MOPED ARMY

Oct 12, 2019 04:48PM

When I first got it this is actually what I did before I bought the foam element, and it was actually much worse (noticeable deceleration when I opened the throttle all the way). This was before I got the new carburetor and cleaned the exhaust, though, should I try it again? I could try a cone filter too.

I may also try running it without the exhaust pipe to rule that out but I don't want my neighbors to hate me.(edited)

Re: Am I four-stroking? And what to do about it

P D /

https://www.manualslib.com/manual/999530/Suzuki-Fa50.html

Oct 12, 2019 05:32PM

You might try applying the choke at WOT . If it runs better , you'll know the main jet should be a touch bigger .

These carbs are pretty simple . Tear the original apart and clean it thuroughly .

Note which size jets are installed and compare that to what's suppose to be stock .

Here are a service and owners manuals . Download them and become very good friends with them .

https://www.manualslib.com/manual/998156/Suzuki-Fa50.html

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 12, 2019 06:02PM

I will try those suggestions. Now that I have two carburetors I'm a little less skittish about ruining one ;)

I'll try running with the choke on but if everything is stock I shouldn't need to rejet though, right? I worry if I rejet I might just be band-aiding some other issue, like an air leak... Admittedly, I reused the old gasket for the new carburetor.

I'll get back in a few hours but still open to suggestions so I can try 'em all at once. Thanks!(edited)

Re: Am I four-stroking? And what to do about it

Daniel '' /

Go to branch

deesal

Oct 12, 2019 11:10PM

Clone carbs rarely come with internal components that are in tune with your bike.

Re: Am I four-stroking? And what to do about it

Don Ohio /

don45640

Oct 13, 2019 02:15PM

New carb is probably overjetted. When you said you CHANGED the spark plug,was it a new one?

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 13, 2019 03:19PM

Yeah it was brand new, I went out and bought a matching NGK plug.

Re: Am I four-stroking? And what to do about it

Don Ohio /

don45640

Oct 13, 2019 08:16PM

Whenever I have suffered 4-stroking it was always over-jetted or a restrictive airbox.

Re: Am I four-stroking? And what to do about it

Jeffrey Strichart /

Oct 13, 2019 10:03PM

> Don Ohio Wrote:

> -------------------------------------------------------

> Whenever I have suffered 4-stroking it was always over-jetted or a

> restrictive airbox.

It was always removing the stock air filter that fixed it for me. Every time. I bought a brand new Magnum in 1979 or whenever they first came out and it would only go about 22 before it four stroked and would not go any faster. Yanked the air cleaner and went 30 immediately.

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 13, 2019 10:03PM

I’m going to clean the old carb and put it back tomorrow cuz I got the day off but I also noticed the carb leaks a bit of fuel out the overflow at the bottom, would this be an indication it’s running rich or some other problem, or is it normal? It doesn’t seem like a lot, it is barely enough to wet the surfaces the overflow tube is resting on, and make my finger wet if I touch the end of the tube. I can get pictures in the morning for a better visual.

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 13, 2019 10:16PM

I’ll also run it without the air box and see how that goes, it’s just a pain to find a filter than can fit the FA50 given how close the carb is to the rear tire.

Re: Am I four-stroking? And what to do about it

Jeffrey Strichart /

Oct 13, 2019 10:54PM

> Drew Cooper Wrote:

> -------------------------------------------------------

> I’m going to clean the old carb and put it back tomorrow cuz I got the

> day off but I also noticed the carb leaks a bit of fuel out the overflow

> at the bottom, would this be an indication it’s running rich or some

> other problem, or is it normal? It doesn’t seem like a lot, it is barely

> enough to wet the surfaces the overflow tube is resting on, and make my

> finger wet if I touch the end of the tube. I can get pictures in the

> morning for a better visual.

How many times did you press the primer button without starting it?

Re: Am I four-stroking? And what to do about it

Don Ohio /

don45640

Oct 13, 2019 11:28PM

> Jeffrey Strichart Wrote:

> -------------------------------------------------------

> > Don Ohio Wrote:

>

> > -------------------------------------------------------

>

> > Whenever I have suffered 4-stroking it was always over-jetted or a

>

> > restrictive airbox.

>

> It was always removing the stock air filter that fixed it for me. Every

> time. I bought a brand new Magnum in 1979 or whenever they first came

> out and it would only go about 22 before it four stroked and would not

> go any faster. Yanked the air cleaner and went 30 immediately.

I always just took a drill to strategic places on the air box and thereby increased the flow .

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 14, 2019 09:46AM

I don’t have a primer button. There’s a prime lever on the fuelcock but I only had to use that when I first replaced the carburetor.

Re: Am I four-stroking? And what to do about it

Jeffrey Strichart /

Oct 14, 2019 10:10AM

> Drew Cooper Wrote:

> -------------------------------------------------------

> I don’t have a primer button. There’s a prime lever on the fuelcock but

> I only had to use that when I first replaced the carburetor.

Gotcha. Obviously it should not leak out of the overflow for no apparent reason.

Check your carburetor for plugged jets or incorrect float setting. If the jet(s) are plugged even a little it will not run right and gas would accumulate in the bowl while the engine is running and overflow. If the float is not properly set it would fill up and overflow while the bike is parked (if the petcock is on). Turn the petcock to off and empty the bowl. Then turn the petcock back on. If it does not overflow while parked then the float should be ok. Also a faulty petcock could cause a problem but that is rare.

Re: Am I four-stroking? And what to do about it

P D /

Oct 14, 2019 11:03AM

An FA50 uses an automatic fuel valve ( petcock ) .

Unless something is not right or it has been replaced with a different style , anytime the motor is not running or being turned over , fuel will not pass until it is switched to the prime position .

If the carb is leaking out of the drain at the bottom of the bowl : the float may be stuck ; the float valve may be dirty ; the drain screw might need attention or the brass over flow tube could be cracked .

In stock configuration , the FA50 runs best with a OEM type foam air filter set up and the carb adjusted per the manual , exactly .

My FA50 started first kick , most often , and held 30+MPH for as long as I cared to ride , when it was totally stock .

Now , technically , it isn't completely stock : less 1 ring and the piston crown has been 'channeled' which lowered the compression a bit slightly quickened transfer and exhaust flow . The carb has been adjusted to accommodate the changes and the bike does as much as 34 - 35 MPH . The piston and rings are due for replacement as both have about 8,000 miles of pretty hard riding .

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 14, 2019 11:27AM

Mine is completely stock except for the clone carburetor.

I took the air filter off and it didn’t bog down at WOT like before, but it still only topped at 25. I’m gonna try to clean the air filter first and if that doesn’t work I’ll just put the old carburetor back.

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 14, 2019 11:33AM

I guess I’ll have to anyway if it’s gonna keep overflowing

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 14, 2019 05:09PM

Is it possible my throttle may be opening too wide? I read somewhere that if the throttle isn’t flush with the top of the carburetor bore at WOT, and goes too far up, it can cause “turbulence”... Is this adjusted with the nut at the handle?

Re: Am I four-stroking? And what to do about it

P D /

Oct 14, 2019 05:44PM

Slide adjustment is best accomplished via the adjusting ferule atop the carb .

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 15, 2019 03:24PM

I took apart the clone carb and the main jet was completely unlabeled and the overflow was a completely different style than the original. Needless to say I’m gonna take my lumps and clean out the old one.

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 15, 2019 10:38PM

So I put the old carburetor back after what I think was a good cleaning, and it stopped bogging at full throttle but still only went 25. I noticed an air leak (detected with starting fluid; engine died when I applied it to the intake manifold) which applying some Permatex seemed to fix. Any issues with top speed should be with the engine itself at this point, right?

Re: Am I four-stroking? And what to do about it

Jeffrey Strichart /

Oct 16, 2019 01:39AM

> P D Wrote:

> -------------------------------------------------------

> An FA50 uses an automatic fuel valve ( petcock ) .

>

> Unless something is not right or it has been replaced with a different

> style , anytime the motor is not running or being turned over , fuel

> will not pass until it is switched to the prime position .

Interesting. Maybe the valve is faulty?(edited)

Re: Am I four-stroking? And what to do about it

Jeffrey Strichart /

Oct 16, 2019 01:43AM

Good idea. I don't know why China makes such bad products and not just moped parts.

Re: Am I four-stroking? And what to do about it

P D /

Oct 16, 2019 09:27AM

> Drew Cooper Wrote:

> -------------------------------------------------------

> So I put the old carburetor back after what I think was a good cleaning,

> and it stopped bogging at full throttle but still only went 25. I

> noticed an air leak (detected with starting fluid; engine died when I

> applied it to the intake manifold) which applying some Permatex seemed

> to fix. Any issues with top speed should be with the engine itself at

> this point, right?

Not necessarily . Once the motor runs 'good' ( tuned to factory specs ) , then the rest of the machine has to be made to 'run' as good .

>Stock air filter in place .

>Exhaust tight and clean inside . I use cheap oven cleaner which seems to do a good job . I have burned the exhaust out with straight gasoline , but , that can get real exciting very quickly ( don't do it ) . I've heard that drain cleaner does a decent job .

>Transmission has to be copacetic with proper oil applied . I have tried many different oils and have found that 15w-40 diesel oil seems to produce the best results . It should be noted that the best results may not be seen immediately because of 'deposits' left from previous oils .

>The wheels have to be free rolling/spinning ( correct lubed bearings ) with no brake drag .

Obviously , the rear wheel will have a bit more drag when on stand , due to transmission interaction .

Those last few MPHs are the hardest to have .

Always remember that it's the little things that make the big things run . ;)

Re: Am I four-stroking? And what to do about it

Drew Cooper /

Oct 17, 2019 05:16PM

I see. The manual makes a great deal out of cleaning carbon from the combustion chamber and exhaust port as part of the maintenance procedure, and I've already put my stock carburetor and air filter on, as well as fixed any air leaks. It runs consistently at full throttle, but just barely breaks 25 mph. Judging by the amount of carbon I found in the exhaust port while cleaning the pipe, there's probably still a fair amount in the combustion chamber.

So I suppose my next step will be a thorough inspection of the engine and transmission. Maybe a compression test as well? How many kicks will give an accurate reading? Just once? And lastly, the manual only gives a compression ratio of 6.5:1. How does this translate to PSI?(edited)

Re: Am I four-stroking? And what to do about it

P D /