help wanted please.

[59 lammy boy]

I have recently fitted a second hand 186 imola kit with a 28 mm carb and jl3 exhaust and running a standard Italian li 150 gearbox and sprockets.
I've have it dynoed and is now pushing 17 bhp
The problem I have is
in 1St 2nd and 3rd it pulls and goes really really well but when put into 4th it seems to have lost a lot of power and takes ages to climb back on to the power band
I don't think it's the port timings as it would do it in all the gears
Any ideas guys please
regards
Paul

[stonerosesmod]

Are you 100% sure its an italian and not spanish Li150 box?

[59 lammy boy]

Yes I did a 3rd gear ratio test and it's 6.69

[Digger]

What's a third gear ratio test?

[59 lammy boy]

Jack the engine and back wheel off the floor a little
Then put the scoot in 3Rd gear and take the spark plug out to make it easier
You then turn the rear wheel one complete turn and at the same time count how many time the fly wheel goes round. The amount of turns on the fly wheel is your 3rd gear ratio
ie Italian li 150 gearbox and sprockets is 6.69 a Spanish gearbox is 7.03

[Captain Pugwash]

Jack the engine and back wheel off the floor a little
Then put the scoot in 3Rd gear and take the spark plug out to make it easier
You then turn the rear wheel one complete turn and at the same time count how many time the fly wheel goes round. The amount of turns on the fly wheel is your 3rd gear ratio
ie Italian li 150 gearbox and sprockets is 6.69 a Spanish gearbox is 7.03

Very well explained

[coaster]

It might just be that you have to hold on to the revs a bit longer in 3rd when changing up so that it's a bit further up the power band.......a 5 speed box would help as well but nor a cheap solution

[59 lammy boy]

Would a problem with the reeds do this do you think
. I've just had a look at them and there's a slight gap on two of the reed paddles . about 1 and a half mm

[Wack]

Did you check the piston and ring clearances when you fitted the kit? Any blow by on the piston? The small gap between the reeds and block won't have any detremental affects but you could turn the petals over if you're unsure.

[59 lammy boy]

rings all good with no blow by
Maybe I just need to rev it more in 3Rd to get it back onto the power band
Is the imola the kind of kit that you have to rev all the time?

[Donnie]

yep, they love to be thrashed a bit

[mainstand]

Maybe the pipe isn't suited to the kit...

[stonerosesmod]

The imolas do like the revs and im sure the JL3 and gearing would suit it,maybe an ancillotti or gori/mbd box would give better grunt if you borrow one?

[59 lammy boy]

I don't know anyone with one of those boxes
What difference would one of those make please?

[coaster]

The imolas do like the revs and im sure the JL3 and gearing would suit it,maybe an ancillotti or gori/mbd box would give better grunt if you borrow one?

Don't know about the Gori but I'm running an Ancilotti on a TS1 and it hits a brick wall at about 6k RPM which would be no good on an Imola. The JL3 is a good all round pipe but not know for revving much higher either

[Psychedelicropcircle]

Running the same setup although 15-46 pulls in all gears.

[Psychedelicropcircle]

Retreads thread with glasses on and sees 17bhp not sprocket size.... deary me

[mark1]

A JL4 would be better suited than the JL3, as said above, give it some welly in third before you change into 4th.