How to replace the emulsion tubes on a Mk1

[m3psm]

Mods - I tried to post this in knowledge base but couldn't, so feel free to move it over if you want [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

Firstly you need to strip the bike down removing upper and lower fairings, tank, seat and air box.



You’ll then have to remove the battery and battery box. This gives you the space you need to undo the carbs from the inlet manifold. It’s fiddly, but you can get a small allen key in there to undo the two lower jubilee clips.





Once the carbs are free cover the inlet with a cloth to ensure nothing falls in there.

Work on one carb at a time so you have an unmolested example if you forget how anything goes back to together [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

First job is to take the carb top off which is held on with two screws and carefully lift it free. It has a long spring inside which will fall out if you’re not carefull.







Then carefully remove the diaphragm and slide. Make sure you have somewhere clean and dust free to put them. If the diaphragm tears things get expensive, so be careful [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]







Next job is to remove the float bowl at the bottom of the carb. This is held on with four screws, one in each corner. Crack each screw first then undo diagonally opposing screws. When you undo these some petrol will spill out (a couple of tablespoons full). This is just what’s sitting in the bowl.





Once the bowl is off you need to undo the brass bolt that retains the emulsion tubes. This only has about 5 threads and is quite small, so don’t drop it. When it comes off it also has a brass sleeve, so be ready to catch both.







You’re now ready to remove the emulsion tube. To do this, push it from the bottom into the carb. It may need a tap with a screwdriver handle to get it started, then it’s removed through the top of the top of the carb.







As you remove it, make a mental note of where the groove in the tube locates.

Fitting the new one is the exact reverse. On one of mine when I pushed the new one into place it dislodged this aluminium cast piece from the base of the carb.



Simply relocate it though and push the new tub into place and once the brass retaining bolt and sleeve are replaced it’ll be OK.

Now simply put everything back together [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

Once back together the bike will take a few moments to start because the float bowl has to refill with fuel and it’ll not respond to throttle immediately. Once it settles down though it should be fine.

I suggest you try to start it as soon as the fuel tank is plumbed in, even before it’s properly fixed in case you have a leak or other problem. You want to run in for a few minutes and give a little throttle. Also turn the bars from lock to lock to make sure there’s no pinching from trapped cables. Have a good look for any petrol leaks from the float bowls too. If there is you may have to replace the rubber gasket. It should be fine though. Mine was.

Once you know it runs properly and doesn’t leak, put the rest back together and enjoy the new smoother throttle response and improved economy [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

It’s the first time I’ve done this job and the whole job only took an hour and a half and I recon I could do it quicker next time, so for about £40 in parts and less than two hours work, it’s got to be a worthwhile job.

Paul

This post was last modified: 03-02-2008, 07:00 PM by tdm850rider.

[Beancounter]

Dude, your finger is filthy!

I paid about £100 for parts when I did mine two years ago (Factory Pro jet kit and tubes) and it took me a damn sight longer than 90 minutes, but I got there in the end.

Best mod I ever did.

[m3psm]

<!--quoteo(post=46717:date=Sat 7th Jul 2007, 10:10 PM:name=Beancounter)-->QUOTE(Beancounter @ Sat 7th Jul 2007, 10:10 PM) <{POST_SNAPBACK}><!--quotec-->Dude, your finger is filthy!

I paid about £100 for parts when I did mine two years ago (Factory Pro jet kit and tubes) and it took me a damn sight longer than 90 minutes, but I got there in the end.

Best mod I ever did. <!--QuoteEnd--><!--QuoteEEnd-->
Nowt a bit of swarfega can't fix

I didn't mess with the jetting this time around but may have to when I eventually have the money for an exhaust

I had a pretty good idea how to do the job from reading previous posts on here (without reading up first I'd have taken the carbs completely off) so most of the time was spent taking off and replacing bodywork. I recon if I worked pit-stop stylee I could do it in an hour

[Beancounter]

<!--quoteo(post=46723:date=Sat 7th Jul 2007, 10:44 PM:name=m3psm)-->QUOTE(m3psm @ Sat 7th Jul 2007, 10:44 PM) <{POST_SNAPBACK}><!--quotec-->Nowt a bit of swarfega can't fix

I didn't mess with the jetting this time around but may have to when I eventually have the money for an exhaust

I had a pretty good idea how to do the job from reading previous posts on here (without reading up first I'd have taken the carbs completely off) so most of the time was spent taking off and replacing bodywork. I recon if I worked pit-stop stylee I could do it in an hour <!--QuoteEnd--><!--QuoteEEnd-->

Aye, to be fair, most of the time spent on my carbs was removal and re-fitting, mainly because of the throttle and choke cables getting in the/not seating correctly.

Dunno if the jet kit is worth it. I've got a Remus can fitted and, though I've got the Factory Pro kit installed, the bike has never been on a dyno or professionally set up. The bike still runs well if a little rich.

[wicklamulla]

WiCkEd write up and photos ! tanks very much m3psm.

[m3psm]

<!--quoteo(post=46728:date=Sat 7th Jul 2007, 11:27 PM:name=wicklamulla)-->QUOTE(wicklamulla @ Sat 7th Jul 2007, 11:27 PM) <{POST_SNAPBACK}><!--quotec-->WiCkEd write up and photos ! tanks very much m3psm.<!--QuoteEnd--><!--QuoteEEnd-->
No prob Thought I'd do my bit

[dapleb]

Good work. No problems undoing the screw for the float bowls while they were on the boike, I know they can be a real pain? Prefer to take mine off and work on ze bench though its a bit more work.

[m3psm]

<!--quoteo(post=46736:date=Sun 8th Jul 2007, 08:09 AM:name=dapleb)-->QUOTE(dapleb @ Sun 8th Jul 2007, 08:09 AM) <{POST_SNAPBACK}><!--quotec-->Good work. No problems undoing the screw for the float bowls while they were on the boike, I know they can be a real pain? Prefer to take mine off and work on ze bench though its a bit more work.<!--QuoteEnd--><!--QuoteEEnd-->
I left the carbs on because I was racing a rain cloud. ould have prefered to do it on a bench (if I had one) and give them a good clean too and oil the cables.

A couple of the float bowl screws were tight but a good stubby screwdriver got them of. When undoing any tight screws you just need to make sure the srewdriver is a perfect fit, otherwise you round off the screw. That's when the problems really start.

I'll hopefully have a fully kitted out garage and workshop in the next couple of months (subject to planning ) so everything should be a little easier in future

[zardoz]

'Haynes ' had better watch their backs. Very nicely laid out.

[m3psm]

<!--quoteo(post=46751:date=Sun 8th Jul 2007, 02:20 PM:name=danceswithmopeds)-->QUOTE(danceswithmopeds @ Sun 8th Jul 2007, 02:20 PM) <{POST_SNAPBACK}><!--quotec-->'Haynes ' had better watch their backs. Very nicely laid out.<!--QuoteEnd--><!--QuoteEEnd-->
lol To be honest I've had a lot of practice after doing a 40+ page journal on my race car which works out about 400 pages on MS Word so I always have the camera next to the spanners for any job If it makes the job easier for one person it's worth it.

I wouldn't be able to have done half the jobs I've tackled on car or bike without similar posts on enthusiasts forums and it's only fair that you give back what you take out if you can

[shacks]

Hi,
I have a Mk1 and get around 100 miles before the reserve cuts in - Is this about right for commuter miles (mixed) with remus exhaust?. If not I was wonder what emulsion tubes to buy and looking at your excellent guide I might give it a go. However it looks quite scary and was wondering if you were planning to do yours in the spring/summer if so for reassurance purposes I would like to go for a joint effort. If you're up for it drop me line cheers Shacks

[catsbum]

<!--quoteo(post=68048:date=Sun 20th Jan 2008, 10:04 PM:name=shacks)-->QUOTE(shacks @ Sun 20th Jan 2008, 10:04 PM) <{POST_SNAPBACK}><!--quotec-->Hi,
I have a Mk1 and get around 100 miles before the reserve cuts in - Is this about right for commuter miles (mixed) with remus exhaust?. If not I was wonder what emulsion tubes to buy and looking at your excellent guide I might give it a go. However it looks quite scary and was wondering if you were planning to do yours in the spring/summer if so for reassurance purposes I would like to go for a joint effort. If you're up for it drop me line cheers Shacks<!--QuoteEnd--><!--QuoteEEnd-->


Paul

Brilliant post. Worth printing and keeping for reference



Shacks

Errr, I have a question, but can't remember what it is........... [img]style_emoticons/<#EMO_DIR#>/blush.gif[/img]

This post was last modified: 20-01-2008, 10:59 PM by catsbum.

[tdm850rider]

<!--sizeo:4--><!--/sizeo-->Excellent job, totally excellent.<!--sizec--><!--/sizec-->

[k2col]

Excellent guide which I intend to follow in the next week or two!

Is there any difference between the (early) Mk2 and the Mk1 when it comes to changing tubes? (I know late Mk2's can't be done)

This post was last modified: 07-02-2008, 10:18 AM by k2col.

[TonyDevil]

<!--quoteo(post=69954:date=Thu 7th Feb 2008, 10:02 AM:name=k2col)-->QUOTE(k2col @ Thu 7th Feb 2008, 10:02 AM) <{POST_SNAPBACK}><!--quotec-->Excellent guide which I intend to follow in the next week or two!

Is there any difference between the (early) Mk2 and the Mk1 when it comes to changing tubes? (I know late Mk2's can't be done)<!--QuoteEnd--><!--QuoteEEnd-->
nope, no change
they are the same carbs/partno etc [img]style_emoticons/<#EMO_DIR#>/good.gif[/img]

This post was last modified: 07-02-2008, 11:12 AM by TonyDevil.

[shacks]

Chaps,
I know a few of you guys were embarking under the guiding hand and all round oracle knowledge of JHT on more tube replacing. I'm just enquiring how it went and if any more pictures were taken on this subject? I am still waiting for the moral fibre and spine as well as the skill to have a go myself. Any new discoveries from the latest round and are there any other tube days scheduled in between now and the end of may?
Cheers Shacks.

[FJRandy]

Hello people, Randy here from the US.
A couple questions....Is the imulsion tube something that wears out, or was this replacement an aftermarket upgrade?
I've got a '92 3VD, and the carbs are starting to idle rough. I cleaned the pilot jets and it got (somewhat) better, but it's still popping and spitting at idle.
Will replacing the emulsion tubes restore performance, or is this just a precautionary thing? I've owned the bike for a few years now, but I'm just now getting to do some maintainence on it.
Also, what is the "official" name of the part on the microfiche? Part # would really help.

Any info on what to replace/adjust would help as well.
Thanks!
Randy

[tdm850rider]

<!--quoteo(post=80289:date=Tue 22nd Apr 2008, 06:34 PM:name=92 3VD)-->QUOTE(92 3VD @ Tue 22nd Apr 2008, 06:34 PM) <{POST_SNAPBACK}><!--quotec-->Hello people, Randy here from the US.
A couple questions....Is the imulsion tube something that wears out, or was this replacement an aftermarket upgrade?
I've got a '92 3VD, and the carbs are starting to idle rough. I cleaned the pilot jets and it got (somewhat) better, but it's still popping and spitting at idle.
Will replacing the emulsion tubes restore performance, or is this just a precautionary thing? I've owned the bike for a few years now, but I'm just now getting to do some maintainence on it.
Also, what is the "official" name of the part on the microfiche? Part # would really help.

Any info on what to replace/adjust would help as well.
Thanks!
Randy<!--QuoteEnd--><!--QuoteEEnd-->
Hello Randy, Thomas here from the US...
The emulsion tube (brit name) is simply the tube that holds the <b>jet needle</b> in the carb.
What happens is the tubes wear from a round hole to an oval hole as the needle moves in and out.
Being a round needle in an oval hole you tend to get excess fuel leaking in past the sides.

There could be other reasons for the 'popping and spitting' (like air leaks in the carburator system).


If you look closely you can see the 'ovaling'
(The green inserted circles are perfectly round, you can see where both sides 'ovaled off' past the green.)

Replacing worn emulsion tubes will not only restore performance it will increase the fuel economy.

Definition of 'Emulsion Tubes' from the <i>Dictionary of Automotive Terms</i>:
<!--quoteo-->QUOTE<!--quotec--><b>Emulsion tube:</b>
Part of a fixed jet carburetor, in which air is introduced into the mixture through holes to help atomize it and correct excessive richness at higher engine speeds. A perforated tube which extends from an air bleed in the top of the air horn down into the main well. Admits air from the air bleed into the main well to emulsify the fuel in the main well. Improves idle response and stability when the engine is hot and prevents fuel percolation and general hot-starting problems. Also improves response in the main metering circuit during part throttle conditions. Also called main-well tube<!--QuoteEnd--><!--QuoteEEnd-->
<b>HTH</b>

This post was last modified: 23-04-2008, 12:01 AM by tdm850rider.

[k2col]

Hi Randy,

Most of us have replaced the emulsion tubes with Factory Pro tubes, rather than the yamaha originals.

I did this a while back, and along with the tubes, I also bought

- float bowl o-rings
- airbox rubbers
- carb rubbers

The rubbers become hard and stiff over time, and don't seal properly. I'd actually wager a guess that this might be what's causing yours to run rough. My fuel range has drastically increased since we did all this work and performance is slightly improved too.

All the best,
Colin.

PS seach for "toob" and also "factory pro" in all forums and you'll find plenty to read on the subject

[Studley Ramrod]

<!--quoteo(post=80289:date=Tue 22nd Apr 2008, 11:34 PM:name=92 3VD)-->QUOTE(92 3VD @ Tue 22nd Apr 2008, 11:34 PM) <{POST_SNAPBACK}><!--quotec-->Hello people, Randy here from the US.
A couple questions....Is the imulsion tube something that wears out, or was this replacement an aftermarket upgrade?
I've got a '92 3VD, and the carbs are starting to idle rough. I cleaned the pilot jets and it got (somewhat) better, but it's still popping and spitting at idle.
Will replacing the emulsion tubes restore performance, or is this just a precautionary thing? I've owned the bike for a few years now, but I'm just now getting to do some maintainence on it.
Also, what is the "official" name of the part on the microfiche? Part # would really help.

Any info on what to replace/adjust would help as well.
Thanks!
Randy<!--QuoteEnd--><!--QuoteEEnd-->

Hi Randy,
They do get called 'Needle Jets'
microfiche 353GM-14141-94-00 . . NOZZLE, MAIN . . . . .

If your gonna change them, you may want to change the Jet Needles also !
microfiche 4DT-1490J-00-00 . . NEEDLE SET . . .

I did mine using this amazing pictoral....YOU CAN'T REALLY GO WRONG !

Before you spend all yer Dollars, try a simple carb balance/synchronisation. Its AMAZING what a difference it can make. Mine was still lumpy after replacing jets & tubes but a carb sync sorted it out !