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I am piecing together parts to build this engine. It won’t be anything sporty. I’ll be happy with something approaching standard 200 performance. Will be using a standard exhaust, 22 or 24mm carb through airbox, Indian webs with 115mm RD 400 conrod, Suzuki piston, possibly a GT Porcupine head as a concession to increased cooling.

My question is which barrel to use. Somewhere in the garage, I have a few Innocenti 150 barrels including an SX and GP. I’d like to use one of these if I am honest and I know many a successful 150 barrel has been used on this conversion. However, I also have an Indian 175 conversion barrel.

I am not looking to buy another barrel, just use what I have.

Thoughts or experiences gratefully received.

How do you get to 190cc with a 150 barrel as a matter of interest? is it achieved by increasing the bore or stroking or both?

coaster wrote:How do you get to 190cc with a 150 barrel as a matter of interest? is it achieved by increasing the bore or stroking or both?

Bore, hence my question, mate.

Hi Paul

I think a great basis for this conversion would be a Tv 175 barrel which would work great with the long rod.

I know you have stated you don't want to buy another barrel but that would be my route personally.

The best of luck.

The barrel will bore ok. GP 150 or original TV175.
In the 60's I built a few 200's by boring out to 66mm and fitting SX200 pistons. They were thin barrel walls but they worked OK. Rafferty Newman and others offered this as a conversion rebore.
190 is less than 65mm.
Not too long ago I sold a barrel taken out to 200 and it's still out there running.

Cgt75b wrote:Hi Paul

I think a great basis for this conversion would be a Tv 175 barrel which would work great with the long rod.

I know you have stated you don't want to buy another barrel but that would be my route personally.

The best of luck.

I don’t see many TV barrels for sale but, yes, I know what you’re saying, Paddy.

CHRIS in MARGATE wrote:The barrel will bore ok. GP 150 or original TV175.
In the 60's I built a few 200's by boring out to 66mm and fitting SX200 pistons. They were thin barrel walls but they worked OK. Rafferty Newman and others offered this as a conversion rebore.
190 is less than 65mm.
Not too long ago I sold a barrel taken out to 200 and it's still out there running.

This is what I want to hear. I like to re-use stuff, particularly original stuff, like an Italian GP cylinder.

Part of me thinks the Indian 175 conversion barrel might be best, however, somewhere in the back of my mind, I think they might be more likely to seize compared to an original 150 Innocenti barrel ?? Metallurgy ??

I was under the impression that cast Indian barrels were particularly hard. More likely to do with the tolerances and hit and miss production. I wouldn't have thought it would be a problem if you have it bored to a good standard.

I'm thinking about this conversion at moment for a small block i have doing nothing - was looking at using a SIL 150 barrel or the SR 175 barrel so can bore it correctly to match the piston, it states that the layout is based on a TV.

Got an AF crank with RB116 rod and was looking to use a 26mm phbh and a clubman.

I've got some facts and figures collected on this conversion - will post them when I dig them out.

definitely go for a longer rod rather than top/tail a barrel..

SR alloy barrels work very well, but need the porting fettled..

if using a cast barrel I would look for the one with the biggest transfers, and do some porting to match the manifolds, maybe open exhaust/inlet a bit (old fashioned stage 4)..

I have SR barrel, 65mm Suzuki piston, TV crank, 24mm jetex, clubman.. and its a really comfortable motor to drive and has good performance..

Scooter restorations have some of their SR175 barrels in stock for only £70....

Do any of you remember the 190 thread on the old (pre-crash) forum initiated by Little Ern? That was a classic, old-school tuning thread that taught me what little I know.

Still, nostalgia ain't what it used to be.

found some notes I made, not much but.....

1. Barrel
Either Standard 150 GP, SR 175 alloy or TV175
Use SR barrel and bore to suit piston

2. Crank
58x107 – will need barrel top and tailing
58x115 (Yam) – will need 2mm base packer on standard length barrel
58x116 (TV/RB) - will need 1mm base packer on standard length barrel

3. Piston
Suzuki TS185 ERN 64mm – needs skirt shortening to match standard Lambretta
Reprofile 150 head to suit piston crown

Just trying to get my head round this as I've got most of the parts
Just 30 years behind everybody .
Would a standard crank with a 64 mm 39mm crown height piston work in an original sr 190 barrel?

Also I remember reading the linings were soft and wore badly ??

lofty wrote:definitely go for a longer rod rather than top/tail a barrel..

SR alloy barrels work very well, but need the porting fettled..

if using a cast barrel I would look for the one with the biggest transfers, and do some porting to match the manifolds, maybe open exhaust/inlet a bit (old fashioned stage 4)..

I have SR barrel, 65mm Suzuki piston, TV crank, 24mm jetex, clubman.. and its a really comfortable motor to drive and has good performance..

I did see that SR still have some barrels but, from my experience, they do wear out quite quickly and, as you say, need quite a bit of porting to get a smooth torquey engine.

ToBoldlyGo wrote:I was under the impression that cast Indian barrels were particularly hard. More likely to do with the tolerances and hit and miss production. I wouldn't have thought it would be a problem if you have it bored to a good standard.

Thanks for that. I’ll dig the barrels out and have a look at the porting to compare the Indian one to the Italian SX and GP.

Knowledge wrote:Do any of you remember the 190 thread on the old (pre-crash) forum initiated by Little Ern? That was a classic, old-school tuning thread that taught me what little I know.

Still, nostalgia ain't what it used to be.

Yes, I do remember that, also that some versions of the TS185 pistons have a ring peg over one of the ports. I’ll take the barrel with me when I buy the piston just to check

Hi Storkfoot,ive done a couple of different 190 barrels using the ts185 erx piston....i personally wouldnt use any indian 175 barrels,the ones ive tried to set up for friends caused nothing but trouble in 175 format,ideally a tv barrel is best but ive only used italian 150 barrels...
Ive also used a yam 115 rod on a gp crank...
One barrel uses a mitaka 64mm piston..the other ive used a khc 65mm piston which ive converted to reedvalve,non of the pistons had any issues with peg positions
My biggest issue has been with compressions,i reprofiled a 150 head and even altering the combustion area i had issues,altho my exhaust port was very low
Using the same head on the reed barrel with a much taller exhaust port lowered the compression to make kicking it over much better.

Storkfoot wrote:
Yes, I do remember that, also that some versions of the TS185 pistons have a ring peg over one of the ports. I’ll take the barrel with me when I buy the piston just to check

Hi Paul,

Best to go with the TS185ER pistons, as the ring pegs are further apart and therefore don't foul the inlet.

Somewhere I have some genuine NOS Suzuki pistons. I'll have a look and see if there is anything worth having at 64mm. I fear they may be over-sizes.

My current conversion of an SR barrel features a reed valve. The YPVS 350 piston and over-sizes are ideal.

Knowledge wrote:

Storkfoot wrote:
Yes, I do remember that, also that some versions of the TS185 pistons have a ring peg over one of the ports. I’ll take the barrel with me when I buy the piston just to check

Hi Paul,

Best to go with the TS185ER pistons, as the ring pegs are further apart and therefore don't foul the inlet.

Somewhere I have some genuine NOS Suzuki pistons. I'll have a look and see if there is anything worth having at 64mm. I fear they may be over-sizes.

My current conversion of an SR barrel features a reed valve. The YPVS 350 piston and over-sizes are ideal.

Thanks, Martin. Grampian only seem to list the ER version, well they do in the Mitaka :

MODEL BORE CROWN OVERALL DOME G.P. PORT RING PEG CUTOUT COMMENT
SIZE HEIGHT LENGTH HEIGHT DIA Y/N POSITION HEIGHT

TS185ER 64.00 24.50 70.00 4.00 16 N 14.50 0
TS185