Suter two stroke

Arrabbiata1 said:

Ha yeah, always a good run - particularly when approached from the Cat and Fiddle. Haven't been there for years. Last time I did in fact the police were conducted 'random' checks on exhausts, number plates and visors.

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They've done it for decades as far as I'm aware. They nicked me on the 350 outside Darley Moor for the heinous crime of not having matching engine and frame numbers. Despite me explaining the original crankcases were in the shed with holes where they shouldn't have and my v5 reflecting the change of numbers they talked crap to me and issued me with producer summons papers to their station.
The next day I popped into my local station with my papers and got a buddy who happened to work there to give them a call. After he'd bollocked them for trash talking his upstanding friend, I received a letter in the post expressing their deepest regrets and apologies.
The cat and fiddle used to be superb but now it's overcrowded with kids in cars trying to be fast.

Dr No said:

Ahh. Bless.
80s tech 2 stroke tuning. When they thought crankcase comp and a narrow pipe meant competitive power.
Still ridiculously good fun, though.

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My CR500 was tuned by an American guy called Eric Gore. You wouldn't know if he's still working would you?

Just got back from the island and the suter was awesome. what a noise , it sent shivers down my spine.
the rcv was pretty special too.
Matlock bath - I live about 2 minutes from. cops aint so bad these days the tourists are pretty dangerous mind.

yakamoto san said:

Just got back from the island and the suter was awesome. what a noise , it sent shivers down my spine.
the rcv was pretty special too.
Matlock bath - I live about 2 minutes from. cops aint so bad these days the tourists are pretty dangerous mind.

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I got back yesterday, where did you stay?

And yes the Suter made a glorious sound and smell

we sailed over in a yacht and stayed in the yacht in peel harbour.
we watched from a few places but the mitre pub at kirk micheal was a awesome view. ballercraine was also special.
loads going on in peel.
just recovering from the large amounts of alcohol.
i had bike envy all week. will ride over next year.

yamfan said:

They've done it for decades as far as I'm aware. They nicked me on the 350 outside Darley Moor for the heinous crime of not having matching engine and frame numbers. Despite me explaining the original crankcases were in the shed with holes where they shouldn't have and my v5 reflecting the change of numbers they talked crap to me and issued me with producer summons papers to their station.
The next day I popped into my local station with my papers and got a buddy who happened to work there to give them a call. After he'd bollocked them for trash talking his upstanding friend, I received a letter in the post expressing their deepest regrets and apologies.
The cat and fiddle used to be superb but now it's overcrowded with kids in cars trying to be fast.

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Excellent stuff Yam and Arabb.

yamfan said:

My CR500 was tuned by an American guy called Eric Gore. You wouldn't know if he's still working would you?

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Did Gore used to run a website back in the Web 1.0 days?
That and some of Ed Sorbo(?) stuff is all I know if US tuners. Oh and the articles they used to run on RS125s in RRW

Dr No said:

Did Gore used to run a website back in the Web 1.0 days?

That and some of Ed Sorbo(?) stuff is all I know if US tuners. Oh and the articles they used to run on RS125s in RRW

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I don't know much about the guy myself, except when I was racing Supermoto in the late 90s, a mate sent a barrel and head to him for tuning as he'd researched him and was convinced he'd do the best job.
Just before it came back he was offered a works ccm as they wanted to get into the sport as there were only about four 4stroke bikes in the whole British Championship. He took the deal (crazy not to LOL) and gave me first refusal on the CR500 parts.
I snapped them up and "wow" the barrel was relined and bored to 540 odd cc, ported and came with a forged wiseco piston, rings, small end bearings, the lot. The head was skimmed and reprofiled too. It came with all the paperwork and the guy had even engraved his name on the barrel too.
I put it together and ran it in and it was fast, the digital speedo I'd fitted (a decent accurate one not a cheapo thing) indicated it was pulling nearly 140 mph on tall gearing. It's torquey but has an almighty kick when the real power kicks in, if you're not pointing forward when it happens it'll spit you straight off, especially on the dirt.
Great fun though, Eric Gore gets my approval LOL
I'd swap it for the Suter though LOL

Serious question...does anyone think GP would be more interesting or less interesting if they went back to 500cc 2-strokes? Or is the current engine formula more than adequate? I know the electronics would have a huge impact on a modern 2-stroke for rideability, but I wonder if they would still be more fun to watch.

It's a good question matey, but I'd say a difficult one to answer. There are too many variables now, electronic advancement as you say, tyre advancement too. Fuelling would certainly be electronically injected, with sensors for everything just about killing off the black art of setting up carburettors on strokers in different climates.
There are also the cases of riders adapting although most of the top guys cut their teeth on strokers.
Cue the "Vale would win easily, blah blah blah" LOL

yamfan said:

It's a good question matey, but I'd say a difficult one to answer. There are too many variables now, electronic advancement as you say, tyre advancement too. Fuelling would certainly be electronically injected, with sensors for everything just about killing off the black art of setting up carburettors on strokers in different climates.
There are also the cases of riders adapting although most of the top guys cut their teeth on strokers.
Cue the "Vale would win easily, blah blah blah" LOL

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Good points.

I really don't know much about the 2-stroke GP bikes at large. Was wondering if you could answer this, why is/was the exhaust piping design the way it was on the 2-strokes rather than the way it is on a 4-stroke?

Complicated but basically back pressure.

JPSLotus said:

Good points.

I really don't know much about the 2-stroke GP bikes at large. Was wondering if you could answer this, why is/was the exhaust piping design the way it was on the 2-strokes rather than the way it is on a 4-stroke?

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Good question.... I love two strokes!! Personally I really enjoyed watching the mixture when two strokes were racing with the four strokes for a short period when MotoGP switched in 2002. And if they had continued developing the 500 it would be as good as a modern four stroke MotoGP I reckon

I could talk two stroke all day cos I'm sad, but two strokes expansion chamber design is an art. From what I know It's to do with back pressure from the sound waves produced from the engine. The length of the chamber is critical to the power band width and the varying diameter and where the diameter varies alters the pressure. at the exhaust port from the engine the diameter is smaller so spent gases come out of the engine quicker, when the diameter increases, the pressure drops and exhaust gases slow up. when the engine sucks to draw in fuel/oil and air it also pulls some of the exhaust gases back into the cylinder, boosting pressure and power.

MZ discovered the benefits of expansion chamber design I think.

I made an expansion chamber once for my mate's 100cc Kawasaki Aggy Bike. We got the formulae out of a dirt bike magazine. The idea is to accelerate the exhaust gasses during the time that the fuel air mixture is drawn into the engine - actually drawing it into the header of the exhaust pipe as well as the combustion chamber - and then to push it all back into the combustion chamber, just before the piston blocks the exhaust port, to maximise the mass of mixture induced.
This is achieved by the geometry of the expansion chamber, the basic configuration is: header pipe, diffuser cone, baffle cone, tail pipe.
The diffuser cone creates a negative pressure wave to draw the mixture in and the baffle cone produces a positive pressure wave to reverse the flow of the gasses to push mixture back into the combustion chamber.
The timing of all this is a function of the gas velocity, which I guess is more or less constant and the stroke timing, which is of course determined by the RPM. The timing of the negative and positive pressure waves, as determined by the geometry of the exhaust system, is therefore only optimal for a narrow band of RPM and this is the reason two strokes have a so called power band.

JPSLotus said:

Good points.

I really don't know much about the 2-stroke GP bikes at large. Was wondering if you could answer this, why is/was the exhaust piping design the way it was on the 2-strokes rather than the way it is on a 4-stroke?

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https://en.m.wikipedia.org/wiki/Expansion_chamber

povol said:

https://en.m.wikipedia.org/wiki/Expansion_chamber

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Not a bad wiki. The animation is good.

Kaaden rightly gets a lot of credit for the spanny, but DKW were running them on their V3 in 1951. Amazing bit of kit

Richy56 said:

Good question.... I love two strokes!! Personally I really enjoyed watching the mixture when two strokes were racing with the four strokes for a short period when MotoGP switched in 2002. And if they had continued developing the 500 it would be as good as a modern four stroke MotoGP I reckon

I could talk two stroke all day cos I'm sad, but two strokes expansion chamber design is an art. From what I know It's to do with back pressure from the sound waves produced from the engine. The length of the chamber is critical to the power band width and the varying diameter and where the diameter varies alters the pressure. at the exhaust port from the engine the diameter is smaller so spent gases come out of the engine quicker, when the diameter increases, the pressure drops and exhaust gases slow up. when the engine sucks to draw in fuel/oil and air it also pulls some of the exhaust gases back into the cylinder, boosting pressure and power.

MZ discovered the benefits of expansion chamber design I think.

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As another 2 stroke nerd, I have to clarify some of this (sorry). It's not just sound waves. It's better thought of as pressure waves carrying a mass flow. Which makes things interesting. Much easier to bounce air back and forth, but the mass of fuel also needs consideration. Which is where is gets difficult.
Not to mention that the speed of the gas depends on the temp in the pipe....so a hot pipe is "shorter"...
Such a "simple" engine...yet so much to consider.

Thanks guys...that is so fascinating the way acoustic waves are used for benefit in a 2-stroke bike engine. Thanks for linking to the diagram povol.

JPSLotus said:

Thanks guys...that is so fascinating the way acoustic waves are used for benefit in a 2-stroke bike engine. Thanks for linking to the diagram povol.

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Simple engine that took a lot of knowledge and practice to learn how to tune. Like someone said earlier, it really is/was a black art. the slightest change in humidity, elevation, temp, etc would have big affects on their performance. Very finicky. I watched a tuner at VIR dynoing tuning 125's for race teams and it was amazing how much more power he could extract from those engines that were already race tuned by another. He was finding 2-3 hp on just about every bike that i watched him tune.