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TW125 doesn't start


e30lou
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so is the exhaust valve stuck open all the time or have you seen it moving while you turned the motor?

no, its not stuck it moves down then up as i turn the motor. if you watch both the valves as i turn the motor, you can see the intake valve move down then up, then shortly after the exhaust valve does the same.

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Then adjust it, unscrew it until there is the right clearance, you will have to look in the manual what the line on the chain ring means it may have to be at the top in alinment with the centre of the clinder or something, any how it should be in the manual how to check and set clearances, this could be why you had no compression

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That chain"s been rubbing on casing, is there a cam chain adjuster ? on video it sounds like its dropped a valve ,,

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Then adjust it, unscrew it until there is the right clearance, you will have to look in the manual what the line on the chain ring means it may have to be at the top in alinment with the centre of the clinder or something, any how it should be in the manual how to check and set clearances, this could be why you had no compression

i've unscrewed it all the way and the valve just follows it up...it's now high enough so the rocker arm rubs on it. there is no clearance, you can't fit the smallest feeler gauge in between the screw and valve

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i've unscrewed it all the way and the valve just follows it up...it's now high enough so the rocker arm rubs on it. there is no clearance, you can't fit the smallest feeler gauge in between the screw and valve

Then it is still on the cam! so turn your engine...at some point there should be a gapp appears. I suggest you trawl the manual for correct positioning, that mark on the cam sprocket isnt there for nothing...it should be positioned somewhere or align with a static mark

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Then it is still on the cam! so turn your engine...at some point there should be a gapp appears. I suggest you trawl the manual for correct positioning, that mark on the cam sprocket isnt there for nothing...it should be positioned somewhere or align with a static mark

the manual said to get to TDC and align the mark on the cam sprocket with the alignment stud at the top, which i had already done

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and on the next TDC?

i haven't had time to check this but i'm going to do it tomorrow.

i've provide a pic with stages broken down as follows. 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

SANY0220-11.jpg

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is the sring retainer at the top of the spring still attached securely to the valve? you say the top of the spring moves up but you dont say the valve is moving!

The usual arrangement is a couple of collets holding that top spring retainer, they sit in a groove around the valve. If they have come out you wont be using the bike any time soon I dont think

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hey everyone. took the valve covers off and camshaft cover 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

SANY0225.jpg

2. 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 :blink:

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

Reckon you've sussed it OG look at the timing cog, , the little indent on the exhaust valve cover, and he refers to exhaust valve screw damaged, plus the collets sit about a 16th" proud usually, and can't seem to see any in the pics, looks like the collet/collets have jumped out. Just hope they've not damaged much else e30lou. Oil drain, and look for any shrapnel.

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is the sring retainer at the top of the spring still attached securely to the valve? you say the top of the spring moves up but you dont say the valve is moving!

The usual arrangement is a couple of collets holding that top spring retainer, they sit in a groove around the valve. If they have come out you wont be using the bike any time soon I dont think

SANY0229-1.jpg

finally hit the nail on the head, thanks OG :D

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 :thumb:

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was definitely an electrical issue when it cut out, .............

:lol:

.....However I wonder about the compression, it seems to whizz the engine over just a little too easily. .....

:rolleyes:

That chain"s been rubbing on casing, is there a cam chain adjuster ? on video it sounds like its dropped a valve ,,

blackhat had it :thumb:

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:lol:

:rolleyes:

blackhat had it :thumb:

:lol: yeah, does seem funny looking back on it but then that's what these forums are for. to help diagnose things and help one another, right?

thanks blackhat, although i never even saw your post!

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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!! :P

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 :lol:

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