fa50 questions

ok i got this suzuki fa50 to fix for my neighbor. it is in fair shape and the first thing i have to get is spark. i have some spark i took off the mag and one magnet came off. i do not know if it was loose or during the removal it worked loose. anyway, the magnets were clean and the coil ends were not all rusted but a bit corroded. i have had way worse and had a running engine. so i will clean them but i need to know the gap for the plug and the clearance for the mag coils. the last time i messed with a mag system i was like 20 years old. over 50 years now. if i recall on the sears moped that gap was .010 and the plug back then was .035 i say that because the feeler gauge set i have has brass .010 feeler

if i get a good spark i will shoot gas in the cylinder and see if it tries to fire off.

at this time the compression was 25 psi. i shot some penetrating fluid in there and tried again and got 50 so i will give the fluid a day to work. also, i glued the magnet back on for now with silicone caulking if that fails i will jb weld it. but my guess is that silicone will hold it for testing, i do not want to put a bunch of time in this if i can't get spark and sputter out of it,

so can anyone confirm my coil gap and plug gap? i figure i do not need a battery to start this and i picked the key and it is set to run.


Re: fa50 questions

Spark plug gap should be .024" - .031" .

You should be fine with a .010" magneto gap .

I tried different types of glue to rejoin a magnet .

Gorilla glue did not hold . Super glue has done the job for about the last 4 years .

Re: fa50 questions

thanks if i get it to run i will jb weld it i know that will hold it i do not want to put much on that as to throw the balance off.

i have the plug at .035 so i may tap it a bit more and i will make sure the mag is at .010 thanks much for that info.


Re: fa50 questions

ok i gapped the plug and put .010 on both coils i do not get a spark at the kick start speed but do get a good spark at high rpm. i put a drill and socket on the crank and spin it. also, it has 30 psi compression so i know that is not enough. but if i can't get spark there is not need to mess anymore. so i have to know what coil is the mag? i'm thinking it is the top coil with the clear plastic cover on it. the smaller wires on the coil. if i recall the larger wires are to charge the battery. and i tried from .010 to .000 and the spark did not change. so i wonder if i need to try more gap? i figured .010 was the sweet spot because my feel gages have a brass .010 gage. as i recall that was for this type of work as to not have the feelers to stick to the magnets.

could a bac cdi cause low spark at low rpm? it seems that would not matter because you do not spin up a mower with cdi that fast when starting. any yes i know it needs ore compression but i need spark first and if i can't get spark at kick start speed then i'm not going to pursue this as i know the guy will not put lots of money into it.

so what coil do i mess with top of bottom and what is the gap i need to shoot for or do i just mess with it tos see what this bike likes? thanks much for any ideas on this one. bp.

Re: fa50 questions

More air gap will lessen/weaken the spark .

The ends of the magneto coils should be clean .

.010" should produce a decent spark .

I'd start by cleaning all electrical connections , including all ground points .

Don't forget the mounts for the coils .

All have to be bright clean and scratch tight .

Pull and clip 1/4" off both ends of the HT wire . Clean coil and cap contact points .

Use a known good spark plug .

Test the plug cap for continuity/resistance .

You could also test the coils to be sure , but , it sounds like maybe just bad connections .

Re: fa50 questions

yes i figure that but what coil is for spark top or bottom? i'm thinking the top coil because it has smaller wires. i have all connections clean. thanks

Re: fa50 questions

The smaller of the two coils is the primary coil .

Re: fa50 questions

thanks, i figured that was the case. so i took off the coils made sure they were clean and bright the base was clean and had 0 ohms from the coil faces to the engine. took off the coil and have 5.4 ohms from the plug to the plug wire. i did find an issue. the plug cap was not screwed into the wire all the way. after i cleaned it and got the plug cap back into the wire i have a spark at very low crank speed. i did not try it with the kick start yet. i have a drill on the mag nut.

tell me i have the oil tank but i do not see how the oil gets to the oil pump. and that is no tube in the oil tank area to plug into the oil tank. the gas tank has 2 tubes so that is for the main tank and reserve. see the oil pump there is no place for the oil tank to connect so where do i make that connection. pointless to have a oil pump and put oil in the gas. but if i have to do that what is the mix? 30-1 that was what i did for the sears moped i had 50 years ago but this may be 40 or 50 -1

thanks bp


Re: fa50 questions

say i forgot to ask what oil these take in that oil tank. i used 30w in the sears moped i have some 5w40 synthetic. or should i put in straight 30w oil or another weight? don't need to burn it up, thanks bp

Re: fa50 questions

Hmm , kinda looks like someone just looped the oil pump output line intro the feed line that is suppose to connect to the tank .

I'd leave it as is and run premix . At least until you want to spend money .

Premix ratio of 40 to 1 will work . Of the two you list , I'd opt for the 5w40 synthetic .

It'll likely smoke a fair share .

If / when you want to use the injector pump , bleed the pump using the screw on the right / back of the pump .

In the mean time be sure that the motor inlet from the oil pump is sealed , if the pump is actually looped back into itself .

Hopefully you have an OEM air filter to put in place . These bikes don't run well without if everything else is stock .

Here's the service manual :


And , here's the parts fiche , so you can see the order of things :


Re: fa50 questions

p d thanks i got it to run the carb was good not bugs in it but it will not idle and it will not kick start. it has 50 psi compression and i think that is to low to idle. i know what screw is the main slide idle screw but the screw to the front of the carb. that screw looks like is is tamper-proof and when i did adjust it the engine raced a bit. so if you happen to know how i go about setting that one. i could not take it out but it could just be stuck. i see they did have the oil pump monkeyed up i will take a small squeeze type bottle and put some oil in it and take the pump off and spin it up ti see if it does work. then put it back on.

so now it has gas and i just poured some synthetic in the gas i did not measure it and it smokes bad but to much is better than not enough for testing. i know the mix is off because it wants to 4 cycle. any thought on the idle mixture and the compression i have. if i have to pull the cylinder do you happen to know if the head gasket comes off them good so i can reuse it and i figure i can make the barrel to case gasket i have done that before? i have managed to reuse head gaskets when they came off good.

it does not have any air filter on it now that could be some of the idle issues i guess. my sears moped did not make a difference but this one might.

thanks, bp.

Re: fa50 questions

50 # compression is way too low . You're lucky it runs at all .

Pull the head and cylinder to see what condition the piston and rings are in . Post pics .

The OEM head gasket is thin copper . I've used the same gasket every time I needed to get inside . Still good .

The base gasket it paper and likely stuck to one of the surfaces . If it's no good , just cut another .

The forward screw on the carb is the air screw . Run it in until lightly seated and back it out 1 3/4 turns . That would be with an OEM air filter , so , MAYBE you can adjust for none , but , I never had any luck .

Re: fa50 questions

thanks PD i found that info on the manuals you sent me after i replied. the idle air jet is about worn out so i mah have to fab another one or get a new one. tomorrow i will pull the cylinder off and check i'm betting the rings are stuck to the piston. and yes i can fab that paper gasket and if the head copper gasket is like the corvairs you heat them to blue to re aneal them and then use them again.

also i will try to get the oiler going if possible and reconnect it into the system. them manual said something like a drop on and then i did nto see how often that now and then is. thanks for the help. i will let you all know how this goes. i do not know if the neighbor will pay for a new factory air breather assemble he may find something aftermarket. i told him that the site you sent me has them for 55$

thanks, bob p.

Re: fa50 questions

P D. i took off the cylinder and the top ring has 3.9mm end clearance the bottom is 4.6mm the book says top is 3.6mm bottom 4.0mm so the rings do have some wear. the piston has some scratches but real bad, but i will talk to the owner and see if he want to spring for the rings and piston. i can hone the cylinder, i did a bit of honing and it cleaned up good. but the cylinder does have a bit of taper as i had a time getting the piston back into the bottom. after the piston got back to its normal run spot it was way easier. new rings i will use a compressor. and go in from the top.

i now have to get the float-adjusted. it was flooding out and then i lowered it and i think i went a bit to far. i got tired so i quit for now.

i messed with the thing for a few hours with no spark after i put the oil tank back in service and bled it out, come to fine out i had the darn cutoff engaged. as soon as i figured that out i had plenty of spark. and i did get it to go ith starting fluid but that was on the readjusted float that is now to low. i see it needs to be 22.1mm from the carb base to the bottom of the float.

also, it may need new reeds as when i had the carb off and spun it over i felt air pushing against my hand from the reeds. but for now, i'm not dropping the engine to change them out. it ran with these so i'll leave well enough alone for now. my guess is i will get it running and they will ride it 2 times and quit.

so to recoup. the gas tank and the fuel valve seem to be working the oil tank is connected and blead but i don't yet see oil coming out of the pump outlet but it has not ran yet. it has oil in the gas for now. and it looks like it might need rings also when i took the head off there was leakage at the head gasket so that may need changing. i run the head over a flat surface to see if it looked warped and it did not but the next time it is off i will run it over a sheet of maybe 800 paper to get it flat as i can.

thanks so far for the help and ideas. it is all starting to come back from when i had the sears moped.

bob p

Re: fa50 questions

ok i got it running and the carb float set and the idle set but only at a very fast idle! i also discovered why the oil pump was bypassed. there is no shaft that goes to the crank support shaft. i do not know why that was removed and i do not think at this time i will take the gearbox apart to find out why. they can mix the oil and gas.

also, it has less than 50 psi compression so that is one reason it is not going to idle. and when i ahd the carb off i spun it up with the drill and i fee back pressure from the reed valves. even at low rpms so i think those are bent a bit and not seating and causeing blowback. that will by itself cause no idle. and i see it is a job taking that off so tomorrow i may take my 90 deg driver and have at it. i see they can be turned over and maybe i can get more life from them.

also if the parts place takes paypal i will order standard rings and head gasket and base gasket and make the carb and a few others. and see if i can get it to hand start.

so now e know why those pictures showed the oil pump the way it was. if i can locate that shaft and the owner wants to mess with it i will get one and we will install it next year. i see the redd valve and that shaft on ebay so he may want to install it this year. we will see. if i can get it to idle good then i may be worth putting parts into it. thanks bp.

Re: fa50 questions

ok today i dropped the engine far enough to get the reed valves out and they were not closed. see photos. i flipped them over and did not make any difference. so if the parts store can't find any and the owner can't get the tool room he works at to help him make a set then i'm done. if has a good spark and will fire with starting fluid but just will not go with gas if i block 90% of the carb i can get it to fire but i can't block the carb hold the drill and turn the throttle to get it to go. and turning in the idle screw is not enough. i got 75 psi compression using the good tester. 50 psi using the pushin tester. so not enough there. but i do not want to put $$ into it if i can't get the thing to run. fairly good. so that must be why it sat in their storage locker for years. thanks, bp.


Re: fa50 idle issue now

ok guys i found the reed valve petals were not covering the body so i sanded the area flat and then made a new set of petals out of an insurance card. that was a plastic car and behold it started on it own with no starting fluid and ran up to some speed and i was able to get it to idle but it will not stay at an idle. plus it needs the choke open.

i have the float set to the 22.4? mm from the bowl base to the top of the float. just like you do with car carbs. i didhave the carb all apart and cleaned if but maybe i missed somthing. maybe i can find a carb somewhere they must have use those on other engines. i can kick it over by hand and it will start st that in itself is a big plus.

the petcock works as it should i can do a cheek puff and it will pump a bit of gas. the gas is not runnig out of the carb and it is not flooding. now it could be the credit card petal is a bit to tough for it ti idle. i get 75 psi compression with the kick start by hand and 85 psi using the drill motor. so for the heck of it i will put new rings in it. the cylinder looks good for that and the piston is usable.

so can anyone help me with the idle? do you think the petals can cause that if they are a bit to stiff? and maybe the lower compression may be part of the issue? or might i have a buggered-up carb that is out of adjustment or the air mixture is buggered? i had to put a slot in that as the slot was gone, had a time getting it out of the carb. thanks for any ideas and help on this i'm getting closer. by the way the reed valve body was warped when i put a straight edge on it the center was higher than the part that bolted it down. that is why i could not get the petal to set down on the opening. after i ran it over the sandpaper i got it flat and just the lower section just around the opening. so when i made the petal i made it so it sat on the lower part. also i do not have it spitting back out the carb. thanks. bp.

Re: fa50 idle issue now

If it's gonna stay a basically stock motor , you'll likely never get it run purrr fect without a stock air filter set up . Maybe kinda almost close , but ...

Re: fa50 idle issue now

ok because they are had to find and if i do find one it will be pricey. do you know what i might try to take the stock filters in place? i can get a bent pipe but would have to get the filter. is the original one a paper filter? if so i wonder if i can get one of those that are aftermarket for single barrel carbs on cars? if you have an ideal please send it my way. i'm going to put new rings in it i will order them tomorrow. the owner is going to see if he can get his toolroom to make a new petal for it. out of .030 spring stock. they have that stuff for the dies to shim up when they repair them. thanks.

Re: fa50 idle issue now

The OEM filter material is an open cell foam .

I think it's not so important the material used to filter as it is amount of restriction created by the OEM filter body as a whole . Then there's flow to consider : turbulent verses directed .

Maybe post a want to buy ad in the BUY / SELL section on this site .

It's possible someone might have the OEM assembly laying around , bent tube and all .

Re: fa50 idle issue now

thank i may have to do that.

Re: fa50 idle issue now

well went to post for a filter unit and someone has a post for all the fa50 parts he can get. so i will try to make something for testing anyway. also, did i tell you the petals that were in the bike did not fit and the reed housing was warped so the center was higher than the edges! so i sanded it down until it was flat and i made new petals out of a credit card. so it is possible those are a bit to thick and stiff. so for the heck of it tomorrow i will make some out of the material you get business cards made from that is magnetic. it moves easy and the engine should be able to open and close then easy enough. and this time i'm going to try and make them as one unit without the split, so they will not break so fast. i know it is not the correct material but that will tell me if the idle is because the credit card material is a bit to stiff and idle speed will not let them open good enough, if that works then i will get some stainless .020 material and try again with that. and also i have a note out to boyesen they make and sell reed material. this is a bit of work but i'm getting a bit of knowledge from this. getting to know what works and what doesn't work. thanks

Re: fa50 questions

ok small update! i got another reed block unit in the mail from ebay. it is a complete unit so if it fails at least then i have a good pattern for the reed/petal. and i ordered new rings and gaskets. so next week when they get here i can assemble the cylinder again and put in that reed block unit and give it a go. also i may get the shaft that drives the oil pump so he does not have to mix gas. but tomorrow i will make a test pin and run the pump to make sure it will move oil.

so next week i will stop back and let you know how it went. i honed the cylinder and it cleaned up great. thanks, bp

Re: fa50 questions

Douglas Mackinnon /

I too am rehabbing an FA50. I made my own air filter housing from a small thrift store cookie tin, spaghetti strainer and sponge. I tend to over engineer things.. I used drinking fountain and bar sink drain basins to pass air from back to front then thru filter media, then back out the rear again. A little steel angle bracket and you can use the original housing mount hole support it to the gear case.

Re: fa50 questions

that sounds like a fab job for sure. because this guy is not into making it look like it came from the factory what i did so far is take a 1" cpvc 90 deg elbo and cut it down so the elbo would fit in the area and clear the tire. and then pointed it to the right side and drilled and put in 2 screws. this will get me to the size of 34mm od and then i can get a straight air filter assy from ebay for 5$ and be done with it. but first i have to get it running i have another reed valve assy off ebay in the mail so now i will have a pattern for the petal and a spare housing. i have rings and gaskets in the mail also so next week i will be putting it back together and see just how it does. also it did not have a key so i found another key that i fabbed to fit the locks and then made the locks fit the key. so it is getting close. thanks for the info on your airbreather. if he decides he wants one that looks more like factory i now have your idea to follow. thanks bp.

Re: fa50 questions

Douglas Mackinnon /

I saw you’re from Muskegon, I buy a lot of stuff from Babbitts superstore located there. I wish I was closer and could save on shipping and wait times.

Re: fa50 questions

i do not do much business with them. i see they are a bit more costly than that place in g.r called partspitstop.


but i do not buy much from them just noticed they were a bit cheaper. this moped is the first i have got parts from them. years ago i think i got the burgman 650 scooter from them when they had a different name. thanks, bp.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account