Stalling, backfiring, strange spooge

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Mildew
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Stalling, backfiring, strange spooge

Post by Mildew »

Sorry for writing a novel here.

Bike Specs:
2004 220
Fresh Wiseco top end this month
Stock exhaust
PJ 42
MJ 145
Needle clip Position 2
AS- I adjust daily to meet conditions- usually within 1/4 turn from 1.5
5 month old 607s

I'm hoping this is a pre-mix related problem. I've had this bike about 8 months and only ran Amsoil Interceptor for the first 5 months until my distributor became unresponsive. Since then, for the next 3 months, I ran H1R. Last weekend I tried Golden Spectro. I was uncomfortable with the oil so instead of the recommended 53:1 I mixed @ 43:1 with 93 oct eth-free gas.

Last weekend I burned about 2 galons with a fresh BR8eix. This weekend my bike started to have an exhaust backfire when I'd shut the bike down. Finally it quit on me and i thought I was out of gas. I flipped it to reserve and could only go about 10 feet before it would stall and backfire. I changed the plug on the trail to a new BR8ES and rode back to the truck. the bike felt better than it had before the stalling but underpowered.

The plug was black and full of carbon.

When I got home, I washed the bike and removed the silencer drain plug and to my surprise, nothing came out. I started the bike and feathered my hand over the exhaust and and a 3", almost solid piece of spoo came out like a worm. I let the pipe get warm and continued to feather the gas and place my hand over the pipe. The spoo that came out was enough to almost fill a coffee cup and ranged in consistency form toothpaste to Hidden Valley Ranch dressing.

My best guess is to go back to Interceptor @ 50:1 and ride it like I stole it but thought I had better check here first.

Thanks
2004 KDX 220
2002 YZ 125
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rbates9
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Post by rbates9 »

Sounds very odd. I am not familure with the BR8eix plug but maybe that may have had something to do with it. I was using golden spectro for a long time at 32:1 and didn't have too much spoo problems. Might be you need to adjust your jetting to your new fuel mix.
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scheckaet
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Post by scheckaet »

I'd start with a good clean up of expansion chamber and silencer. Maybe it was already filled up with spooge and only came out now...
Make sure you use gas from the same place and that they haven't recently added more ethanol or whatever the hell they add in there :roll:
jet the bike with whatever ratio you're using NOW. If you've changed mix brand AND ratio, the odds are the jetting will change.
Make sure your electrical connections are good maybe something gets loose when the bike is warm / hot.
underpowered? like the kips doesn't work or like jetting is off?
Mildew
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Post by Mildew »

The IEX is just an iridium plug. I normally use a BR8ES but some times I'll use an EG or IEX. The only difference I ever noticed is $.

It's hard to explain the underpowered part. It felt like it couldn't breathe. I think it was caused by the silencer being full of thick spooge.
2004 KDX 220
2002 YZ 125
island220
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Post by island220 »

Ive heard you should never change premix unless with fresh rebuild cleaned kips exhaust ect, deferent oils dont always mix well
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scheckaet
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Post by scheckaet »

now that island mention it, I had a similar problem way back, I changed mix, and didn't empty the gas I had left in the tank.
I would foul plug and the bike wouldn't run worth a damn, almost impossible to restart.
I emptied the tank and the problem was solved.
Might be what you experienced if you mix 2 different batch of oil or premix.
Mildew
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Post by Mildew »

Ya know, I honestly can't remember if I mixed batches of fuel or not. If I did I think i would have only done it if there was a tiny bit left in the tank.

I drained the tank and carb this morning. I'll have to miss Supercross but I think I'll try to get out to the woods today to see if that was the problem.

From the start I thought this was some kind of premix issue and your replies are starting to validate that.

Another thing I forgot to mention was that it was making what sounded like a backfire in the middle of the expansion chamber. It was difficult to pinpoint with the double-walled, quiet pipe and a helmet on. It was really reduced after the plug change but still there. All I can do is guess what caused that but I'm leaning toward possibly increased back pressure from all the thick spooge in the silencer.

I appreciate the replies.
2004 KDX 220
2002 YZ 125
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scheckaet
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Post by scheckaet »

gap your plug also (they usually come pretty close from factory though).
maybe you're experiencing ping? knock? from bad gas. What octane are you using? I get the highest I can get at the pump (93?) and can tell the bike run better than on 89.
Mildew
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Post by Mildew »

I went out for a little ride this morning. Everything seemed fine. I was only able to go about six miles. My buddy's KX25f died and I had to tow him out of the woods.

This wasn't enough of a test to say that the problem is fixed but it ran perfect.
All I did was drain the fuel and replace it with 94oct and H1R @40:1
2004 KDX 220
2002 YZ 125
mrkingers
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Post by mrkingers »

Hi, I had a Yamaha IT465 last year that did this.
I tried everything. I accidentally left the baffle out of the silencer and started it, sounded good, took it for a spin and it flew.
I had cleaned out the exhaust after filling it with nuts and washers and shook the crap out of it. Obviously it didn't work.!
I bought a new DG silencer from dirtoverstock.com and it was like riding a new bike.
At that time i did a quick vid and stuck it on youtube for the Yamaha IT guys to look at.

The bike was hard to start, struggled to hold idle. Would hardly rev and generally ran awful.

Try riding the bike with the silencer off? and see what happens
KarlP
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Post by KarlP »

The stock silencer is known to plug up occasionally.

I kept thinking I was getting to be a better and better rider; I was using full throttle more and more. This is on a nearly stock KDX220 some years ago. I finally sent my head and carb off to RBD for his work. When I installed them, the bike would hardly go at all. RBD had supplied the carb with a 150 MJ, I ended up getting it to run sort of with a 140 MJ. When I called RBD he asked me if I had left a rag in the airbox. I took the seat off and the air cleaner out. He asked me to start it up and rev it a bit with him on the phone.
At that point I could see the carb inlet and the exhaust outlet. We both came to the same conclusion at the same time. The smoke coming out of the exhaust looked like about as much as a cigarette burning.

I had a spare silencer and put it on. Off to the races!
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
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Mildew
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Post by Mildew »

Sorry, I've been away and haven't seen these latest replies.
The bike is still running fine. I still don't know for sure what the problem was. I haven't used gas from that station or that oil since.

I finally ordered a gallon and a half of Interceptor. Interceptor makes my bike happy.

I rode for 4 days out of state over the Memorial weekend. Elevation was over 1,000 feet different than here and I got a little more spoo than usual but everything is good.
2004 KDX 220
2002 YZ 125
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