Scooterotica

Compression height on a TS185 piston is 30mm so it will go straight onto a TV rodded crank.
It's an easy conversion.

Ian Hepworth wrote:Compression height on a TS185 piston is 30mm so it will go straight onto a TV rodded crank.
It's an easy conversion.

Have deleted my previous posts, as I must be mistaken... Please ignore my previous posts as my piston measurements were from memory, which I assumed were right... Ian will most probably have more up to date info... my memory must be worse than I thought... Sorry
Just checked in Websters tuning manual... TS 185 = 32mm compression height... and in Scooterotica tech info = 24.5 crown to gudgeon pin... so 32.5 by that... So It looks like I was wrong ... but the TV rod is 9 mm different the piston only 7mm..

Its probably easier to do a dry run build of your top end components and then it'll become obvious what size packer if any you require..........as Ian says you might not need any. BUT casings vary in gasket face height and you might want to alter your port timings with the use of a packer to suit your desired engine characteristics. You may also want to add a boost port (like the Mugello kits) or even increase your inlet timing by cutting your piston skirt - all easier with a dry build.
These sort of conversions have always appealled to me, probably because they require slightly more than just bolting on a kit or an oversize piston......maybe because its that the Lambretta can offer you a cheaper, better alternative if you just get to grips with it a tad more, which is why they were made in the first place.......it could well just be the fiddle factor....
Maybe post your work here, bit by bit - with all port timing info etc?? Or could this turn into Little Erns monster all over again?

Its nearly 10 years since I did one of these Suzuki barrels... But I have done a couple of Yam pistons lately which are 30mm compression height these do fit onto a TV rod like the Yamaha blaster piston fitted to the RB20...

Ian Hepworth wrote:Compression height on a TS185 piston is 30mm so it will go straight onto a TV rodded crank.
It's an easy conversion.

J1MS wrote:

Ian Hepworth wrote:Compression height on a TS185 piston is 30mm so it will go straight onto a TV rodded crank.
It's an easy conversion.

Have deleted my previous posts, as I must be mistaken... Please ignore my previous posts as my piston measurements were from memory, which I assumed were right... Ian will most probably have more up to date info... my memory must be worse than I thought... Sorry
Just checked in Websters tuning manual... TS 185 = 32mm compression height... and in Scooterotica tech info = 24.5 crown to gudgeon pin... so 32.5 by that... So It looks like I was wrong ... but the TV rod is 9 mm different the piston only 7mm..

Alright, I have the Wiseco ts piston in my hand. 32.5 from the middle of the wrist pin(gudgeon pin), which is deck height. Ian, where did you get the 30mm measurement from?
so, 39-32.5=6.5mm piston difference
116-107= 9mm rod difference
9-6.5=2.5 packer needed
How can it just drop straight in Ian? I hope it can. I've already got way too much unbillable time into this scoot... a coupla' extra base gaskets is easy.
Anyone else got any different measurement to add to the confusion? :biggrin:


addendum- I am familiar with the Kwacka jet ski/rd rod conversion Jims, done it a few times now with great succuess.

come to think of it it's 32mm, not sure. been looking at numbers all day.

The best way I think to do the packing is measure in degrees what transfer timings you want as this is wher its hardest to alter later adjust the height of the barrel to suit then rmove whats needed off the top to bring the deck height back to correct need about 1.2mm piston to head clearance thats how I did mine but its been a while and all barrels are a little different in height so there is no definite amount to remove just aproximates... Sorry for confusion and thanks Ian for putting me right as I was convinced it was 34mm... Bad memory once you get past.... erm... forgot ...

Thanks everyone, will let you know what happens.

Well, it's about done.
Didn't really do much porting as such, except on the exhaust where I widened it a couple mm. Just flowed and matched to casings. Made a packing plate from a road sign. 1.43 sqiush
First to be needing attention was the clutch. Had some funky TDC? clutch plates that were already with the motor and were new, so I used them, but slip city. So, surflex's and yammy springs, sorted.
Only prob I seem to be having now is a little blowback at idle, coming out of the brass orifice hole at front of carb, depositing a little fuel in the bellows giving a tiny stutter when taking off from idle. 50 pilot fitted/20mm carb/KBA big bore.. Same scenario on two different carbs.
Is this something worth trying to fix with altered jetting, or is it happening because of how long the piston clears the inlet port going up to TDC and back again. Skirt of piston clears port by a good 6mm at TDC.
Other than this issue, it feels as strong as any 200 I have ridden or built and pulls the TV gearing easily.
Cheers for all the helps and advices

dirtyhandslopez wrote:Well, it's about done.
Didn't really do much porting as such, except on the exhaust where I widened it a couple mm. Just flowed and matched to casings. Made a packing plate from a road sign. 1.43 sqiush
First to be needing attention was the clutch. Had some funky TDC? clutch plates that were already with the motor and were new, so I used them, but slip city. So, surflex's and yammy springs, sorted.
Only prob I seem to be having now is a little blowback at idle, coming out of the brass orifice hole at front of carb, depositing a little fuel in the bellows giving a tiny stutter when taking off from idle. 50 pilot fitted/20mm carb/KBA big bore.. Same scenario on two different carbs.
Is this something worth trying to fix with altered jetting, or is it happening because of how long the piston clears the inlet port going up to TDC and back again. Skirt of piston clears port by a good 6mm at TDC.
Other than this issue, it feels as strong as any 200 I have ridden or built and pulls the TV gearing easily.
Cheers for all the helps and advices

Hello mate, nice to hear its running...