Valves and rocker arms *edit* piston and valve location?

[Dalemac]

Well....

i had the head and barrells skimmed by an engineering company which went to a professional motorcycle engine rebuilders.

i knew they would need to remove the valves, so gave them the head with valves still in, expecting them to remove them and give them back to me in labelled bags, so i could then relap them and ensure they are seated correctly, before putting them back in and putting the engine back together.

When i picked up the head, i didnt get told much, just that the head was only very slightly warped and that the valves had been removed and reinstalled. i presumed they had relaped the valves and inserted them in properly, considering the high price, and considering they went to a company dedicated to working on motorcycle engines.

so i put the bike back together, then when i come to the camshafts i notice that the rocker arms are not in the correct place to allow the camshafts to sit on the bearings properly, when they are correctly alligned for valve adjustment.

as you can see in the pics, the rocker arm is sitting on the valves correctly, but the valves are too high, pushing the rocker arms up and not allowing the camshafts to sit properly.

https://i9.photobucket.com/albums/a51/dalemckeown/Image112.jpg

https://i9.photobucket.com/albums/a51/dalemckeown/Image114.jpg

now i wouldnt mind but i wasnt told they hadnt been relapped and needed doing - otherwise i wouldnt have wasted the best part of a day rebuilding the head, checking everything and then checking again.

oso now i need to undo all the work i have just done, sort the valves out and them do everything again!


feels like im never going to get this bike sorted!
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YBR125 -> GPZ500S -> SL1000

[sickpup]

First strip the head back off the bike and clean all that crap out of it.

Second try bolting the cam down.

[Dalemac]

thanks for the reply sickpup, however the head is actually really clean, the camera just picks up little things. i have cleaned the whole thing inside and out before spraying with brake cleaner and re oiling everything.


the only thing i can think of is if the cam is supposed to be pushing down onthe valves at this point, but i dont enough about them to be sure....i mean will the exhaust valves for the left cylinder be open when the left piston is at the bottom of the bore?

thirdly i just watched blade - is the bloke in your avatar whistler?


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edit: just found the following information:

[yandy_yay]

um, what he said

on a more serious note in a multi cylinder engine like yours there is always going to be 1 or more valves open, thus one or more rockers applying pressure to the camshaft, as sickpub says try tightening down the camshaft, i would do it slowly and evenly the bearing halfs should come together quite easily before to tighten to the specified torque. if the bearing halfs don't come together easilly enough i would take it off strip i down and start over... PITA but better to be sure than sorry.

Andy
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past bikes: (20 years ago) cg-125 (wriiten off), C-50 (thrashed n' finnaly scrapped), CZ-125 (nicked - never recovered, insurance payout was more than i paid for it !!!)
Current bikes: GN 125(now sold), Divvy 600s.

[Gazdaman]

This thread is silly. Bolt it down, it'll compress the valves.

Even if you've got the timing wrong, make sure you turn the engine over by hand for the first time. i.e with a spanner. Then if you do get a piston/valve interface it'll do it very gently and shouldn't do any damage. But I'd say that's good practise anyway.

Gaz

[Dalemac]

you guys were right. i bolted it down and it went on fine. wouldnt have noticed if i wasnt being so precise about everything.

bolted all the bearing caps down and the bloody cams have rotated backwards by about half a link....pain the the bloody arse.
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YBR125 -> GPZ500S -> SL1000

[NiteMare]

have you got a manual to assist you with setting your valve timing ??

if you haven't you stand every chance of bending a valve, especially if you have no experience of rotating an engine by hand (not on the starter), you might not realise the resistance is not a cam lobe and rotate the crank too far....

if you've no manual get one now !!

p.s.
i thought your pictures were showing swarf as well
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it ain't broke...

i ain't fixed it enough

[sickpup]

[Pete.]

[Dalemac]

well, camshafts are finally sorted. got them alligned and turned it over by hand a few times like you said, got a little of resistance followed by the cam belt jumping despite turning it clockwise (how haynes tells you to turn it) but i do remember it doing the same thing when i was setting the crank up to take the camshafts out, so im not particularly worried by that.

guess all i need to do now is adjust my valves, do an oil change and put the rest of the cooling/ fuel systems back on the bike, then i can start it up again for the first time.....oh how im dreading it.
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YBR125 -> GPZ500S -> SL1000

[NiteMare]

[Dalemac]

[sickpup]

The chain hasn't slipped on the cams it has slipped on the crankshaft. Read my above post. Also bolt down the inlet cam first.

[NiteMare]

when setting cam timing.....

the crank has to be in a particular position, there will be timing marks on the end of the crank to indicate where...

then you set the cams in position in relation to the crank ...

now go back to your manual and check you have gone thru the whole process to set your cam/valve timing correctly ....

if you don't this repair could get very expensive


i've enquired about the cost of valves a couple of times due to cambelts snapping, had a citroen xsara snap the belt, 16 valve engine and 10 of them hit the pistons ...

Citroen wanted over £30 per valve , that would have been in excess of £300 without headgasket,oil and cambelt and then there would have been my labour on top (time to reassemble, cutting valves in etc) the total would have been way more than the value of the car....

i've no idea of the cost of your valves
____________________
it ain't broke...

i ain't fixed it enough

[Kickstart]

[Dalemac]

[NiteMare]

it's getting to the stage where it looks like you aren't following the directions you are given ....

get a manual and set your timing stage by stage ...

remove the cams ...

set crank position ...

refit cams correctly ..

set tensioner ..

rotate crank carefully...

recheck timing marks

job done

if you can't follow that then you're best off paying someone to do it before it really costs you
____________________
it ain't broke...

i ain't fixed it enough

[Ariel Badger]

When it is back together do not try to start it. Roate the engine with a socket (spark plugs out) and make sure the valves do not kiss the pistons.
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Bikers make great organ donors, get 115 on your licence today.

[Dalemac]