Needle machining?

[wack 63]

Just got back from a chilly weekend in Yarmouth and on the way down my EGT was showing @700C +when cruising so to avoid a blow up I moved the needle clip to the bottom notch on a TMX 35 using a 56 needle.This didn't solve the problem so changed to a 55 but whatever notch the clip was on it 4 stroked badly when having to sit in 40-50mph traffic,once on the taper it ran fine and dropped the EGT to @600C at 1/4 throttle .Now I am wondering if the 56 needle (which is what it normally runs) could be machined ie thinner at the 1/4 throttle point to richen this area.Has any one tried this? The scoot has been dyno'd in the past and is usually fine ,just that we got a good run down on the A47 so tended to sit at the same throttle position for mile after mile.

[sean brady scooters]

mmm ,interesting. this has been mentioned and brought up before..
but ultimatley what you require is a delly carb..

[soulsurfer]

I think this could be a problem with tuned Lambrettas that rears its head with different riding styles and conditions when you have an egt guage to display it. There is also the issue of not being able to replicate the situation on a dyno. It can happen with a Dellorto too. I think there's something to be said for machining needles and it's not a new thing. The retro fitted powerjet is another part to help solve this too.

[oldbiker]

Mikuni carbs are ok on jap bikes, but the fast jap bikes use them because they are made in japan and tend to be designed for a specific bike.

If you spend a little time at the track you may notice that most fast bikes, scoots and karts use amal or dellauto. There is probably a reason for this.

I personaly am not a fan of mikunis and think the ones on my bike are crap, the spares are rediculusly expensive £40 for a needle and needle jet.

Though they do have one advantage and that is that they are very light.

Consider seans words

[Honeymonster]

Try Allens Performance, http://www.allensperformance.co.uk/ Steve was developing a specialist lathe just for needles, haven't spoken for a while, don't know if it came to anything.

[wack 63]

Thanks chaps I do have a VHSA 32 on my other GP which I could try it's just the hassle of altering cables and jets then all the plug chops to be ready for Cleethorpes.Personally I think Mikunis are a pain to set up and all the stupid screws holding it together,give me a Dellorto anyday.Unfortunately the motor came with a TMX when I bought it.