Author Topic: Enfield runs like I have a rev limiter.  (Read 16156 times)

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boggy

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on: March 28, 2011, 06:24:21 pm
Last summer I posted about a problem I was having.  I mis-diagnosed it a bit but was corrected by anther forum member.

So the problem is that in any gear, it seems like I hit a rev limit and the engine flubs out.  It's about halfway to 3/4 of the way through the rpm's,  If I get their gently, I hit the limit and it starts to go.  I can feel the engine firing as it lurches forward, then I can feel it kick out as it slows a bit, rinse, repeat.  If I just crank the throttle, it just flubs.  It does not stall since as soon as it gets back to halfway through the rpm's, I get my power back.  The speed is not an issue as this can happen in any gear.

SO.  I had a LONG list of electrical issues to sort through from forum members.  I THOUGHT I had fixed it with a bad connection at the ammeter.  Not the case.  Took the bike out from winter storage, gave the electrics a once over, and the problem persists.

Before I get long winded, I'm wondering if the problem could be in the carburetor.  I have a 30mm flat-slide with a wide open exhaust.  The bike ran rich when I purchased it so I leaned it out a bit with the air screw.  Could the problem be any of the following:

-Too much fuel getting in?
-Too much air getting in?
-Float bowl overfilled?

I have not tried draining the float. I have no prior carb experience.  I'm wondering if I just need to fiddle with the air screw a bit.  Or adjust the float.

Let me know if anyone things this COULD or COULD NOT be the culprit.  My bike is still not under my roof but I'll be working on it this weekend.  I'd just like to know if any of what I'm guessing could be an area to investigate.

As always, thanks in advance for any help you can give me.
Boggy

Here's a link to my carb's schematic.
http://scootrs.com/images/pwk-type.png

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2006 DRZ400SM


RGT

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Reply #1 on: March 28, 2011, 06:43:38 pm
when you adjust the air screw you are adjusting the mixture at idle only, so if it starts and idles good leave that alone for now. If your float were way off you would probably have trouble with idle, it would not hurt to check and make sure the level is correct, but it sound more like what my bike does when I run too rich a jet or have the fuel needle set too high. you might try dropping your fuel neede down a notch. If you have a leaner/smaller main jet I would try that and see if it gets better or worse. I would start by taking the bike out and run it at that stumbling point for a short stretch and immediately shut off the igntion and pull in the clucth and coast to the side of the road, pull the plug and see if the center elctrode and inside of the plug is covered in black soot or is it looking bleached out white and that should tell you if you are rich or lean....


boggy

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Reply #2 on: March 28, 2011, 07:06:22 pm
I fouled a plug when I first got the bike few years back from running it too rich.  No rev limit problems then.  Since adjusting it I check my plug somewhat regularly but it never looks sooty or white. 

Now, my "fuel needle' is the one that is attached to the throttle slide, correct?  There are 5 notches for the little clip that raises it or lowers it (man, its TINY increments!).  Mine is one notch higher than center.  That was the first thing I check after taking it out of storage as I thought maybe I flubbed it when I changed throttle cables last summer (around when the problem started).  That is an easy check... so just lower that clip down a notch or two?  Man, that little clip is TIGHT on there. I check to see if I moved it an was reassured by how tight it is.  How do I take it off without damaging it or the needle?

Thanks RGT.
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RGT

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Reply #3 on: March 28, 2011, 07:36:09 pm
yes that is your fuel needle, lowering the clip raises the needle and lets in more fuel. I usually grab the clip with needlenose plier. You really want to see what the plug color is at the point of the problem which is why I described the plug chop procedure above. If you just pull the plug after you get home you will not get an indication of what was going on at your problem point.


boggy

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Reply #4 on: March 28, 2011, 07:44:10 pm
pull the plug and see if the center elctrode and inside of the plug is covered in black soot or is it looking bleached out white and that should tell you if you are rich or lean....

Interesting.  Ok, so just to clarify, I want to pull the plug and check it immediately.  I read this in the Snidal manual too, but I guess I didn't realize it was an immediate, "in the moment" check.  I figured if it got sooty or white, that is the way it would stay when I got home and pulled the plug.  For the life of me I couldn't figure out why Snidal was telling me to pull it after a 30 second run.
« Last Edit: March 29, 2011, 03:54:32 am by boggy »
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baird4444

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Reply #5 on: March 28, 2011, 11:29:18 pm
This sounds like a "Rich bog" to me.  You can accelerate to a point and then it just
stops....  hence the rev limiter statement. My guess is that you are WAY to
rich. Check for the sooty plug on a plug chop to confirm and then change to
a smaller jet.  These things aren't as easy to dial in as the Micarb...
           - Mike
                     
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GreenMachine

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Reply #6 on: March 29, 2011, 12:16:39 am
micarb is easy isn't it...depending on endowment, it seems to have a wee bit of leeway...
Oh Magoo you done it again


UncleErnie

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Reply #7 on: March 29, 2011, 03:11:22 am
If you have a kink i the gas line that lets you run the bike, but still resrticts the flow, you can be running out of gas until the gas line refilss at a lower speed.
I might be your tank cap vent is clogged, too.
Run what ya brung


boggy

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Reply #8 on: March 29, 2011, 04:03:02 am
Ok - I'll do the plug chop if the rain holds off for the weekend.  Thanks for the tip - I thought just pulling the plug was enough, but I get it now.

So if I am too rich then I'll try lowering the fuel needle (it only has one more notch to go) which will lean it out.

If that doesn't do it I guess I'll need to address the main jet.

Uncle Ernie, if the fuel vents through my gas cap I think I'm ok as at the moment it leaks like an iced tea pitcher.  I did pull my fuel line too.

I think I got all that right? Seems like a good place to start.  Thanks guys.

Boggy
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Ragmas

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Reply #9 on: March 29, 2011, 11:52:26 am
Ok - I'll do the plug chop if the rain holds off for the weekend.  Thanks for the tip - I thought just pulling the plug was enough, but I get it now.

So if I am too rich then I'll try lowering the fuel needle (it only has one more notch to go) which will lean it out.

If that doesn't do it I guess I'll need to address the main jet.

Uncle Ernie, if the fuel vents through my gas cap I think I'm ok as at the moment it leaks like an iced tea pitcher.  I did pull my fuel line too.

I think I got all that right? Seems like a good place to start.  Thanks guys.

Boggy


A quick tip on removing needle clip.  (hard to explain with out pictures but here I go.)

Get a socket of whatever size you can fir the cli into.  Now, lay the needle in its side ( so it lookslike a fencing foil, rapier sword, lying down.  Make sure the clip's openg in facing down.  Take the aforementioned socket and place it over the clip.  Push down gently and the clip should pop off into the socket.  Stow clip somewhere safe or replace forthwith.  Replace in the same manner as removal.

Good luck.
Sam
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Little Falls, NY


The Garbone

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Reply #10 on: March 29, 2011, 01:59:57 pm
Dirty air filter?
Gary
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boggy

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Reply #11 on: March 29, 2011, 03:44:12 pm
Thanks for the tip Ragmas.  That clip is perfect dimensions for losing.

Garbone... Freshly cleaned filter. Even ran it sans-filter last fall to try and diagnose.

Thanks.




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Ragmas

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Reply #12 on: March 30, 2011, 02:25:13 pm
Thanks for the tip Ragmas.  That clip is perfect dimensions for losing.

Garbone... Freshly cleaned filter. Even ran it sans-filter last fall to try and diagnose.

Thanks.






I am glad you were able to understand my blathering.

Good luck,

Sam
2009 G-5 Military
Little Falls, NY


boggy

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Reply #13 on: April 03, 2011, 11:14:27 pm
I lowered the needle by raising the clip to the needle's top most position and the problem persists.  About the same as before.

I did a plug chop and it was indeed sooty.

I guess the next step would be to address the main jet?  I've searched the threads here for a good #s to start with but I don't see any definite answers.  I pulled my carb off - Can you get an indication of what the jet sizes are if you take them out?  Are they stamped on there?

Here's the thing that makes me crazy - when I bought this bike 2 seasons ago (used) it was running fine.  

Could either a bent needle or a bad battery give me the same problem?  I'm grasping here.

Baird, I read on here that you have a 30mm flat... you have numbers you're happy with?
« Last Edit: April 03, 2011, 11:19:36 pm by boggy »
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boggy

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Reply #14 on: April 04, 2011, 12:45:42 am
I lowered the needle by raising the clip to the needle's top most position and the problem persists.  About the same as before.

I did a plug chop and it was indeed sooty.

My main jet is at 135 and my pilot is 38.

Here's the thing that makes me crazy - when I bought this bike 2 seasons ago (used) it was running fine. Really strong performer.

EDIT
I just took off the carb to see what was going on.  Here is a major WTF that I can't figure out.  Check out the photo below.  On this carb, there is the idle screw.  On the other side there is a hole in the same spot. It goes to the same spot the idle screw goes but has a hole maybe half the diameter.  On my carb, it is half-sealed up with what looks like epoxy.  I say half filled because it's falling apart and there is a hole I can blow air through.  What the hell is this?

Here's a link to the carb schematic. That hole is shown, but not identified.
http://scootrs.com/images/pwk-type.png
« Last Edit: April 04, 2011, 01:26:15 am by boggy »
2007 AVL
2006 DRZ400SM