Carburetor Cleaning

Hi all,

Two days ago I stole my mom's carburetors off her '81 550 Maxim for my '82 550 Seca, trying to test if my performance problem was actually the carbs or not. Turns out, my problem was indeed the carburetors. After taking the bike for a short ride, all the top end power was back! I could rev all they way to the redline and still make good power!

However, there are two problems.

A. My mom's carburetors (carburetors A) seem to have a pilot jet clogged. It's stuttery and noisy when I first get on the throttle at lower rpm's (around 3-6k).

B. My own carburetors (carburetors B) seem to have a main jet clogged. It's stuttery and noisy when I open the throttle all the way at lower rpm's (around 3-6k), and I experience the same issues above 7.5-8k rpm. I've discussed this specific issue before in my first thread, but never got a working answer due to the overload of questions in topic.

With problem A, I cleaned carburetors A with carb and choke cleaner thoroughly to no avail. What I'm now thinking is I didn't clean them properly. I sprayed the straw cleaner up both carb jets, without taking anything off but the float bowl.

Carburetors B have not been taken apart yet, except the tops to check for holes in the diaphragms, although I believe that the main jets will be easier to clean because they have a larger diameter.

With all that said, my question is this:

Are the two carburetor problems really due to dirty carbs, and how can I thoroughly clean them to prevent the issues from returning in the near future?

P.S.
Carburetors A have diaphragms that look puffy and bloated, but I seem to experience no problems because of them. Carbs B may have this issue as well, but I have not checked yet.

 

Did you check and adjust your valves...sometimes a tight valve can make it appear to be carb related...you need to go to church ...completely take carbs apart soak them in cleaner...replace all rubber seals....please by all means follow these steps you will be happy you did. Im sure Kmoe and hogfiddles and Chacal will all agree.

 

+1 what he ^ said.

Gary H.

 

Spraying carb cleaner into a carb does not count for a cleaning. You have to dissemble the carb and clean each part with cleaner and brushes. Small wires help to clean and unclog holes in jets.
Carb cleaner is to rinse the carbs out after they are cleaned.

As long as the diaphrams don't have any holes or tears they are good.

 

In The Church of Clean.

Do that ^^^^^

 

your moms carbs are also jetted dfifferent than yours. seca has a larger pilot air jet under the diaphram and different slide needles.
your seca has a hotter cam and requires the different jetting .

look at this link to see the inside of your carbs to understand the passages

Something New, Something Naked
main jet is likely the emulsion tubes clogged under the main jet

you should clean moms carbs for her

you have to remove the parts to clean the carbs also the main air jet in the carb is not removable

 

I want to add this .
just pulling and swapping a set of carbs is not going to do much for you, other than showing the motor will run.
you would have to adjust mixture screws and do a carb sync to get the best Idea of how the motor will run.
also the unknown state of clean with the swap carb brings up question is it carbs or motor? in your case it is most likely the the difference of the jetting . Yamaha would not have made them different if they were off the shelf interchangeable.

your maxim carbs were set for the condition of that motor and you did see problems that may or may not in the carbs the only way to determine that would be to tune and sync carbs to the seca. which still will leave you with the wrong carbs/jetting for a seca

I have a spare set of Clean carbs I use to test if a motor runs but it is just to see it start and make the choice of moving forward with my project.
I ohm out the ignition, do the valve clearance check first spec them, compression test, then if all is ok I do a test start to see if motor is blowing smoke or making bad noise.
the carbs I remove go to clean and evaluation.
then I start a pricing list to see where I need to go
my cost at that point would be a few shims ,spark plugs, maybe a part from my spares if needed

i may have drifted a little here

 

So there we have conclusive proof. Maxims are for 'old dears' and 'young buck's' ride Secas - I knew it!

 

Yep

 

Thanks for your advice, guys.
You have provided a wealth of information on the topic, and some great tips to help me along.

I'll be sure to do a thorough cleaning on both sets of carburetors, and to switch them back to their proper bikes tomorrow.

Good thing I replaced my intake rubbers They were all about to rip apart on my next carb change

 

I have a Maxim and a Seca does that make me an Old Buck or a Young dear

 

More likely just confused.

 

Carb cleaner cannot improve the efficiency of any engine. Spambot needs to get a real job.

 

The carbs on a motorcycle are not a downdraft design ,spraying cleaned does not clean the passages out. Soaking is only true way to clean passages and jets. IE taking carbs to the Church of clean full tear down breaking the "rack" removing ALL shaft seals etc . remember there is little exposed that can be cleaned it all in the throat and in the float bowl the jets and enrichment jets . Most of the time if carbs have sat for a period of time the fuel turns to jelly ,and plugs up the jets and passages.

 

Depends on which motorcycle.

 

Not sure why I did it, but I onced sprayed Gumout into my carb intakes through the airbox, and a short time later ended up with a leaky float valve. Coincidence??? I believe that stuff can dissolve old rubber and may have kept valve from seating correctly...never will use Gumout inside the carbs again.

Seafoam in the gas tank has done a good job keeping passages open and clean on my XJ. It probably won't clean a fouled or plugged passage...

 

I doubt that the gum out caused that. You'd have hadn't figure out a way to get the spray that was sucked into the engine cylinders, to go against the air current, and the draw of the fuel, and have it go "upstream' through the emulsion tube,through the main jet, through the bowl of gas, and back into the fuel valve needle......and the needle would have to be rubber-tipped, rather than metal tipped-----

 

Agreed. I just found it an interesting coincidence...

In any case, never spraying it in there again.