Jim Smidts parts in my Seeley

Here's the process of installing lightweight parts in a 850 Seeley.
The crank was almost the only original part left in my engine, and it broke!
No other damage as the crank and a small crack in my Maney cases.
My friend Yoshan, a former japanees Yamaha Racing Factory engineer, living in belgium is a top welder, we first made a shaft to replace the crank during the welding, we bolt the Maney cases togheter, heat it up to 250 degrees celsius and weld it, after cooling we find a small difference between the cases, on the surface wher the cylinder is coming on, so we mild 0.2mm from the cases top.
The Maney cylinder and cases are assembled w/o base gasket, but with - 0.2mm from the top of the cases I must use a copper 0.5mm gasket, this is 0.3mm to mutch, to ritch 10.5 CR but it will be safe.
I put also new bushes for the camshaft and new bearings for the crank

After afew weeks I receive the parts from JS Motorsport: Cristmas in August


The one piece nitrided billet crank is a piece of mecanical art





The longer bushless lightweight Carrillo rods installed.
Stage 2 cam with lightweight BSA style lifters, pushrods springs and valves (All JS) where installed a few thousend Kms before the crank broke and is still as new





The new lightweight high compression pistons compared to used pistons. I find a difference from almost 100 grams beteween the Maney's pistons and the JS: amazing!





Checking combustion chamber volume with liquid to determine compression.





Clay on the pistons to check the squish band clearance.
After the clay I did the mesurment using lead wire in place of clay, this is more accurate to me; 1.8 squish was the result, that will give me a CR from 9.8 to 1, still safe.





The pistons with ring compressors ready to install into the cylinders.
I rebore the cylinder to 77.5 that give me the Jim requested clearance of 0.14 for the pistons
I use the normal cylinder head gasket (0.75mm)





Motor complete ready to go into frame.





Motor in frame.





Bike finished and ready to go.






First test rides: The engine run so smooth, w/o vibes and with a larger power band, oil pressure is 60 PSI at 4000 RPM, don't ask me so far about maximum power, I first need to break in the engine,but it feel very promasing. I keep you posted soon about the power
I wish to thanks Jim Smidts, Yoshan, Bruno Rossi from the machine shop and Frank Jordens the No 1 Norton specialist in the country.
Yves

Yves, I was going to reply sooner, but I had to take a cold shower after looking at your pictures!

Fantastic build, really can't wait to hear your Dyno results and, more importantly, your 'seat of the pants' report when you can utilise max power.

I've just finished mine, but looking at that crank makes me want to strip it again. I shall resist though. I think!

Out of interest, when you say you have a 1.8 squish, do you mean 1.8mm? With steel rods and billet crank I would think you could half that and still be safe.

That engine in such a light cycle will make for a fabulous road bike. Please do keep us posted as you bed it in and up the revs.

I have the same Mk3 Seeley frame with 850 motor. I don't use the normal front brace to the engine. I have a single piece of larger diameter chrome/moly tube gusseted at the ends with a slight curve in it to allow some spring. I suggest you might need to keep an eye on your front brace in case it breaks somewhere due to vibration and stresses.

Yves,
That is a fantastic bike. Bet it handles well. I often thought about building a Seeley framed bike, but the vibration problem always put me off. Maybe with the JS parts that is less of a problem? Also, as I presume this is a road bike, what fuel do you use to prevent pinking with the 10.5:1 cr .
Martyn.

Oooh Martin VIBRATION!!!!!! with a Seeley Commando. Shock horror.

If I had just the foam on the seat like the race bike I might go blind at the lights. No that's not true
I had mine balanced at Basset Down & my only problem was the tank drumming at 70mph in top. I have added more TZ tank rubbers but it really needs a block of foam under the centre of the tank. This is a MK3 which is nearly back on the road again. I loved racing it away from the lights but have now fitted a 20 tooth gearbox sprocket for the coast road.

Yves bike is the biz & he hasn't stopped playing with it.

Chris

Chris,
Don't get me wrong. I like bikes to feel like they have an engine & am happy with plenty of vibes, but big Norton motors did (before JS) have a reputation for destructive vibration. If bits keep braking/falling off it kind of spoils the fun after 100 miles or so.

yves norton said:

Here's the process of installing lightweight parts in a 850 Seeley.
The crank was almost the only original part left in my engine, and it broke!
No other damage as the crank and a small crack in my Maney cases.
My friend Yoshan, a former japanees Yamaha Racing Factory engineer, living in belgium is a top welder, we first made a shaft to replace the crank during the welding, we bolt the Maney cases togheter, heat it up to 250 degrees celsius and weld it, after cooling we find a small difference between the cases, on the surface wher the cylinder is coming on, so we mild 0.2mm from the cases top.
The Maney cylinder and cases are assembled w/o base gasket, but with - 0.2mm from the top of the cases I must use a copper 0.5mm gasket, this is 0.3mm to mutch, to ritch 10.5 CR but it will be safe.
I put also new bushes for the camshaft and new bearings for the crank

After a few weeks I receive the parts from JS Motorsport: Cristmas in August

First test rides: The engine run so smooth, w/o vibes and with a larger power band, oil pressure is 60 PSI at 4000 RPM, don't ask me so far about maximum power, I first need to break in the engine,but it feel very promasing. I keep you posted soon about the power
I wish to thanks Jim Smidts, Yoshan, Bruno Rossi from the machine shop and Frank Jordens the No 1 Norton specialist in the country.
Yves

Click to expand...

Yves,

Just curious about the oil pressure, which sounds very good. Bone stock or... different pump, restrictors installed, rerouting of oil flow, etc?

Fast Eddie said:

Yves, I was going to reply sooner, but I had to take a cold shower after looking at your pictures!

Fantastic build, really can't wait to hear your Dyno results and, more importantly, your 'seat of the pants' report when you can utilise max power.

I've just finished mine, but looking at that crank makes me want to strip it again. I shall resist though. I think!

Out of interest, when you say you have a 1.8 squish, do you mean 1.8mm? With steel rods and billet crank I would think you could half that and still be safe.

That engine in such a light cycle will make for a fabulous road bike. Please do keep us posted as you bed it in and up the revs.

Click to expand...

Hi Fast Eddie, yes I mean 1.8mm squish, to me this is to mutch also, but becouse of milling the top of the cases -0.2mm, I have to use a cooper base gasket from 0.5mm.
I order a steel base gasket from 0.2mm (lazer cut) and I will put this one next winter, so I will reach 10.5 to 1 CR
I will also give my cylinders a carbide or Nikasil treatment, but now I wish to ride, I am far away from the year average of 10.000 kms I ride every season
Yves

acotrel said:

I have the same Mk3 Seeley frame with 850 motor. I don't use the normal front brace to the engine. I have a single piece of larger diameter chrome/moly tube gusseted at the ends with a slight curve in it to allow some spring. I suggest you might need to keep an eye on your front brace in case it breaks somewhere due to vibration and stresses.

Click to expand...

Hi there, I have 60.000 kms with the Seeley and never had a problem with the front brace, I spend a full day every week for maintenance and cleaning and I will keep a eye on it
Thanks Yves

Matchless said:

Yves,
That is a fantastic bike. Bet it handles well. I often thought about building a Seeley framed bike, but the vibration problem always put me off. Maybe with the JS parts that is less of a problem? Also, as I presume this is a road bike, what fuel do you use to prevent pinking with the 10.5:1 cr .
Martyn.

Click to expand...

Even before the JS parts, the vibes was not a problem, some days I ride 700 kms at once and don't end up with my collar bones in my stomac.
I use normal fuel (the Belgiam fuel is better as the one in the UK) and never have detonations or pinking, but if I ride to the UK I wlll ad Millers octane booster to the fuel.
Thanks Yves

WZ507 said:

yves norton said:

Here's the process of installing lightweight parts in a 850 Seeley.
The crank was almost the only original part left in my engine, and it broke!
No other damage as the crank and a small crack in my Maney cases.
My friend Yoshan, a former japanees Yamaha Racing Factory engineer, living in belgium is a top welder, we first made a shaft to replace the crank during the welding, we bolt the Maney cases togheter, heat it up to 250 degrees celsius and weld it, after cooling we find a small difference between the cases, on the surface wher the cylinder is coming on, so we mild 0.2mm from the cases top.
The Maney cylinder and cases are assembled w/o base gasket, but with - 0.2mm from the top of the cases I must use a copper 0.5mm gasket, this is 0.3mm to mutch, to ritch 10.5 CR but it will be safe.
I put also new bushes for the camshaft and new bearings for the crank

After a few weeks I receive the parts from JS Motorsport: Cristmas in August

First test rides: The engine run so smooth, w/o vibes and with a larger power band, oil pressure is 60 PSI at 4000 RPM, don't ask me so far about maximum power, I first need to break in the engine,but it feel very promasing. I keep you posted soon about the power
I wish to thanks Jim Smidts, Yoshan, Bruno Rossi from the machine shop and Frank Jordens the No 1 Norton specialist in the country.
Yves

Click to expand...

Yves,

Just curious about the oil pressure, which sounds very good. Bone stock or... different pump, restrictors installed, rerouting of oil flow, etc?

Click to expand...

I use Denicol Racing Mineral oil, and, before the JS parts the pressure was 45 PSI at 4.000 RPM, I think the 60 PSI will go down after bed in, no different oil pump, restrictors or rerouting of oil flow, I just ad a oil cooler that start working when I reach 80 degress celcius thanks to a thermostat
yves

yves norton said:

WZ507 said:

yves norton said:

First test rides: The engine run so smooth, w/o vibes and with a larger power band, oil pressure is 60 PSI at 4000 RPM,
Yves

Click to expand...

Yves,

Just curious about the oil pressure, which sounds very good. Bone stock or... different pump, restrictors installed, rerouting of oil flow, etc?

Click to expand...

I use Denicol Racing Mineral oil, and, before the JS parts the pressure was 45 PSI at 4.000 RPM, I think the 60 PSI will go down after bed in, no different oil pump, restrictors or rerouting of oil flow, I just ad a oil cooler that start working when I reach 80 degress celcius thanks to a thermostat
yves

Click to expand...

40 weight oil for cool weather should be better if you're using 50 wt.

yves norton said:

Matchless said:

Yves,
That is a fantastic bike. Bet it handles well. I often thought about building a Seeley framed bike, but the vibration problem always put me off. Maybe with the JS parts that is less of a problem? Also, as I presume this is a road bike, what fuel do you use to prevent pinking with the 10.5:1 cr .
Martyn.

Click to expand...

Even before the JS parts, the vibes was not a problem, some days I ride 700 kms at once and don't end up with my collar bones in my stomac.
I use normal fuel (the Belgiam fuel is better as the one in the UK) and never have detonations or pinking, but if I ride to the UK I wlll ad Millers octane booster to the fuel.
Thanks Yves

Click to expand...

With the Seeley, getting the crank balance factor right to suit the application is very important. My bike is a pig at low speed. When it idles it actually moves back and forth due to the crank imbalance. A soon as you are moving, it is practically vibrationless. I wouldn't recommend it for use on public roads unless you live where there is no slow traffic. The other thing about the high BF with a rigidly mounted motor is that it changes the feel of the bike, you know it really means business when everything smoothes out at about 3000 RPM. There is nothing worse than a light crank with a low BF in a big twin motor, for stuffing performance. The bike becomes revvy, vibrating when at high speed and difficult to ride well.

If you want to ride something interesting, find yourself a 1963 unit construction Triumph Bonneville rebalance the heavy crank to 75% and fit the two E3134 cams (exhaust for the unit Bonnie has a different number) and use a fairly non-restrictive exhaust. Everything happens at 4,000 RPM - a beautiful experience and the cops will love you.