yb100 problem

[webi]

hi my yb100 seems to have no power in 4th gear and rattles when i get in top end of each gear bike only reaches 45mph max i can feel the bike rattling throughout the whole bike any help would be appreciated

cheers webi

[blackhat250]

Aye webi " your goona have to take a look at the top end for starters, your performance is down, so worn rings or piston slap will give the rattle, vibration thru the whole bike could be numerous things,

Chain/ sprockets / tyres/ wheel bearing. your YB should pull "65,mph" i rode one earlier this yearB)

[webi]

Aye webi " your goona have to take a look at the top end for starters, your performance is down, so worn rings or piston slap will give the rattle, vibration thru the whole bike could be numerous things,

Chain/ sprockets / tyres/ wheel bearing. your YB should pull "65,mph" i rode one earlier this yearB)

cheers mate will take a look btw dont know if this helps but even with the weather like it is now it starts first kick in the morning with no choke it doesnt sound like piston slap its just a rattle and only when i get to the high end of a gear it seems to pull ok in all other gears apart from 4th

1st to 2nd 15mph

2nd to 3rd 30mph

3rd to 4th 45mph

and thats all it will do

[webi]

cheers mate will take a look btw dont know if this helps but even with the weather like it is now it starts first kick in the morning with no choke it doesnt sound like piston slap its just a rattle and only when i get to the high end of a gear it seems to pull ok in all other gears apart from 4th

1st to 2nd 15mph

2nd to 3rd 30mph

3rd to 4th 45mph

and thats all it will do

forgot something it does also get very hot and isnt to good on fuel

[blackhat250]

Aha sounds like choke is dodgy , or running too rich . The mixture screw [ small brass slot headed left side of carb] Screw home - then turn 1.5 turn out, air filtre? clean -

[webi]

Aha sounds like choke is dodgy , or running too rich . The mixture screw [ small brass slot headed left side of carb] Screw home - then turn 1.5 turn out, air filtre? clean -

mixture screw is set right air filter is ripped but was the same before that happened if i pull the choke up the bike splutters and cuts out it just doesnt sound or feel like it has any power in 4th at all

[webi]

update: took it out today and it feels like every few seconds it hesitates i can feel it im also thinking about getting a rebore and new piston

[webi]

took it to the garage he seems stumped he said it doesnt need a top end rebuild but something isnt right could anyone tell me of any signs of ignition timing being set up wrong please?

[Airhead]

webi does this bike have points and a condensor (capacitor) ?

[webi]

yep replaced condenser not so long ago

[Airhead]

Have a look at the points, are they burned and pitted? Are they sparking when the bike is running?

[webi]

Have a look at the points, are they burned and pitted? Are they sparking when the bike is running?

they spark but i can sometimes see it come out of the side of the points

[Airhead]

Right thats not good, you should fit new points and another new condensor. I dont know the bikes make-up. Has it got a auto spark advance fitted, theses can easily sieze up and be stuck in one place...or on the other hand they can wear and this usually means they will be too advanced at low revs. Has it got one?

Have you got a Haynes book?

Can you fit new points and time the bike?

Can you tell if it has an auto advance and whether it is working correctly?

[webi]

Right thats not good, you should fit new points and another new condensor. I dont know the bikes make-up. Has it got a auto spark advance fitted, theses can easily sieze up and be stuck in one place...or on the other hand they can wear and this usually means they will be too advanced at low revs. Has it got one?

Have you got a Haynes book?

Can you fit new points and time the bike?

Can you tell if it has an auto advance and whether it is working correctly?

got haynes book can fit the points dont know about time it and i cant tell atm if it has a auto advance one thing i forgot to say before is that when i am riding it it sort of hesitates every so often

[Airhead]

........i forgot to say before is that when i am riding it it sort of hesitates every so often

Well have a good old read of the haynes book, see if it mentions the auto advance, a giveaway will be if you can twist the points cam back and forth, that will mean it does have one (unless its siezed up, then you might not be able to tell)

anyway i'm sure there will be a pic in the haynes book, basically all it does is throw some bob weights outward as the engine speed increases, in turn the movement of these weights turns the points cam which advances the ignition timing. as revs fall springs pull the weights back in and the timing retards again.

is that clear

[webi]

Well have a good old read of the haynes book, see if it mentions the auto advance, a giveaway will be if you can twist the points cam back and forth, that will mean it does have one (unless its siezed up, then you might not be able to tell)

anyway i'm sure there will be a pic in the haynes book, basically all it does is throw some bob weights outward as the engine speed increases, in turn the movement of these weights turns the points cam which advances the ignition timing. as revs fall springs pull the weights back in and the timing retards again.

is that clear

my bike does not have a auto advance

[Airhead]

ok fit new points and condenser, adjust the point gap as per spec and time it as will be in the haynes book. Hopefully that will fix it.

[webi]

ok fit new points and condenser, adjust the point gap as per spec and time it as will be in the haynes book. Hopefully that will fix it.

right ill try and explain this the points touch together and then break when the engine is running i see a spark only a little one coming of the points when they are closed.

[Airhead]

is the point gap and timing set right?

[webi]

is the point gap and timing set right?

gap is set right i dont know about timing though as i have no idea how to check or alter it