Anyone as experience with 920 engine?

Hello there,
I wish to do something on my engine this winter, maybe a 920cc
Of course, like always, I wish to find some owners with good or bad experiences with 920cc
At the moment I have a 820 Maney cylinder with all the stuff from Jim Schmidt. Very good and fast
Thanks for your replay
Yves

Maybe this time next year I can give you some feedback Yves as I'm currently putting a 920 together for mine.

I'd suggest you talk to JS about the pistons he did for me, raised crowns and slight dishes machined into them to allow a tight squish yet still keep the CR reasonable, at around 10.5:1 I estimate.

These pistons are still WAY lighter than stock 850 pistons.

It's what your Seeley deserves my friend...!

Fast Eddie said:

Maybe this time next year I can give you some feedback Yves as I'm currently putting a 920 together for mine.

I'd suggest you talk to JS about the pistons he did for me, raised crowns and slight dishes machined into them to allow a tight squish yet still keep the CR reasonable, at around 10.5:1 I estimate.

These pistons are still WAY lighter than stock 850 pistons.

It's what your Seeley deserves my friend...!

Click to expand...

Do you use a Maney cylinder? can you bore a 820 maney cylinder to 920 or you have to change the sleeves?
Yves

yves norton seeley said:

Fast Eddie said:

Maybe this time next year I can give you some feedback Yves as I'm currently putting a 920 together for mine.

I'd suggest you talk to JS about the pistons he did for me, raised crowns and slight dishes machined into them to allow a tight squish yet still keep the CR reasonable, at around 10.5:1 I estimate.

These pistons are still WAY lighter than stock 850 pistons.

It's what your Seeley deserves my friend...!

Click to expand...

Do you use a Maney cylinder? can you bore a 820 maney cylinder to 920 or you have to change the sleeves?
Yves

Click to expand...

Yes I used a Maney cylinder (and cases, and crank) with JS pistons and rods.

I don't know if you could bore yours out Yves but I doubt it. I'm sure Steve wouldn't charge much to fit new sleeves though.

I assume you'd have to get the crank re balanced wouldn't you Yves?

I also assume you'd have to bore out the case mouths to suit the 920 liners?

So it's a full engine strip down job.

Fast Eddie said:

I assume you'd have to get the crank re balanced wouldn't you Yves?

I also assume you'd have to bore out the case mouths to suit the 920 liners?

So it's a full engine strip down job.

Click to expand...

I will strip the engine anyway
Other options are:
Use the JS3 Smooth Ramp? maybe to hard for road use?
Ask Maney for a stage 1 or 2 on my FA head?

yves norton seeley said:

Fast Eddie said:

I assume you'd have to get the crank re balanced wouldn't you Yves?

I also assume you'd have to bore out the case mouths to suit the 920 liners?

So it's a full engine strip down job.

Click to expand...

I will strip the engine anyway
Other options are:
Use the JS3 Smooth Ramp? maybe to hard for road use?
Ask Maney for a stage 1 or 2 on my FA head?

Click to expand...

I think Maney has a different philosophy to FA. His work would basically bore out all of the good design work in the FA head I think? If I had a FA head I would either leave it alone, or send it to Sir Jim Comstock...!

What cam do you have currently Yves?

If I read the graphs correctly, a JS3 is pretty much like a 2S kinda lift profile isn't it?

Whether or not it's too much is really down to how you want to ride it I think.

Fast Eddie said:

yves norton seeley said:

Fast Eddie said:

I assume you'd have to get the crank re balanced wouldn't you Yves?

I also assume you'd have to bore out the case mouths to suit the 920 liners?

So it's a full engine strip down job.

Click to expand...

I will strip the engine anyway
Other options are:
Use the JS3 Smooth Ramp? maybe to hard for road use?
Ask Maney for a stage 1 or 2 on my FA head?

Click to expand...

I think Maney has a different philosophy to FA. His work would basically bore out all of the good design work in the FA head I think? If I had a FA head I would either leave it alone, or send it to Sir Jim Comstock...!

What cam do you have currently Yves?




If I read the graphs correctly, a JS3 is pretty much like a 2S kinda lift profile isn't it?

Whether or not it's too much is really down to how you want to ride it I think.

Click to expand...

Iuse a JS 2 cam

'Because I can' is never a good reason for doing anything. What are you going to use your bike for ? - Fast enough is good enough. With my own bike, I know from experience how much go I need to win races without sticking my neck out. And at present, it is there. If I race it and find it has not got enough go, then I will improve it. With your bike the 920cc motor might be simply a chase for more bragging rights ?

acotrel said:

'Because I can' is never a good reason for doing anything.......

Click to expand...

I gotta disagree with you on this, I think it is a great reason! Also what's wrong with bragging rights, who want to be demure.

I can see only one good reason for Yves doing this - to have a Seeley Commando which every Seeley Commando should be. However what is more important function or bragging rights ? I love his drum brakes, however I would point out that his motor is basically an 850 which puts his bike solidly into the disc brake era. It all depends on what you are trying to achieve - authenticity or functionality. I have the same problem with my Seeley Commando - the 850 motor puts it into the next historic racing period.

yves norton seeley said:

I wish to do something on my engine this winter, maybe a 920cc
Of course, like always, I wish to find some owners with good or bad experiences with 920cc

Click to expand...

I assume you have reviewed this thread:

http://www.accessnorton.com/norton-commando-land-speed-racer-update-t27583.html

You might want to PM Eldo on this forum as it is his 920 bike. He may be able to put you on to Herb Becker who is a wealth of knowledge and usually willing to help.

Fast Eddie said:

If I read the graphs correctly, a JS3 is pretty much like a 2S kinda lift profile isn't it?

Click to expand...

The JS3 (AKA D+ or Sifton 460) intake has a little more lift and duration than the Norton 2s. The 2S exhaust lobe is much smaller than the 2S intake lobe.

The Norton 7s cam is closer. It also has a smaller exhaust lobe.

Both lobes are the same (big) on the JS3. Its about the biggest practical Norton race cam except for the Sifton 480 which is an extreme cam.

jseng1 said:

Fast Eddie said:

If I read the graphs correctly, a JS3 is pretty much like a 2S kinda lift profile isn't it?

Click to expand...

The JS3 (AKA D+ or Sifton 460) intake has a little more lift and duration than the Norton 2s. The 2S exhaust lobe is much smaller than the 2S intake lobe.

The Norton 7s cam is closer. It also has a smaller exhaust lobe.

Both lobes are the same (big) on the JS3. Its about the biggest practical Norton race cam except for the Sifton 480 which is an extreme cam.

Click to expand...

Ok Jim, that does sound like a pretty extreme top end kinda cam then, and thus probably not one most folk would want on a road bike I guess.

acotrel said:

'Because I can' is never a good reason for doing anything. What are you going to use your bike for ? - Fast enough is good enough. With my own bike, I know from experience how much go I need to win races without sticking my neck out. And at present, it is there. If I race it and find it has not got enough go, then I will improve it. With your bike the 920cc motor might be simply a chase for more bragging rights ?

Click to expand...

There you go again Alan, forcing me to repeat myself here "if you've got nothing to add to this conversation, then please be quiet".

Alan, we all know that you come from the school of thought that says the standard Commando engine represents the pinnacle of internal combustion engine efficiency and performance. Perhaps even the pinnacle of human scientific / engineering achievement.

But, there are other schools of thought, some people actually see it as a 50 year old engine that was already 10 years out of date when it was new!

Some people see it as a motorbike engine that gives them some fun in life. Yves is not a racer, he has no capacity limit to work within, he can do whatever he likes. More cubes should add more grunt which should add more fun. Yves bike is for fun. So it's a perfect fit.

Well that's how I see it anyway. I have an 850 that flies and gives and honest 64rwhp. But that ain't stopping me put a 920 engine together for it! Bragging rights? I don't think so, it's just for fun, for my personal idea of fun.

But I do have another more pressing reason if I'm honest, I've got no choice you see, after all, mine is 'The Trident Hunter' and sadly, some of those pesky Tridents are a bit nippy...

Fast Eddie said:

Maybe this time next year I can give you some feedback Yves as I'm currently putting a 920 together for mine.

I'd suggest you talk to JS about the pistons he did for me, raised crowns and slight dishes machined into them to allow a tight squish yet still keep the CR reasonable, at around 10.5:1 I estimate.

These pistons are still WAY lighter than stock 850 pistons.

It's what your Seeley deserves my friend...!

Click to expand...

Here is the 81mm dished piston Fast Eddie is talking about (with tight squish band giving approx 10.5 C.R.)

acotrel said:

'Because I can' is never a good reason for doing anything. What are you going to use your bike for ? - Fast enough is good enough. With my own bike, I know from experience how much go I need to win races without sticking my neck out. And at present, it is there. If I race it and find it has not got enough go, then I will improve it. With your bike the 920cc motor might be simply a chase for more bragging rights ?

Click to expand...

Hi Acotrel,
If bragging rights means the feeling you gat when you make some changes on your engine,an you do a first test ride and you feel more power, or when you open to WOT comming out of a corner, and you feel the reaction of the bike then yes I am chasing bragging rights.
Of course I am proud of my Selley, like everyone is proud of is bike.
I know very well that there will always be a more beautifull or faster bike somewhere in the world, my goal is to own a bike that I like for is look and for is power, and the majority like what I am doing.
If bragging rights means that, when I go to an rally or classic race, that I will stand near my bike the whole day to have an erection listening to the comments from the other riders, this is no true
Persons knowing me will tell you the same thing
My own good plesure, thats the most important
Yves

Yves, your bike gives ME an erection. It is what a Seeley should be. My own engine is about 890cc and with methanol, that is fast enough for my purposes on a race track. If you are using your bike on public roads, why do you need more ? Even on petrol, when the Commandos first came out they were amongst the fastest bikes on the road, and that includes H2 Kawasaki two strokes. A Z900 was only slightly faster, but it had much more reliability. I suggest many people are trying to turn their Nortons into something they never can be. Many modern bikes will blow them into the weeds, but that is not the point of the argument. With a Commando, you are pushing the ceiling. If you do that with an R1 Yamaha or a Fireblade on public roads, the exercise becomes absurd.

Hi there,
I just receive a antsword from Maney, and he says that you can not bore a 820 Maney cylinder to 920
His proposal is to buy a Maney 920 cylinder
I am surprised that nobody give me some background about 920??
Thanks
yves

yves norton seeley said:

Hi there,
I just receive a antsword from Maney, and he says that you can not bore a 820 Maney cylinder to 920
His proposal is to buy a Maney 920 cylinder
I am surprised that nobody give me some background about 920??
Thanks
yves

Click to expand...

Hi Yves,

I have a lot of personal experience with 920s, but it's almost all on race bikes, and all with sleeved iron cylinders. Since you are looking at an alloy cylinder for street use, I didn't think my experience would be of much use to you. I have put together one 920 engine using a Maney cylinder, but it hasn't been run yet by the friend I built it for, so I don't have any feedback yet.

I've posted quite a bit here on the forum about the sleeved iron cylinder 920s I've run. If that sort of data is of interest to you, let me know, and I'll dig up the links.

Ken