Plug chop

[DUSTY05]

i say put the 280s in it and let it ride!!

[peak-j]

I put the 290's in it, pulls hard through all gears. It will either go or blow at the dunes next weekend!

 

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[shee4202]

Hello all,

I wasnt sure if i should of started a new topic or piggy back on this one since its essentially the same topic.

I'm looking to get thoughts on the color of these plugs. I performed a plug chop at ¼ throttle (pilot circuit, air screw= 2 turns out/where max idle obtained), 1/2 throttle (needle, Clip pos second from the top), and WOT (Main circuit). They all look a bit lean to me, but the engine runs good on all circuits except the top end of the main. The top of the main just cuts off at the tip top.  I don't know if that's because the main is too small or if my carburetors are too small. I'm debating richening out each circuit a tad bit. What are your guy's thought's?

All of these plug chops were around 65-70 degree F and at ~1000' above sea level. This is my normal riding altitude. 

I'm running a 485cc cheetah engine with Trinity inframe pipes and k&n air filters. My timing is at 4° advance.Carbs are Mikuni VM36mm's. I'm running on 93 octane pump gas with klutz benol oil.

I only ride trails so I'm not looking to compromise too much of my low and mid range power.

[Jereme6655]

33 minutes ago, shee4202 said:

Hello all,

I wasnt sure if i should of started a new topic or piggy back on this one since its essentially the same topic.

I'm looking to get thoughts on the color of these plugs. I performed a plug chop at ¼ throttle (pilot circuit, air screw= 2 turns out/where max idle obtained), 1/2 throttle (needle, Clip pos second from the top), and WOT (Main circuit). They all look a bit lean to me, but the engine runs good on all circuits except the top end of the main. The top of the main just cuts off at the tip top.  I don't know if that's because the main is too small or if my carburetors are too small. I'm debating richening out each circuit a tad bit. What are your guy's thought's?

All of these plug chops were around 65-70 degree F and at ~1000' above sea level. This is my normal riding altitude. 

I'm running a 485cc cheetah engine with Trinity inframe pipes and k&n air filters. My timing is at 4° advance.Carbs are Mikuni VM36mm's. I'm running on 93 octane pump gas with klutz benol oil.

I only ride trails so I'm not looking to compromise too much of my low and mid range power.

Personally…to me…..I’d richer that up. It appears to be already on the ragged edge of lean.  Granted this is just my opinion. But I also don’t like rejetting mid day when the temps come up. But in a serious note….im not a fan of that light of jetting marks at all. 

[shee4202]

This is the first time that im really fine tuning this machine. Im also pretty new to the plug chop method. Also, I feel the same way about going a little richer all around. So I'm looking for dang near the color of the plug from the beginning of this thread?

Unfortunately I have to wait until spring to get back out there but I want to hit the ground running as soon as I get a nice warm day.

In the mean time, doing some PM. Cleaning carbs, air filters, chain, powervalves, polished parts. Inspecting the Reed Assembly's, changing exhaust pipe and silancer orings. 

 

[kawa110]

Run it more fat, your bearings and piston rings will be happy. Easier to change fouled or dirty plugs then replace a leaned out top end.

Unless ur racing for money, run it on the edge of lean and get the most power you can, just be prepared to replace pistons.


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[Tedder]

Done properly, a plug chop only gives a read of the main circuit at wide open throttle. It's useful to me on my asphalt motors but that's all it covers.

[shee4202]

If not plug chops for pilot and needle, what is the best way to dial them circuits in, feel, response and exhaust smoke?