advice needed please

[bazza3004]

Hi, running the latest imola kit with mec 60mil crank , indian elec ign , 30 phbh with av266 x13 needle on 2nd clip 40 slide and 55 idle jet. The motor runs well and cleanly until I hit about 45-50 (speedo indicated) at probably 1/2 to 3/4 throttle and then it starts to splutter abit. Once ive got through this spot it continues to rev on cleanly . If I turn the choke on whilst at this point the splutter is worse. Can anyone give me any advise , im assuming the problem lies with the jetting....but which one.
PS the timing is set to 16*

[Donnie]

from where you are getting the splutter it sounds like needle / atomiser to me, i'd drop the needle to the top clip and see if that's better. Odd though as Im running a muggy 186 on 30phbh and have recently gone av266 / x13 needle and was the same on second clip, move to top clip and it's lovely!

[crooky]

I had same on my sr 190 with 28 delly bogged at 45 had it on dyno moved clip up and cleared it great good luck with it

[bazza3004]

Thanks for the help i will try dropping the needle as you say tomorrow and let you no how it goes. Thanks again.

[Donnie]

make sure you do your plug chops though

When i got mine on this setting it was spot on! Too spot on where I was paranoid it cant be so right, done lots of chops though to be sure and it's been fine.

[bazza3004]

Cheers donnie. I was a bit the same . Done loads of chops at previous needle / carb setting and always showed to ne running a bit rich eg dark choc colour.
I have now dropped the needle to top clip and took it out for a good run. There is now no splutter and the engine run/revs cleanly through the range. I will do some more plug chops tomoz to check alls ok but so far so good.
Thanks for the help on this matter. Baz.

[Donnie]

Good man

It's a pain in the backside doing jetting and plug chops but it's well worth it!

[corrado]

, 30 phbh with av266 x13 needle on 2nd clip 40 slide and 55 idle jet. The motor runs well and cleanly until I hit about 45-50 (speedo indicated) at probably 1/2 to 3/4 throttle and then it starts to splutter abit.

Just shows how strange jetting can be ... my 26mm PHBH is set pretty much as above [50 pilot, 125 main] but 4 strokey until half throttle when it clears out and runs fine, more or less the opposite of above. Dropped needle to top clip, no difference. Dropped main to 120 and plug looked a bit on the lean side at 3/4 throttle plus it made no difference to the richness below half throttle.
Tried AV264 with X13 no different, tried X7 with AV266 no different, reluctant to try X7 & AV264 as sooner or later it'll work and I'll hole the piston.

[Donnie]

could be your slide martin? ie a 40 on a 26 may be richer than needed?

[corrado]

I'd been thinking that Paul as the area covered in the throttle progression matches where it 4 strokes. It's sods law that it'll be the expensive bit that needs changing.
I'm going to try my Mikuni TMX27 off my Imola first before I go changing slides at £25 a pop.