Long stroke 150?

[Scooterslag]

Just a random thought while I was at work (my jobs pretty boring ) I've often wondered why innocenti didn't carry on making engines with a longer stroke crank after the TV175, its a great engine, lovely power delivery, silky smooth etc Recently I've come across a couple of TV175 cranks for half decent coin on ebay and thought how about making a long stoke 150 using the TV crank, packer and GP150 top end (Italian though the Indian GP barrel has a crap port layout and less power) What would be required? would the piston need to be shortened? compression ration changed? like I said before its just a random thought though I do like the idea of a smoother 150 engine. Paul

[rossclark]

The stroke is still 57mm it's the rod and the crown height of the piston that's different for the 175 crank.

You would need about a 9mm packer or find a piston with a crown height that matched that of the TV piston

[Eden]

58*

Typo

[rossclark]

The stroke is still 58mm it's the rod and the crown height of the piston that's different for the 175 crank.

You would need about a 8mm packer or find a piston with a crown height that matched that of the TV piston

Corrected

Apologies, mixing my strokes (been playing with the other marque)

[Scooterslag]

cheers for the replies, Paul

[Adam_Winstone]

TV Series 1 was 60mm stroke... so the question still stands.

[rossclark]

Hmm, but would the crank fit?

[Warkton Tornado No.1]

I don't doubt that a crank with a stroke of up to 62 mm could fit & with a bore of, say Ø57 mm, utilising the transfer port area (@ the deck) available you could end up with a powerful, strong motor. Ultimately, a sleeved down large block cylinder would reap the best rewards.

I've said before that undersquare is the way to go with two strokes, as proven by MX bikes that have that format.

[Scooterslag]

TV Series 1 was 60mm stroke... so the question still stands.

ah didn't know that Adam, hmmm... yeah could it be done?

[Scooterslag]

I don't doubt that a crank with a stroke of up to 62 mm could fit & with a bore of, say Ø57 mm, utilising the transfer port area (@ the deck) available you could end up with a powerful, strong motor. Ultimately, a sleeved down large block cylinder would reap the best rewards.

I've said before that undersquare is the way to go with two strokes, as proven by MX bikes that have that format.

Very interesting, I've only got a smallblock case/cylinder so that would have to do. Paul

[Warkton Tornado No.1]

If your case is later Spanish it will have the larger transfer external area as per their 200 blocks.

Now, that likely configuration with ample meat on the cylinder walls probably would enable safe ditching of the fan. Refer to the 'debate' elsewhere! Ha!

BTW. The 175's were very smooth, IMO.

[Scooterslag]

If your case is later Spanish it will have the larger transfer external area as per their 200 blocks.

Now, that likely configuration with ample meat on the cylinder walls probably would enable safe ditching of the fan. Refer to the 'debate' elsewhere! Ha!

BTW. The 175's were very smooth, IMO.

Its a LI150S case, I'd probably keep the fan (belts and braces and all that ) yeah just love the TV175 engine- so lovely to ride

[Adam_Winstone]

My pal's mild tune RS Suzuki 185 with full length barrel + packer + 116 rod (58mm stroke) was a dream to ride and considerably faster than some of my bigger cc engines and this has played on my mind ever since. I've little doubt that the 116 rod helped it to be so nice to ride.

Adam

[dscscotty]

Back in my old group 3 racing days-Gary Bicknell (Leeds-Central/Chiselspeed) ran a 60x57-bore, this was a very quick 150 and went against the grain as the norm was 54x60bore, very fast chiselspeed tuned 150.

[Scooterlam]

on this subject, I have in my shed a barrel I got off a mate some years back.
apparently a race engine (aren't they all).
It came with a 60mm crank complete with alloy web stuffers, the piston is 30mm from center of pin to edge of the crown has 1mm rings and seems a quality light item , the barrel is topped and has a 4mm base packer, it looks like it was a barrel that warranted a bit of work as a fin has been broken and welded back. the head has been dowelled the porting is tidy.
the bore is 60mm so it makes it that mythical "Square" engine.
any thoughts how this ought to go. the exhaust port looks tall and not wide (possibly bottom taken out to give flush to piston face at Bdc.

really appreciate your thoughts

just done calcs and volume is 170cc, was there ever a class for this.

[dscscotty]

Hi there, 170cc would have exceeded the cc limit for 150/standards/specials. I doubt it would be a race barrel as the cc would be to high for 150 classes and would give away a lot of cc's for 200 class. Kawasaki KH500 piston start @ bore size 60mm.

[Warkton Tornado No.1]

I think an actual, real 'Vince' (not the person that has adopted Vince as a pseudonym) that raced Group Five for LLRT under Dave Websters guidance used a sleeved down TS1 barrel with a longer stroke than normally ascociated with 150's

People would often confuse a short stroke engine's ability to pick up & rev freely with it's ability to provide torque, which is what you want in huge spadefuls!

[Captain Pugwash]

Mick White ran a short stroke crank on a KH500 piston in the Dave Webster built & tuned 150 special. Around 1986-87 I think it was.
I can still remember when we were at a race track somewhere up in Cumbria where Mick showed us three different Dave Webster tuned barrels for use on his race bike, one I remember had a bridged exhaust port, but all three were for use with a KH 500 piston on a 54mm stroke.
Each barrel different from the other, all sleeved down 200 barrels, but they were all very well ported.

Mick White was a very good rider on a very quick group 5 scooter.

[dscscotty]

Ponderosa was the track near Carlisle, I briefly ran a group 5 using TS1 sleeved to 60mm bore-KH500 X 54mm Stroke-very quick scooter, passed about our club (DSC) for a few years.

[Wack]

Vince Smith was the MSC rider and looking thru my old programs he's listed as riding a 133cc and a 145cc. I know it was a quick bike as we often had a tussle on track.