Hello not sure if I am asking this in the right place, I recently rebuilt the top end and put a fmf pipe and silencer on as well as put a 280 main in. My question, is it common to see a rusty red colored plug? I was waiting do plug chops until i bought a few but was wondering if I'm way off on my jetting
Rust colored spark plug
- Thread starter 2004
- Start date
A #280 main should be close and on the richer side if the pipe is the only mod. Needle on the middle slot.
Did you just pull the plug out after riding it, if so the plug should look a little oily and blackish.
If you have altered the breathing in any other way such as a foam air filter or taken the air box lid off you will need to jet up 2 or 3 sizes larger.
Have you tested the motor for air leaks since rebuild, if not you could be sucking air producing a dangerously lean mixture.
Did you just pull the plug out after riding it, if so the plug should look a little oily and blackish.
If you have altered the breathing in any other way such as a foam air filter or taken the air box lid off you will need to jet up 2 or 3 sizes larger.
Have you tested the motor for air leaks since rebuild, if not you could be sucking air producing a dangerously lean mixture.
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How much time on the plug? New since rebuild? What did it look like before build? What kind of oil you using? What kind and heat range is plug?
Blaner
Your Friendly South African Ambassador
Rusty red is not a good colour, you ideally want a dark brown, so id agree with Blaaster and say you are a touch lean. However, a 280 should be more than enough. Do the leak test. Chances are a reed cage gasket leak.
Thanks guys, the plug was new when it was rebuilt I had the stock pipe on and did my heat cycles with it. After putting on the fmf, changing to a foam air filter and rejeting the carb I took it for a little rip and it seemed kind of boggy so i pulled the lid off the air box and it took it for another little rip and it ran strong. I pulled the plug and it was a rusty color. I will do a leak down test. Another question I have is if i had a leak would taking off the lid make a noticeable difference?
Blaner
Your Friendly South African Ambassador
A leak test is performed in order to test the engines ability to remain sealed under pressures equal to those experienced under operation.
A leak (failed leak test) indicates the presence of an bad seal somewhere that, if it is allowing pressure to escape can also allow air to be introduced under vacuum. Added air to to the engine via a leak is not measured by the carb and thus the correct amount of fuel is not added. this allows the motor to run LEAN which is very dangerous.
A leak test device connects to the engine via the intake boot with the carb removed. All airways behind that are not included in the test and do not matter (airbox) because they provide air the carb along the correct path.
Taking the airbox lid off does provide more air for the engine but all this air must pass through the carb and me metered and jetted for.
Common leak spots:
A leak (failed leak test) indicates the presence of an bad seal somewhere that, if it is allowing pressure to escape can also allow air to be introduced under vacuum. Added air to to the engine via a leak is not measured by the carb and thus the correct amount of fuel is not added. this allows the motor to run LEAN which is very dangerous.
A leak test device connects to the engine via the intake boot with the carb removed. All airways behind that are not included in the test and do not matter (airbox) because they provide air the carb along the correct path.
Taking the airbox lid off does provide more air for the engine but all this air must pass through the carb and me metered and jetted for.
Common leak spots:
- Reed cage mating to cylider
- head gasket failure
- base gasket failure
- crank seal failure
- Incorrectly torqued or loose spark plug
Blaner
Your Friendly South African Ambassador
Remember to put the piston at BDC before doing a leak test. This allows the test to extend to the head gasket. if you put the piston at TDC, the head gasket is protected from the air pressure by the rings and hence will not reflect on a leak test even if blown.
Hello everyone, I know it has been a while but thought I would let you know the result of my leak test. The reed cage was leaking something terrible, I sealed it up and am now running a 280 may even go down to a 270 main, it pulls hard and have had a few nice long trouble free rides. As always thanks for the help. And sorry about the delayed response in my findings.
Many thanks for taking the time to return and post results, for us guys who offer help it is payment.
Leave the #280 there if it is pulling strongly, a richer mix is insurance.
Some rep points on the way, just a little way of saying thanks.
Leave the #280 there if it is pulling strongly, a richer mix is insurance.
Some rep points on the way, just a little way of saying thanks.
