Rich or Lean?

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Rich or Lean?

Post  bamfslap on Thu Aug 26, 2010 1:14 am

I've looked up symptoms to find if my bike is running lean or rich. It runs like a turd and I want to get this sorted out. Some signs point either way. Here's the facts:

-When I whack the throttle at idle it will want to die unless I back off
-Starts great when I give it gas and kick. One kick usually when it's cold.
-Need choke on a cold start even though it's (90+ degrees) hot out (not sure if that's normal). And some other times when the bike's warm.
-Will idle high after it's warm unless I flick the throttle slightly to "calm" it down, causes me to run the bike on a lower idle in case of said reving problem. Valves recently checked/adjusted, still does it.
-Spark plug is NOT white, but a greysih color
-Idles great at first, worse later on in the ride
-Doesn't run any better without the air filter
-Adjusting the pilot screw doesn't seem to help

Can only go about 100 miles before hitting reserve on a 4+ gallon desert tank (Clarke), not sure if this is attributed to my more aggressive riding style, but a when I got the bike last fall when it was cool out I could go 140 miles before hitting reserve. I'm pretty sure it's running rich, but then I'll see symptom on a site indicating it's lean. I'm so confused. beat head

Thanks.
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Re: Rich or Lean?

Post  AURORA on Fri Aug 27, 2010 2:58 pm

Take a picture of the spark plug and post it so we can see the plug.

Put a can of Sea Foam in your fuel tank.

Utah can have high elevations, i.e., you might be running excessively rich, what are you running for the slow jet and main jet?
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Re: Rich or Lean?

Post  bamfslap on Sat Aug 28, 2010 2:14 am

I screwed in the pilot screw a tad before I went on a longer ride with my buddy today and I definitely see an improvement. I don't think it's totally solved though. The "calming" down the idle is probably the most frustrating part. I also noticed when I let out of the throttle it feels like it's "sucking" in more than previous bikes I've used. That's probably because I run the idle low though I am guessing.

http://i102.photobucket.com/albums/m102/lawlislol/downsized_08270016281.jpg?t=1282956905

Looked up some pics online and it looks like that's signs of carbon build up due to running rich. I'm not sure the sizes in my carb. My elevation is 5566 feet and I picked up the bike from a guy in a city with 4373 ft. Doesn't seem good. Yeah, the title in my avatar is pretty fitting. Embarassed

I'll run a can of sea foam first thing tomorrow. Should I get a jetting kit? What sizes should I use? It has a white bros R4 pipe and holes in the air side fender if that helps. Carburetors are huge gray area for me.
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Re: Rich or Lean?

Post  AURORA on Sat Aug 28, 2010 9:41 pm

Looks pretty rich.

Go to this jetting link:

http://www.xr650r.us/jetting/
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Re: Rich or Lean?

Post  bamfslap on Sun Aug 29, 2010 6:27 am

I decided to just open the carburetor. I made my way to the pilot jet (or slow jet as it says in the manual?) and it's 70S! I assume that means it's getting a lot more fuel than it needs at my elevation (as we've concluded previously)? The guide says 65 for my elevation. Should I try out a 65?

Going to look at the main jet next.

EDIT: Took a break for a while. Took out the main jet and it's 175. Chart says 165 for my elevation.

With an after market pipe and the side cut out, I should add 2 sizes, so a 170 right?

Should I try a 170 first, then 65 or 68 pilot jet after?

http://www.bikebandit.com/keihin-main-jet-kit-5-pack

Are those compatible with the stock carb?
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Re: Rich or Lean?

Post  AURORA on Sun Aug 29, 2010 3:56 pm

bamfslap wrote:I decided to just open the carburetor. I made my way to the pilot jet (or slow jet as it says in the manual?) and it's 70S! I assume that means it's getting a lot more fuel than it needs at my elevation (as we've concluded previously)? The guide says 65 for my elevation. Should I try out a 65?

Going to look at the main jet next.

EDIT: Took a break for a while. Took out the main jet and it's 175. Chart says 165 for my elevation.

With an after market pipe and the side cut out, I should add 2 sizes, so a 170 right?

Should I try a 170 first, then 65 or 68 pilot jet after?

http://www.bikebandit.com/keihin-main-jet-kit-5-pack

Are those compatible with the stock carb?

What temperature are you aming for?
Are you going to use an HRC tip?
Using 70 degrees and 4000 feet ( I would lean, no pun intended, for running a little rich than lean, I would go with both at the same time, the 65 maybe 68s and the 170.

Intake carb insulator 16211-MBN-640
170 Main Jet Honda Part Number: 99101-357-1700
175 Main jet 99101-357-1750
178 Main Jet 99101-357-1780
180 Main Jet 99101-357-1800
185 Main Jet 99101-357-1850
B53E comp needle & seat 16012-MBN-641 or 16012-MBN-671
65 slow jet 99105-MBN-0650
68s slow jet 99105-MBN-0680


Cheapest Honda Parts: http://www.hdlparts.com/fiche_select2.asp?category=Motorcycles&make=Honda&year=2003&fveh=4339

They are running an additional 10% off, enter LABORDAY in coupon code, through Sept 7, 2010


Last edited by AURORA on Mon Aug 30, 2010 1:00 am; edited 2 times in total
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Re: Rich or Lean?

Post  bamfslap on Sun Aug 29, 2010 7:29 pm

70 degrees is good. No HRC tip as far as I know. Went ahead and ordered the parts. Thanks so much, I appreciate your help so much and especially your time and patience. I will update this thread with the results. In the mean time now that I have the pig stripped I am going to do some cleaning (with a damp rag of course).

Thanks again.
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Re: Rich or Lean?

Post  bamfslap on Sat Sep 11, 2010 5:00 am

So my jets finally came today. The performance has definitely improved. I can whack the throttle open in high gears and not have it bog out like before (unless I am going slow and whack say 5th gear). The hanging idle still exists or it still sucks in a crap load when I close the throttle. One or the other. It's random which one the bike chooses. Any ideas? The throttle cable is kind of slacked I noticed, though I don't think I can adjust it anymore. Guess I'll look into replacing it.

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Re: Rich or Lean?

Post  AURORA on Sun Sep 12, 2010 12:40 am

What are you running for a front and rear sprocket?

When did you last adjust the valves?


Last edited by AURORA on Sun Sep 12, 2010 2:10 am; edited 1 time in total
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Re: Rich or Lean?

Post  AURORA on Sun Sep 12, 2010 12:51 am

http://www.4strokes.com/tech/honda/uncork_brp/

Are you running an oval or round carburator insulator?

Carb insulator using part # 16211-MBN-640 ( an O shape instead of 0 shape )

Install the new carb insulatoron the front of the carb and align the "fork" in the rubber

[img][/img]

Fuel System
#1 Q: What is the stock jetting for Euro/ED, NA, Aus/SA bikes? Stock jetting for the NA bikes are a 125 main, 65s pilot and lean needle. (Note that XR250's come with a main jet bigger than a #125!!!) Most of the rest of the world gets a 175 main and 65s pilot.

#2 Q: What do I do with the smog pump? To fully tick off the Tree Huggers and disable every Spotted Owl you can, remove it and discard. This things only duty is to feed exhaust gases back into the air intake. That's about as appealing to your bike as you sniffing your own underwear. Just pull it off and block off the tubes with one of a few different methods. You can spend money for a block off kit (Baja Designs, White Brothers), cut the tubes 1/2" from the plate, roll them back and braze, insert screws covered with silicone, or whatever your little heart desires. Big thing is to make sure they don't leak. See also my redundant answer above.

#3 Q: What is the recommended uncorked jetting? Altitude and choice of exhaust tip is going to make a difference here, but ballpark is a 170 to 175 main and a 68S pilot for below 1000'. The richer pilot is a must have to keep things cooler at low speeds. Also, throw in a B53E needle, Honda PN 16012-MBN-641. It comes as a set with a new seat and has a richer grind at the tip, allowing more fuel at the lower throttle ranges. This info comes direct from a Honda service bulletin. (The Wrench 2/00)

Here's a couple variations that pop up. Some run as high as a 180 jet with stronger midrange results than the 175. They are easy to change, so grab a few extras and fiddle. Just remember to change only ONE THING AT A TIME when doing carb adjustments. It makes trouble shooting easier. Also, some have had bad luck with the B53E needle, getting funky throttle results with it. I run the stocker with no problems and have not yet tried the HRC one. I will asap for a comparison here.

#4 Q: How do I properly adjust the pilot screw? First, a quick definition to clear up a common misconception I see. The BRP has a pilot screw that can also be called a fuel screw because it is located on the outlet side of the carb. That means that screwing it in meters less fuel to the pilot circuit, while screwing it out meters more fuel to the circuit. If the screw were on the inlet side of the carb, it would be called an air screw and do just the opposite. Screwing it in would supply less air, screwing it out would supply more. Someone please correct me if I'm wrong, or if you have a better, more understandable, definition.

Anyway, here's the adjustment procedure for a fuel screw per Gary, our local group Einstein on stuff like this:

Make sure your engine is fully warmed up and set the pilot screw to 1.5 turns out. Then with the 68s installed, turn the pilot screw clockwise until the idle slows. Then turn the pilot screw counterclockwise until the idle slows again. Make a mental note of how many turns you made in between the low idle points. Then turn the pilot screw half way between the low idle points to finish the adjustment. If you turn the adjuster counterclockwise and the idle doesn't drop down, then you need a larger pilot jet. If you turn the pilot screw clockwise and the idle doesn't drop down, then you need a smaller pilot jet. After adjusting your pilot circuit, re-adjust your idle speed if necessary.

#5 Q: What's so special about the "S" in a 68s pilot jet? The 68s has smaller holes than a standard pilot. It will change the flow characteristics and atomization of the fuel. You can run a regular jet in there if you want, but then you won't be on the same playing field as the rest of us, meaning that we can't help you! The PN for the 68S is 99105-MBN-0680. If you need larger, just substitute the size you need where the "68" is.

#6 Q: How big is the carb? Keihin non-pumper 40mm. Many say replace it with the Edelbrock Quicksilver. Coined as a miracle cure for all that ails the BRP, plus athletes foot. Generally speaking, those who were recent converts from two stroke bikes find that an accelerator pump ("pumper carb") help cure the hesitation when the throttle is opened rapidly at low engine RPMs. The rest of us apply the "Doctor, it hurts when I do this" rule and live with the stocker.

#7 Q: Why doesn't my new bike idle down right away? As much as I'd like to again quote Mr. Owl, I won't. Some, maybe most, BRPs have a hanging idle that seems to disappear after time. Part of it may be lean jetting, and the other part, I believe, is badly adjusted cables. After you adjust the free play, pull off the covers and seat and check for a tiny bit of slack on BOTH of the throttle cables. Since I discovered these were taught, even though I had the correct free play at the grip, the problem has not made an appearance. It would explain why the problem "magically" disappears after the bike is used. The cables stretch and eliminate it.

Another theoretical answer that makes quite a bit of sense is valve adjustment. Several of the guys have cited this as the issue and done a simple adjustment procedure to get 'er done. Learn the procedure here.

#8 Q: Why is there fuel coming from my vent tubes? To a point, that is normal. The vents allow excess fuel in the bowl to be bled off instead of being forced up through the jets and into the intake charge. You will always see this with the stock, or most others, carb.

If you are leaking fuel on a modest incline or even when the bike is on it's stand, chances are that your float level is too high. Another sign of this is a "burble" or stall of the bike when crossing whoops or landing from a jump. It's easily fixed by following the step by step in your service manual. You HAVE bought one, right?

#9 Q: I have an extra vent tube, where does it go? Chances are, you're looking at a tube around 6 or 8 inches long with a very short crook at the end, and it's coming from the barb by the cutoff valve.

Directly above this point on the frame backbone, on the rubber isolater the tank sits on, there is a square cutout just rearward of the ziptie. Tuck the vent up through that so the crook on the end keeps it from sliding back out. Didn't think it'd be that simple, did you?
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Re: Rich or Lean?

Post  AURORA on Sun Sep 12, 2010 1:57 am

bamfslap wrote:So my jets finally came today. The performance has definitely improved. I can whack the throttle open in high gears and not have it bog out like before (unless I am going slow and whack say 5th gear). The hanging idle still exists or it still sucks in a crap load when I close the throttle. One or the other. It's random which one the bike chooses. Any ideas? The throttle cable is kind of slacked I noticed, though I don't think I can adjust it anymore. Guess I'll look into replacing it.


Remember, you are not running a pumper carb but a vacuum carb. Wacking the throttle vs a very hard roll on, from a dead stop will also make a difference in bogging vs when the bike is at speed.
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Re: Rich or Lean?

Post  AURORA on Sun Sep 12, 2010 2:09 am

The hanging idle still exists or it still sucks in a crap load when I close the throttle. One or the other. It's random which one the bike chooses. Any ideas? The throttle cable is kind of slacked I noticed, though I don't think I can adjust it anymore. Guess I'll look into replacing it.

[/quote]

What do you mean by stills sucks in a crap load?

With the carb on the bike, will the throttle valve full retract (noting your throttle cable issue).

I'll double check for an air leak. I just replaced the isolator with the upgraded one, maybe I didn't get it seated the whole way...but I don't think that is the case.

Again:

What happens if you turn the idle screw all the way in? ...does the idle drop significantly and/or idle roughly or even kills the motor??? ...if there is not a significant change at "zero turns out" compared to one or more turns out that indicates that the pilot is too large.


NOW MAKE ANY CHANGES ONE AT A TIME AND MAINTAIN A WRITTEN RECORD OF THE CHANGE AND RESULTS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Re: Rich or Lean?

Post  bamfslap on Mon Sep 13, 2010 1:40 am

Sorry, been a busy weekend.

I finally got it solved. I realized that the throttle cable still had loads of adjustment at the throttle controller. While this didn't solve the two problems, it made it more responsive (like you mentioned, I was doing tests one at a time), cranking up the idle I got rid of the "sucking" problem on deceleration but the random batshit idle got worse as a result. Solved one problem. Now I knew it probably wasn't the valves (as I recently adjusted them and it didn't solve it) but it was almost next on my list. I decided to test different clip positions on the needle. It seemed right on the chart, but I figured it wouldn't hurt to try and lower it. I put it from 2 to 3 I'm pretty sure. Started her up and success!

With the correct jets and the idle being fantastic it's such a huge relief. Starts on the first kick every time with no choke or throttle or any stupid methods (I killed it a few times in a pretty technical wash I found and each time I started it and let it idle all I could do was grin). Runs fantastic. Now I can ride with a peace of mind. Thanks Smile

And yeah by whacking I mean hard roll on I think if that's what you mean. Didn't know the term. BRP smile
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Re: Rich or Lean?

Post  AURORA on Tue Sep 14, 2010 1:16 am

Happy Days! banana rider
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