Saving Old Seagulls

It's fast (it's a 170 on a 5R leg)

Yikes..

Look out, Chas will be along shortly


Geez, a monster, i bet that "barks" when at full chat.
Nice... but too fast for me



Jon

Pipe look long enough, for about 5500.

Looks great

Homage to Charles I would say
We need video, we all like a bit of video.

H A

Is that you know who running away with a competitors motor whilst they were not looking? That tuned exhaust reminds me of a V1 engine.

6,980 rpm
Charles will need to add an expansion chamber to keep up ...
Video at idle: http://youtu.be/ja39zS-4dwU

Is that a Mikuni 24MM Flat Slide, I always try to stick with Amal 420, bit more "seagull" less moped.

Running at almost 7000 you must be using needle rollers throughout, or ball races.

H-A

Not on a 170 powerhead?

Oyster 49 wrote:Not on a 170 powerhead?

Why not on a 170 powerhead?

You have not delved deep enough yet Adrian

Is has been done.

H A

OK, time to delve...

170 standard crank not good so a new one would need to be made with a pressed in big end pin, along with a new conrod machined to take the needle roller big end. Is there enough meat in the crankcases to machine out for ball bearings? Also how is the crankcase then sealed? Is there enough meat to machine a bore for oil seals top and bottom? I'm intrigued as I've never stripped a 170 down.

The 170 is of course a looper is it not? Is this why it is a favourate with the racers? I did look at one of Charle's powerheads in bits once, very interesting.

I do have a century I have a few plans for..mostly for fun really though.

Oyster 49 wrote: 170 standard crank not good so a new one would need to be made with a pressed in big end pin, along with a new conrod machined to take the needle roller big end.

Is there enough meat in the crankcases to machine out for ball bearings? Also how is the crankcase then sealed? Is there enough meat to machine a bore for oil seals top and bottom? I'm intrigued as I've never stripped a 170 down.

The 170 is of course a looper is it not? Is this why it is a favourate with the racers? I did look at one of Charle's powerheads in bits once, very interesting.


I do have a century I have a few plans for..mostly for fun really though.

Made by Seagull.


Cast new crankcase, with room for bearings.



Look at the Kingfisher or 5r powerhead, Gordon Blair tweaked them.

H-A

I've never really got close to the more modern engines, as one has never come up near me. So is the crank made specially, or just modified?

Is this the dark side..?

I couldn't afford to have new casings cast like Charles did!
Powerhead is a looper, yes. Carb is big (and yes, off a moped) but we wanted to see just how fast we could make it go.
If you want to add bearings to a set of 170 casings you will need to build up the outside as there isn't enough meat on them in stock form.
The 6,980rpm was with two people in our 24' plywood boat.
Dark side?...probably to the purists

Oyster 49 wrote:So is the crank made specially, or just modified?
Is this the dark side..?

Crank and conrod are standard.

Yes this is the dark side

H A

How do you get a needle roller big end then?