engine misfire

[leebo]

reet to start off evening all
ive got a misfire its not plugs or ht leads plenty of spark there
im guessing worn valve seat or rings??
and will i be able to do the repair without taking out the engine
2.l Aircooled its also poping a bit from the same cylinder wonering if it could be valve timing if someone has tightened it down too far in the past and the valves not closing right
any ideas

[jason k]

induction air leak?

[leebo]

possable il take a look tommorow to rule that out

[leebo]

reet ive just changed the manifold gaskets it still has a missfire
any more ideas anyone????

[jason k]

Which did you do Carb base or inlet gaskets?

[leebo]

inlet gaskets

[jason k]

Try spraying wd round the carb base when running. A leak will.show.itself as the wd gets.sucked In

[leebo]

its a single carb but it was the same with the twin solex on

[82JEW75]

Drain oil.
Rocker cover off.
Check tappets/valves.


Otherwise, if you're going to have the head off to investigate, you want to drop the engine.

Only 8 bolts and a couple of wires, can be out in well under an hour and sooooo much easier then struggling under the van.

[leebo]

right reset valves still the same its also blowing a bit of oil through the exhaust

[Tug]

Whip the rockers off and check the height of the valves..are they all the same height ? If not and one is higher than the rest then it could be a valve seat pulling.....Just had this with mine. I had a very occasional misfire and I knew something was not right. So I whipped off the covers and hey presto number 3 exhaust was higher by 4mm.

Stripped the head off and yes....the seat had pulled in to the head causing a bad seal with the valve.

Glenn.

[leebo]

well i messed about looking for the easy fix and it was as i first thought rings and pison has gone on number 1 looks like someones dropped something down there at some point i can smooth out the pits on the head but the piston is well gone bore is fine thank god so im gonna need a single piston and a set of rings anybody know where i can buy a single piston from

[82JEW75]

No 2l spares here I'm afraid, now if it was a CT engine...

As far as I know, you can only buy pistons in sets of 4 as they have to be matched for weight. We've got a few CT pistons floating around from a previous rebuild, but nothing CU, sorry.

Normally come as a set of pistons + barrels, so condition of the bore is not really an issue if you're buying new.

Excuse for a top-end rebuild?

[leebo]

looks that way ive just borrowed a few hundred from me mam ,shes a good en, so new pistons here i come,
thanks for the info matey as id hit a brick wall looking
cheers and il stick a few pics on of my buggered piston see if we can have a competition for the worst lol