Modern Vespa

Howdy All,


I need to convert my 52/120 IJ to a 52/100 by filling the 1.20 mm air openings with solder and drilling them out to 1.00mm.

Is the procedure to solder up the flat screw driver end and the very bottom tip of the Idle Jet. Then Carefully drill the soldered ends being very careful not pass the drill past the cross drilled fuel holes?

I have never done this and could use all the advice I can get.

Thanks in advance!

Hec

In my experience, just the main hole (one at the tip) needs soldering.

That's the idea, but sounds like a great way to both end up with the wrong size hole, and little solder bits in the combustion chamber.

Are you sure that's the size you need? If yes, I'd suggest opening up a smaller hole with the adequate precise tools instead. 48/100 and 50/100 (T5) get progressively richer; you could try one of those first and turn the bottom hole into a 52 if needed.

My 1980 P-125X Resto Mod project is in the final stages of jetting. I hope! Current set up is now AC120/BE3/120 MJ, 50/120 IJ air mix 2-1/2 turns open, and a B7RES Plug. The 50/120 IJ may be too lean for my next jetting change. My next jetting change will be taking the main jet from a 120 to 118. Doing this and leaving the 50/120 IJ may be to drastic interms of leaning out the air/fuel mix. So the thinking is reduce the MJ to 118 and richen up the IJ with a 52/100 IJ. I do have a 55/100 I could try first which is a tad richer than the 52/100 IJ.

Hec

I'd recommend doing things in steps rather than several at a time, to avoid not knowing for sure which change produced what effect. There's nothing drastic about going from 120 to 118 MJ so I'm sure the IJ can wait until you sort that out.

Yeah worry about the main jet first. Then come back to the idle.

Howdy All,

So after the last round of jetting, I am still too rich with the 55/100 IJ. I need to start working down to leaner IJ's one step at a time. I will solder up the screwdriver slotted end on my 52/120 and drill it 1.0mm making it a 52/100 IJ If the 52/100 is too rich I would like to try a 50/100, but I don't have one!

Does anyone out there have spare 50/100 IJ they can spare? I can order one but with shipping it will be close to $30! Maybe I can trade for one of my other IJ's or just buy it from you? Shipping shouldn't be more than a U.S. postage stamp.

Thought I would ask!

Hec

A 100-something idle jet isn't going to flow enough air no matter how much you mess with the fuel opening. I bet your spark plug is black and borderline fouled.

Trying to get rid of the 1/4 throttle sputter has driven people to madness. Consider it a feature of the kit rather than a flaw.

My advice is to ditch the 100 and move to a 120 or 140.

I took a screenshot of Ray8's VMC Stelvio 177 build where he posted his final settings. His build is very similar to mine. I think I may be slowly gravitating towards his final settings. I am running an air filter though. I bet I end up close to his settings.

Hec

Blast from the past right there!

Current jetting is 55/160, Lemarxon X234, his LML slide, and his 22mm sleeve.
MJ idk, as it was reamed from a 122 up (less than 128). AC reamed from a 140 to idk (less than 160). No filter.
Much more a delight than then.

I know what I would do, but shipping may be problematic/expensive for you:

https://www.kmtproducts.co.uk/?cat=DELLORTO-TYPE-JETS&subcat=D31-SI-CARB-IDLE-JETS--Dellorto-Type-9892-&page_id=62&menu_id=&category_id=1&sub_category_id=32

Thank you! They have quite the Idle Jet selection! Best selection I have come across yet!

Hec

And the kmt are supposed to be precise, as in actually the size written on the side...