carb issues

keef1989

New Member
hi everyone, I'm sure it's been covered a few times before, but i'm struggling so please help!
fitted a 150 barrel, big valve head, stainless front pipe, tulip style exhaust, and an easy start cdi all from ooracing.

what seems to be the optimal carb setup for this, especially regarding jetting. I read somewhere on here that somebody was running the standard carb with standard jetting, but I seem to have poor starting and once engine is warm it cuts out quite frequently, turning the air/fuel seems unresponsive.

am i missing something maybe ignition timing?
 
What color is your spark plug after a ride? I went through a similar situation and make sure you install the main jet big/rich enough to let the spark plug color be a dark tan color. Then piston can't take much heat before warping w/ the lean stock carb. jetting
 
it's on the white side, and deffo running hot. I'll try a larger main jet, sorry carbs are a bit of a black art to me... used to fuel injection and ecu mapping!
 
I think it'll be ok to try a main jet a good bit larger;too big won't hurt but too lean will. I think if it's a 100 in there stock then install a 120 and check plug color.A milk chocolate color is desired especially during Break-in.I recommend getting a few different incremental sizes for instance(but not the exact same numbers possibly..) 105,107.5,110,112.5,115 and so on and one of them will give you the optimum spark plug color after many 'jetting runs'.
 
Everything you ever wanted to know about jetting the Skyteam Ace carb should be here. This is specific to the standard carb that comes with the 125 Ace...
https://docs.google.com/spreadsheets/d/1USvziYIyzfyxfZA1YYpQf9eP4djb0GLWbvWcmME88Gk/edit#gid=1

This has been put together by trawling the DTT Skyteam Ace thread and the Ace Facebook page for information and then seeking confirmation from some of the most experienced Ace modifiers. Once I got this together, I used the info to easily get my bike running right.

Reading the chart in there you will find that a 48 keihin pilot will be correct and 100 keihin main (or 92.5 mikuni main) should be in the ballpark for you, but get one smaller and one bigger by whichever manufacturer you use, so you can experiment.

If you have anything to add once you get things sorted, let me know and I will update it.

Cheers
Richard
 
thanks for the replies chaps, has been a great help. various sizes of jets ordered, the fun shall commence this weekend!
 
The air cooled engines run safest w/ a dark(during Break-in) milk chocolate color or best w/ a light tan color spark plug center insulator porcelain when choosing the correct and final size main jet.I usually set the needle clip position(if adjustable..) in the middle so you can fine-tune the midrange jetting later.
 
Indeed a number of people have found that raising the needle by a whisker improves mid range, depending on egr, exhaust, air filter and brand/size of main jet

If the engine is hesitating around 4,500rpm you can try raising the needle to richen up the mixture. You will need to source some tiny washers (perhaps from a radio controlled airplane shop?)

However if you get to this stage, you may like to go and buy a more tunable Mikuni or Molkt carb, that has multiple slots to adjust the needle.
 
Yay! sorted! I am running a mikuni vm26. 100 main (needle set second to lowest clip) 22.5 idle. Borrowed a colour tune and its running lovely throughout the range. Again thanks for the help guys :)
 
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