Lambretta Port timings

[bristolLambretta]

Hi there just wonder if these seemed ok to use...

Exhuast - 184
Transfers + Boost - 123 (trying to stagger the boost a tiny bit earlier, maybe?)
Inlet - 163

This all on a Mugello 186 (58/107) Li150 block, opened tranfers and matched to head. Flowed as best I can.

Anyone have any thoughts about what would be the optimum timings for a Road/Race tune? What is the formula for working out timing to be in harmony? I have been working to the 350-exhuast = Inlet, is that correct? Im not sure where I read that..

is there a way to work out where the power band will come in? (dont say dyno, im trying to get this setup prior to taking it to Readspeed for final jetting)

Any help would be much appreciated folks!!


other info...
Exhuast sytem is a JL3 Road Snail/Curly (not the best i know but i want a sleeper so no big pipes out the side!)

Carb Delly 28PHBH with Manchald Filter

Squish 1mm

Oh and its a full body Series 2 trying to pull Li150 box with 47/16 and im a fatty.

[J1MS]

Think you might struggle to pull that gearing on that set-up.

[bristolLambretta]

Im not too worried about gearing at this stage. Thats the next problem. My question is really about the port timings.

It did easily pull a 46/15 before i opened the transfers etc so the 47/16 is not really a big jump but time will tell. I wil keep you posted on the gearing, i can always go to a 47/15 and have some crazy short geared sprint bike if need be..as i say gearing isnt my question at this point...

what sort of timings does a Mugello run as standard, anyone?

[bristolLambretta]

Think you might struggle to pull that gearing on that set-up.

I have taken this onboard and put the 47/15 in as I dont want to fall into the old overgeared trap...this then now gives me a 5.33 final...

I hope these timings run? Thats my main worry..Im going to put it together tonight and make test it tomorrow if it starts and will tick over that is!!! A mate came over to look and said 'you are either brave, or stupid' I may be a little of both!

P

[J1MS]

I think it will run but the power might be a little higher up the rev range.
I can't really comment on the mugello as I have had very little experience of them, but I'm sure some on here will have good solid info/advice for you.

Port timings would probably suit a more revvy pipe.

I've started an engine for. My SX with a cast indian barrel and the timings are approx 180 ex, 130 tr, 170 in.
It will be running an old micron pipe.

[Special X]

For tractable road use with a series 2 and a "fatty"

172 exhaust
123/124 transfer
150 inlet

This is fairly close to standard my mk 1 came with

168 ex
124 trf
148 inlet

For "fast road" (revvy) use on same steed

180 exhaust
126/8 transfer
155 inlet

And ditch the JL3 and use a JL4 . . the barrel will want to rev to around 8,250 rpm and the JL3 won't oblige. You'll need 5.4 - 5.5 gearing to make the most of the revvy version Giving a top speed of well over 70mph (at least on a series 3 it would, I'm not sure about wind resistance on an S2)

IMHO 1mm squish is an accident waiting to happen unless used on the track. 1.2mm is the lowest I would ever use on the road

[Special X]

I think it will run but the power might be a little higher up the rev range.
I can't really comment on the mugello as I have had very little experience of them, but I'm sure some on here will have good solid info/advice for you.

Port timings would probably suit a more revvy pipe.

I've started an engine for. My SX with a cast indian barrel and the timings are approx 180 ex, 130 tr, 170 in.
It will be running an old micron pipe.

Are you using a reed valve on that?

[fred]

with 170 inlet timing i would've thought it's piston ported. these are are roughly the same timings my mate is using 180,130,160,and it pulls like a train,and thts with li 150 17/46