Sr125 build help!

Hello..... New to the forum.... I'm from California where higher displacement 2 strokes are very rare... I'm a 2t junkie and got
ahold of an aprilia sr125 motor... It's condition is pretty beat up but I plan on building it inside out.... I'm going to run a malossi 172cc big bore kit.... Can u guys help me on deciding which crank, exhaust and carb to run! The crank can have close to stock specs but better quality..... I notice that popular carbs are the malossi dellorto 25mm but not sure if i should go 25mm or 28mm? As for the exhaust I want the best...i hear the pm52 is a good pipe....but how would the performance be with a modded pm59 on an AC 172cc motor???...... Any help and advice would be greatly appreciated.... Thanks in advance

 

Read the tuning section it will answer most of those questions but in my opinion
DONT get the Pm Pipe..if your want to spend that money i say get either a jolly moto 280
or tdr pipe £240 better powerm quality and looks than the pm- (search "tdr" in the forum search section)
OR Malossi £300ish
New variator. Malosi or polini, blue clutch springs
Cranks
3 choices
bgm 52mm crank £180ish
bgm 54mm £200ish but you will have to have porting done to get the best out of it (150ish once youve paid for postage their and back)
malossi 52mm crank £300ish

Hope that helps mate

 

helps more than you think....thanks!!! i probably wont go with the 54mm crank since im not lookin for that much power........any good quality aftermarket crank will do....thanks again for your help.

 

its strang because when i search "tdr" i get nothing

 

Hi,

Depends on what you want it for but the "two stroke junkie" is a give away . :good:

You don`t want it to ride to the local mall and back with a bag of groceries on the pillion seat I assume?

You are mechanichally "savvy" and realise rings and "de-coke" are part of the procedure?

You want a fast auto stroker for weekend blasting.

The procedure is:

Malossi 172 A/C kit, raise the exhaust port 1.5mm and widen 1mm at each side in a smooth radius concentrating on a line drawn from the piston in the bore just as the tranfer tops close (increase blowdown).Plenty of chamfer to give the rings an easy time (don`t worry you wont upset the timing too much it`s a steetable tune).

Drop all ports 2mm. Tranfers/ boost and exhaust and match the bottoms to the new crank which is going to be a 54mm stroke. :good:

Use a 1.00mm packer (std stroke is 52mm + another 2mm divided by the centre line of the stroke means 52+54 = 106 divided by 2 =53) plus the normal Malossi 0.5mm base gasket and aim for a squish of 0.8mm.

Open the exhaust flange exit to 32mm (normally 29mm)

Cut the base of the cylinder away in-line with the reedblock, cut away the sides.

Cut 5mm off the base of the piston and drill two 8mm holes in the back of the piston.

Flow the cases, alter the reedblock,lighten the flywheel,chamfer the head,index the plug,change the variator, belt, match the rollers,flow the stub,match the transfers/gaskets, add a gear-up, change the clutch springs,change the stator and cdi for an L/C one, then start sorting out the carb:

As you can see... it`s a lot of work and there are only a few trusted people around that actually know what they are doing with these engines, It`s not an old TS175 or a DT250 but a whole new ball game with Auto transmission.

But get it right and it`s a fucking hoot!" :cheers:

No need to shift gears! and in a straight line even with lower power than an Aprilla Rs or an RD 350YPVS you can piss all over them BECAUSE you don`t have to shift!

Oh and no need to search the link is in my sig.
As is another repected buider /tuner of auto scoots Shiny Red.

 

Whoa... That's a wealth of info! Yeah I found the site googling haha.... Was that u on the track ?!? Sick!!! Yeah I love 2t but I live in the city near LA...scooters around here are considered fast if they reach 70mph so I don't have to build it to full potential..... For my area a stock or close to stock crank, nice pipe, bbk, carb, gear- up and a lil tranny work will do.... Oh yeah gilera ignition as well to be honest I'm not planning on tracking it... More like racing for pride...wat u think now bd? 52mm enough? Or u still think I should go 54? I'll post some picks of wat I'm planning to put it on.... Thanks for all your help so far...
How do I order a tdr pipe ?

 

In that case I`d think something along these lines:

Malossi 172 and leave stock port timings but still open up the exhaust exit to 32mm if your going to run one of our exhausts.

52mm HPC crank running on NTN bearings, you can do some mild case flowing while your in there but not essential.

Modded std reedblock running carbon petals (reedblock mod is on this site or gilerarunner.net somewhere).

25mm Delorto carb.

Liquid cooled ignition system/cdi/stator.

Polini variator set to 180 spacing and Polini 180 belt.

Std clutch running Malossi green springs.

Gear up

TDR exhaust, you can email me regarding this pete@tdrscooters.com as we`d need the measurements I posted on this forum to make sure it clears the unusual SR Mounts and to work out carriage to the USA.

Yes I ride Blue Dwarf and Dave (my brother) rides Red Dwarf

 

with a setup like that wat top speeds will i likely achieve? just wondering......i know these motors can hit over a hundred but always wondered with a setup like this what the top speed would be.......i wanna cruise most of the time but punch it when i want to....and yes i hit up pete and im waiting for a response.......i saw that shineyred posted in scooter news section that they got a TDR pipe fitted on an AC motor so im stocked....cant wait man

 

Top speed depends a lot on conditions/rider weight etc etc but with a set-up like this you should realise high 80`s to low 90`s with the right conditions.

We will need the measurements i posted, don`t want to send an exhaust all the way to the USA and not have it fit! We know they fit the A/C motors but it`s that silent bloc mount on the SR we`re not sure of, we`ll make a jig when we get those figures.

Did`nt receive an email? PM me your email address and I`ll contact you.

 

80-90mph sounds good to me....to be honest if she cruises at 75 constant without struggle ill be more than stoked....anything above is icing on the cake......about the measurements, my motor is on its way to me....im not sure if im even going to have the silent block on it.....it was shipped out on thursday and i was told it would take 5-7 days to get to me so i should get it by next saturday latest...as soon as it does ill take some quality detailed pics to show you what im workin with..... as for now i think its just the bare motor without the silent blocks and may be like this


hope this makes sense...^^^ so without the silent block im pretty much limitless when it comes to choosing a pipe for a 125/180 piaggio 2t or are there other factors other than the silent block?

 

The only limiting factor would be the width of the air cooled magneto cover, some pipes produced for the L/C models may foul/hit or run so close as to melt it.

 

yeah dont want the fan shroud to melt.....but wat about this one? i know its a prototype but looks like it fits... same shroud as the sr too....
http://scootershack.co.uk/viewtopic.php?f=2&t=18247

 

That`s the pattern we use now,all of our exhausts for the Runner/Drag/Typhoon follow the same line to within a few mm (they are hand built so allow for a discrepency of a couple of mm).
We would still like to be sure though and would prefer to have the measurements.... but if your happy to order one on spec that it will fit that`s up to you

 

what ill do is get some measurements in first but i really dont think heating would be a problem.....ive worked on many 4t motors with similar fan shrouds and havent seen a problem yet....the header is about half and inch to an inch away from the shroud and is scorching and we havent seen a problem yet....haha.....when the motor comes in ill see if if theres the silent block to take some measurements but if there isnt any i dont mind buying it as is....thanks for all the replies so far.... i have one question... i got some pics of the motor and the shroud is in bad shape.....is there a source there where i can get a shroud and plastic cover for the topend?

 

Tried the usual suspects such as SIP or Scootercentre.com?

Failing that you could also try Aprilia themselves.

 

ok......i found a source through aprilia direct for the fan shroud.....just wanted to share with you where this motor is going into and why i chose the aprilia sr125 over the gilera runner motor... :grin:
1. its aprilia
2. the wheels
3. AC and dont have to mount a radiator like my current project..

heres a pic of my current project...aprilia sr50 ditech/honda ruckus "APRILIKUS V.1 w/nos" i then grew a love for aprilia but wanted more power...i wanted to reach high 80- low 90mph.......the rims will match and i will achieve my desired speeds with the sr125 motor.....the ditech motor is very fun, reaches speeds up to 65-67ph but at the same time i get about 100mpg....well here she is....cant wait for "APRILIKUS V.2" :yahoo:

 

hmmmmmmmm a few things are not adding up lol... thats all i gotta say on this one.

 

not sure what you mean^^^... well blue dwarf got news that the new motors coming in on friday and it does have the silent blocks according to the seller...ill definately have the measurements for you.......thanks for all your help and suggestions so far.....

 

Ok... Been a Lil busy with the new job so hvent had time to post but got the motor in!!! I'll take pics... I need some help... I have 2 weeks to order this:
wiring harness
rectifier
flasher relay
starter relay
etc/ electrical related items
I hve 2 weeks cuz my friend is goin' to London to visit family and I'm ordering these things from eBay... Should I order the items off an aprilia sr or should I order these parts off a gilera.... ? Or does it not matter? I already ordered a runner stator so u guys know and shiney is goin' to lighten the flywheel for me

 

i wonder if can do a disc conversion on the sr125 using sr50 parts? cratch: