HELP! some minor tuning issues

treyoh5 · Jun 3, 2011

hello everyone. id like to take a sec and thank everyone who has contributed information to this forum as it has proved to be invaluable to me in helping out with my first build. but i have scoured the forum and read countless pages on my problem but have wound up with few leads.

with that said, im having some issues with tuning my motor. i have a 66cc china girl with a cnsv1 carb mounted to her and it has already been broken in. im running a 44th sprocket. i live in miami and am at roughly sea level so plenty of o2 here.

my question is; im reaching speeds of 27mph and cant seem to make it any faster, i have raised the c-clip to its middle point and tinkered with the fuel/air mix screw and beleive i hit a sweet spot. i tried running it with the c-clip on the 2nd notch from the top and have reached 30mph but upon inspecting the plug it had a light grey color on the electrode tip on this setting. so the question is
A) is this speed about right for the kit
B)is running it leaner and having the grey tip harmful for the engine
C)is there anything i can do to reach 35mph or am i up a creek w/o a paddle

my apologies if this has been posted already but i do appreciate any leads and/or advice
thanks.

2door · Jun 3, 2011

Are you trying to run on Bird Road or State Road 836? I suggest the Palmetto Expresway or Coral Way, maybe even Old Cuttler.

Just kidding; I'm an old Miami transplant.
Truthfully I'd suggest checking the color of your spark plug to get an idea of where you're at on fuel/air mix. The darker the plug, the richer your mix. You'll want a nice chocolate brown color, not grey or white. The lighter the electrode color the leaner you're running. At sea level you'll probably be running a tad lean so I'd suggest lowering the 'C' clip and doing a few plug chops to check your mixture.
Good luck and say hello to all of my old friends in 'The Grove' for me.
Tom

treyoh5 · Jun 3, 2011

Lol, thanks for the reply 2door.
Ill keep adjusting but what do you mean by chopping the plug?

2door · Jun 3, 2011

Ride it hard for a couple of blocks, shut it down and allow to cool for a few minutes then pull the plug. Check the color of the porcelain at the electrodes. That's where you want to look at plug color. The poreclian will tell you if you're rich or lean.
What fuel/oil mix are you running? You should be no more that 24:1 (24 parts gasoline to 1 part oil) Many kit instructions will tell you to run 16:1 but we've established that that is way too much oil. Break in should be a couple of gallons then move down to a 32:1 mix. Let us know how you're doing.
Hope this helps.
Tom

treyoh5 · Jun 3, 2011

Thanks ill try it out tomorrow in the day light as far as fuel mix I ran 32:1 for break in then switched to 50:1 Lucas semi-syn

GearNut · Jun 4, 2011

Just speculating here, but if your exhaust is plugged up, even a little, you will get a slower top speed. Some of them are not assembled correctly from the factory. Heck, some of them are closed off internally from the factory so bad they won't flow enough to let a bird fart through them.
I am not saying to go all hog wild and gut it or drill a hundred holes on the baffle tubes.
It just might be worth checking out is all.

treyoh5 · Jun 4, 2011

after trying to drill some extra holes in the end cap of the stock muffler and getting a nice gash in my finger in the process i decided just to ditch it, ill check the inlet side for any clogs, being a car guy im on a constant quest for better air flow!

i also sealed the carb onto the intake with some black silicone goop

treyoh5 · Jun 4, 2011

Alright just checked the plug this is what I got

The porcelain tip is a nice chocolate color a little on the light side, checked my exhaust and its got flow so I'm kinda stumped right now.

2door · Jun 4, 2011

Your plug is a bit on the lean side. Richen your mixture just a little. More fuel to air.
Tom

treyoh5 · Jun 5, 2011

Will do sir, thanks. Will report results .

treyoh5 · Jun 5, 2011

just test rode her after moving c-clip down a notch, she ran like hot stink up to 27mph then started slowing down to 24mph and began 4-stroking. im unded the impression that i need a bigger jet but i dont really know how/what to drill out.

GearNut · Jun 5, 2011

Ok, this is puzzling. 4 stroking is caused by a too rich mixture. If it just seems to loose power and not rev out then it is a too lean mixture.

2door · Jun 6, 2011

But his plug is almost white. And that was before he richened the mix. It could be that his defination of "four stroking" is incorrect and in fact he's still a little lean.

treyoh5. Try lowering the clip one more notch or the lowest one and get back to us with the results. I'd still try the Palmetto for speed runs

(When I was a kid the big thrill was trying to see how fast we could take the big bend.)
Tom

treyoh5 · Jun 6, 2011

Will do, I may be Incorrect on my description of four strokin, she loses power slowly its not a quick bog down.

2door, I've taken that turn on the Palmetto at 132mph [in my rx8 ;-) ]

treyoh5 · Jun 6, 2011

alright so i rejetted my carbs main jet with a 1/16th bit (smallest i have) and it zooms up to 25mph under 1/4-1/2 throttle and dies out if i go WOT. will adjust the c-clip needle position to leanest tomorrow morning and report results

GearNut · Jun 7, 2011

Adjusting the c-clip position on the needle will only affect the fuel mixture from 1/8 throttle to 3/4 throttle position.
After 3/4 throttle, it is controlled by the fuel jet as the needle aperture is wide open after 3/4 throttle.

treyoh5 · Jun 7, 2011

ahh thanks for enlightening me, as you pretty much guessed adjusting the c clip did nothing for me other than make me fiddle with my idle screw

still getting a complete loss of power when i rip full throttle (i may have gone too big with the main jet size (1/16) ugh.

GearNut · Jun 8, 2011

What color is the plug now?

treyoh5 · Jun 8, 2011

couldnt ride her today, i adjusted the float level last night and changed the stopcock (petcock) to one with better fuel flow. woke up this morning and all my gas was on the floor... might have overfilled and leaked through a bad gasket in the bowl or something, will diagnose when i get home later today.

GearNut · Jun 8, 2011

Gas on floor! Yikes! Good luck fixing the leak, that's a dangerous one for sure.

HELP! some minor tuning issues

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