Forum

[Mark M]

Les, it's not my bike, it's Mr Grrrrrr's. I was just commenting on the decompressor arrangements, not trying to diagnose the problem!
REgards, Mark

[grrrrrr]

Ok I,ve stripped her down again no leak from head gasket or tube seals
top of the barrel was dry apart from sealer I put on head gasket.Looked
inside the exhaust port and there is a crack 1/4" away from the guide
which was clearly visible through the black carbon deposits.That said it
would leak into the rocker cover rather than an external part of the head.
have ordered a second hand head and two new guides anyway and will take it from there.
Holidays are coming up so will not be able to do much more for a while.At least I have
the sunbeam to potter around on if it stops raining long enough.Will update when the heads done
thanks guys
mark

[Alan R]

-------Hi guys. We've not mentioned anything about that apparent loss of compression each time the smoke appears ( or rather AFTER, ie when the engine has stopped. )MARK---First...just for the record }--is that your type of engine in the you-tube video ?? Second..after you have stopped the engine, and allowed it to cool down again, has compression been restored ?? , third....when you have the engine running is this with the fuel tank fitted on the bike ?? or is it removed and you are using a temp. supply ? ie can you see ALL of the cylinder head upper areas ?? and finally fourth...when you de-coked the head etc. did you remove the valves, springs etc to clean them ???......... LES }---I take your point about a possible external oil leak but at the moment Mark says he can't pin-point an exact position. Am I right about the head being an Iron one ?? I've not worked on a model G before---hence the video clip, just to be sure we're all on the same bike, as it were.

[Alan R]

---------sorry, your last reply was posted whilst I was typing. Let's hope the spare head does the trick ?? At least you have got the practice time in by now--LoL !!!

[Presto]

Mark M - I have a feeling Les H was addressing the 'other' mark, ie grrrrrr

[Alan R]

-------Mr Grrrrrr, from my own experiences might I suggest that--if at all possible---have the new guides fitted by heating the head (or, conversely cold- shrinking the guides) rather than hammer them in ?? It's a lot more "sympathetic" and less likely to do any damage.

[grrrrrr]

I use coventry boring for that type of work they put new guides and re cut the valve seats and skimmed the head
on my sunbeam did a good job.I didn,t know you could hammer them in I always thought they where pressed on.

[Alan R]

Hello again---------P-L-E-A-S-E don't HAMMER anything !!!!--especially if cast iron. These guides are an interference fit ie they are approx 1 to 2 thou oversize for the hole in which they are being fitted. Shrink-fit is ideal as they become momentarily a few thou.undersize and can be placed directly into the cyl head in a loose state. As they warm up so they expand into the hole and take up a snug & firm fit. A press can be utilised provided it's done SLOWLY and ACCURATELY ie They must be lined-up right from the very start of pressure being applied------and there is always the risk that during transit they might pick-up and jam. Whilst working on the railways we would use BOC-supplied "DRY-ICE" to shrink cylinder liners before fitment.(You can't hammer those in----approx 2ft long !!). It's an industry accepted method---not my theoretical idea.

[Les H]

Thanks RICHARDR...yes you are right, I was referring to "grrrrr", and not Mark M....so applogies to Mark M for the confusion, I was not referring to you at all. I should have stuck to the username of "grrrrr"...I find it difficult to choose sometimes if someone has signed their post off with their actual name.

[Mark M]

Les, thanks, I wasn't offended just trying to make sure the right person was being addressed! That's the reason (apart from having nothing to hide!) that I, like you, use my actual name. Now we've dealt with all that lets hope the other Mark gets this sorted!
REgards, Mark