TV175 S3 piston options

[Pompeydave]

Hi all, bought a ‘64 TV175 Azzuro Blue restoration project at the IOW and I’m keeping it as is and just replacing worn out parts to preserve the patina. Accordingly, the engine is 6v running on points and a full rebuild is nearly done. Found that the sixth oversize 63.2 piston is Rota flavour, with the crappy brass pegs and sure enough the top peg is missing. Sticky’s book suggests that for this reason they’re not a good make to use but I’m struggling to find a good 63.2 replacement made by either Asso, Vertex, Borgo, Hepolite or Mahle.

Rimini have got a NOS Borgo three ring version at 63.4 and 63.6 but I’d have to rebore the cylinder of course. Any opinions out there re my options? I can get an Indian ‘Diamond’ piston at 63.2 but I’m a bit suspicious of the quality.

[Storkfoot]

Is this the piston you have?



I have never used this but it looks ok for a standard engine.

On my standard TV175, I used an Indian GOL piston from CamLam. I’ve not done high miles on it but it has been fine. It wasn’t as oversize as 63.2 though.

If you go for a rebore to 64, you could go for a Suzuki Ts185Er piston but then you are looking at a cylinder head reprofile and a small packer.

[Pompeydave]

No I’ve just got the standard piston which is knackered. Didn’t realise GOL were Indian. Trying to avoid Indian or the TS185 as I want to keep it as standard as possible.

[Storkfoot]

No I’ve just got the standard piston which is knackered. Didn’t realise GOL were Indian. Trying to avoid Indian or the TS185 as I want to keep it as standard as possible.

Just searched GOL. It seems they are Italian

[Pompeydave]

Yeah, I thought they’d be ok but Sticky’s book says avoid

[Fast n Furious]

If they are still manufactured to the same 1960's spec, then they will be just as crap today as they used to be.
If memory serves...... they had very poor coefficient of expansion and would readily seize.

[Pompeydave]

Hmmm, so I could eventually find the right Borgo NOS piston (Rimini have them but they want €120 plus postage) and it will still be pretty useless. Could I use a 64mm Wossner TS185ER without any head modifications? I.E. just a 2mm base packer or a 3mm base packer and just thin paper head gaskets? Either way would the head still need reprofiling?

I notice also that the Wossner TS185ER version doesn’t have a window in it as the standard TV175 has, it’s an open skirt- would that be a deal breaker for a TV175 barrel? Have seen an open skirt piston being used on Storkfoot’s ‘What to do with this TV175 engine’ thread, so I assume it will be ok?

[lofty]

I used a TS185 piston for some time with a regular TV175 head, it performed fine, I later used a head with the correct profile and performance/reliability were not noticeably different.

regarding skirt, for a standard barrel you will need to ensure a full skirt (no reed windows) as its piston ported, I think most, if not all, TS185's were piston ported anyway..

[Pompeydave]

Ok thanks lofty. I’ve emailed Wiseco to ask if their TS185 piston will foul a TV175 barrel and they’ve come back with the following ring position info:

‘The piston we offer for the TS185 is pinned 14.986mm to the left on the top pin and 14.986mm to the right on the bottom pin’.

Can anyone tell offhand from those figures whether it will foul the ports?

[Fast n Furious]

The transfer port apertures are located about 25mm offset from the piston centre line. So no problem here.
The top of the inlet port is about 11.5mm down from the bottom of the exhaust port. With the right thickness aluminium base packer, the 2nd ring shouldn't fall into the inlet port.
IMD pistons make a cast version of the TS185 and typically cost less than £50 on fleabay. These pistons are ok although the rings are known to be a bit soft but that could just be because they get run on 2% oil istead of 4%.
Recommend 3 thou piston to bore clearance and 10 thou ring gap.

[Pompeydave]

Thanks, I’ve seen the IMD version but I prefer a forged piston.

[Storkfoot]

For your information, the TS185ER piston that I bought from IMD was produced by TKJR, a Japanese company. These pistons are less than half the price of the Wossner. If I was building an engine that revved hard and was to be ridden hard, I may well go with the Wossner. But, a standard TV

The reprofiling of the cylinder head. This does not cost much. I’m unsure why you would not get this done when you are altering the dome of the piston. If you use a 150 cylinder head, you can save the TV175 cylinder head should you ever go back to the standard dome piston.

[Pompeydave]

Yeah I realise that going for a forged piston in a largely standard TV175 is overkill but I just don’t want to risk a lockup if I give it the full beans. I do a lot of long distance nationals from Pompey (Kelso on a Quattrini equipped GP for example) and it’s no fun being sat by the side of the road wishing you’d spent a bit more on quality parts. Forged is always going to be better than cast.

Re the head, I’m wondering if I can use a centre bowl 125 head and just machine it out to keep the CR down?

[Pompeydave]

Actually, having thought a bit more about this I think the cast TKRJ piston is good enough. I’m not building a highly tuned engine. Just found one on eBay for £33. Ordered.

I’ll need a 2mm base packer I believe?

Any thoughts on using the centre bowl 125 head please?

[alex_hughes]

A little late since you’ve ordered a piston but for the record, the Suzuki piston required is TS185E. It has pegs in the correct location. The TS185 has pegs in the wrong location.

The TS185E also has recesses in the side where the gudgeon pin fits so easy to identify.

I’d recommend reshaping the head. MB can do this. Harry Barlow did mine but he’s off shortly.

It’s still possible to get original Suzuki pistons for low prices. EBay or Robinsons my usual suppliers

[Pompeydave]

TS185ER is the piston I’ve ordered so it’s the correct one.

[Storkfoot]

The transfer port apertures are located about 25mm offset from the piston centre line. So no problem here.
The top of the inlet port is about 11.5mm down from the bottom of the exhaust port. With the right thickness aluminium base packer, the 2nd ring shouldn't fall into the inlet port.
IMD pistons make a cast version of the TS185 and typically cost less than £50 on fleabay. These pistons are ok although the rings are known to be a bit soft but that could just be because they get run on 2% oil istead of 4%.
Recommend 3 thou piston to bore clearance and 10 thou ring gap.

I have a 3mm packer and the rings are not visible in the inlet port. I can check this as the engine remains on the bench.

[Pompeydave]

Great, many thanks Storkfoot.