twlou

Oh and yeah it's air-cooled

Spark plug is the right one, checked the manual and the guy at the workshop had it replaced too which was about 2 weeks ago now. How will I know if it's running rich?

hello again everyone

right, just a slight issue this time. after i've been riding my bike for say 20 miles or so, it seems to take a while to get power at slow speeds. for instance, i travelled back from work the other day(18miles) and when slowing down through town it took a while to respond(say 3-4 seconds) when i opened the throttle at slow speeds. it also cut out idling at a set of traffic lights and didn't start so was very embarrassing pushing it off to the side! it did start after i left it for say 5 mins. it has no problem starting in the morning and it's fine on short trips. another thought could be that it's overheating?

oh, it's a tw125.... as if the regulars didn't know

Whats the bike?

 

Are you new here?

http://www.themotorbikeforum.co.uk/view ... =5&t=39849

all sorted now, did a full battery recharge although it didn't need much to charge up. seeing as the light switch has broken off i had to use a thin screwdriver to flick the switch off and then tried starting it. fired up fine when lights off, but struggled with the lights on

bit of a pain though as i need to flick it on/off all the time with the screwdriver. can't seem to find a replacement switch online as most only come as a unit, which means a lot of money! would it be possible to run a separate switch for the lights does anyone know?

just had another thought, could be completely wrong, but noticed the bulb had a higher wattage than what the manual states it should have. would that make a difference? manual says replacement should be 45w/40w and the bulb in it says 60w/55w also i have to have my headlight switch turned on all the time as the little plastic bit has broken off

if you have got a trickle charger then charge it overnight and see what happens then or check voltages on battery terminals to see if its charging,did shop take the engine out to repair it if so have they plugged all the wires back in correctly

yeah assuming he did as it needed a new valve, piston kit and head gasket. i have a battery charger so will stick it on charge overnight then see how it goes. if not i'll give the shop a call tomorrow. could it be the reg/rect? if so i have a spare so could stick that on failing other options

hi everyone, i've since got my bike back from the workshop(for an engine issue) and although i had put a new battery in the guy at the shop said it needed a charge as it had been sitting for a week. i rode it for about 15 miles and then stopped for i would say 10 mins as the headlight wasn't coming on. couldn't get the light working so thought i would just sort when i got home. went to start it and it wouldn't run, it was like the battery was dying. managed to bump start it to get it home, did another 20 miles which I thought would charge it up. got home to check the headlight, had a fiddle about with the switch and it came on ok. but then went to start the bike again and it wouldn't start!!

wondering whether this is the headlight draining the battery somehow, or possibly not ridden it enough to charge battery fully??

hi everyone. just an update to say i've got my bike back and it's running fine. thanks for all the help

hey everyone, well here's the update. it's costing a fair bit but i want it back on the road....

it needs:

piston kit

rocker arm

exhaust valve

spring seat valve

collets

head gasket

LABOUR!!

should have the bike back on the road by the end of next week. the guy said that the collets had broken damaging the spring seat and therefore forcing the valve onto the adjustment screw. so overall verdict: exhaust valve knackered = no compression = no vrooooom vroooom

hope this helps a few people too:

Service Manual for the TW 125

http://www.scribd.com/doc/27325375/Yamaha-TW-125-Service-Manual-1999

At the top of each valve is a clip, called a 'collet' that stops the spring coming off the top of the valve, perhaps you have lost this somewhere, meaning that the spring is able to come right off the valve?

Just a thought. Hope you get it sorted

http://i1082.photobucket.com/albums/j374/e30lou/SANY0229-1.jpg

Hodgy, you were absolutely right! The collet was damaged as you can see from the pic. Roy from the bike shop(RP Motorsports) has literally just come and taken the bike away. I had everything exposed so he could instantly see the problem. also pointed out how freely the valve moved from side to side. he said this was why the bike would have cut out in the first place, no compression, and of course why it won't start!

i'll hear back later on today from him with a full and final verdict. will let everyone know as i know in my experience it's always nice to know what the problem was and how it was solved for other people's sake.

thanks so much for everyone's support and guidance

my understanding is when the valves are both shut the valve springs will be fully extended, not compressed like when they are pushing the valves open. so if this exhaust valve spring continues to extend then i'm going to assume either the valve is bent or the spring needs replacing

 

If they were fully extended there'd be no pressure on the valve to keep it shut

i was confused by what you were saying as i was sure that the spring compresses to open the valve and remains extended to close the valve. i've searched the web and several videos/animations confirm this.

for example:

http://youtu.be/UjcIJJnpprs

this is as best as i can describe what's happening, so please bear with me:

1. loosen

2. turn anti-clockwise

3. bottom of screw moves up

4. top of spring also moves up

there is never any clearance. i can turn that screw all the way up and the top of the spring will sit against the rocker arm. if i carry out the same principle on the intake valve i will get a gap/clearance and the top of its spring does not move

http://i1082.photobucket.com/albums/j374/e30lou/SANY0220-11.jpg

The spring holds the vave in the closed position and the rocker opens it at the right thime. You really need to read your manual. It's very hard to fix any machine if you don't understand first principles. I think It's bogof who has an avatar that shows how it works. Suck , squeeze, bang, blow.

http://auto.howstuffworks.com/motorcycle1.htm

oh i understand how the engine works which is why i'm not sure why the spring is still rising whilst i'm loosening the adjustment screw. it should be exactly like the intake valve, if i loosen THIS adjustment screw the valve will not move, the spring doesn't extend so there is a gap UNLIKE the exhaust valve.

my understanding is when the valves are both shut the valve springs will be fully extended, not compressed like when they are pushing the valves open. so if this exhaust valve spring continues to extend then i'm going to assume either the valve is bent or the spring needs replacing

i'll put a video up tomorrow if it helps to explain things clearer

From what you've said in earlier posts , sounds like you have an exhaust valve problem. The spring holds the valve shut, so if the valve is rising with the adjuster it's not closed. The gap is to ensure the valve is closed. If the valve doesn't close, theres no compression and so the engine won't run, which may well explain the strange noises. Get your mechanic to check here first.

Ah that's interesting then. So why would the spring be holding the valve shut?

ok, i went to my local garage(thanks chopster125 ) and we had a little chat. he agrees with the electrical issue, change the ignition coil so tomorrow when that arrives i'll do that. when i described the noise from me bump starting it he said it might be that the starter clutch isn't engaging hence that loud clicking noise. so had a look at the manual.......looks like a big job unless anyone can ease my mind

failing tomorrow's lecky stuff, i'll have to just bite the bullet and take it to him. he's even offered to pick it up for me! will keep you all posted.......thanks so much for everyone's input so far, much appreciated

http://i1082.photobucket.com/albums/j374/e30lou/SANY0220-1-1.jpg

where i have arrowed it you can see the damage to the adjustment screw. you can't put even the smallest feeler gauge in between the bottom of it and the top of the valve. if you undo the 10mm bolt and try to turn the adjustment screw(it should be easy if the intake one is anything to go by) it's very difficult, i had to use pliers. as you turn it the valve moves up with the screw, as if it's trying to push itself against it. hope that makes sense

hey everyone. took the valve covers off this morning and this is what i found:

1. took the camshaft cover off and it looks as if the timing chain had been rubbing on the inside somehow

http://i1082.photobucket.com/albums/j374/e30lou/SANY0225.jpg

2. took the valve covers off and looking at the exhaust valve, the screw was damaged/cracked. it was sat very tightly against the valve tip so i tried adjusting it but the valve kept moving up with the screw and there was never any clearance

http://i1082.photobucket.com/albums/j374/e30lou/SANY0220-1.jpg

i also noticed the top of the exhaust valve cover had a little indent inside it which is where i think the top of the screw had been hitting it

i made sure the piston was at TDC before i touched the valves. i could also see both valves move down and up so there's no issue there.

apologies on the size of pics

Stupid question...but I'll ask anyway....is your oil level OK. You haven't lost all the oil have you?

No, there's plenty in there

When the engine cut out on you what actually happened? Any loud noises or whatever?

Stupid question...but I'll ask anyway....is your oil level OK. You haven't lost all the oil have you?

The compression can be checked using a checker (around £20) but you can just pull the plug out and spin the motor briefly and put your finger over or near the plug hole. You'll feel the pulses of air when the piston comes up. This is not an accurate way of checking it, but it'll indicate if you've got some compression: ie. not holed a piston or dropped a valve.

Actually maybe you should open the rocker covers and just check that a valve hasn't dropped before going too far. That noise when you were trying to bump it was a bit loud for just poorly adjusted tappets.

No there were no loud noises although thinking back I do recall a rapid tapping noise when I was riding it. The bike literally cut out, had no response from the throttle but lights still worked. When I tried starting it again, what you see in my first video is what happened. There's definitely some sort of compression there as when I was peering inside the plug hole I could feel air blowing in my face

I'm not sure I know what you mean by rocker cover?

Hooked it up to my car, didn't do anything. Still doesn't start.

thinking about it, that sound is probably the valves and they need adjusting. could be wrong though?

here's another video of me trying to bump start the bike. you can hear a "click clack" noise and i'm sure it's coming from the engine area. perhaps i wasn't going fast enough

see what everyone thinks

So you get a spark, sometimes. There is fuel getting through.

At this point I would get a car and a pair of jump leads.

right ok, i have my car and a set of jump leads.........easy to hook up?