Flat spot on top (Sometimes)

[Maul]

Sled is an 07 Dragon 700, home brew turbo but normal parts, 2860 turbo, OVS air box, attitude box, and so on.

The problem I'm having is the sled will run great on one climb then the next it will rev up and start to pull but in 2-3 secs in will fall on its face at wot like its running out of fuel. I think if it was a fuel problem it should do it every time.

Thought maybe it was hot charge temps so took side panel off and tested it. At first I thought I had it but then after 3 pulls then bam dead again. I let it sit for a good 20 mins and hit the hill again but the problem was there on the first pull so I don't think its a temp problem.

Im having a hard time because its so inconsistent and I can't seem to repeat the problem any wich way. It just decides to crap out at random times.

Any ideas?

 

[sledhead9825]

Whats your AFR at WOT ?

 

[Maul]

12.2-12.6

 

[sledhead9825]

Try a little more fuel. Look for high 11s to low 12s.

 

[Maul]

That makes since if it was running out of fuel and leaning out but why would it not do it every time at wot.

 

[sledhead9825]

Like you said 12.2 to 12.6 . At 12.2 your okay at 12.6 going a little lean and they dont like it. On my machine it is dialed it runs great, but my AFR is always floating between 11.9 to 12.2. Give it a try.

 

[Maul]

ok Ill add some fuel. But I have seen it around 13 and it was pulling strong then.
I know thats lean but why would it not lean out and fall on it face then but does sometimes at 12.6

 

[sledhead9825]

If you saw 13 and it felt like it was making power. It was false. If it was really at 13, its not making power. These engines do not make power at 13 AFR WOT. IMO. Try a little fuel and only do one thing at a time.

 

[sledhead9825]

What make of AFR gauge are you using?

 

[Maul]

AEM

 

[Maul]

So went out and added fuel. Things just got worse. The flat spot was sooner and more often but AF was good.
I started taking away fuel slowly and things got better the more I took away.

Rode the last 2 days and the sled ran great no bog or flat spot at all.
I believe my gauge is wrong at this point because I'm seeing high 13s to mid 14s and even 16s in the mid.

I don't think there is anyway that it could run that good at those numbers.
Kinda scary to see those numbers but the sled ran really good and the plugs look good for 2 days straight.