Recent power loss

[hardleydavidson]

Hi,

I have a little 50cc that has until recently been getting me up the hill on my journey home from work, albeit in 2nd and at around 20mph. I don't expect to get much more than that, I'm a big lad with a small bike but recently it's started slowing down to the point where 1st is struggling and then it dies. Restart the ignition and take off in 1st and I can make it the rest of the way.

I've charged the battery, removed the fuel cap and replaced it incase there's a vacuum issue but I can't put my finger on what it is. For some reason new fuel seems to make a difference and after a longer journey it seems better. It's also being tempremental when I stop and not idling properly even though I haven't touched the idle screw at all.

It's 50cc 4 stroke

Any ideas??

[Chrissb6]

Check the air filter there may also be a fuel filter in there to check over. Sounds to me like the motor being starved of one or the other

[hardleydavidson]

Ok, so I've charged the battery, checked the fuel lines and fuel filter, checked the airflow and air filter, Checked the electrics and given it an oil change, adjusted the rear wheel and tightened the slack chain.

Still having power issues up hill.

I'm thinking it may be a duff battery, I don't have much cash for a new charged battery but the dry (DIY) one's a are dirt cheap, are they any good? how hard is it to fill them?

[eastanglianbiker]

battey is not expensive and are ebay to fill http://www.ebay.co.uk/itm/Battery-Lexte ... 873wt_958e

[Adam]

Did you check tyre pressures? If not take it up the garage an pay 50p to use the air machine then you'll know they're (almost) correct.

Now this might be/sound stupid but how steep is the hill? I'm thinking as you mentioned it seems better with fresh fuel that there might not be enough in the tank when you're going up the hill to feed the bike, because of it being liquid it will naturally slosh to the back of the tank. I could be completely wrong and I don't have any idea what your bike looks like but I thought I'd throw it out there.

[Chrissb6]

Hi l would doubt very much that there's a battery issue here. If the motor is running the battery should not be discharging as the bike electric's are taken care of by the alternator. If you have checked over what's been mentioned take it out for a run, if possible get the motor onto a steep hill and do a plug chop this will tell if the fuel air ratio is correct. Do a Google search to help you understand plug chop further. If the plug is white the motor running lean which could mean a partly blocked main jet or an air leak on the carb, if black and wet - running rich it could be the plug -coil is breaking down or if you have been running cheap 2 stroke oil your motor my required a decoke. but l'm not completely sure the later is still required these days with modern 2 stroke oils.

[hardleydavidson]

Thanks guys,

I'll give the plug chop a go and see what it's like. The tyres could probably do with a pump up too would this affect power uphill?, I'm wondering if water is getting in anywhere, we've had a lot of rain down these parts. When I checked the bike over the rubber cover where the throttle cable meets the carb was split quite badly. There was also some oil in the air filter which for the life of me I can't work out how it got in there. Way back when I first got the bike I had the exact same problem which turned out to be the carb, a new carb sorted it and I haven't touched it since so in theory the carb settings should still be the same. Could it also be compression? I'm thinking if the rings are worn then it might struggle under load?

[Adam]

Whilst you've got your plug out stick your thumb over the hole and start the bike it should have enough compression to push your thumb off if not then that's probably your problem.

Well you'd be riding on more surface area of the tyre so it would require more power to get the wheel turning, if they're low it's worth doing anyway.

[eastanglianbiker]

should check tyre pressures weekly anyway gauges can be bought cheap enough so you dont need to go to garage every time to check them

[hardleydavidson]

This is weird, made it up the hill last night, lights on as well so it's definitely not the battery. I was in 2nd but only doing 10mph, seems like overall the bike is running better but somewhere along the line i've lost 10mph on the flat and uphill. Could be the oil change has made a difference.

Was only this morning it dawned on me, when I adjusted the rear wheel to sort out the slack chain, I didn't readjust the rear brake, brake light isn't on but I reckon it might be semi engaged.

[Chrissb6]

Hi, adjusting the chain will make no difference to the rear brake set up. You might want to check that you are not subconsciously riding with your foot covering the rear brake pedal.

[hardleydavidson]

Shifting the rear wheel back with the adjusters will lengthen the distance between the drum and the pedal exterting pressure on the rod? at least in my head that's how it works??

[Chrissb6]

Shifting the rear wheel back with the adjusters will lengthen the distance between the drum and the pedal exterting pressure on the rod? at least in my head that's how it works??

No mate, the cable outer sheath if yours is cable operated will be anchored to the drum, the inner cable will pull the lever towards it thus applying the brake, there's enough slack in the cable to allow for the wheel to move back and forward without need to adjust the brake.

[hardleydavidson]

Ahhh I see, thanks

Must be another reason for it being sluggish then, going to try the compression test tonight wouldn't be surprised if it needs new rings.

[DreamytimeEscorts]

What state is your air filter in?

[hardleydavidson]

Air filter looks ok, bit of oil in there when I last looked but only a very small amount.

It's seems to run better after a longish ride, the hill in question isn't a problem after say a 5 mile warm up, the exhaust sounds a bit diferent too mor e of a phut phut to it so I'm beginning to think there may be some air getting in somewhere.