Scooterotica

I'm attempting to build a budget engine for myself out of a GP125 motor, since i have an old TV175 barrel and TS185 pistons are cheaper than asso ones, i'm going to build a suzuki conversion on a long rod.
Questions:
What is the correct clearance in mm for this piston in a cast cylinder?

Has anyone got the webster port heights (or other relevant porting advice) in mm from top of cylinder to top of port for this conversion?

Anyone got an already converted head for sale for this conversion? PM me!

I'm sure there will be more questions as i get into this project.

Cheers John

done just that with a TV175 cylinder and a TS185. Ran mine at 3 thou clearance (Old money)- loads of short sharp runs on running in for 500 miles. No nip ups and no rattles. Running very well indeed.

Good Luck

Chris

Agree with the clearance reccomendation of 3 thou (0.075mm).


Webster does not provide any heights for this conversion (only the short barrel 107 rod)

The TS185 short version has a 170 degree exhaust duration, 130 transfer 165 inlet.

His Kawazaki H2 230 (same 32mm Compression Height as the TS 185 piston) has 170 degree exhaust, 120 transfer and 165 inlet

This uses height above port: exhaust 37mm, transfer 47mm inlet 70mm. with a std 68mm piston skirt and 116mm rod.

I think you can reduce the extreme inlet timing a bit with the skirt length.

Hope this helps a bit (probably not)

I have a SR 190 barrel tuned by Harry Barlow along with a TS185 piston which he's trimmed the skirt on the inlet side and cut in a slot to work with the mugello style boost port that he's carved in the barrel. It's all been done to work with a TV rodded GP crank and is currently on the bench so I could take some measurements for you if you'd find them useful.

I concur 3-3.5 thou Nowt Less !!!!

Agreed.

Stokie (You're obviously not 'Vale' then). That skirt measurement would be a good help for John if you can post it.

Podolski's shot deflected of Cameron was obviously an 'off-side' decision, missed again by another 'super-club' hounded ref! (thought i would just sneak that in)

Cheers if u can do that with the skirt length!

Well if you're going to start talking about the football and dare to mention the 'V' word then you can forget the f@@king measurements.

Cheers for the replies so far!
so 0.075mm clearance.
If you could measure up the port heights for me stokie that would be great, also the piston skirt measurment would be good. Since i'm doing this one myself and its a cast cylinder i doubt i'll be cutting a boost port into the cylinder wall though!
Port heights on the standard barrel are:
exhaust : 41mm - top, 60mm - Bottom
Transfer : 47mm - top, 60mm - Bottom
Inlet: 75mm - Top, 93mm - Bottom. (these are approx measurements using a vernier caliper)

One more question:
I have the minimum of porting tools and since this will be my first real attempt at porting a cast cylinder, am i right in thinking it is better to use the long rod and packers and gaskets to get my desired transfer timing, then use the length of the piston skirt to get the inlet timing close to what i want and then only have to port the exhaust port? Getting to grips with the transfer angles and doing much more than flowing the inlet will have to wait until i find something ally to play with.
I'm chasing a mild tune that will work well with an old school expansion (scootRS/PM type) and a small carb 24/26mm.

"work well" = any improvement over a 175 conversion with satisfaction that i did it myself.

johnd wrote:Cheers for the replies so far!
so 0.075mm clearance.
If you could measure up the port heights for me stokie that would be great, also the piston skirt measurment would be good. Since i'm doing this one myself and its a cast cylinder i doubt i'll be cutting a boost port into the cylinder wall though!
Port heights on the standard barrel are:
exhaust : 41mm - top, 60mm - Bottom
Transfer : 47mm - top, 60mm - Bottom
Inlet: 75mm - Top, 93mm - Bottom. (these are approx measurements using a vernier caliper)

Just messin' about the football, I don't follow it at all, the closest I got to supporting Stoke was working with some N40 lads on the door of the Freetown Club in 1990 / 91.
Yanker - are you local to me? I saw you mentioned the Wheatsheaf in another thread.

I made a port map and according to my steel rule and £1 reading glasses the measurements are;

Ex 37mm from top of port to top of barrel. 60mm from bottom of port to top of barrel.
Trans 44mm / 60mm
Inlet 71mm / 93mm

I'll nip out and measure the piston in a bit.