TMX35/TS225 lean spot

[oakerz]

I know this topic has been discussed many times and seems to be a common issue.

Just finished running my Humiliator TS225 in after a piston change due to a loose head and resultant holed piston (DOH!). The engined had been set up on a dyno previously (approx 23bhp) and a very slight lean spot noted at 3/4 throttle, which wasn't thought to be a big problem at the time (unfortunately this now equates to an indicated 65/70mph, right where I want to be cruising).
Humiliator Kit
V force reeds
MB manifold
Indian ignition system
JL3
TMX35, open mouth.
B8 plug
squish 1.2mm

Post dyno settings:
310 main
55 needle (4th clip from bottom)
20/22.5 pilot (can't remember now)

Since being able to open the engine up I have noted detonation at 3/4 throttle after a few miles and a lean looking plug. So adjusted needle one clip; way too rich. Reset needle then changed main to 320, this has cured the pinking, but a plug chop still indicates a lean condition.
The rideability is v good and responsive, needle could maybe do with leaning off a tad mid range, I notice that many people run with a 56 needle.
Not quite sure where to go next as 330 main would seem to be on the large side as indicated on the dyno as we dropped from Vince's original 350 main set up to the 310 main, 56 needle would be leaner and on paper not appear to improve the lean spot. I suppose a B9 plug will help run cooler, but possibly not cure the lean condition?

Current set up:
320 main
55 needle (4th clip from bottom)
20/22.5 pilot (can't remember now)

Any idea's on a cure or suggested changes to the set up to improve the problem?

Thanks

Mark

[fishi]

what is a Humilator Kit/TS1 ????

and what are the differences to a standard TS1 ???? has it more power/torque ???? I have heared some things about this kit, but haven´t see any yet. Is it reliable ??? better then an y other tune, from MBD, Harry or someelse ???

have you some pics you can post of it ???



fishi

[oakerz]

Fishi,

Probably easier to read this from the West Coast site:

http://www.lambretta.net/shop/shopexd.asp?id=600

Mark

[camel]

i run a home tuned ts1 with a devtour and 35 tmx
i run a 310 main and a 56 needle on the second clip
i must stress i run a ram air filter

[cryogenic]

Hi Oakerz i run a 240 ts on a similar set up however i have
340 main
56 needle 2nd clip down from top
22.5 pilot
i also use an EGT and this will show a a heat spike around the 3/4 throttle all 2 strokes do this naturally no doubt you`ve read this on this forum.
John at scooterloopy told me a trick when one clip change sends it rich. rub fine wet and dry about ten times up and down the needle this will alter the diametre by thous keep doing this in increments until it richens up to the desired amount. Be careful not to oval the needle.
Good Luck :baddevil:

[soulsurfer]

John at scooterloopy told me a trick when one clip change sends it rich. rub fine wet and dry about ten times up and down the needle this will alter the diametre by thous keep doing this in increments until it richens up to the desired amount. Be careful not to oval the needle.
Good Luck :baddevil:

You can also try a thin washer under the clip to get 1/2 clip positions

Personally, I think there are a lot of people using Mikuni carbs with cruising speed lean spots but unless using EGT guages they are unaware of this possible future holed piston.

[J1MS]

You can ride the scooter at steady throttle openings trying to find the lean spot, then put the needle in a battery powered drill on a mount, or the drill held in a vice, then use very fine wet & dry, spin the needle with the drill and relieve the corresponding point that relates to the weak point, then finish with a little scotch brite and replace and repeat till its richened up enough to lower the heat spike at that point, but not too much as to over richen the engine as your only trying to enrichen the heat spike.... Your not going to make it any hotter only richer and it will only cost the price of a needle if you do it wrong...

[oakerz]

Thanks for the advice chaps