………..to all old experienced hands for needing to ask a few embarrassingly simple questions which will help me, a mere scotting novice, with my recently-acquired late 1930s Flying Squirrel.
Firstly, and most urgently, I decided to whip the cylinder head off to do a decoke and replace a missing/broken stud. I have, of course, ended up with the block and head on the work-bench a one never-to-be-parted unit. What is the best method of getting the head off the block when they seem to be irresolutely welded together? It seems that the studs and head are well stuck together and I have, so far, only tried removing the studs using the ‘two nuts’ method with singular lack of success in shifting even one stud. Help, please.
The other couple of questions are:-
1. The gearbox oil level plug is situated at the front of the box and the level inside must vary considerably depending on whether the bike is standing on its own two wheels or has the rear wheel lifted into the air with the bike up on the rear stand. Which is correct for checking the gearbox oil level on the stand or not?
2. There is a distinct bend, or kink, in the lower radiator hose. This must be usual due to the way the pipes out of the radiator and into the cylinder head do not line up. Is the bend a problem, does it restrict flow, is there a way of getting rid of the kink?
3. (I lied about ‘a couple’ of questions). The oil pump drive was mentioned in the piece printed in Yowl which I sent in asking what the drive is – reduction gear or a spacer – and wondering about its origins. Unfortunately, the photo did not appear in the magazine so please follow the link below and I hope that someone will recognise it and be able to tell me if it is a proprietary fitting and, if so, by whom it was made.
Many thanks for any help, answers, forthcoming.
Welcome back to Scotting. “Novice” ?! I don’t think so….
Your stuck cylinder head is a very common problem, and you will find endless postings about it on this website and in Technicalities, but one thing is certain, it is not going to be easy. That is why, in the latest Yowl, my advert offering cylinder barrels for sale, emphasised that the cylinder head was separate and not stuck on. Good luck with it anyway, and don’t use stainless steel replacement studs.
I have never seen your oil-pump mounting gizmo before, and it looks as if it is just a heat isolating thing to try and isolate the pump from anything which will upset the critical settings. Can’t be sure though from the photo.
When Martin Hodkin saw your article in the latest Yowl he remarked that he hoped to see you at Northern Section meetings as it is many years since he has seen you.
Best wishes, and again good luck with the cylinder head.
Never an enviable job, but as I am obliged to do it from time to time as part of a full rebuild and upgrade, I gave myself the best chance by making some equipment. First I leave the whole thing in a tub of diesel for three weeks of so, Then I have a thick steel baseplate with two 24mm long bolts on the cylinder centres. On top of these bolts there are steel platforms inside large nylon bungs, the top of which are coutoured to match the Scott cylinder head. There are 4 bolts to engage the tapped holes that usually hold the block down. In this way, I can apply a fair bit of pressure, but it is applied in such a way as to minimise any danger of damage. Once pressure is applied, each nut is hit with an aluminium drift and a medium lump hammer. I have not failed yet, but I suppose there could be a first time!
My advice is always not to remove the head unless absolutely necessary, as the block is easily rebored with the head in situ. Also, the Scott head gasket is a thick spongy thing like a matress, which is OK for sealing, but if you do not pull it down evenly, then the head can become bowed. Once you take it off, it might be necessary to reface it. As the brass water tubes will also be corroded in, then to reface the head with the tube in situ needs some rather large plant. To precis this piece “If it’s not broke, don’t fix it” Kindest Regards and Happy Christmas to all
Thanks to Brian and Roger for replying. I looked through ‘Technicalities’ and all I could find seemed to say the same as Roger did – leave well alone.
Roger put it ‘if its not broke, don’t fix it’ which raises another question – is it ‘broke’?
I was trying to remove the head not only for a decoke but also because one stud is either missing or broken. One of the middle two, the one at the front immediately behind the front radiator hose tube, is just a hole which may or may not have the remenants of a stud in it.
The bike was running and not leaking (either water or gasses) with that stud inoperative so what are the opions – is it safe to run the bike with a missing stud, or will I be doing other damage to it?
You can probe down the hole and find if the stud is missing or sheared off when a previous owner tried to remove it.
My guess is the latter is true. If the bolt is just missing, then if more luck than probibility was on your side, you might be able to just put one in.
If it is sheared, as I suspect, then if the head is not leaking water or compression pressure, then just leave it until you have a problem that is worth doing something about. If you do not like the appearence of the empty hole, just stick the top end of a barrel bolt and nut in with some silicone. Result, all will look OK and the bike will go correctly. If you do not have any Scott type steel bolts, contact me as I have a bucket of them.
Likewise, although I am not looking for work, if anyone has a head they can not get off, I will always try to pull in a job like that for a fellow owner. Regards Roger