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Darth Wader

Running lean - will it damage engine?

13 posts in this topic

Hey guys, quick question for you. I've done all the mods with the AIS kit, gray wire, pipe, throttle stop, etc...I used the TT AIS kit though and didn't get a jetting kit (I won't have that much variance). At this point the bike is uncorked but, it is still on stock jets. I have new ones coming but, not til' Mon. or Tues.

Here's my question: Is the bike running too lean to ride? Am I risking the engine? I'm itching to ride, at least a little, this weekend but, don't want to burn it up. How far out of whack is my A/F with the stock 165 & 45 vs. the recommended 168 & 48 (coming)? Is it running lean enough to necessitate keeping it parked a few more days?

Thanks for your insight!!

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Good question.

What are all of the things that a lean condition cause in a four stroke? Well one thing is it will run like a raped aped wile lean.

Yes, Running lean will damage your engine :crazy:

But it really isn't that hard to rebuild your toy, and there is no guarantee that you will burn the motor up, so I say go ride her :ride:

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45 would't be too bad. with the 165 I wouldn't run it wide open--just in case.

Just adjust the pilot screw so it dosent backfire on de-accell and you should probably be ok.

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well - you probably should have waited for the jets BEFORE you uncorked the thing and then ridden her safely in stock trim.

As you already know, when a bike runs lean it also runs hot, burns plug electrodes and can pre-ignite (bad). If you really MUST ride it then either get it back closer to stock for this ride (or) - and these are just 'stop gap' measures

1. turn out the fuel screw to compensate for a lean pilot

2. lower the clip on the needle to richen up the mid-range

3. replace the std exhaust to choke it up a little

4. don't race your mates all day !

just my 2c worth - good luck

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I think you will be OK, just dont run at WOT all day long.

Also as mentioned, I would open the fuel screw by 1/4 and see how it runs. Also dropping the clip by one position just for added protection sounds like good advice IMO.

The main jet 165 is close to OK but keep in mind the 168 theoretically allows around 4% more fuel flow volume at fully open throttle, so you engine will run a little lean...

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If the bike runs okay without surging or gasping for air it will be fine.

If it start to ping under load then you have to back off and wait for jets.

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I would not ride it because it may be way too lean. I always intend for a little check ride, but 30-45 later I get back to the house. My 05 stock was super lean before I did all the free mods and PMB insert, and would only have gotten worse with the mods. I went with a JD kit Blue and upped the main to a 168 and it was a little rich due to colder temperature. The Temp is finally getting warmer, and the bike is running better. So, you may not burn anything up but you will probably be making a lean bike worse. I also start riding around the 700-1000' range. I don't get the glowing read header to the muffler joint anymore! Even when riding before it would glow for 3-4 inches. Now only when riding does it glow for about 1/2-1". I have seen guys smoke pistons and valves by running too lean. I would not want to "rebuild" a brand new bike just because I could. Ok, I am rambling now.

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drop the clip (raise the needle), crank the fuel screw out and see how lean it is.

Was it jetted correctly to begin with? Chances are it was fat to start with and needed to be leaned out..

Have you even check how lean it is, or our you just throwing it out there?

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I am at 5500 ft with stock jetting, but the rest of the mods - opened airbox per GYTR AIS instructions, removed AIS, blocked air cut valve open, throttle stop mod, grey wire cut, inner stock insert outlet pipe removed (probably will but PMB insert).

Pulled plug today (after street riding in supermoto form) - the insulator and electrode were just "clean." Not really any color on top of the base materials. A little black near the threads, but not brown, tan or even white on top of the insulator and electrode areas. The bike doesn't pop on deceleration and the power seems smooth throughout the range.

Am I lean?

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I am at 5500 ft with stock jetting, but the rest of the mods - opened airbox per GYTR AIS instructions, removed AIS, blocked air cut valve open, throttle stop mod, grey wire cut, inner stock insert outlet pipe removed (probably will but PMB insert).

Pulled plug today (after street riding in supermoto form) - the insulator and electrode were just "clean." Not really any color on top of the base materials. A little black near the threads, but not brown, tan or even white on top of the insulator and electrode areas. The bike doesn't pop on deceleration and the power seems smooth throughout the range.

Am I lean?

You are guaranteed running lean.. and you lose HP this way..

This page shows you how youre spark plug should look like:

Spark plug colour

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Seems like I'm a 19/20, but there is not much buildup of any kind. Maybe its because the plus only has ~15 total hours (mostly street)?

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