fa50 will not idle

ok now i have this issue, it still will not idle no matter where i set the air screw and the slide screw. it has new rings, a base and a head gasket. the compression did not seem to change, still was 50 psi. i took the carb apart and all the jets and blew air thew them and i could feel air go thru the carb where it looked to me where the air was supposed to go.

i put a 90 deg cpvc elbow on the carb and i put a pc of sponge in it and cut it down until it was just to thin to stay in the port, and still it will rev and hold speed and then just start slowing down and stop. i can crank it back up but i can't for the life of me get the thing to idle. so outside of a bad carb what else might i look for?

i have set the air screw from closed to all the way out and the main slide screw i adjust it to slow the engine and i get it to say 2000 rpm and then it starts to slow down and stop.

i'm no stranger to engines but i do 4 cycles not 2 cycles, i guess it could have bad crank seals but how do you test for them. and i guess if it does then it is better off going as a part bike as i'm not tearing it apart for crank seals.

anyway to me it sounds like a carb or crank seal i do not see anything dripping from the coil side, but i guess it could be leaking on the drive side. so may i would take the fill cap and loosen that and spray with soap to see if i have bubbles? i guess that will tell me. or loosen the oil pump and spray that and see?

thanks for any ideas on how to get one of these to idle bp.

Re: fa50 will not idle

ok i still have th idle issue but this is what i have done to try to make sure it is not something else.

it has a new head and base gaskets and new rings. i get 85 to 90 psi at 1500 rpms crank speed at the flywheel. i tested with the carb slide out of the carb this time i tested with the sllide out and the muffler off the same psi readings. i just took off the barrel to make sure the rings were not broken and istalled incorrectly they were correct and the thicker ring on top the thinner with the expander at #2 and the taper on the top. the timing mark it just before tdc. i use a screwdriver and touch the top of the piston and then move it to see where the timing mark is when i feel the touch and it is just before the tdc mark on the flywheel if has a blue spark at kick start speed on the bench using my hand to crank it over. i just set the main jet in the slide to #3 groove on the pin and i took out the idle screw spring to make sure that was not binding and causing the idle screw to not seat . so i closed the idle screw and back it out 1 1/2 turns. it cranks up cold with the choke lever and then will run with that closed. but it will not stay at idle. it will idle fast i think it could be 1000 rpms and it will stay there for a bit and then just start slowing down and stop unless i rev it a bit and the cycle starts over.

so does anyone have any idea what might be going on? if it was electrical i do not think twisting the throttle would make a difference. i sprayed starting fluid around the carb base and the reed valve unit and it does not make any difference. i spray it at the cylinder base and no difference i spray the head with soap and no bubbles.

so outside of a bad carb i'm stumped. so maybe someone here has some tests i have failed to do. thanks for any ideas. i told the owner to get a new carb from amazon so if he does i will install that and see if that makes a difference if not i will have him return it. outside of that like i said i'm stumped. i can make it rev faster with the main idle screw and as i lower the speed and adjust the air mix it will change speed a bit but not much and then just stop. it has no air filter but i did put a 90 deg cpvc elbow on it and then put an air compressor filter over that elbow and it made no difference. i cut that thinner and thinner until i could see thru it and quit that. thanks bp

Re: fa50 will not idle

ok i checked the timing with a car timing induction light and at 1000 to 2000 rpms it sets at 10 deg. i put a degree wheel on the flywheel and marked off 10 deg increments up to 50 deg and it gets to 10 and stops. if i rev the shit out of it the time actually drops. when it is about ready to stop the timing drops down to 5 then 0 so the cdi is doing something. i can make the idle change with the main screw on the slide but the air screw does nothing. so i must have some blockage in there that i can't see or there is a passage that is just not clean.

has anyone had luck with those carbs from the zoom zoom site? they are in livonia mi. i do not know if they make the carbs of if they are resellers. my guess is they are resellers and this stuff comes from china but for 40$ it may be worth a try to see if i have a bad carb.

Re: fa50 will not idle

You might also spray brake cleaner through the tube that extends down that hole and be sure the cleaner comes out where it's suppose to . ;)

Re: fa50 will not idle

Douglas Mackinnon /

Bob, do you have the small O ring and brass washer in place for the throttle speed screw? The service manual doesn’t show them but an exploded diagram does. I’d be Leary of the super cheap clone carbs…Too good to be true for $30-40. A lot of them have the mounting flange cocked so there’s no way to mount them. The one advertised by the zoom zoom group doesn’t have a photo from that vantage point to say for sure.

Re: fa50 will not idle

ok i put some carb clean into that port and it went thru to the bowl so that appears to be clean. i also put air to it and it did let air into the bowl.

as for that carb the seller sent me photos of the carb and it looks the same as the original. ebay does not show all 4 sides but the mount is the same. because it is free returns i really have nothing to lose but time.

as for that o ring and washer, i guess i do not know. if you're saying for the screw that adjusts the slide then i do not know if your saying for the air mix screw then no there is nothing on that screw. i kind of think that is not the correct jet. when i got the bike that screw was so worn that i had a time getting it out and then i had to cut a new slot just to use the driver for adjusting it. and when the engine is running that screw almost does nothing.


Re: fa50 will not idle

ok last one with the jets


Re: fa50 will not idle

ok update i got that carb installed it and it runs way better. also i think i asked about the muffler having all the extra holes, well they had to be plugged up. the new carb did a lot to get the bike to run but when i put a rag over those holes it ran way better. i kind of figured that based on my experience years ago with a sears moped.

so i was able to adjust the main slider jet finely and also the air mix actually did something. the old carb may have had the wrong air mix needle installed and it very well could have been plugged up even though i did try to clean it.

thanks for the help and after i get the rear tire repaired and take it for a test run i will stop back and let you all know how it did. again thanks

Re: fa50 will not idle

ok i had it running good. we drove it around and then it took a dump. only starts now if i hold my hand of the carb. and it has tons of blowback. so the petals must have failed. so tomorrow i wake them out and see what is going on. may have to get some of those carbon fibre blanks and make new ones. but it did run and it did drive down the street. so now he wants to sell it. go figure i do all that work and he thinks he wants to sell it.

anyway just figured i would let you know that i did get it to go and was able to take it for a spin thanks for the help. if i have any more problems i will stop back and see if anyone has answers bp.

Re: fa50 will not idle

> bob palmer wrote:

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

> ok i had it running good. we drove it around and then it took a dump.

> only starts now if i hold my hand of the carb. and it has tons of

> blowback. so the petals must have failed. so tomorrow i wake them out

> and see what is going on. may have to get some of those carbon fibre

> blanks and make new ones. but it did run and it did drive down the

> street. so now he wants to sell it. go figure i do all that work and he

> thinks he wants to sell it.


> anyway just figured i would let you know that i did get it to go and was

> able to take it for a spin thanks for the help. if i have any more

> problems i will stop back and see if anyone has answers bp.

Come on over to my place . I would like a free mechanic .

Re: fa50 will not idle

found out the issue the reed valves bent to stay open. so i will try to find some new materials to make some out of. i turned these over and it started up fast and ran even better but i expect these are getting old and will need to be changed out again. so if anyone knows of a good material i can make some out of please let me know. i guess i can get some .015" feeler gauge material if i can find it i need 32mm x 39mm and the thickness that works for the material i find. maybe some here have some good suggestions. thanks bp

Re: fa50 will not idle

Re: fa50 will not idle

well thanks alot for this. it helps. so what your saying is to get that what your calling paper but is the same material they make the reeds from and then make my own? i can make them. in fact i actually made a template of the reed petals in the mike now. but because it bent so far after only a short time running i expect the will bend again.

the steel reed petals are like maybe .015 to .020" thick. as i help them in my finger to clean and inspect them and to trace for the template. and the stuff you sent me is ..045" thick.

also can you tell me if i need to make some type of backer for the paper? i have been reading about some reeds have something called backers on them. i do have the curved section that what i think would be for keeping the petals from bending over backward. but should i think of the backers for the reed type paper?

or maybe just get those reeds already made for the bike. thanks

Re: fa50 will not idle

Yep, you can indeed buy a sheet of the reed material (often called paper, though it is often made of fiberglass or carbon fiber) and cut your own reeds. Reeds wear out, so if you plan on riding this one bike a lot buying a sheet is cheaper in the long run.

I'm not sure what you mean by backers; most reed blocks, the FA50 one included, have curved bits of steel called reed stops, like this (FA50 reed block pictured):


Re: fa50 will not idle

yes that is the item and that is the stop i called that a backer. but then i discovered the backers actually go over the reeds to help support them. i have talked to a person at that website that was given to me earlier. i have the original style and they gave me 2 other possible items. so tomorrow i will tale the owner and see what he would lke to do. my guess is if he is going to sell it then he may not do a thing but if he wants to ride it he may spring for on of them. thanks for the help on this one. i went out to the shop again an hour ago and 3 kicks and it was running and it was idling perfectly it does not reve up quite as fast as i think it can go but it was cold and not warmed up and the carb may need just a bit more tweaking. again thanks to all you guys for the great help.

Re: fa50 will not idle

so here is another item i think i found wrong. the owner heard some noise in the gearbox. i told him it was normal but he still wanted me to check it out. so i took off the cover and after half the gears and washers fell out i did not see anything out of place, but for the parts that fell. so the chain tensioners are not broken but a bit loose for my taste but i left them be. and i put the parts back to what they looked like they should be. the kick starter now will not kick start unless i hold the rear brake. i believe that is the way it is supposed to be just because there is a reason suzuki put the lever that is controlled by the rear brake and that lever. so now I have to hold the brake to kickstart it.

also after i turned over the reed plate the bike starts in 4 kicks with the choke on. and sets there and idles like a kitten. so it looks like those petals have to be tight against the housing, i read lots of online stories where the guys were saying the petals had to be open just a bit. that may be so for other bikes but not for this one. when i had them the other way with a bit of an opening it was hard to start and just did not want to idle. then they got warped a bit and the bike would not start. so i turned them over and now it runs real good. not so much on high speed but we will work on that in warm weather as that might be why it is not quite running fast as i think it could run. the air might be just too cold for it. plus i will get some of those carbon fibre or fibreglass petals for it and see how they do. I have some saved now for when it gets a bit warmer out.


Re: fa50 will not idle

"hold the brake to kickstart it."

Exactly how it's suppose to be . ;)

Re: fa50 will not idle

i do not know but the rear brake cable attaches to some arm inside the gearbox and that moves when the brake is applied. i put it back together like the book shows and that is how it is working now. i'm leaning on that being a bit of a safety item as when you kick start it you have a brake applied to help keep it from taking off on you. let's see if anyone has one of these agrees with me. thanks

Re: fa50 will not idle

That arm in the gearbox controls the starter clutch.

Re: fa50 will not idle

i guess so the book said you have to squeeze the left brake before kick starting it. so because they have the brake cable attached to the starter that must be what it does. it engages the starter gear so you can use the kick starter.

Re: fa50 will not idle

You're right, it just brings the kickstarter gear and the kickstart idle gear into mesh, it's not a clutch per se.

Re: fa50 will not idle

thanks. i only mentioned that as a passing subject from the help i had going. i got it running rather well for 30 deg weather outside. based on how it ran when it was brought over to me. but some said to check the clutch because i had the rear tire spinning and i thought it should not be spinning at the idle speed but it does i guess. anyway, when i had it apart to check on the clutch and half the gears fell out i had to figure out how they went back in there. so i got the parts diagram on my phone and put it back as close as i could from those photos. anyway, when i tried to kickstart it and the started just dropped i thought here i go i messed up something. so i looked up the operation book and it showed holding the rear brake for kickstarting it.

also, the YT's and i asked an ebay seller and he told m it had to be squeezed to kick start it. so now it is back as it should have been. anyway, thanks for the replies on that. it never hurts to get opinions just in case my data was incorrect. like i said at the beginning it has been like 50 years since i worked on one of these things. tons of cars and trucks and a few large scooters but no mopeds since then. all it needs now is a battery so i can repair the driving systems on it if he wants. but i think he is going to wait till warmer weather. thanks again

Re: fa50 will not idle

ok got the bike running now it had a warped reed and i turned that over and it runs well and idles good 2 to 3 kicks in 30deg and it starts. i took the gear cover off and found the clutch had plenty of friction material on it and the springs were good and strong. also fixed the Kickstarter it was assembled wrong and it needs the rear brake held so the kickstart will engage. must be a safety item. that is what a few ebay sellers told me and i contacted a local suzuki dealer where they got this bike and they told me i had it correct now. also if i need to get new reeds i have a company that has some they think will fit just find. so for now all is well, the last thing will be the electrical for turn signals and horn and brake lights this summer. thanks for the help on this.

Re: fa50 will not idle

Chris Henige /

That clone carb is closer to the OEM one that I got for my FZ50. The bowl is much more squat than the clone carb I bought which I could not get to run right. Ended up buying a used OEM carb and rebuilt it.

does the FA50 use that encapsulated nut on the carb flange? I had to cut mine off so I could use the original air filter bracket/housing.

Re: fa50 will not idle

Chris Henige /

Did you end up with 85-90 psi compression? Is that low? Mine is at 90 and am thinking about honing/new rings.

Re: fa50 will not idle

chris i do not know what the compression is now i did not bother to check it. 80 psi is good enough i have a snowblower that runs perfectly on 50 psi and that one is a flat head, seem lawnmowers run with that low compression just fine so why not the moped. so you do not have to have 100 psi i got new rings and honed the cylinder out and the compression never went up. so that was a total was of time and money.

as far as the carb. search for the zoomzoomparts.com website they may have what you're looking for. they had the exact same carb that i took off and it did the job perfectly. one thing the reeds or some call petals have to set down on the housing. some were telling me they had to be real close but not touching. i found out they had to touch. when they had like .010 clearance it was hard to start. now they touch with a bit of tension and it starts in 2 to 3 kicks. and runs good.

look this guy up on ebay m.j.zee he is the one i got the carb from. he may have what you need. also he does email you to answer your questions. he is in mi. by flint.

good luck

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