Cleaning Carb parts with an ultrasonic cleaner

[tmkaos]

I've seen a high fuel level (rich condition) cause those exact same symptoms. 
The 155 air jet is stock, what was in it before?

Since it's relatively easy to do, try leaning the needle position 1 or 2 grooves and see what the effect is.  That will tell you which way to go.

DavidR.

Hi David, thanks for replying..

The only changes I made were upsizing the main jets and raising the needles 1 groove, as per Randy's advise. And then obviously the balancing.. Every other part is stock.  So just to clarify, "leaning" the needles would involve lowering them again?

And  by a "high fuel level" do you mean the float levels? I must admit, I didn't check the height, I just made sure they were all the same, and as I didn't notice any issues prior to breaking down the carbs as others have described from having incorrect float heights I left them alone. That may have been an oversight.. 

Cheers,

James

[SlowOldGuy]

Try leaning it 1/2 groove (yes, moving the needle back down leans it).

Move the clip UP one whole groove (which will drop the needle), but install a small washer under the clip that will pull the needle back UP 1/2 groove.  The net position will be 1/2 groove leaner.

A washer approximately as thick as the groove will work nicely at giving 1/2 groove adjustment increments

Bottomline is you need to make a move in any direction to see if it get worse or better in order to know where to go from here.  Bogging and stumbling can result from rich AND lean conditions.  Change something simple (needles don't require removing the carb assembly) and go from there.

Good luck, report progress.
DavidR.

[tmkaos]

I've finally found the time to get back into the carbs (our first little girl is due in 3 weeks!) - after running her (the FJ) to work and back for a month or so now, the joke around work is to get a free ride home, follow James's bike and your car will run off the fumes coming out of his exhaust...

Anyway, so last night while I was doing some overtime I pulled out the slides and raised the needles back their original positions in the middle groove. I also went from 2.5 turns out on the idle mixture screws down to 2 out.  Blip test is good, smells much better at idle, before the over-rich fumes were really bad. At low throttle settings when warm it seems happier, no more stumbles. It also seems to have lost the worst part of it's flat spot under 3500rpm. There's still a slight heisitation there but I understand a 4-1 exhaust has that characteristic.

I need to synch the carbs again now I've played with them, so that's happening tonight during some more overtime.

This has been an interesting excercise, and I'm wondering if there's a marked difference in the composition and performance of the fuel we use here in NZ compared to States, where the majority of advice on tuning has come from. It seems most people Stateside have reccommended I richen it up, when in reality it seems happier running leaner.

My state-of-tune measure includes an empty stretch of road  leading away from an intersection that requires 1st gear. As I roll out of the intersection I snap onto WOT at a certain marker. If the bike is going well, it'l just pick up the front wheel by the tiniest amounts (I'm a heavy guy - no power wheelies for me). As I get 2nd there is a slight rise and again if the bike is on song it'l get very light on the front end over that. I'd say the bike is back to where it was before it got sick and I pulled the carbs to rebuild them, so I'm happy with that.

Be interesting to see as summer kicks in here how the fuel economy is now with bigger mains on longer rides - I have noticed commuting to work she's drinking a lot more, but now I've leaned it back out we'll see.

Anyway, I'll let you know how she goes with another synch.

Ride safe,

James

[SlowOldGuy]

It seems most people Stateside have reccommended I richen it up, when in reality it seems happier running leaner.
James

That's because most people don't know what they're talking about.  See my previous post.

DavidR.

[andyb]

This has been an interesting excercise, and I'm wondering if there's a marked difference in the composition and performance of the fuel we use here in NZ compared to States, where the majority of advice on tuning has come from. It seems most people Stateside have reccommended I richen it up, when in reality it seems happier running leaner.

There's a noticable variation in fuel in the US alone, both between states as well as between brands.  A variation between continents would be unusual to not exist.

David's most likely correct.  Don't worry much on the extreme bottom until the needles are working well.  One thing at a time.

All tuning is a compromise, it's just a question of finding the spot where you're happy with how it runs.

[tmkaos]

All tuning is a compromise, it's just a question of finding the spot where you're happy with how it runs.

You are both absolutely correct - the main issue I have is that without any other FJ's to ride with or have a go on I'm not comparing apples with apples, all I can really go off is seat of my pants, which is fine, but it'd just be nice to be able to say, "yes, my FJ is just as quick as his"

But I can't really complain, if I didn't have something to tinker with I'd get pretty damn bored! 

[Flynt]

I recommend you go leaner and do the 5 degree advance mod...  I have had good results doing some individual fine tuning of pilot jets, do 1/4 turn in and out with blips to get each cyl right on.  The advance just lifts a vail of fog from the whole experience.

Frank

[tmkaos]

and do the 5 degree advance mod...   The advance just lifts a vail of fog from the whole experience.

Frank

I have been thinking abut this.. it's not like it's too hard to get to either, and I'm an engineer for crying out loud I don't really have any excuses. If I was to do it would i be advised to do another synch afterwards, or is it a set and forget type of mod?  I'll have to visit the files section again..  Maybe I'll be doing more than a sych during overtime tonight...

Appreciate the input guys!

James

[FJmonkey]

I have been thinking abut this.. it's not like it's too hard to get to either, and I'm an engineer for crying out loud I don't really have any excuses. If I was to do it would i be advised to do another synch afterwards, or is it a set and forget type of mod?  I'll have to visit the files section again..  Maybe I'll be doing more than a sych during overtime tonight...

Appreciate the input guys!

James

From one engineer type to another, the advance is ignition, if your carbs are balanced, then they are balanced the ignition is not a function of Sync.... Go for it, I will be doing the same 5 degree-ish  advance. After I get my fuel delivery issue sorted. 

[Flynt]

would i be advised to do another synch afterwards, or is it a set and forget type of mod? 

Advance is set and forget, unless you ping of course...  Balanced carbs is a given.

Frank

[SlowOldGuy]

Where do you work?  I want to get paid overtime for working on my FJ!

:-)

DavidR.

[tmkaos]

Where do you work?  I want to get paid overtime for working on my FJ!

:-)

DavidR.

Yeah it's a pretty sweet deal..

When we do overtime it's til 7pm (7am start) and everyone else leaves at 4pm, even the bosses. As long as my CNC is running they don't really mind what we get up to. I built my suppressor for my .308 Remington that way, most of a circuit racer too, a few years ago. You've just gotta be doing a job that gives you enough time between checking dimensions and swapping out parts to do anything useful.
I'm making parts for superyacht deck winches tonight so I'll have the time.

Just on the original reason for me posting this thread, I didn't end up using our work ultrasonic to clean anything as the chemical mix we use is way corrosive to ali, but one of the apprentices saw me playing with it and thought it'd be a great way to clean up an antique stationary engine he'd bought to restore - he left it in for a hour, lost .3mm off the piston diameter and gained .4mm in the bore.. Doh... Oh well he's here to learn.. He learnt that lesson very well. To his credit though he figured out how to make a new piston and rebored the engine to suit..

James

[tmkaos]

So... Just to confirm my Gunson carb balancer is a bit shit to be honest. I couldn't justify the expense of a Morgan or similar but I guess you get what you pay for, don't you?  Anyway, carbs are balanced to best of my and my balancer's ability.

Tried to do the ignition advance - would you believe, I run a $100,000 CNC machine, 1 of several in the shop, we have mills, we have lathes, we have gas torches, we have hammers, we have grinders both cylindrical and surface, we have everything a large engineering firm should - but do you think I could locate a damn impact screwdriver to get the covers off? 

So that's for another night. Just to confirm for those of you in the know, I want to slot the plate so it rotates CW as you look at it, correct? That is what I got from looking thru Andyb's guide to mods FAQ anyway..

Cheers, safe riding. I'm off to test if my tuning magic has made a difference!

Kookaloo!!!!

James

[JMR]

So... Just to confirm my Gunson carb balancer is a bit shit to be honest. I couldn't justify the expense of a Morgan or similar but I guess you get what you pay for, don't you?  Anyway, carbs are balanced to best of my and my balancer's ability.

Tried to do the ignition advance - would you believe, I run a $100,000 CNC machine, 1 of several in the shop, we have mills, we have lathes, we have gas torches, we have hammers, we have grinders both cylindrical and surface, we have everything a large engineering firm should - but do you think I could locate a damn impact screwdriver to get the covers off? 

So that's for another night. Just to confirm for those of you in the know, I want to slot the plate so it rotates CW as you look at it, correct? That is what I got from looking thru Andyb's guide to mods FAQ anyway..

Cheers, safe riding. I'm off to test if my tuning magic has made a difference!

Kookaloo!!!!

James

Correct. Than again, I'd take a mercury synch tool over vacuum gauges any day.

[rktmanfj]

One of my local mechanic friends happened to post up this demo of his ultrasonic cleaning today:

Ultrasonic Cleaning