sticky vavle aaarrrggghhh!

[grumpuszed1]

next installment of my engine re-build, all back together,got the bike mot'd and taxed done 50 miles great! going out on it, brrrrrrrrr, from the engine,clutch pulled in real quick,engine stalled, turned engine over on kick start(real slow) its locked up.1 hour wait for mr AA, got top end stripped down and what do i find? no1 inlet vavle has got jammed,and so contacted with piston, no real damage to the piston, but vavle bent, guide f****d and me left scratching my head, all the vavles,guides,pistons,cam bearings are brand new, installed guides (the steel ones) myself, reamed them out 7mm after fitting, measured springs all within tolerance. so what happened? i removed all the vavles again to check them, the one that jammed had picked up on the vavle stem, two positions had big score marks on them with metal built up on them. i assembled the vavles with clean engine oil when i put them in so dont really know what went wrong,any body got any ideas? i dont know if i did something wrong and dont want it to happen again. please help

[Garn 1]

Grumpus, I can think of only a few things that may have happened.
Assuming you have already done 50 miles on it.

1. You have bent the valve when initialy setting the timing.
2. Your oil pump has come loose and the top-end has been starved for lubricant and a valve has siezed due to local overheating.
3. The timing chain had not been tensioned and has slipped a couple of teeth.

All are pretty unlikely, however, I have heard of stranger things happening.
RegardZ.

[DogsbolloxofZ1B]

Sorry to hear of your bad news. One important factor when replacing the guides, as you probably know, is to ensure you re-cut the seats to be in perfect axial/contact alignment again. If you didn't and merely lapped the valves then this maybe a consequence.
I was aware of this when rebuilding my Z1B so had SERDI's install tighter tolerance inserts into the original guides and re-cut the seats.

Good luck..

[grumpuszed1]

no i wasnt aware that you had to recut the vavle seats,and yes i did simply re-grind the vavles with lapping compound. not sure what SERDI'S is ? is it a garage? can i simply get a tool to re-cut the seats? if so where from? all the old guides were binned as they were the old bronze type and got a bit mashed when i drove them out. got a new vavle/guide on order so further help would be much appreciated, also do you know how much clearance between vavle stem and guide, the vavles are 6.97mm and guide reamed out to 7mm so 0.03mm this is just over a thou should this be more?

[Glen]

It's a good job that I have read this article as I have just replaced the valve guides on Z1B. Next I will ream them out and then re-cut valve seats. Where do I get a tool for re-cutting the valve seats. Can I hire one and if so where abouts in Essex

[grumpuszed1]

hi glen dont try to do this yourself! i have just had a talk with a local guy in plymouth who does engine rebuilds (paul inch) he said if you attempt it you will f**k it, so i am letting him do it! and at ?2.00 per valve its not worth doing yourself.

[DogsbolloxofZ1B]

Here's a link to SERDI UK LTD, a great bunch of guys and prompt service.
Make sure you get a quote though to avoid surprises..

http://www.serdi.co.uk/serdi/htm/contact_us.htm

[Glen]

Thanks Dogs'.
Serdi have quoted me ?141 inclusive of valve stem Micro polish, seat cutting, postage and Vat.
The seats will have 3 angles cut.
That sounds good value to me.
I should be sending them up next week.

[grumpuszed1]

hi can anyone explain the 3 angles that are invovled in the valve seat? or better still download a diagram of the seat geometry? i ask because i want to make the guy who is doing my valve seats aware of whats involved. he probably already knows but i want to make sure. ta

[Ed Z1-R]

The info on the angles for cutting in valve seats are/would be explained in the maintenence section of a genuine workshop manual.
Dunno if they differ between z900/z1000
but only have info for the latter.
Sorry no can download

[Pigford]

Valve faces are often cut at 30 & 75 degs, then the valve contact surface is cut/lapped/ground at 45 degs to the specified width to get a nice seal.

http://www.fordscorpio.co.uk/manual/eng ... lvSeat.pdf

[grumpuszed1]

thanks for the heads up!

[Ed Z1-R]

thats interesting Pigford,
The z1000 manual states angles as
#1; 45
#2; 30
#3; 60


not disputing its just wots in there

[Pigford]

Ed, 30/45/60 is probably right, just giving an example, if you got an old Ford Scorpio its OK

[Ed Z1-R]

FORD SCORPIO
HOW DARE YOU
to put the record straight i procured a Rover road rocket in GPO rascal red
its the biz dude