Building a new engine

[Snails]

Thanks. I thought it was used for something else so that's helped.

On a plus point I have go quite a few of the missing parts for my engine - so thanks to those you have helped in that respect



Just need to get the drive bearing so I can crack on but can never quite get up enough money to place the SR order I want. It does not help being let down by non payers on ebay.

Think I will have to bite the bullet and order from elsewhere with some vespa stuff I want.

[shocky]

Scootopia do some fantastic stuff in bearingsu think the flywheel side is about 16 quid and looks fantastic quality drive side bearing was about 8

[Snails]

Thanks Shocky. I managed to scrape together enough cash to place my SR order so I've gone with their bearings.

Anyway having a refresh read of the Spanners book before I started to fit the bottom end I thought I'd check the mag housing first - it suggests that the mag housing should slide into the engine casing easily - but mine is anything but easy - there are no obvious high spots on either the mag or the casing. All mag houses should fit shouldn't they? Even if they are supposed to be for a 200? I know the cut out for gas flow may be wrong but it should still fit according to the book. Mine looks right anyway, although I would say for sure whether it's for a small block until I've seen it in place.

Any suggestions?

[shocky]

I gotsome of4hose square foam sanding blocks from poundland in some warm water just kept going round and round till it went in a little then it showed the high spots andthe filed those and then more sanding

[Snails]

Thanks Shocky it's fitting now. I tried your suggestion but never did find any visible high spots but eventually it just went in. I guess that it's not the surfaces that seal the two parts together so I'm not too worried about having over done it.

[Snails]

Wow, I've actually made some progress!

I'm planning on fitting my top end and taking some further measurements before deciding what tuning action to take, if any

Now that I'm ready to do this a couple of questions spring to mind.

1. Should I use the small end bearing supplied with my Asso piston? I dont think I will be using small end shims and it seems a bit on the small side without them. I'm going to phone chiselspeed and check that the are shims on the big end but I'm pretty sure that there is.

2. Will it need the barrel/bore tolerance checking and possibly a hone? I'm thinking it cant hurt to get it checked. I'll do this after doing the tuning work if I do any.

[Grumpy225]

2. Will it need the barrel/bore tolerance checking and possibly a hone? I'm thinking it cant hurt to get it checked. I'll do this after doing the tuning work if I do any.

yes, I have every kit checked out. For an iron lined cylinder I run them at .0035" (inch) clearance. Tighter (about .002"-.0025") for platted cylinders. Measure before tuning, hone afterwards.

0 seizures in 20 years, 32:1 oil ratio every time.

[Snails]

2. Will it need the barrel/bore tolerance checking and possibly a hone? I'm thinking it cant hurt to get it checked. I'll do this after doing the tuning work if I do any.

yes, I have every kit checked out. For an iron lined cylinder I run them at .0035" (inch) clearance. Tighter (about .002"-.0025") for platted cylinders. Measure before tuning, hone afterwards.

0 seizures in 20 years, 32:1 oil ratio every time.

Is there any accurate way to measure this at home?

Also, I have checked my ring gap and its around 0.15mm which is a little tight according to Stickys. It does suggest that they can be filed but does not say what with. Any suggestions?

[rosscla]

Feeler gauges down the side of the barrel

a small needle file would do for the filing

[Grumpy225]

Is there any accurate way to measure this at home?

Also, I have checked my ring gap and its around 0.15mm which is a little tight according to Stickys. It does suggest that they can be filed but does not say what with. Any suggestions?

Feeler gauges are not an accurate way to measure the bore/piston clearance.

You'd want to use an inside micrometer. Measured at a couple of points, usually right above the exhaust port.

http://www.use-enco.com/CGI/INSRIT?PART ... NO=2615151

It's not an expensive tool but not one you would use all the time unless you are boring cylinders.

Ring gap is a little tight like you said. Rosscla nailed it with the file.