Author Topic: Valley MX Open Practice Video (Read 6594 times)

Allison#51 · « **on:** August 14, 2015, 08:30:50 AM »

http://youtu.be/3TQcvJc0taQ
Here's a video from practice Wednesday. It was the first time I've really got to open her up and it was a lot of fun. I'm fighting a low end bog though and I was hoping you guys could help me get to the bottom of it. I know my gearings too tall but I think there's more of an issue with the way it was cutting out. It seemed like the longer I went into a run the more it did it like I was losing fuel once the level got down a little ways. I also might be a little lean on the low to midrange adjustment on the smartcarb.

Tbone07 · « **Reply #1 on:** August 14, 2015, 08:58:19 AM »

What's your engine size and gearing at this point?

zcarlson12 · « **Reply #2 on:** August 14, 2015, 11:11:32 AM »

I'm probably way off but do you run your petcock in the ON position or RES? I only fill my tank to the little "knobs" inside the tank and run it on RES when I race. I ran into a similar problem a couple years ago, just a thought. Good ride by the way.

rablack21 · « **Reply #3 on:** August 14, 2015, 11:41:55 AM »

Man, that track looks like fun. It's interesting that the bog was not taking place until about 2 minutes into the video. It wasn't really happening before then that I could hear. Are you running an airbox? Is it possible you could have gotten water in the airbox? Also, as Zac asked, is it possible you could have been low on fuel?

Allison#51 · « **Reply #4 on:** August 14, 2015, 12:35:35 PM »

Engine is stock cylinder ported by Neil cr ignition 38 cast smartcarb. I believe a 19cc dome 110 dragon fuel. Gearing is 14-36 but I think I have a 38 I can throw on. Petcock has been modified. I drilled the ports out and ground the stop so the lever can be turned to where it'll flow out of both tubes. It had fuel. I do have foam in the tank though... I have a stock airbox with some outer wears vents. It's dry. Thanks guys

rablack21 · « **Reply #5 on:** August 14, 2015, 12:42:36 PM »

Quote from: Allison#51;57129

Engine is stock cylinder ported by Neil cr ignition 38 cast smartcarb. I believe a 19cc dome 110 dragon fuel. Gearing is 14-36 but I think I have a 38 I can throw on. Petcock has been modified. I drilled the ports out and ground the stop so the lever can be turned to where it'll flow out of both tubes. It had fuel. I do have foam in the tank though... I have a stock airbox with some outer wears vents. It's dry. Thanks guys

Gearing is definitely too tall, especially for that loamy and loose of a track. It actually looks sandy as well, but that would not cause the bog that you are hearing. Ok. So we know then that it is not fuel or water in the airbox. How old is the spark plug? Do you know what the float bowl fuel level height is?

Allison#51 · « **Reply #6 on:** August 14, 2015, 12:43:26 PM »

Plug is a BR9EIX

Allison#51 · « **Reply #7 on:** August 14, 2015, 12:45:40 PM »

Quote from: rablack21;57130

Gearing is definitely too tall, especially for that loamy and loose of a track. It actually looks sandy as well, but that would not cause the bog that you are hearing. Ok. So we know then that it is not fuel or water in the airbox. How old is the spark plug? Do you know what the float bowl fuel level height is?

When I first set the carb up I checked the float level and it was right on the 22mm from the top that sc recommends.

rablack21 · « **Reply #8 on:** August 14, 2015, 12:52:00 PM »

You might just try throwing in a cheap plug like the BR9ES just to see if the bog goes away. It may just be that it is time for a new plug.

Allison#51 · « **Reply #9 on:** August 14, 2015, 12:57:16 PM »

Okay I'll grab some today. I was planning on getting some more of the iridiums if I could find them too. When I was at the track it did the same thing with two different plugs. The second one I put in wasn't new but slightly used. I thought these iridiums were supposed to last a long time. Think it could be that same issue you had from the bad o rings on the nozzle?

rablack21 · « **Reply #10 on:** August 14, 2015, 01:06:42 PM »

Quote from: Allison#51;57134

Okay I'll grab some today. I was planning on getting some more of the iridiums if I could find them too. When I was at the track it did the same thing with two different plugs. The second one I put in wasn't new but slightly used. I thought these iridiums were supposed to last a long time. Think it could be that same issue you had from the bad o rings on the nozzle?

Does your engine seem like it is smoking a little bit more than it was?

Allison#51 · « **Reply #11 on:** August 14, 2015, 01:29:48 PM »

No I don't think so. Doesn't smoke much really

Allison#51 · « **Reply #12 on:** August 14, 2015, 02:02:13 PM »

The pipe looks lean like it got real hot. Turned colors and even burnt the sticker. End cap has kind of a white smoke. I was revving the crap out of it but I never saw the coolant temp over 180 when I came off and the plug looks decent. Hmm

rablack21 · « **Reply #13 on:** August 14, 2015, 02:11:07 PM »

I think the pipe color is unrelated. Because if anything, your plug looks a little rich, definitely not lean, from the pic you posted. Have you ran it since the practice? If so, did it still have the slight bog?

Allison#51 · « **Reply #14 on:** August 14, 2015, 02:12:53 PM »

I'm thinking about shortening the pipe section up some more it seemed to help last time I did it.