Spit back on carb along with sluggish response on throttle

[davedidsmith]

Looking for some advise, been running a GP on a 185 mugello. Broke down last week on what I thought was a blocked jet. Stripped and cleaned carb, then discovered no spark. I tested the same and found that the LT coil was knackered. Replaced the stator today. She's set at 19deg timing, however out for a run and carb is very sluggish responding to throttle, also quite a bit of spit back.
Carb is a 28 mm PHBH,40 slide, MJ122, pilot 55, AV264, X13second clip and a pm pipe.

[Knowledge]

I assume that it was running OK prior to the breakdown?

[davedidsmith]

I assume that it was running OK prior to the breakdown?

Not bad, struggled a bit to start when cold, hand over the mouth of the carb, realised after stripping the carb that the mix screw was way out, did as sticky's and half turn out and she started second kick.

[MickYork]

The new stator might have incorrect timing marks and you might be over retarded. Check your timing with a strobe.

[davedidsmith]

The new stator might have incorrect timing marks and you might be over retarded. Check your timing with a strobe.

checked the timing all ok also had the carb on and off various times spit back is not as bad however throttle in second and third is slill sluggish. Think it may be jetting?.

[davedidsmith]

Changed the jetting to 118mj, x7 second clip and 50 pilot and thought I had the prob solved however still when opening throttle fully in third she seems to splutter. Any ideas welcome,

[al pushpak]

Hi, might be worth trying the needle on the top clip setting & if you have access to one you could also try blowing all the jets & carb out with a high pressure air line hope, you get sorted. Al

[davedidsmith]

Hi, might be worth trying the needle on the top clip setting & if you have access to one you could also try blowing all the jets & carb out with a high pressure air line hope, you get sorted. Al

Tried that Al, still no joy. Also tried on third clip, without success. Changed the jetting to 115mj 50 pilot andx13 clip with 40 slide. If anything worse. Back to square one. It feels like fuel starvation however checked and getting 340 ml per minute which should be fine? Ready to rip of the carb and go back standard.

[roli150lam]

Have you read thread -how to check your jetting using choke test.It is in Carburretor section on this forum.

[Gary Harwood]

I'm no expert but my Mugello 186 developed a spluttering similar to your description. We changed the fuel tank....no better. Changed CDI, plug cap and lead.....no better. Thoroughly cleaned carb......no better. Eventually got it on a dyno and concluded it really was a fuel problem.....turned out to be the slide in the carb. Changed it from a 40 to a 50.....bingo! Now runs fine.

[Adam_Winstone]

If it was fine before stator swap, I'd try another stator (if I could beg, steal, borrow one from mates) as many problems that feel like carburation issues turn out to be electrical, based on a poor spark failing to burn off mixture and making the jetting feel rich or as though it is flooding.

[davedidsmith]

I'm no expert but my Mugello 186 developed a spluttering similar to your description. We changed the fuel tank....no better. Changed CDI, plug cap and lead.....no better. Thoroughly cleaned carb......no better. Eventually got it on a dyno and concluded it really was a fuel problem.....turned out to be the slide in the carb. Changed it from a 40 to a 50.....bingo! Now runs fine.

Gary tried the 50 slide and still the same, get to about 40-45 and she starts to die, thinking it may be the stator right enough as everything was ok prior to this. Unfortunately away to work on Tuesday for a month away so don 't have time purchase a stator. The joys of living in the north of Scotland Thanks guys for all the advise,

[davedidsmith]

Gents,

Changed the Stator, Cdi, regulator, checked and double checked the timing, slides, needles and jets, have the same problem, half throttle seems ok, start to open up and she dies,

Wits end loyal

[davedidsmith]

Think I have it, tried a few set ups settled on one I found on other Forum. Touch wood she seems in good fettle.

Thanks again

[Markpm]

What was the problem??

[davedidsmith]

Mark,

Jetting, changed out Stator x 2, CDI, Regulator and jetting numerous times, seen below on Scooterotica site and thought why not, she's running and pulling fine now.

118 Main
70 Choke
40 Slide
X7 needle (3rd clip, but may move to 2nd once i'm happy that plug colour is ok)
50 Pilot
AV266 Atomiser