clamps (1" C-clamps are great for this) to allow just enough opening that the levels don't jump around.

If you are using a home-brew manometer with plain tubes, you need enough height to keep from drawing the fluid. Or a larger diameter for the tubes.

But this job can be a pain without the right tool.

Hope this helps.

Bob

v65 · Mar 18, 2008

mattster31 said:
Hey there,
So I decide to change my plugs. I figure while I am there, I might as well pull the valve cover and check the clearances...........they were OK

Then I thought.............."hey, why don't I clean the throttle bodies and sync them"

Well I followed a members post as to how to make your own manometer, and it looked great!

When I run the engine with the lines plugged in, the levels initially change slightly. Well I think it's going great until cylinder 2 and 3 seem to be wanting to suck the fluid right out of the lines!!!! There is also so much turbulence in the fluid it would make it impossible to read anyways!!!! I am quite sure there are no air leaks. Perhaps I am using tubing that's too small??

The throttle bodies can't be that far out of sync as is seems to run fairly smooth, so I don't know what the deal is. I think I might just have to buy a pro unit or pay a shop to do it.

Any suggestions anyone??????

Got a picture of your setup?

Pierre · Mar 18, 2008

Have a Motion Pro and TBS is very easy to do.

I think you problem come from having to much vacuum, you need to add a reducer in your tubing. By doing this you should have a more stable reading.

mike25 · Mar 18, 2008

Do you have a home made ATF, or water gauge?

mattster31 · Mar 18, 2008

mike25 said:
Do you have a home made ATF, or water gauge?

I basically copied a fellow members instructions. Although I didn't use the big vacuum chambers at the top (may be the problem or the tubing is too small)

-I used 1/4" O.D tubing filled with ATF fluid

-4 runs 10' long

-used T's to connect them at the bottom so they are looped together

-strapped them to a board 3' long

When I tried to sync.....I hung the board next to the bike, at the throttle body level, and looped the tubes up over the rafters (8') and back down to the bike.

Like I said...........it seemed to work initially...........but them it just went nuts. Way too much turbulence!!!

I will try again with larger tubing and I think I will build those vacuum chambers.

Thanks for the help guys!

v65 · Mar 18, 2008

Mine works fine with the chambers.

mattster31 · Mar 18, 2008

v65 said:
Mine works fine with the chambers.

Thanks...I will give it a go.

Ramblin Man · Mar 20, 2008

You know, as a do it yourselfer I'm all for doing it yourself, but when it comes to tuning my 12,000 dollar motorcycle, I think I'll just spend the 40 bucks it costs and buy a carb tuner that works out out of the box.

I understand the desire to create, I really do. But consider the goal and then factor in your material and the time ($$$) it takes to build, then test and then fix and ask youself if it wouldn't have just been cheaper to buy the thing and be done with it.

Zorlac · Mar 20, 2008

I like simple and cheap, especially when basic physics is involved.

I made one, and it works great, a little more involved in that you can only do 2 at a time.

If you do make one, constrict one or both hoses at some point with fairly small diameter tubing to dampen the vacuum pulses.

Mine worked fine on my FJR TBS, maybe you need a longer column of ATF mine is close to 4ft total length.

https://www.ncf.ca/~ag136/carbsynch.htm

My version below.

https://tinypic.com/dh8z8j.jpg

https://tinypic.com/dh90qv.jpg

Rickster · Mar 20, 2008

I made this one Clicky

I also have a motion pro regular, and the home made one is about 5 times more sensitive than the motion pro model (it's the less expensive mercury manometer). I have used both.

I also use a single tube version differential manometer for my 2-cylinder motorcycles.

mattster31 · Apr 5, 2008

So I finally got around to finishing my "Rickster" manometer. Initially I had left out the vacuum chambers.............it needs them. So, away I went. I basically built it to "Ricksters" plans, however I used different materials. ABS for everything....including the support, and brass hose barbs. The only reason I used a 6' piece of ABS for the main support is because it was there.......laying lonely in my garage for over 8 yrs, it now has purpose. It makes it very easy to store up against a wall or to hang from the rafters in the garage when doing the "sync".

This works very well! Very sensitive! Thanks Rickster!!!

Constant Mesh · Apr 6, 2008

Looks like a rocket motor! I think you may have oversized your canisters a bit.

mcatrophy · Apr 7, 2008

QUOTE (mattster31 @ Mar 18 2008, 10:06 PM) <{POST_SNAPBACK}>

...

When I run the engine with the lines plugged in, the levels initially change slightly. Well I think it's going great until cylinder 2 and 3 seem to be wanting to suck the fluid right out of the lines!!!! There is also so much turbulence in the fluid it would make it impossible to read anyways!!!! I am quite sure there are no air leaks. Perhaps I am using tubing that's too small??

...

Any suggestions anyone??????

Made my own manometer, used engine oil as the fluid (self damping, so not much vibration, hopefully not too much damage if sucked into engine).

I had an air leak at one junction, allowed two columns to rapidly rise. Leak can be seen from the bottem left-hand T-piece, you can see the air at the bottom. Sounds a bit like your problem. Cured mine by binding some wire round where the pipes join the T-pieces.

More piccies here.

ELP_JC · Apr 7, 2008

I'm with 'rambling man'. If I'm going to mess with my engine, it'd be with precision instruments, but to each his own. Engine is not going to grenade or anything, but it's probably not going to be as smooth as it could be either IMO. It's not that expensive to buy one, and you can sell it when you don't need it anymore, so the expense is a lot less than the purchase price; look at it that way. Later.

JC

MrTwisty · Apr 7, 2008

mattster31 said:
Initially I had left out the vacuum chambers.............it needs them.

Yep, it is a matter of volume. The little plastic tubes do not provide enough air volume, so the engine just sucks the fluid into the throttle bodies.

The vacuum chambers are like shock absorbers, providing a cushion of air between the engine and the oil.

mcatrophy · Apr 8, 2008

QUOTE (MrTwisty @ Apr 8 2008, 04:44 AM) <{POST_SNAPBACK}>
QUOTE (mattster31 @ Apr 5 2008, 11:26 PM) <{POST_SNAPBACK}>
Initially I had left out the vacuum chambers.............it needs them.
Yep, it is a matter of volume. The little plastic tubes do not provide enough air volume, so the engine just sucks the fluid into the throttle bodies.
The vacuum chambers are like shock absorbers, providing a cushion of air between the engine and the oil.

With no "volume", just a total of 2 metres of pipe for each cylinder, this picture is with engine running.

It only sucked up when I had a leak, and then it was slowly enough that I could take a picture (see previous post).

Because I was concerned about sucking up, I did initially put clamps on all the pipes, then release them slowly. In the end, they were not needed.

I say again, using engine oil gives a lot of damping. To the extent that adjustment has to be done slowly, allowing a few seconds after each movement of the adjustment screw.

Sirby · May 1, 2008

Pierre said:
Have a Motion Pro and TBS is very easy to do.

I just picked up the Motion Pro carb tuner. I ordered the Yamaha adapters from Whitehorse also just in case I need them. I haven't gone to work on the TB sync yet. Do you think on my '06 FJR I will need the brass adapter tubes? I hope that the TB's have stubs already in place to slip the hoses onto, and I can return thses adapters. Anybody want to chime in here?

Thanks .

-Sirby

can't sync the throttle bodies

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