What gives?

[briyenkieth]

ok this is another carb question. The bike is a 400 stock internals, jc whitney reverse megaphone muffs, stock jets in the carbs/rebuilt w/ new rings and new boots and rings. As of now im still waiting on pods and jets to show up. So I don't have any filtration. After much fiddling with the floats and learning a new way to use my slide caliper, they are set at 26mm per manual. Air fuel mix screw at one turn out and needle set in lowest/richest notch. To my understanding it would run pretty bad and it does, however opposite of what would be expected. Im carbon fouling plugs,color chart says rich. This is got me so upside down right now.

[Nessism]

Could be poor spark. Can you see a fat blue spark if you lay a plug on the side of the engine and turn over the engine? The plug boots can develop resistance too so check them if you have an ohm meter.

[mighty13d]

don't hold the plug while turning the bike over. If you want to, make sure a camera is on you when you do!!! I think a lot of people have done this. Hopefully only once though.

[briyenkieth]

I do have a nice blue spark, just checked. Could the boots still be bad? Oh and I know better than to hold the plug, learned that young! The more I think about it I think I may need to check my floats. Manual says a +/- of .030" and that ain't much. This would make it rich wouldn't it? I've read a bunch of threads and the manual over and over now and this is driving nuts.

[Billy Ricks]

I do have a nice blue spark, just checked. Could the boots still be bad? Oh and I know better than to hold the plug, learned that young! The more I think about it I think I may need to check my floats. Manual says a +/- of .030" and that ain't much. This would make it rich wouldn't it? I've read a bunch of threads and the manual over and over now and this is driving nuts.

Fuel level in the bowl does indeed have plenty to do with mixture. Full rich on the needle is too far with the exhaust you have. It's probably pretty close to stock as far as flow. Bad boots would lean out the mixture. Fix those two things then wait on your pods before you try to sort things out completely. Just keep reading your plugs doing chops at different rpms.

[Steve]

After much fiddling with the floats and learning a new way to use my slide caliper, they are set at 26mm per manual. Air fuel mix screw at one turn out and needle set in lowest/richest notch. To my understanding it would run pretty bad and it does, however opposite of what would be expected. Im carbon fouling plugs,color chart says rich. This is got me so upside down right now.

Just what is it that you were expecting? Assuming that 26mm is the spec, having the needle at its richest position and the pilot jets turned richer than stock (usually 5/8 to 3/4 turn out), you somehow expected it to run lean? Your carbon-fouled plugs show that it is running rich, as your settings would indicate.

Just keep reading your plugs doing chops at different rpms.

Actually, plug chops are done at specific throttle openings, rather than RPM. For example, it's possible to see over 6,000 rpm with very small throttle openings while sitting in neutral. You will NOT be into the main jet under those circumstances. Your best bet is to mark the throttle grip and housing with IDLE, FULL, 1/2 and 1/4 throttle openings, then hold the throttle at those settings to do your plug chops.

Here is how I did it:


.

[Billy Ricks]

Just what is it that you were expecting? Assuming that 26mm is the spec, having the needle at its richest position and the pilot jets turned richer than stock (usually 5/8 to 3/4 turn out), you somehow expected it to run lean? Your carbon-fouled plugs show that it is running rich, as your settings would indicate.



Actually, plug chops are done at specific throttle openings, rather than RPM. For example, it's possible to see over 6,000 rpm with very small throttle openings while sitting in neutral. You will NOT be into the main jet under those circumstances. Your best bet is to mark the throttle grip and housing with IDLE, FULL, 1/2 and 1/4 throttle openings, then hold the throttle at those settings to do your plug chops.

Here is how I did it:


.

Good explanation of the plug chops. I should have gone into more detail or provided a link. I thought maybe they would do a search and do their own DD. He'll need to do most of the chops in lower gears to be at the right throttle openings and not be going 120 mph just so he knows. Probably 4th for WOT so he can keep it pegged there long enough.

[briyenkieth]

thanks for the help and suggestions guys. Yes I really thought it would be lean. The float level and mix screw are set to the manual, I have two books and they concurr. I am guilty of the needle setting. So to start I'm going to check float level and move the needle back to the stock setting. Then start checking plugs again today.
I did polish and rebuild my master cylinder last night. Amazing how much a new cap and resivoir make a difference.

[briyenkieth]

ok big thanks guys!! I'm lean all over throttle range. Which is were I should be with no filters and stock jets and such. Shop says jets today or tomorrow, pods by next week. Insert image of sad clown here. At least I'm were I should be. I think it was mostly the floats. They were still a bit off and with only .030 of tolerance a bit is like a mile.as a side to one reply I am friendly with the search feature. I've read so many carb threads it made my head spin and that's when I started asking for help. Again thanks for giving me the help I needed.