[wessex_man]

Wise move if it aint broke don't fix it.

Never really had a problem with the oil pump. Just got to make sure it's air tight. It can take a bit of time to get up to the sight gauge though. It's long way to travel before it gets to the sight gauge.

[huw warrington]

So an update to my previous post... It's a glorious sunny spring day here in N.Wales and I just been on a 25 mile ride on the Sunbeam! it's going great and I was cruising at about 50mph according to the Bonniksen.

I decided to leave the gasket under the barrel in situ. When my father restored the bike over 20 years ago now, it was running sweetly, so I decided to leave well alone. The piston appears to be the correct type for a model 9, i.e. a slight raise with valve cutouts, but not a pronounced dome like the model 90.

On closer inspection the exhaust valve had badly pitted. Grinding the valve soon restored full compression. It forced me to look elsewhere for the trouble, so I retimed the mag and bought super unleaded petrol and added some Redex Lead Replacement. Hopefully things should settle down.

The only problem I have to solve now is to get the oil pumping through. I can see why they dropped the 1928 vacuum oil pump arrangement after only 1 year, it's rubbish! I was manually pumping a full plunger of oil every few miles or so. possibly too much, but better safe than sorry. 

Any words of advice from other 28'ers on how to get the oil pump to work??

[wessex_man]

Re the metal gasket. I don't have one on my 1928 M9. But really removal of yours it will depend on what piston you have fitted and the valve clearences. Also remember as you increase compression it can be a bit harder to start. You may have to hone the barrel to remove a ridge as well. It depends on just how much wear you have.

As an illustration

On a 1931 90 engine, currently in progress I couldn't get the piston I wanted so have had to get a 40 thou Norton 16H piston modified for the profile of the high compression Sunbeam, ( very minor changes). This needs a spacer ring of about 2mm  and compression falls between the standard beam and high compression beam. It also has the right balance and weight within a few grams. I am hoping that the bike will start more easily but offer a bit more preformance than standard. Time will tell.

The 1931 high compression JP one you can get will probably run, but is too heavy, (in excess of 50gms) and I think you should have to re-balance the flywheels. I know because I bought one and compared it with a worn out original one. 

Also I've found out is that all the M9 beam pistons I've weighed are all within a few grams of each other, regardless of type.

[huw warrington]

So I removed the valves this weekend to lap them and de-coke the cylinder head.  I've taken delivery of the KLG ML50 longer spark plug but it won't screw in due to crud encrusting the bottom of the thread. So I've ordered a 18mm x1.5 tap from the green spark plug co in order to try and clean the thread.

On an unrelated note, there appears to be a metal gasket between bottom of the cylinder barrel and the crankcase, presumably to lower the compression? What would be the impact of removing this? Increased power? Would I need to tweak the carb? or is having lower compression better in these days of unleaded petrol?

[wessex_man]

I use a 3/4 reach plug in my M9's

I personally prefer the Lodge CB3's but it's a case of finding them.

Green Spark Plug Company KLG ML50 is the Lodge CB3 equivalent. 3/4 reach 18mm. Works ok.

http://www.gsparkplug.com/catalogsearch/result/?q=cb3

(He hasn't had any CB3's for years).

I agree the valve greasers a personal mod. It's not lubricated up there. I use graphite grease which tends to stay.

[phutton]

Easy question first - the cups around the valve springs are not original. An interesting idea used on quite a few machines in the 1930s, including Levis and Velocette but not on a 1928 M9!

The 1928 Supplementary Manual for the OHV models specifies a Lodge H1-3, clearly now obsolete. According to the Green Spark Plug Co website, the nearest equivalent is the Champion D9. Both are 1/2" reach

[huw warrington]

I inherited my father's 1928 Model 9 a couple of years ago. There was no spark so I fitted a spare magneto, and it got it to start. I went two miles down the road before it spluttered to a halt with no compression. I suspect that by poking down the plughole to find TDC to time the mag I must have dislodged some crud that had then gotten itself under the exhaust valve?

Anyway, fast forward two years, and I have finally taken the head off to have a look; see attached photos. Why is there crud around the plughole? Is it because the Champion D14 plug was too short?  What plug do I need?

Also, its's going to be a job to take the valves out to regrind, as there seems to be shrouds/casing around the coil springs. Were these standard on a Model 9 of 1928? What's are the advantages of having them?

Thanks in advance for any advice.

Huw Williams.