Author Topic: APT Smart Carb Testing today 40mm Billet Sphynx 363 (Read 36562 times)

Pumashine · « **Reply #45 on:** October 10, 2014, 08:55:45 AM »

Quote from: Burns363R;44246

I will be trying a slightly leaner FMR tonight and see how it performs. I feel that it is also rich on top.

Oh man, you had me real worried there Kyle. I have been trying to richen up the lower end to get the top end richer. My plug chop was extra white at WOT. I am a little confused since you did not pull the plug at WOT but after returning to the garage.

Burns363R · « **Reply #46 on:** October 10, 2014, 08:57:40 AM »

I was WOT up until right before the garage, and i coasted most of the way into it.

I didnt get a chance to change needles last night. I will tonight.

Tony, you really need to know which FMR you have in your bike.

Pumashine · « **Reply #47 on:** October 10, 2014, 09:03:04 AM »

Quote from: Burns363R;44306

Tony, you really need to know which FMR you have in your bike.

You know how frustrating it is to talk to Tom the one that answers the phone. He is very nice to talk to but I get the feeling he is not a tech.

Burns363R · « **Reply #48 on:** October 10, 2014, 09:04:26 AM »

Agreed, he doesnt know his stuff. Cory has been really helpful for me. He recommended me going back and trying the 76 now that i have proper fuel flow.

Pumashine · « **Reply #49 on:** October 10, 2014, 09:11:21 AM »

Quote from: Burns363R;44308

Agreed, he doesnt know his stuff.

Tom told me to set the float level 1/4" below the top of the float bowl. The manual says 17mm and he says 6mm. I misplaced Cory's phone number damn it. Do you know his cell #?

rablack21 · « **Reply #50 on:** October 10, 2014, 09:25:07 AM »

Corey cell - 307-761-1251. I try to only talk to Corey. He is very helpful.

Burns363R · « **Reply #51 on:** October 10, 2014, 09:45:33 AM »

Ya im right at 17mm for mine. Funny thing is cory told me 22mm the other day for some reason. But 17mm is good, i may try to go a little more, somthing like 16mm next time i dare take the carb out. Its a mother to get in there.

rablack21 · « **Reply #52 on:** October 10, 2014, 10:03:40 AM »

Quote from: Burns363R;44315

Ya im right at 17mm for mine. Funny thing is cory told me 22mm the other day for some reason. But 17mm is good, i may try to go a little more, somthing like 16mm next time i dare take the carb out. Its a mother to get in there.

Kyles, if I remember correctly, 22mm is also what the manual says and is normal for most applications. However, I think if you have a strong "sucker", then 22mm is not enough to keep up with the demand.

Pumashine · « **Reply #53 on:** October 10, 2014, 10:05:43 AM »

Quote from: Burns363R;44315

Ya im right at 17mm for mine. Funny thing is cory told me 22mm the other day for some reason. But 17mm is good, i may try to go a little more, somthing like 16mm next time i dare take the carb out. Its a mother to get in there.

Yes, Its frustrating taking it off and make an adjustment than does not do anything different. Pardon me on the manual quote of 17mm. It is actually 20mm, just over 3/4". I checked it before installing the carb so I should be good. Still seems lean, but maybe I am just used to too rich.

rablack21 · « **Reply #54 on:** October 10, 2014, 10:17:30 AM »

Have you done any plug chops lately, Tony? If so, can you post some pics. Maybe we can help.

Pumashine · « **Reply #55 on:** October 10, 2014, 10:43:22 AM »

Quote from: rablack21;44321

Have you done any plug chops lately, Tony? If so, can you post some pics. Maybe we can help.

I will do them tomorrow. I keep forgetting to put a new kill switch in.

rsss396 · « **Reply #56 on:** October 10, 2014, 11:49:39 AM »

Quote from: Burns363R;44246

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.

the B9 will be less prone to promoting pre-ignition and detonation because it runs cooler than the B8, but the B8 is less likely to foul

Burns363R · « **Reply #57 on:** October 10, 2014, 11:54:49 AM »

The bike had a B9 in it anyways. Yes the higher the number the colder the plug, which leads to less detonation caused from the plug (detonation can be caused by other things obviously). But easier fouling. I said that wrong.

Jerry Hall · « **Reply #58 on:** October 10, 2014, 12:08:05 PM »

Quote from: Pumashine;44305

Oh man, you had me real worried there Kyle. I have been trying to richen up the lower end to get the top end richer. My plug chop was extra white at WOT. I am a little confused since you did not pull the plug at WOT but after returning to the garage.

A white spark plug is not an indication of being lean. A white spark plug is an indication of the amount of time on the spark plug and the temperature of the porcelain since the spark plug was installed. If Kyle puts a new spark plug in his engine that is rich enough to miss-fire and made ONE short WOT pass, the porcelain will come out looking like a new spark plug. It takes some time for the porcelain to turn tan on a well tuned carburetor. If your spark plug turns tan in one short plug chop pass the porcelain temperature is too high. High porcelain temperatures are due to excessive combustion temperatures or a heat range that is too hot. High combustion temperature is ok as long as the engine is properly designed/developed and not experiencing any detonation.

Using an eye loop magnifier to read spark plugs is essential if you are attempting to find the main jet size that will produce the most power before piston killing detonation occurs. Using an eye loop will allow one to see indications of slight detonation before you get to the point that you hurt a piston. If your engine is rich enough to miss-fire at high RPMs it is a waste of time looking at the spark plug unless something is wrong with your build that causes it to experience detonation as it is pulling up through the low to mid RPM range.

Burns363R · « **Reply #59 on:** October 10, 2014, 01:43:12 PM »

Quote from: Jerry Hall;44234

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.

New Run. New plug B9ES slightly leaner setting, but not much, 3 clicks leaner. Same 1/2 mile down and back run, motor was warm before the new plug was installed and ran.