Break in questions...

7

73AMC

Member
racerx said:
Measure the intake port ID. If it's 22mm, or larger, I'd go for a VM22, starting with #22.5 pilot/160 main jet combo. Worst case, you might have to drop down to a #20 pilot but that's highly doubtful; 125cc should move just enough air at idle to keep this carb reasonably responsive. As for main jetting, anything from #130 - #180 is possible, depending upon how much hp your specific L125 makes. If you don't mind throwing some extra bucks at the problem, for the sake of time, order a set of mains ranging from 140-170 and get to work testing.

FYI...if you compare your existing carb to the VM22, side-by-side, you'll probably be shocked by the real world size difference. 26mm is too much venturi for 125cc and less than 10hp and the folks who came up with your engine kit knew this. They also knew that appealing to the "bigger is better" mindset is effective marketing strategy.
Click to expand...

So I ordered the VM 22 with multiple mains. I didnt order any other pilots and the 22 comes with a 30 for a pilot, should I order a different pilot(s)?
 
6

69ST

Well-Known Member
You've answered your own question with that quoted earlier post. I think you'll find that the engine will start easily, no choke needed, with that grossly oversized pilot jet...it'll also take light-throttle pretty eagerly. Unfortunately, you'll have a pig-rich idle too.
 
7

73AMC

Member
I put on my fresh VM22 with the 22.5/160 combo. Took it for a drive after she was warm and it bogged at 1/2 throttle. Came home and dropped the clip on the needle another notch and installed a fresh plug. No more bog and she runs real smooth. Here is what the plug looks like.

c64e3fdd.jpg
3371595d.jpg
7cfb49ec.jpg

Seems pretty clean running. What do you guys think? Drop it one more notch?
 
6

69ST

Well-Known Member
Yep, I'd keep going rich until you find the limit and rich misfire occurs at WOT. The plug looks too clean but, that could just be from insufficient mileage on that plug. Pump piss...uhhh...gasoline makes it difficult to get an accurate read on plug coloration when you're close. Judging by your running description, you're at the fine-tuning stage.
 
7

73AMC

Member
I dropped it to the last notch on the needle and did some more driving and hill pulls and shut her down. Here is what the plug looked like...

0f6df127.jpg
f7828009.jpg
deb1f9e6.jpg

Do I change out my main jet now?
 
Top