Scooterotica

Hi, I wish to tweak my GP150 iron barrel, firstly increasing bore size to 175cc and following this a guide for the porting;
http://drunkmunkey6969.googlepages.com/ ... nceporting

Can anyone offer more info or tips, experiences?

cheers

red ghost wrote:Hi, I wish to tweak my GP150 iron barrel, firstly increasing bore size to 175cc and following this a guide for the porting;
http://drunkmunkey6969.googlepages.com/ ... nceporting

Can anyone offer more info or tips, experiences?

cheers

Wouldn't a Mugello 186 make more sense?

With the Iron cylinder you need to factor in the price of the rebore, piston, head machining and time involved grinding it out against a spanking new alloy kit...........

Avantone wrote:

red ghost wrote:Hi, I wish to tweak my GP150 iron barrel, firstly increasing bore size to 175cc and following this a guide for the porting;
http://drunkmunkey6969.googlepages.com/ ... nceporting

Can anyone offer more info or tips, experiences?

cheers

Wouldn't a Mugello 186 make more sense?

With the Iron cylinder you need to factor in the price of the rebore, piston, head machining and time involved grinding it out against a spanking new alloy kit...........

I hear what you're saying, but I can do all the work myself, 10 yrs of engine reconditioning..

I will go for an alloy kit when the economy picks up,as I live in Australia the cost of shipping bites,hard

So at the mo I'm on a budget.

I appreciate what you're saying.

It would be worth finding out the actual port timings to back up the measurements, but be aware the bottle-neck in this setup is the transfer port windows themselves (the timing and sizes are unchanged - the Mugello gives way more timed area).

Tony

I ran a MB stage 4 tuned 175 conversion in my GP150 - with a 30mm PHBH and clubman.
Nice rideable motor on the stock Italian gearbox & sprockets - decent performance gain in all areas over the 150.
I've got a port map somewhere I think - I could scan it and email it if you want?

i done 1 of these with a 62mm asso piston (2 thin rings) and the port timings i used were
180 degrees exhaust, 65% of the bore (about 40mm)
160 degrees inlet, as wide as the skirt would allow ( i broke into the manifold stud hole)
30mm phbh 130 main
55 pilot
40 slide
av 262 atomiser ( cant remember needle)
pm pipe
pacemaker box with 16/46 primaries

it went rather well

If you're looking for a Jap piston to go into a barrel, there's a guy called Brett south of Brisbane who has heaps of NOS pistons. He trades under the name of Retro-Moto (I think).

You might like to think about a 185 conversion (64mm) using a genuine TS185 piston.

I'm going to visit Brett when I come to Oz next year. He sounds like a top bloke.

Stokie wrote:I ran a MB stage 4 tuned 175 conversion in my GP150 - with a 30mm PHBH and clubman.
Nice rideable motor on the stock Italian gearbox & sprockets - decent performance gain in all areas over the 150.
I've got a port map somewhere I think - I could scan it and email it if you want?

if you can,that will help alot..
cheers

Knowledge wrote:If you're looking for a Jap piston to go into a barrel, there's a guy called Brett south of Brisbane who has heaps of NOS pistons. He trades under the name of Retro-Moto (I think).

You might like to think about a 185 conversion (64mm) using a genuine TS185 piston.

I'm going to visit Brett when I come to Oz next year. He sounds like a top bloke.

Sounds like we should meet up for a beer..

Red ghost ,darren here from the lambretta club of south australia i have been tuning cast barrels ,ie , porting and jap conversions for over 20 years in oz ,185s ,230s and 240s ,if you need a hand with port timings , or porting work contact me ,on this site or paradise lost sc ,west australia,all of the info and how to do is available over here.