The last post on jetting...I hope.

syko

Member
Jan 10, 2004
182
0
I am going to try my best to make this THE LAST post on jetting as so far I have taken up the bandwidth limit for this site on my boring jetting posts alone.
so here goes:


I tried my incredibly lean settings of:
top clip on needle jet.
380 main
35 pilot and two and half turns on air screw.
32:1 fuel mix

the bike was a little better however the brand new BR9EIX plug i put in for the day started to foul up. I took it out at the end of the day and saw it was pretty black although during my riding it perfromed reasonably well and I wouldn't have known it was fouling if i hadn't have taken it out.

However, i noticed that if I reved the bike very quickly (short sharp revs) it goes all boggy a kind of bwoooooaaaaaaaag noise until i stop reving when it then comes back to normal. :ugg:

I have been told that this usually means too lean somewhere on the jetting but how can this be if my plug is still starting to foul up.
It would make more sense to me obviously if it was too lean as the jetting is as lean as you can pretty much get but still the plug is going black.
It can't be my riding because even thought the track was a very tight, slow track I always keep it in the high revs even if that means me being in 1st gear for much part of the track (basically it is only very occasionaly when I am in the bottom end of the revs)

So, once again, I am still lost.
I am wondering if it is perhaps unburnt oil in the chamber. one thing I haven't done after break in is take the cylinder head off and give it a good clean out. I noticed quite a few times that the grey pipe which comes out of the front of the engine where the cylinder is was spewing out a bit of thick black oil. Not lots but whenever i stopped the bike for 20 mins i would notice there was a couple or three big droplets of black oil coming out.
could that signify anything or is that normal.
would giveing the chamber a good clean out help things or sticking in the 8 plug i bought to really burn it all off.

any ideas?


(once again, I am sorry for these mind numbing jetting questions and all I can say is that i have been overwhelmed by the replies I ahve had from previous posts so far, to take time out to try and answer my questions is massively appreciated and if it wasn't for this site and you guys i wouldn't have a bike that runs. Thankyou) :cool:
 

Porstala F9

Member
Jul 30, 2003
345
0
What brand oil are you premixing? Also, what is the temp over there, and how long are you warming it up for?

So did you try the 8 heat range plug yet?
The heat range might have something to do with it, and is deffinetly worth a try. I say put it in and try.. but I would put those jets a little richer. That seems pretty lean! I would put the clip back at the 2nd position instead of the top position. Usually if you have to put it at the top position, you should buy a leaner needle alltogether, but I dont belive that is the problem, and that might be where the bog is coming from. Maybe doing that, and putting a 400 main in when trying the 8 might work. Try it out :)

But if all this and all else fails, there may just be another problem.. Its unlikely for a newer bike to have fouling problems unrelated to jetting, but I guess its a possibility. A very small possibility though, my guess is the jetting.

That black goop is normal I belive. Everyones bike around here does that anyways..

Good Luck!
 

syko

Member
Jan 10, 2004
182
0
Hi Tiylu.
I'm using silkolene synthetic competion race oil.
I warm it up for a good few minute before I do anything.
the temp is averaging about 81F (27C)

No, i didn't try the 8 plug yet, I bought one but didn't get chance to run it. I wanted to try a brand new 9 plug on my lean settings to see what happened which ended up with a fouled plug.
we are sea level here as well.

what do you think about giving the chamber a clean out. It does reccomend doing that in the manual after break in but i didn't do it. do you think that could contribute anything to all this?

also, the bog was there when i had the needle on 2 a couple of weeks ago. so could it be the pilot maybe being too lean? it's a 35 in there at the moment.
I would be surprised too if it has another fault, it has about 5-6 hours use on it and that includes break in and I have hardly thrashed the thing yet.
 

MXJIM_10

Member
Jun 8, 2004
7
0
I would go back to stock jetting and start over from there.My bike has stock jetting and rips.No fouled plugs .WHY bother with what a plug looks likeas long as the bike runs good?Also, use the original plug type.I would go down one size on pilot jet. Hope this helps.
 

Porstala F9

Member
Jul 30, 2003
345
0
Hmm, well I would try to put the jetting a little richer to be on the safe side, and try out the 8 for a little. It cant hurt ;)

As with cleaning it out, I would do that as a last resort, to of course jetting and trying the 8 out and looking for other problems. I probably fouled at least 10-15 spark plugs and since the day I got my bike, have yet to dissasemble the top end. They do suggest taking it apart, inspecting it, and measuring some things as well as changing the piston rings, but I didnt do any of this and even after how incredibly rich my bike was running and fouling all these plugs, I rejet and for almost half a year now, I have been on the same spark plug.

Just to make sure, you do turn off the fuel tap to off after you are done riding right? Also, burning out the excess fuel from the float by ilding the bike with the fuel off can help, or just tilting the bike on its side draining it out is sometimes good too. Also, be sure to mix up the gas before you go riding. I always hold in my front brake, and shake the bike around for a little before starting it to ensure that the oil and gas are mixed properly, and not all oil is sunk to the bottom of the fuel tank, and eventually goes right into the engine making a rich mixture. But this is probably not your problem.

Good luck, I'm sure youl figure it out! :aj:
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
Syko were going practicing this weekend so hopefully you can come and we can figure this problem out, i cant add you to my messenger as i will never get anything done.I get little enough done now already:) i will pm you if you want to go.
 

ScottS

Member
Dec 29, 1999
478
0
any chance you are sucking a little tranny fluid into the engine ? that might foul the plug even though you have leaned it out. is it possible you mixed the fuel wrong ( too much oil) that would lean it out too and explain the spooge.
 

ScottS

Member
Dec 29, 1999
478
0
Could possibly be an ignition problem too- with a new bike it is hard to figure out if it has never run right, usually they run right for a while and then go south, usually easier to find the problem. With a new bike we assume everything is correct but that is obviously not the case- a leaky float valve for example might flood the engine, or the choke circuit might be on even though it looks like you shut it off ( you did shut it off, didn't you ?) because the carb is assembled wrong etc etc
 
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