Carburetor Adjustment

[Jess]

Ok...

I know there are other threads on Carb adjustment... But I wanted a new clean thread that would be easy to find.

Svereal folks have asked me for a written procedure but I type like crap...

I remembered an excellent article that covers it...

I asked the author for permission to post it here and he was fine with it...

It is my opinion that more than 50% of carb issues are due to improper rebuild of the carby...

I beleive the only way to get a carby truely clean is to place it in a commercial ( not chinese ebay crap) ultrasonic cleaner for 30 minutes to an hour, and is why that is the only way I will do it.

Mine came from a comapny that made dental appliances (bridges and the like ) that went under. Thing cost over 3K new... but it is big enough to completly submerse that caburetor.

With my comments in mind... Here it is!

[Jess]

With BIG Thanks To Roland Van Cauter:

Roland is (I think) Dutch... so english is not his native language. While his english is excellent, some of his sentax is different than what I am used to... Read it a couple times and it will become clear.

I made a few additions, and one translation, all in italics...

Hope it helps... It is smack dab on... If you can correctly follow these procedures... Your carby will be right and you will have a big smile.

EDIT: by Wayne. This is very good but it has one error in the sequence of operation. If you set your Port Valve using Roland's non-gauge method (after the limiter plate releases the secondary), you'll have it opening later than the final advice from the factory. This may work fine, but this edit is to correct a misunderstanding with how the angles are calculated. The last factory setting was PV opens 6 degrees before limiter plate moves. If you want to know why this is correct, read the rest of the red print, otherwise move on to Roland's excellent guide.

The error has no bearing on how you set the angles using the gauge. All angles given by Suzuki assume that the resting angle of the fully closed primary is Zero. That's where you'd set your angle gauge to zero. Roland correctly explains why 82 degrees is actually full open on the primary. It's because when the primary is fully closed, it's actually 8 degrees off being fully vertical in the throat. So on the angle gauge the maximum when it's full parallel to the throat is 82 degrees (82 + 8 = 90). Other than this, ignore the 8 degrees for setting the angles. It only has a bearing if you're trying to understand how it works. Although irrelevant to the setting procedure, he correctly says the throttle at 35 degrees is really at 43 degrees (35 + 8)and it's at this point the last factory advice was for timing the port valve. But he assumes that the limiter plate at 41 degrees is based on an absolute zero. It's not, it too is based on the assumed zero found when the primary is fully closed. So when the limiter plate moves at 41 degrees, it's actually releasing the secondary at 49 degrees absolute (41 + 8). IE, 6 degrees AFTER the port valve (35 + 8 = 43). The port valve, in the last factory advice, opens 6 degrees BEFORE the secondary is released by the limiter plate They are all based on the same 'zero". There's a video at the end of this thread that demonstrates how all the angles are referenced to zero including the limiter plate that stops the secondary from opening.

Here it is: ( A few weeks ago I changed the cables and with this help I wrote 5 years ago I succeeded at once in adjusting without any flat spot)

As I notice that there are plenty RE-5 owners whom have problems with theset-up of their carburettor I like to explain how this set-up can be madewithout the need of special tools .The only special tool you need are your brains.Everybody is talking about how difficult it is to adjust the RE5 carburettorbut in reality it is very simple.

There are usually two main problems:1. The carburettor. itself2. Tuning the cables. Let’s start with point 1Typical problems : spark plugs whom are getting wet , irregular idle , badstarting ,erratically running engine in medium and high speed range.
How to begin (For those who have the manual pages are mentioned)Remove the tank and fan . It’s not necessary to remove radiator, oil cooleror exhaust. Now it’s easy to remove the carburettor. (3 bolts and the oilline). Remove & clean all the jets mentioned on page 65 & 66 . Don’t worryabout the adjustment of the pilot screw , that’ll be mentioned later.

Ignore point 7 because that never causes trouble . The float level normally never changes ,alltough avoid to tough the arm by force . And now comes somethingimportant !! If you don’t want severe trouble , don’t use the same floatchamber gasket again!!!

This gasket is fabricated from a kind of rubber andis in most of the cases about 25 years old and totally hardened. This means the sealing between the cap and the carburettor body is allmost nonexistent. This means that a twist of the grip results in a injection of fuelin the air passages of several jets (secondary main system) . This causesthe spark plug to get wet in a few minutes. When the engine (and thecarburettor ) is hot . The fuel vaporises and is getting through the leaksconstantly in the air circuit. So the engine runs erratically in all speedranges.

How to check if your gasket has hardened . See at the outside if thecarburettor has a wet or greasy spot around the gasket area. Normally thismust be completely dry .If your sparkplug is wet (in a warm engine) and you’re certain the plug is OK suspect the gasket. Page 68 d. will be mentioned later .

An other problem ( a floodingcarburettor) is often caused by a leaking fuel cock. Change the fuel cockgasket ( the one with 5 holes in it) and the problem is solved. (Also, check the oring in the diaphram...per Jess)

Now we’re ready for point 2.2. Adjusting the cables :Typical problem is the powerdip between primary and secondary system andloss of power.Don’t use the service manual for this because the information in it isupdated by Suzuki Service Bulletin NR 9 (page 4,5,6,7,8 & 9)A little explanation:Point 1 : Be sure to turn in all the cable adjusters or you’ll haveproblems with the adjustment of the oil metering pump. Point 5: This adjusting screw is not available on the early RE-5M typesPoint 6: Not necessary to remove the carburettor. Point 8: As I found a way to adjust the cables without the carb. angleindicator the rubber plug doesn’t has to be removed. For those whom have theindicator , they may follow the service bulletin. Point 11 till 14 can be ignored unless the carburettor has dropped to theground or something like that. Point 15 b.2.: The proper angle is 78 to 82° Here we need some further explanation. Even if the primary throttle valve is totally closed ,the angle of it will be 8° compared with the inlet (primarybore) it closes. ( Service Manual page 58 rule 8). So , if one mounts theangle indicator as described in point 12 of SSB9 , the throttle valve has still an opening angle of 8° whereby the indicator shows 0° . So, when theindicator angle shows 82° , the throttle valve has it’s maximum opening (82° + 8° = 90°) and that’s something you can easily verify by looking in the primary bore.

What they only want to say with point 8 is turn the throttle grip totally open and check if the primary throttle valve has it’smaximum opening . Point 15 b.3.: Check if the throttle valve closes till it’s minimum (8°) .Punt 15 d.: Port valve timing Now I shall explain why we don’t need the angle indicator . To understand this you have to know a little theory how the carburettor is working. Of course you can read this theory also in the service manual on page 58 and the next pages. As you noticed yet there are two throttle valves in the carburettor. The primary throttle valve in the primary bore which has been mentioned yet and an other one which is located in the secondary bore (under the primary bore) and which is called the secondary throttle valve. Well, to be correct there is an third valve (port valve) which is also situated in the secondary bore but which can’t be seen because this port valve is located in the trochoid housing and behind the secondary valve This port valve and the primary throttle valve are commanded by the throttle cables. The secondary throttle valve is actuated by the vacuum developed in the primary bore by opening the primary throttle.

What is the now the meaning of the throttle cable set-up? Never more or less than when one opens the grip the secondary throttle and the port valve will open perfect simultaneously on a certain moment. And that seems to me perfect logical because when in the same inlet 2 valves are situated behind each other and only one opens the inlet will still be closed by the other. How this really happens is explained here: The moment that the two valves are opening together is when the primary throttle valve has opened 43°To prevent the secondary throttle valve from opening to soon,(this valve is as I said actuated by vacuum), it is blocked by the limiter plate (see service manual page 59). When the primary throttle valve has reached an opening angle of about 41° the limiter plate deblocks the secondary throttle valve. And this is something you can see very good if you look to the front side of the carburettor (between the radiator and the carburettor) with help of a torch (flashlight... Jess) .

If you twists the grip you can see the limiter plate move on a certain moment. This moment should be the moment too for the port valve to start opening. After this theory we will continue with our SSB.point 15 d.1.: The correct timing is 35° on the angle indicator ,( when the primary throttle valve opens 35 + 8° = 43°).

With other words a fraction after the limiter plate begins to move. This is the error. When the primary reaches 35 on the angle indicator (where Suzuki sets the PV to open) the limiter plate is not free. It opens at 41 from the same reference point as all the others so actually opens at 41 + 8 = 49 degrees). The primary at 35 (and most importantly the port valve) are BEFORE the limiter plate moves. Easily verified by watching it all happen on the carb as shown in video below). To be short , in place of looking to the angle indicator one even can observe the start of movement of the limiter plate . When it has moved about1 à 1,5 mm the port valve has to open too. No, the port valve should already have started to open BEFORE the limiter plate moves. This accounts, among other things, for the inertial affect on stationary air In practice this works perfect on my bike and several others I’ve adjusted It may very well on some bikes, but it's not what Suzuki advises. PV opens before limiter plate movement if you follow the Suzuki guidelines and use the angle indicator. Or, if you want to do it without the gauge, do the opposite of what Roland says here. Set the PV to open a fraction before the limiter plate moves.

Point 19 : adjustment pilot screw: You can do it as described but in practice around 1 ½ turns is a good basis. Some more theory : the pilot screw is necessary to make the fuel-air mixture in the primary circuit the same as in the secondary circuit. With a bad adjustment (weak mixture) the dip around 3500 rpm never disappears even with correct adjusted cables. And the last points of interest : the air filter . Only use a genuine one because if it isn’t made of the original material , the mixture can get too poor or too rich too. Be sure the fuel pipe don’t touch the air inlet collector . When this collector gets hot due to very warm and humid weather it heats the fuel before it enters the carburettor and can cause vapour lock.


Carby Angles

[tom93gts]

Excellent, thanks for posting this!

[Crusader]

I used the above guide and worked like a charm.

Except i modified it a little.

Dont need to take anything off apart from the port valve cover and the fan.

Get another person to help you turn the throttle and with a torch look when the limiter plate starts to move, while your watching the port valve move. then just adjust slowly and keep double checking by slowly moving throttle and talking with your team mate.

This way seems easier as you dont have to take off the tank and fight with the torch + throttle while looking at both the port valve and limiter plate.

Cheers,

[Jess]

You guys and your damn torch... I'm afraid of setting the silly thing on fire... so I use a flashlight ;D

Wink... wink...

Best,

Jess

[aerologic]

Rats! I still have the flat spot. I've adjusted the port valve as described above. What I haven't found on this site is how to adjust the pilot screw. I've started at 1.5 turns. How does one adjust that? Is there a logical procedure? I remember Sam telling me to move it a degree or two. Did I hear that right? Is it that finicky? I've moved it a LOT more than that with no noticable effect.

Sam cleaned my carb so I should be OK there although I do get a couple drops a day dripping from the carb. I'm not happy about that. Petcock is dry.

Plug is new.

The bike revs fine, i.e. it sounds good when reving it in neutral.

What seems most odd to me is I will make some adjustment and then I accelerate and I say" now I got it" but after a while it seems to get weak and I have trouble climbing a small hill on the road. The bike seems to "come and go".

Now I do suspect that my thermostat is bad. It was new from Sam but the bike never warms up all the way even though it's hot in Cincinnati now. I never hear the fan run anymore even though I did back when it was cold. So maybe the bikes temperare is not constant. Maybe that accounts for the bike coming and going? I need to take out the thermostat and put it in boiling water. It was just too hot today to work in the garage.

Thanks!!!

[aerologic]

Thermostat is OK. It opens up at 160 degrees. Why won't my RE-5 warm up? It used to, dang it, back when it was cold out. I have new temperature sensors for the fan and gauge. Gauge now does not get to the "normal operating" line like it used to. The gauge moves around a bit while I'm riding.

[don07tncav]

Was looking for a dummies guide to carb adjustment thread, this one may help me out!