lost power By hooklink (Read 3,220 times)

[hooklink]

Hi folks
after all you help getting me sorted with my sons magneto on his 50cc scooter thanks every one.Next problem the bike has now lost engine power it ran all right for about 20 / 30 miles over the day then when my son pulled up out side the chip shop the bike cut out when he came back 5 Min's later the bike was hard to start.He managed to get the bike back home but if he let the throttle off completely it would cut out. Now we have it at home i have checked it has fuel and it is flowing properly.what is happening is you have to open the throttle to get it started once started if you open throttle wide open it does not rev up properly may be it gets to about half revs if you hold it there the revs very up and down a little bit but still not to full revs.if you let the throttle off it will cut out.Hope this is enough information for some one to make a judgment on what might be the problem
many thanks every one

[Alleyoop]

Sure sounds like your Valves closed up. Adjust your valves Dieing out when you stop and hard starting is a sure sign the valves closed up on you.
Alleyoop

[Cruiser]

I agree with Alleyoop. Here's a great tutorial on valve adjusting from Big Guy.

www.powerscooters.org/manuals/ebay/Valve%20Guide%20Adjusting/Valve%20Troubleshooting%20&%20Adjusting.pdf

[hooklink]

Hi folks
just to keep you up to date with the lose of power on my sons scooter as yet i have not had time to have a look at the valve clearence but i have managed to remove carb blow all the jets out but it is no better if any thing it has got worse i can just about to get it to run on about half throtle but when i say run it is just a bitter faster than tick over revs but the funny thing is it runs quite smooth if you can keep the throtle in the right place open it up any more and it will cut out shut the throtle and it will cut out.So the question to you all is are you still thinking it is the valve closed up or does any one think it might be some thing diffrent if not then tomorrow the the valves are going to be my first port of call
many thanks hooklink

[Alleyoop]

Hooklink,
I am sure it is your valves, it is also getting very hot and starting to seize on you. Right now you are probably getting what they call a soft seize and will again start up after it cools down. But if you get a Hard Seize it will lock up and your engine will be KAPUT.
Alleyoop

[hooklink]

hi my friend
it's not getting hotter than normal so i dont think it is seizeing at the moment so it looks like it's time to start removing body panels well thats a job for tomorrow im off to bed now so wish me luck
cheers hooklink

[hooklink]

hi every one
right story so far i have replaced spark plug and checked valve clearence today and they are ok so i started the bike what i have noticed is i can turn the fuel mixture screw all the way in and all the way out and it makes no diffrence to the running so im now looking for more ideas if any one has any many thanks hooklink

[Alleyoop]

If the engine is HOT and the Enricher(CHOKE) is OFF, meaning the Plunger Has extended out and closed off the Extra Fuel when cold then the problem points to your Pilot Jet passages are Clogged and or your Pilot Jet.
Alleyoop

[hooklink]

alleyoop is there any way of checking the choke im not ofay with these carbs on on side i have the throtel cable which goes to the butterfly in side that works fine. on the other side i have a black electric thing which im lead to belive its a heater for the choke on top is the houseing for the centre plunger with the needle that goes in to the main jet that does not seem to rise or fall which surprised me and on the back left as you look at the carb from the front is a plunger that is liked to the throtle this does not ingage untill i get to just over half throtle hope all this makes sence and is of some help to you tp help me lol
cheers hooklink

[HDRYDR]

Jan 12, 2011 16:44:23 GMT -6 hooklink said:

Hi folks
after all you help getting me sorted with my sons magneto on his 50cc scooter thanks every one.Next problem the bike has now lost engine power it ran all right for about 20 / 30 miles over the day then when my son pulled up out side the chip shop the bike cut out when he came back 5 Min's later the bike was hard to start.He managed to get the bike back home but if he let the throttle off completely it would cut out. Now we have it at home i have checked it has fuel and it is flowing properly.what is happening is you have to open the throttle to get it started once started if you open throttle wide open it does not rev up properly may be it gets to about half revs if you hold it there the revs very up and down a little bit but still not to full revs.if you let the throttle off it will cut out.Hope this is enough information for some one to make a judgment on what might be the problem
many thanks every one

I would check the float level, it may be getting fuel but when you try to go faster the float level is to low and there just isn't any fuel there. Holding the throttle all the way open will let any fuel through but when you try to run it at lower speeds the level or volume is just not there. Also the needle adjusting screw may have been flattened out by bottoming the needle out till it is blunt.
Take off the bowl and see if you have fuel flowing into the bowl clearly by hand oppurating the the float by lifting it up to close it or down to let it in. It should flow right out while it is down. Adjust it by bending the flat tab under the needle which controlls the flow or if the needle is so blunt you'll need to deal with that problem.

[Alleyoop]

Hooklink,
The black thing on the other side where the throttle cable is, that is your CHOKE. It should have two wires comeing from it. On the other side by your throttle cable that is a pump so when you smash the throttle it pumps extra fuel.

How A CHOKE WORKS:
scooterdoc.proboards.com/index.cgi?board=techtips&action=display&thread=2283

The Choke is for COLD starts only and should shut off the extra fuel in about 3-4 minutes as the engine is warming up. You can test it to see if it is working. Take it off before you start you engine and look at it, if you see a spring between the top of the plunger and the rubber holder then it is EXTENDED and it is not working. If the plunger is a little inside the hole of the rubber holder then lay it on its side and put your thumb or hand of the hole and start your engine. Covering the hole with your hand is acting like your choke is on, so keep it on and let it warm up. Now you should see the Plunger EXTENDING out as it is warming up IF IT extends out then it is working. If it does NOT extend out then it is NOT working.

I Posted a VIDEO of how the Enricher(CHOKE) works as well as Just time pictures as it is warming up and you can see it extended out as the engine is running.

If starts good for you COLD and idles up and then idles down after it is warmed up your choke is working.
If it is working and you turn the Air/Fuel Mixture screw in either direction and nothing happens then your Pilot Jet and or Passages are Clogged. After it is warmed up the Air/Fuel Mixture Screw should change the way the engine runs.
Close the Air/Fuel Mixture Screw until it stops(COUNT THE NUMBER OF TURNS), then take it out and check if it has a point on the tip of the Screw, Now be carefull there should be a Spring,washer and o-ring in that order. The washer and o-ring are tiny so be carefull and not drop them cause you may not find them again.
Then Take some Carb Cleaner and Spray into the hole real good then put the air/fuel mixture back in and screw it back in until it stops and then turn it back the number of turns it was originally set. Now you can try and turn it either way 1/4 turn and see if the rpms go up or down. What you want is to get the HIGHEST rpms out of the Air/Fuel mixture.

HOW TO ADJUST YOUR AIR/FUEL MIXTURE SCREW:
scooterdoc.proboards.com/index.cgi?action=display&board=intake&thread=1499

If the way you turned it the RPMS go up Turn it 1/4 again until the RPMS drop or stay the same . When they stay the same or drop Turn it the other way 1/8 turn and that should be your highest RPM setting out of the Air/Fuel Mixture.
Your Idle should be around 1400-1800 in that range wherever it idles the smoothest, that you control with the IDLE SPEED screw.
Alleyoop

[brndnpnt]

Jan 12, 2011 17:02:56 GMT -6 Alleyoop said:

Sure sounds like your Valves closed up. Adjust your valves Dieing out when you stop and hard starting is a sure sign the valves closed up on you.
Alleyoop

Also what about dieing out when you give it a little gas or try to maintain a low speeds around 0 40mph. could that be valves?

[hooklink]

Hi all
just to keep you up to date tried re setting the valves over the week end still no diffrence. so going to do a compresion test on tuesday when i have a compresion tester but there was one thing i noticed was that when i line the T up on the crank case the the cam chain puller is out of line large hole at the top is at about 5 past to 10 past 12 if i line the 3 holes up on the cam chain puller the magneto mark goes round to almost on the F mark so im now wondering if the timing has jumped a tooth
any more thought on this feel free to reply lol
many thanks hooklink

[brndnpnt]

mabe you have a hole in your carb dighram like I just found out. How many mines on your bike..

[brndnpnt]

Jan 17, 2011 14:04:25 GMT -6 brndnpnt said:

mabe you have a hole in your carb dighram like I just found out. How many mines on your bike..

Take some good pictures of the top of your black carb diaghram and send it to me or one of the other scooter professinals mabe thats why you have lost power like me