HI, all. whats going on here? week saturday went out bike perfect, started first time every time, lots of torque, compression. came home put in shed, next day raining, did not touch the bike, monday morning nice day, got out bike, will not start, everything totally dead, except good spark, checked carb,cut off switch, ptrol getting through ect. but noticed absolutely no compression. took out spark plug, thumb over the hole turned it over nothing, would not blow a small feather away. how can it suddenly do this?? put in a new cam as the old one was corroded, new one has a steel hardend lobe, if anyone wants one. which side of the engine do the valves come out. left side where the cam is or the flywheel side, can,t get the flyweel off yet, no puller. must be the valves but why suddenly fail?/ no broken bits in the sump. oil perfect and clean ect. let me know thanks mirage
instant compression lost??
- Thread starter mirage
- Start date
thanks for your input racie 35. but the valves move up and down fine, timing spot on. with the new cam fitted, reset the tappets, you call lashing,they do make a tapping sound, maybe thats how they got the name. however still no idea what has happened. i could turn the flywheel with my fingers, spin it like a top. less resistance than spinning a bicycle wheel. my bicycle pump has a hundred time more pressure. weird.
OKGUYS, yippee! found the problem. not as serious as it looked, in short, it was the valve settings ie tappets. lashing ect, something had moved after i had set the new lashing gap to the new steel honda gxh50 cam. maybe the plastic cam followers needed to bed into the new cam. however when i rechecked the gaps, they where to tightmand the tdc was giving a different setting to the raise of the push rods. they were at odds with each other. however, the valve open and close ok pushing my thumb off the plug hole, so i was on the right track. engine starts easy and quiet. looking forward to a road test, big gale at the moment blowing, try it tomorow. ps the steel cam on e bay. they don,t ship to the usa. it was £9.50 not bad price and free postage to me. bye
It is still a mystery though why the engine suddenly decided to fail with the old worn out cam, and the valve settings unchanged, but i did notice a lot of gap on the lashings with old cam before i changed it. but ran great, 43.3 mph go figure. i have a 75 tooth rear sprocket and a 16 tooth drive sprocket, i will tell you how to fix different sprockets to the original 11 tooth freewheel if anyone wants to know.
hi guys. new post. bike went perfect, pulled like a steam engine. now yesterday engine died on me a mile from home fortunatley. very good spark. cut out switch working perfect. carb cleaned out, all petrol fillters cleaned, petrol getting through. removed plug. lots of blow and suck. reset the tappets, and checked valves opening and closing ok. as that was the problem last time. No attempt at firing.Has the timing jumped a tooth somehow?? can,t think of anything else. did not feel like draining the oil. and taking cover off. if it was something else i missed, no air leaks. was going great, then just died.why?
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hi. mirage me again, huasheng 4 stroke 49cc. update, managed to start the engine, by putting a drop of petrol in the plug hole. and using a hot spark plug, ngkcr5 hsb. spark like a bolt of lightening. can recommend them. however only runs for a few seconds. no petrol being pulled through, even after i took the carb to bits, blew through all the jets holes ect. what is stopping the suction. do i need a new carb?? as it started i now assume it was not the timing that was out. why won.t it pull the fuel through?? it was running fine, no missing, spluttering. mis fires. flat spots ect, i keep getting these weird problems. re checked the valve settings again. all as i left them. any ideas please, thanks
Sounds like something clogged the fuel line or carb. Pull the line off the carb first to check for flow from the tank..it should run right out. If it does you'll probably hafta take the carb apart and look for dirt etc. I'm assuming you have no vaccuum leaks
did you use a fuel filter? petcock plugged? pull the fuel line see if it flows. and remember ''a loose valve is a happy valve''. an old limey saying.
hi guys.thanks racie 35, and dmb. i was not born yesterday. forget all the normal remedys. think outside the box, i have fuel every where, except going into the engine and firing, I have re done the valve settings, removed the cover for the timing cam ect, no jumped tooth, while i did this, i marked the flywheel and engine case with centre pops at the top dead centre, so it would be easier to determine the exact t.d.c in future. note the valves when closed are not at t.d.c for best position. best a quarter of an inch before t.d.c then set the tappets. i was getting lots of false readings before. also not turning the flywheel twice before setting the t.d.c for valve settings, my bad. however, still no sign of starting. would like to try a new carb if i can get one, but in the uk it is cheaper to buy a whole new engine from china, $63 from china. the same as carb from the usa. plus postage, and probably import duty on top. no viable. i modifed my starting bell with a slot and a starter cord like an outboard seagull engine. works perfectly. you all should do it. like a spare wheel for your car. well must go before i get cut off. wiil update if i find a solution. but looks terminal at the moment. keep thinking guys, this is one for the books, mirage
mirage, P.S i forgot to mention that i made a flywheel puller and removed the flywheel, to see if the woodruff key had sheared, and alterered the firing point. as this is a classic problem on lawn mowers, no such luck. perfect condition. it was a long shot, but worth a try. clutching at straw now. i wonder if a blown rear light bulb with stop it from starting.L.O.L. SEE THIS IS WHAT IT IS COMMING TO. but i think a new carb, is the next step to prove a point, but if it works i will still not know why the old carb suddenly decided not to work. does the c.d.i fail to start the engine, even though it has a briliant spark??? insufficient in some way?? running out of ideas. bye
you mentioned that it runs a bit if you add fuel - if carb is bad, then I'd expect that your spark plug is dry after attempts to start it - is this true?
if so, you need to check the carb for flow of both fuel & air - a fine strand of copper wire will clean out both fuel passages & air passages & air vents
a lot can go wrong with a carb that will hurt performance, but failure to deliver any fuel at all is usually a blockage somewhere
if so, you need to check the carb for flow of both fuel & air - a fine strand of copper wire will clean out both fuel passages & air passages & air vents
a lot can go wrong with a carb that will hurt performance, but failure to deliver any fuel at all is usually a blockage somewhere
hi just gor cut off again, after a long reply, got to start again. yes crassius. the plug was dry initially. but now wet with putting petrol in the plug hole. but only runs for a few seconds. i have ordered a new pump type carb. to see if this will solve the problem. but it does not come with all the spacers and gaskets etc. and the throttle cable is pulling from the side rather than at the rear of the carb, terry blow has a good video on you tube how to convert this carb in place of the huasheng carb, can,t get a huasheng carb from anywhere in the uk. would like to get one from china, but they don,t sell them without the engine. none on e bay, and most u.s.a companys will not ship to the uk. i think most of them think engaland is on mars. i always thought it was a fuel problem. but i have poked through every hole in the carb to no avail. will update when carb arrives, that is going to take some work.
HI, everyone. update been two months now, still won,t start as it should, bought a pump type carb, oops wrong one, was for a back pack type motor weed blower or something, was cheap so have to write that off, now got a new nt carb, nice and simple, they should put these on as standard in the kits, next problem, a manifold to go with it, got one from gasbikes, at great expence, why is the U.S.A. postage so dear? $59 crazy. still had to have it. fitted it. still won,t start, after a lot of trial and error setting the valves, i noticed the settings would not stay set, when i tightened the locking nut on the rocker arm the screw moved. the bottom half of the screw was patially stripped, thats why i could not get a reliable setting before, all over the place, so now i want a new rocker arm or setting screw. the call them studs in china, i came up with the idea of putting washers under the rocker arm at the bottom to stop the screw being pulled up. clever but still wont start. let you know what happens next
follow up, as it was the tappet screw that was the cause, i thought the old carb must hav been ok. so put it back on to prove a point. still no start. will start with easy start though the carb, but will not suck fuel in, still something wrong with the valves, but untill i get a new rocker arm, will not know for sure. can,t get the compression i had, i think that is the problem, can the timeing be out or the cdi falty.; even though i get an enormous spark. best i have ever seen. I am thinking of getting a new engine, and using it for spares and copying all its settings to get an answer, i am at my wits end. LUCKY WIT, LOL. BYE
me again mirage, here is an update, gave up on old engine, bought a new one, removed the new cdi from it and put on old motor, to prove something, still no start. so off with the old engine, installed, all new standard carb, thought i had better get it running with the standard h/s carb, and put the new cdi back on it of course, stiil will not start, easy start in the carb runs for 2 secs, then stops, played with it for hours, adjusting the air mix screw, useless. so took off the huasheng carb, fitted my new nt carb, no air scew to mess with, so should be simple. nothing will not run at all. i have a temp fuel rig. a thick tube on the carb fuel inlet, i top up with perol so it should run, but does not. not touched the valve settings, they looked about right 6 thou both. not tight, my orignal engine started after the first 3 pulls from new, 5 years ago, beginning to think now that was a million to one chance, just lucky. i wish i could get back all i have spent on this bike, then i would buy an electric bike, i have had enough. you can improve things if you can get an engine going, but when they don,t you have nothing to work with. i suppose it is a long shot, but fresh new petrol might help. but this is a 4 stroke never had a fuel problem even standing over winter, anyone know where i can get a direct injection easy start system. my engine will only start that way.WHAT the **** is wrong. frustrated sorry guys.
HI all, latest info. it was mainly the fuel that had not enough alcohol in it to fire the engine. the nt carb started first time with fresh new potent fuel. the nt carb seemed to have more torque, but was very noisy, and rough running, sounded like a ducati and vibrates like a road drill, not suitable for a four stroke. so gone back to the standard h/s carb, used the old original carb. started easily. so was the fuel problem, although the valve settings was a contributing factor, hence giving me false info. the bike now runs quiet, and fast, not as good as my old engine though, may put that back sometime to prove a point. still running in so hopefully will run smoother, got the 2 shoe heavy duty clutch like a dax. that came as standard on this new engine, seems to have plenty of top end speed, but when i tried one of these clutches on my old engine, it was unrideable. used to grab to much from stationery. snatching ect. had to go back to the 3 shoe all steel clutch, still the best all rounder. just adjusted the h/s carb, air screw. as was not pulling up hills like it should. but engine only done 520 miles so still a bit tight i expect. will let you know how it goes, still need a new rocker arm for the old engine though. but i could not live the noise and violent vibration of the N/T CARB . why is it coss it is more straight though, more air going through the engine, felt like a completly different engine. moral keep your fuel clean and potent.
