small block top end kits and porting

[tonydevon]

Greetings all, I have hopefully just secured myself my first proper Lambretta, an italian GP 125? but its had a 175 kit put on thats knackered due to siezing, I suspect not jetted or probably not running it in, as it failed a long way from home on its first outing apparantly

anyway I am trying to work out the best way to get it back on the road pretty quickly, I had thought of just putting another cheapy top end on from ebay etc, but that seems false economy, but my bank balance does prefer the sound of £200 odd rather than about £800 at a guess

I seen the RB20 kit, this seems to get good reviews, obviously need to look into a crank and carb also oops there goes the xmas fund LOL

what I was wondering is if you can have a top end ported once its been used? or is it best done from brand new.

[tea5ive]

bang for bucks, cast 150 with a proper 175 conversion and stage 4 tune + jettex + indian big bore. or a little more money same converion with a phbh 25-28mm . muchos cheapos and will last ages

[bristolmod]

bang for bucks, cast 150 with a proper 175 conversion and stage 4 tune + jettex + indian big bore. or a little more money same converion with a phbh 25-28mm . muchos cheapos and will last ages

agree- but I'd go a little bigger by using a proper TV175 cylinder bored to 64mm (c. 186cc's) and reprofiled head etc.

Chris

[cgt75b]

Clean up the piston and bore jet correctly and away you go again. The only expense is your own time, but you will have the satisfaction of knowing you have fixed it at no expense. Which for me is what it is all about best of luck hope you get it fixed.

[tonydevon]

oh so many options and not a clue what to do, spent about 7-8 hours just surfing the web and reading reviews etc in the last 2 days

the CASA 185 or mugello 186 are both currently getting a good thinking about

hopefully order/buy something on Thursday and then I can look at spending my christmas rebuilding it, sticky manual by my side the entire festive period LOL

[Adam_Winstone]

It is all false economy and a waste of money if the causes of the previous seizing are not resolved. Bearing in mind that you can spend your £200 budget just having it set up correctly, that doesn't leave you anything for a new top end. To date, I've never known a kit to run correctly on the set-up/jetting details that has been supplied with it (not without some tweaking anyway) so don't expect to simply spend £200 and have a reliable engine.

You may appreciate this already but I just thuoght I'd mention it.

Good luck with whatever kit you opt for.

Adam

[tonydevon]

thanks Adam, the mention of £200 was more just based on what I had seen cheap kits for on ebay, having spent hours now trawling the web I know the error of my ways and I think the best way to go forward is to just keep it more bottom of the tree in terms of power plans etc and just try to get it right.

I am hoping to sort the engine back to life for about £500-600, probably have to go second hand with a carb to help costs.

from my chats with previous owner it appears the 175 kit on the scooter was fitted, and then it was taken on a long run with a young excited pilot LOL, think the mixture of zero running in, most likely not rejetted correctly, and ebay kits, was a poor combination, however it did make it about 80 miles

part of my problem is I dont have any local scooter shops, or a shop that would even know what end of the scooter the engine was under LOL

[shep]

I've got the AF 200 smallblock kit on mine, 42mm Clubman and 22mm Jetex.
Sit all day long at 50mph and do a genuine 65 flat out, I think they're about £200ish.

[Darrell Taylor]

? what is the rest of the motor like,would it be best to start afresh if its history is unknown and following a failure
the rb needs special 116 crank and an rb pipe too so lots of spend so other kits suited to common cranks/pipes would be better
is it reed valve (inlet and reed to buy) or piston port (just a cheap inlet manifold) ur after ,left or right carb
is it on a small taper crank and flywheel,is it 12v electrics?
what do you want from the motor are you wanting to keep with ts1 guys(20bhp) rb20/imola/mugello or ride with the standard scoots (10bhp minimum to keep up) basic ebay kits etc

i feel below would provide a middle ground and have 12 to 15 bhp within your budget or below

sil 175 kit with mahle piston and hi comp head £120 mild tune/clean up £80
or a used mugello 186kit
60 107 bgm type crank full circle £130
crank bearings/seals/gaskets £50
exhaust ? expansion or clubman always loads available second hand £100 look for jl3
24 to 28 carb new £90 s/h £40
ignition kit £50 to £150 depending on type also new / sh option

a few ideas

[tonydevon]

many thanks for the input, after a few emails with a "localish" dealer I think I know what direction Im going in

the scooter has with it a PM tuning expansion exhaust, and also an AF clubman, so that helps with choices, it is already fitted with electronic ignition, and I have just robbed my spares box and found a spare 28mm PHBH dellorto carb from my cagiva Mito.

looks like a mugello kit, MEC crank and bearings, seals and gaskets will be the way forward, been offered a good deal for the bundle buy, so hopefully all will be good with the world, a lot of learning and planning is going to have to happen, cant afford to mess it up

then just have to try and find a dyno somewhere in the southwest that can make sure its setup

or could I ship the motor, pipe and carb to a dyno place? does anyone have a dummy test frame for testing motors without the original scooter?