Author Topic: APT Smart Carb Testing today 40mm Billet Sphynx 363 (Read 35837 times)

Burns363R · « **Reply #30 on:** October 08, 2014, 09:16:59 PM »

Why dont the videos imbed on this site?

j@y · « **Reply #31 on:** October 08, 2014, 09:42:07 PM »

Nice! She looks ready now. Bring on the 4 pokes

Pumashine · « **Reply #32 on:** October 08, 2014, 09:42:28 PM »

What was the trick to setting the float height?

Burns363R · « **Reply #33 on:** October 08, 2014, 09:57:48 PM »

Fill the carb up and take the body off the bowl and measure the fuel level.

Or put a tube on the bowl drain and open the drain with the tube going back up toward the top of the carb so you can get a bowl reading. Cory told me 22mm down from the gasket face. I found that my bike like the 17mm level better. Basically it allows the needle to fall farther from the seat and allow more fuel flow under WOT.

DnB_Racing · « **Reply #34 on:** October 08, 2014, 09:59:49 PM »

wow that's one LOOOONG wot..but it sounded great...

Id be afraid to open one for that long...do you have a temp gauge if so what was your temp once you parked it??

Pumashine · « **Reply #35 on:** October 08, 2014, 10:13:06 PM »

Quote from: Burns363R;44182

Cory told me 22mm down from the gasket face. I found that my bike like the 17mm level better. Basically it allows the needle to fall farther from the seat and allow more fuel flow under WOT.

Where was it set when the carb ran out of fuel?

Burns363R · « **Reply #36 on:** October 08, 2014, 10:18:47 PM »

28mm maybe? I cant remember, but it was wrong because the tab was pushed down below plane of the rest of the float system. It should at plain or slightly farther away from the body.. This is the tab that controls the float. If any of that even makes sense in typing.

I have a temp gauge on it. Maybe 160? It was way to cool IMHO for as long as it ran. I probably idled for 5 minutes before i went out on it. outside air temp is 60, so that plays a big factor. And i have switched to a BB stinger on my pipe, so temps should be down.

Pumashine · « **Reply #37 on:** October 08, 2014, 10:56:34 PM »

Quote from: Burns363R;44187

28mm maybe? I cant remember, but it was wrong because the tab was pushed down below plane of the rest of the float system. It should at plain or slightly farther away from the body.. This is the tab that controls the float. If any of that even makes sense in typing.

I went through the adjustment process to keep the carb from flooding. I never got an answer from APT why the float level effected the fuel delivery rate. Thanks for the info Kyle! Just want to know in case I run out of fuel again.

rablack21 · « **Reply #38 on:** October 09, 2014, 07:04:26 AM »

Yep, starting to sound better now. Tony, as Kyle described on the float bowl, I had the same conversation with Corey as well. That is why float level is so important, probably even more so on a modified engine. That's why that is one of the first things to check in the instruction manual. Is it bothersome to do when you first get your carb and you just want to put it on and rip? Yes, but it is worth taking the time to do.

Burns363R · « **Reply #39 on:** October 09, 2014, 07:40:25 AM »

The instruction manual said nothing about float level based on engine performance, just checking for to make sure it doesnt overflow. FYI.

Burns363R · « **Reply #40 on:** October 09, 2014, 07:42:47 AM »

Im wondering what the performance would be like if you run to rich of metering rod. Im awaiting a text back from Cory. I was lean to start so i put my 74 FMR in, and then i raised the bowl. Obviously the plug looks great and the bike runs great, but i still feel its missing something. I wonder if i need to step the FMR back now. With the way these FMR work, the carb will adjust the fuel based on the engine demand, but if its not using a optimized FMR, you may not get the best atomization off of it.

rablack21 · « **Reply #41 on:** October 09, 2014, 07:52:26 AM »

Quote from: Burns363R;44201

The instruction manual said nothing about float level based on engine performance, just checking for to make sure it doesnt overflow. FYI.

I never said that it did. But if it is somehow off from the factory (somehow bumped or accidentally changed through assembly or packaging or whatever) then it could negatively affect performance. That is ONE of the reasons they have you check it once you get it. And yes, overflowing would be a negative as well. lol

rsss396 · « **Reply #42 on:** October 09, 2014, 11:14:16 AM »

It sounds like to me, if a simple power jet was added you could easily fix the topend lean issue some guys are having, even Honda used power jets in the late 90's but they had elec versions that would turn on and off.

Jerry Hall · « **Reply #43 on:** October 09, 2014, 12:37:09 PM »

Quote from: Burns363R;44177

Did another WOT long pull tonight. Bike felt great. I changed the cover on the Go Pro and you can hear it alot better. The Go Pro is mounted to the handle bars, hence the weird angles when I'm doing wheelies. The pics of the spark plug are from right after killing the throttle when i came back into the garage. Looks pretty good to me. sounds like we have a winner.

http://youtu.be/lBFdg-jGZ98?list=UURhJ3oFnLARwWYVG9fDuWKQ

It sounds like the engine is slightly rich on that mile long plug chop. Maybe it is the camera's microphone but I think I can hear a rich missfire at the peak RPMs.

From the looks of the video it looks like you are running about 70 MPH or less. With the gearing you are running the engine will be running way past the power peak and may act rich and give inaccurate plug readings. The tip of the spark plug shows rich from what I can see in the pictures. We really need to be looking at the spark plug under a 2 to 5 power magnification. The spark plug steel shell shows the combustion temperatures were in the ballpark somewhere in the RPM range but the spark plug porcelain tip was too cold the last 15 seconds or so of operation. The porcelain tip showing rich may also be due to running a heat range that is too cold. Trying to read a spark plug for best combustion temperature is meaningless if the heat range is not correct. Is that a B9ES spark plug?

If you changed the gearing to increase the speed about 15 to 20 mph, I think that the spark plug would show a more accurate reading of the mixture on top end that produces the best acceleration and is safe while the engine is under acceleration.

Summary:

Be careful reading spark plugs on plug chops that do not imitate running the engine (loading the engine) the same way it will be raced or used. If you ride/race the quad where the engine is spending most it it's time in the over-reved state like shown in the video, I think that the jetting is rich and safe at that RPM. If you ride on a track where you spend most of your time accelerating through the gears and then breaking for corners and such, I would suggest revising your method of testing for determining the correct air/fuel mixture by reading spark plugs.

Burns363R · « **Reply #44 on:** October 09, 2014, 01:27:35 PM »

I appreciate the input Jerry. I will be trying a slightly leaner FMR tonight and see how it performs. I feel that it is also rich on top. The motor feels like its being held back. But that gearing and tires in combination with the 2" of loose sand may be putting to much load on the bike. I feel like it should rev out better. I believe that is a B8 Plug. I will go to a B9 which i usually run, but switched to the the b8 in an attempt to stop detonation

My goal with this test is to make sure it wont melt down in the open fields that occur during harescramble racing.