Suzuki FA50 PROBLEMS

I'm having a problem with my 2 fa50's. I cleaned the carburetor really good twice on both, new fuel filter and threw out the old inline ones, drained and replaced the oil and gas, new battery, new fuel lines and vacuums, replaced the CDI, reed vales, piston, cylinder, hot tanked the exhaust, k&N air filter and a few other things. I cannot get it to run good when i give it WOT, it idles fine and only works somewhat well with the choke on. I also ajusted the needle and replaced that also and switched carbs.

What do I need to do so it will run right. Top speed of 24 right now but bogs down intermitently. PLEASE HELP!!

Re: Suzuki FA50 PROBLEMS

I also replaced the oil pump and checked the timing.

Re: Suzuki FA50 PROBLEMS

"I cannot get it to run good when i give it WOT"

What is your symptom?

I guess it's bogging or loosing power till you close the throttle a bit.

First of all I don't like in line filters unless it is a gravity barrier type with n paper element, there are filters in the tank nipples and the tank is plastic so you don't have rust and junk except what comes in with the fuel. Use a clean plastic fuel can.

If you are using a K&N filter you need to up jet.

So far the best way to do this is to drill it.

Try covering the filter with duct tape to increase the restriction.

Also if you moved the slide needle you may want to move it back to the middle position till you get the WOT performance improved, then fine tune the low and mid end response by adjusting the needle position.

Rusty

Re: Suzuki FA50 PROBLEMS

How much bigger do I need to drill the jet? Is there a special numbered bit I should use. I'm pretty familiar with adjusting the carb on the exterior and I'll put the needle back in the middle position. Where do I put the extra hose for the carb that pertrudes out the left side at the top?

Re: Suzuki FA50 PROBLEMS

By adding the K+N you've increased WOT air intake without enabling the engine to pump any better than it did as 100% stock condition. The result is predictable.. the engine runs lean at WOT with that stock mainjet. Choking forces a more correct, richer air:fuel mixture.

Why not go back to the stock air filter and thereby correct the air-fuel ratio?

Keeping the K+N and upjetting will not improve engine pumping efficieny and enable the engine to burn more fuel and produce more power. All it will do is make more fuel available and hurt fuel economy..

To get better performance, intake improvements need to be matched by port and/or exhaust improvements... improve the engine's pumping ability throughout it.

If you're not after high performance (and you shouldn;t be at this point, imo .. just get the freakin thing to run correctly as stock) then ditch the K+N and get on with it.

Re: Suzuki FA50 PROBLEMS

Joe,

I really respect your knowledge about 2 stroke engines and usually you make a lot of sense to me, however.

Consider this.

The FA50 and FZ50 engine is subject to restriction in the USA.

The restrictions lie in the carb, manifold, air box and to a lesser extent the muffler.

The engine is capable of producing more power and has a greater capacity for breathing in and out then it is being allowed to do so.

Therefore, in my opinion buy eliminating restrictions and increasing jet size you can take advantage of the unused capacity for power in this engine.

In Europe this is a 2.5hp engine and the only difference it the carb and manifold.

Increase the flow thru the carb and manifold and the engine will produce more power provided the jetting is changed to match.

I am running a jet that has been drilled with a #53 drill and it needs to be larger.

Also my carb has been enlarged along with the manifold by the previous owner.

If you search around here you will find more info on drilling jets and where to find drills.

I will be using Salsa's drill when I start drilling again.

I am still in a learning curve with this and I do appreciate the input from Joe and others.

Rusty

Re: Suzuki FA50 PROBLEMS

Aaron In Bellingham WA /

Thanks guys! I will drill my jet and go from there.

Re: Suzuki FA50 PROBLEMS

if that's the case, and i'm sure you know waht you're talking about, then sure .. go for better carburetion.

But Aaron's first message sounded like that bike had a genuine tuning problem.. one which a whole slew of replacement parts and maintanance proceedures failed to cure (assuming 24mph and bogging at top speed is not normal behavior for the FA50).

In that case i'd never recommend modifying anything.. modifying a sick bike is most often a trip into the Twilight Zone.

Re: Suzuki FA50 PROBLEMS

Joe,

There you go making perfect sense again.

I forgot to mention what you just said.

Before you go about making any changes from a stock config, it had better be working PERFECTLY first or as you sait it's a trip to the zone with you!

Rusty

Re: Suzuki FA50 PROBLEMS

jOHNNYdOUBE /

Shit, my Fa50 is acting like that too.

Sometimes, hold it WOT and it sounds like its running out of fuel then rev's up again. on the stand.

Cleaned everything. Twice.

Re: Suzuki FA50 PROBLEMS

Fred Melonhead /

god .. this thread is 2 years old ?

Re: Suzuki FA50 PROBLEMS

Fred Melonhead /

""Sometimes, hold it WOT and it sounds like its running out of fuel then rev’s up again. on the stand.

Cleaned everything. Twice.""

... and ... is it running an air filter ? ... or not ?

Re: Suzuki FA50 PROBLEMS

No, just air-filter box.

Didn't buy one yet.

Found out the porcelain on the plug was cracked from dropping the motor to check the reeds and clean the carb.

Probably was scattering the spark.

Then did a compression check, it is only at 90psi.

Should it be higher then 130psi??

I think changing the rings and honing the cylinder should be next.

It was bought for $180 not running, I opened intake and found a piece of junk in the reeds and cleaned them.

That's when I cracked the plug dropping the motor and bending the plug tip.

So, no more WOT crap, just a 90psi compression check.

It goes 25 uphill moderate, 27 long flats and 33 down most small hills.

When I hit the choke, it has a power increase.

Re: Suzuki FA50 PROBLEMS

I agree with this post.

Re: Suzuki FA50 PROBLEMS

Fred Melonhead /

meee tooooo

except the part about the part on the part with the thing

Re: Suzuki FA50 PROBLEMS

I am about to purchase a 1980 fa50 it has 1307 miles on it and I hope to get it for 200 not running. the guy wants 275 for the bike and also has a 1982 honda urban express (same price doesn't run)with 8000 miles on it which one would you bye? do you think the Suzuki will be a problem that should be avoided?

Re: Suzuki FA50 PROBLEMS

buy it.

Re: Suzuki FA50 PROBLEMS

I bought the Fa50, It had what looked like green cottage cheese in the float bowl. The muffler was plugged up solid, it has a seized rear brake cable and needs a battery. I am installing the parts and will attempt to start the bike after I receive the battery from e-bay.

Let you all know how I make out soon

Mark

Re: Suzuki FA50 PROBLEMS

My fa50's also doing stupid things. It'll die at WOT. Will about 15 mph. I cleaned the carb an rebuilt the top end. still don't' know what's going on.

Re: Suzuki FA50 PROBLEMS

You do not need a battery. Clean carb/exhaust, compression check, clean reeds, kick over, then clean little plastic strainers in the gas tank, try again.

Re: Suzuki FA50 PROBLEMS

I got the little sucker going last night but had a dirty stuck throttle cable so today I will clean and reinstall to test drive. Regarding your WOT issue take the fuel petcock valve apart and check the diaphram it may be shot, I have never seen a vacuum diaphram to assist in fuel delivery for a two stroke set up located in the gas tank petcock valve but this one has one there. Check it out, let me know.

Mark

Re: Suzuki FA50 PROBLEMS

Ghost to to motha /

I walked into my kcal Suzuki dealer, showed him my main jet, asked if I. Could have the next larger three sizes. Five bucks sndim out the foot. No drilling.

Re: Suzuki FA50 PROBLEMS

Ghost to to motha /

Dang my iPhone auto spell sucks it

Re: Suzuki FA50 PROBLEMS

I just got the little Savage going it seems to run better than my Honda Urban Express. I haven't taken it on the road yet I didn't have time this morning, I had to go to work but while running it on the stand the throttle responds is excellent I hope it is the same when my lard ass is on it (200 lbs)

Re: Suzuki FA50 PROBLEMS

By the way if any one is having trouble with these bikes I noticed a pinhole size passageway often overlooked that is located on the side of the float bowl (seperate from the main body of carb) it is fairly hardto clear out and may be the source of you problems check it out let us know.

Re: Suzuki FA50 PROBLEMS

I just got home from work fired the FA up took it for a test run and yup bogs down at WOT. I am going to try setting the jet needle up a step to see if that helps.

let you know how i made out too cold right now to work on it maybe tomorrow

Re: Suzuki FA50 PROBLEMS

nope no success with the carb tuning i will now advance the timing a bit being careful to mark the plate before moving it ahead so I can return it to its previous setting The bike is not eating up the fuel at higher rpms it is acting like the spark is not keeping up with the fuel compression stroke at a certain rpm threshold. The reason why I say this is because i removed the air cleaner and noticed fuel on the rubber hosing adapter in the air box

Re: Suzuki FA50 PROBLEMS

Always keep an aircleaner on or you will get some stones up the carb.

Re: Suzuki FA50 PROBLEMS

well changing the timing did nothing I will now proceed to make sure the choke circuit is shutting off completely, the bike appears to be having to much gasoline delivered at mid level to high circuit operation if the choke is not shutting off all the way that is a place to start.

Re: Suzuki FA50 PROBLEMS

I think the carb main jet tapered needle chamber was corroded after sitting for so long and now does not match the tapered shape or mating surface required for proper fuel metered flow. I lowered the needle setting on the piston air valve to it lowest setting and only realized a minor improvement toward WOT performance. Oh I forgot to mention the symptom and diagnosis of this problem is too much fuel and sloppy fuel delivery at greater than half throttle position (high circuit fuel delivery failure) in other words toss the carb in the trash and buy a new one, when I say new I mean brand new NOT REBUILT!

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