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Message started by mmosel on 08/23/11 at 00:51:51

Title: Running lean and doing damage?
Post by mmosel on 08/23/11 at 00:51:51

Ok so, now that I've got my new muffler on, and my K&N air filter, I am definitely running lean. I can feel it, I can hear it.

My question is, can I ride it like this without doing serious damage to it?

I realize I will need to rejet. In a way I'm looking forward to it, but I don't know how long of a job it is. And if it is a 2 day job, then it will end up being a 8 day job or something.

So before I can get to rejetting it, can I still ride it safely, that is the question.

Title: Re: Running lean and doing damage?
Post by snowdevil on 08/23/11 at 01:47:20

Here's a video to explain how to change them. Maybe an hour start to finish to replace the jets.

http://www.youtube.com/rycamotors#p/u/6/rFFuF9QZ4IM

I don't know about doing damage running lean. We'll have to leave that question to the pro's here.

Title: Re: Running lean and doing damage?
Post by dasch on 08/23/11 at 02:03:46

Lean condition increases exhaust gas temperature. Obviously increases overall engine temperature. I heard stories of melted pistons, burned valves etc... can't confirm nor deny. Rejet is technically easy. And you will enjoy your bike much more if it's running the way it should.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/23/11 at 03:10:15

Thanks for the info and video link!

Do you guys take the whole carb off everytime you rejet? Or can I just do it while it's on the bike. Doesn't seem like there is much to changing the jets themselves really. Take off the bowl and unscrew.

Any problem if I hold off on the spacer mod for now, or should I suck it up and do that now too. :o

I'm in the pacific northwest, near sea level, so I think I need to go much richer. Maybe I'll start out where the Ryca guys jet in LA.

55 Pilot / 155 Main Jet.

Title: Re: Running lean and doing damage?
Post by dasch on 08/23/11 at 04:51:13

55/155 is what you have now? That should... not... be lean... hmmm.

Advice: Try the needle mod first, and see how it behaves. And mixture screw, open it up one turn. I'm thinking 55/155 combination is just fine.

To answer the question, to rejet I think I remember I simply unhooked gas cable, loosened the clamp and rotated the carb. That gives you access to both needle and jets.

Title: Re: Running lean and doing damage?
Post by 2whlthrpy on 08/23/11 at 04:51:40

I just recently did both the spacer and the jets. As stated, changing the jets and the spacer are both easy, the only real problem is getting the screws out without buggering them up. That said, they are much easier to reach and handle with the carb off. I was hesitant at first to remove the carb but that is actually very easy, just remove the battery box first and it slides right out. Oh yeah, replace those screws to the bowl and the top of carb with hex screws. Read up in the tech section on removing the screws (they have loctite on them) many helpful ideas. I loosened them with a small hammer and small punch then vise grips.

Title: Re: Running lean and doing damage?
Post by Routy on 08/23/11 at 07:14:38

Will you do damage ??

If you are going to be working it hard,....especially in hot weather, yes you could hurt it.
If you must ride it while lean, just don't horse it hard,.....no WOT !
I sure would not hesitate to ride is at an easy 55 mph.....running a little lean if I had to.
IMO, do the jets first, then the spacer only if needed to richen the low to midrange.
Me, I would do it w/ the carb installed, I wouldn't even rotate. But I wouldn't tell you to do it,...! Just don't let the driver slip on a screw ! If you do, its too late.

Title: Re: Running lean and doing damage?
Post by verslagen1 on 08/23/11 at 07:17:27

and put a towel over the starter cause if you drop something it'll be hard to find.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/23/11 at 15:28:06

Ok awesome, thanks for all the advice.

Should I use loctite when replacing the bowl screws?

There is that one little screw that releases the fuel from the bowl. If I replace that, does it have to be brass?

Dasch, I'm not running 55/155. I'm stock. I'm gonna try that combo first.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/23/11 at 20:05:28

Well, after a trip to Ace, I was able to get a 90 degree angled screwdriver, which enabled me to get the bowl off the carb. Without that, it was pretty much impossible to get it off. I was then able to remove the large jet fairly easily ( 145 ). However, I can't get the smaller jet out yet. I have a small screwdriver, but I think it's too small, and I don't want to strip it.

I couldn't find a stubby screwdriver in a medium size, so I can't get the smaller jet out. If I keep pushing it, I know I'll strip it and make it even harder to get out. ( I imagine tapping on it might not be a good idea )

Looks like I'm going to have to either rotate it or take it off completely. Sigh. I guess that means I need to drain the tank and take it off.

Frustrating, because I was only a small jet away from swapping them out and being on the road again.

Title: Re: Running lean and doing damage?
Post by Routy on 08/23/11 at 21:17:48

Sorry for your trouble. I only ever had the bowl off, and the main 145 jet out. I never figured the pilot jet would be any harder to get out.
You sure may have to rotate or remove.

I always read of locktite on the screws, but I never saw any evidence of it on mine, nor did I use any on reassembly. I do know that steel screws into aluminum can seize into place and be very hard to remove,.....even w/o any locktite.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/23/11 at 22:30:28

Well, my bike is officially in pieces. I pulled the carb. Going to be crazy putting it all back together. I just hope I can get this jet out. Not sure what will happen if I can't get it out.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/23/11 at 23:05:47

Ok I had to create a special flat head screwdriver with a grinder. The small ones I had were just too small, and the bigger one wouldn't reach it. I finally got it to pop ( it is stripped on one side ), and turn out. Phewwww.

I guess now that I have the carb out, I should do the spacer mod. I picked up a black #4 today from ace. And now that the tank is off, I can put in a new spark plug. I'm not going to do anything else, I'll be incredibly happy if I can just put it all together and have it running.

Update: Spacer mod is complete and back together.

Hopefully, tomorrow, the bike shop has the jets I need.

Title: Re: Running lean and doing damage?
Post by Routy on 08/24/11 at 04:36:10

As I said before, I would have done the spacer mod later, and only if needed. Doing multiple things to a carb all at one time can cause you lotsa grief if luck isn't w/ you.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/24/11 at 16:21:33

Well, too late, it's already done. My muffler setup is exactly like the Ryca, so I'm going by what they are defaulting to as a starting point. I'm also at sea level and on the west coast. Hopefully I won't have any problems.

Now if I could only find the right jets, I could put her back together again.

Title: Re: Running lean and doing damage?
Post by Gyrobob on 08/24/11 at 18:26:25

3434362A3C35590 wrote:

What is it doing that you interpret as "running lean. I can feel it, I can hear it." ??

The only real danger from running lean is detonation. If it is not pinging, you are okay. Trouble is, sometimes light detonation is not very obvious. If you think it might be pinging even slightly, use premium gas for a while until you get the mixtures right.

Running lean may cause inconsistent combustion which can cause less-than-smooth operation,.. just like a stock late model Savage. They come from the factory on the ragged edge of lean mixtures, so you running yours even leaner won't be that much different,.. just a little cooler.

CHT is maximum at 14.7 air/fuel ratio. (stoichiometric) When mixtures get leaner or richer, temps go down. There are some factors that can modify this just a little, but generally if you run lean or if you run rich, CHT goes down. EGT may go up, but not much gets harmed with high EGT.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/24/11 at 19:23:39

Well, I can feel it in the power and torque. It's slower for sure.

I can also hear it in the carb. It doesn't have that same throttle sound it had before.

I can't ride it anymore now anyway, everything is off and waiting for the jets to arrive - next week sometime I suppose.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/29/11 at 17:54:31

Wow, I ordered on the evening of the 24th from Nichecycle and I received the jets today. I was expecting to get them by the end of the week!

Now I can put her back together again...

Title: Re: Running lean and doing damage?
Post by Oldfeller on 08/29/11 at 18:21:11

http://www.experimentalaircraft.info/articles/aircraft-engines-leaning.php

for those whose CGT and EGT's are a little weak and fuzzy --- a clean refresher course in lean/rich and why and how it happens.

Note: this is all in small aircooled aircraft engine speak, but the engines are fairly close in general construction to a Savage, just more cylinders.

..... and here is a direct quote from the materials (which do agree with what was stated above BTW, just a different conclusion is taken for the results of running lean at WFO throttle settings).

Don't forget to read the whole thing for full context, just not the parts you want. Remember, these folks have a knob to turn to lean/rich their engine and they have danger zone marked gages for CGT and EGT right up above that knob. We don't.

Context, it is a wonderful thing ....

Mixture too lean

Combined with a high power setting this will result in high cylinder temperatures, possible detonation, very hot or burnt exhaust valves and maybe damage to the pistons resulting in a power failure and a possible off airport landing.

Title: Re: Running lean and doing damage?
Post by bill67 on 08/29/11 at 18:54:32

I just read not to long ago on the internet the reason newer cars will go a lot more mile than they did years ago in because with fuel injection your not to lean in the winter and not to rich in the summer. Your always at the right mixture.

Title: Re: Running lean and doing damage?
Post by mmosel on 08/29/11 at 23:10:00

Well, after a little trouble getting the main jet in, and then some trouble installing the carb back onto the bike, I finally got everything put back together. Put it on prime and turned it over. Started on the second try!

I'm excited and I want to ride it, but it's late and I'm exhausted, so it will have to wait til tomorrow, first thing after breakfast.

Can't wait to feel what the difference is.

Title: Re: Running lean and doing damage?
Post by Routy on 08/30/11 at 05:22:10

4F4441411B1A2D0 wrote:

Well that along w/ slower piston speeds, hotter running temps, and better oils, and other stuff, I agree.

So lets get after it !!

Wouldn't that be neat,.....a bolt on EFI kit for.........anything, not just our bikes. I have often wondered,....this day and age, why don't we ever see after market EFI. They make everything else !

Title: Re: Running lean and doing damage?
Post by Gyrobob on 08/30/11 at 05:30:07

2E0D0507040D0D0413610 wrote:

..... and here is a direct quote from the materials (which do agree with what was stated above BTW, just a different conclusion is taken for the results of running lean at WFO throttle settings).

Mixture too lean

Combined with a high power setting this will result in high cylinder temperatures, possible detonation, very hot or burnt exhaust valves and maybe damage to the pistons resulting in a power failure and a possible off airport landing.

What they mean here is that high power settings combined with lean mixtures could lead to detonation, which would then lead to very hot or burnt exhaust valves and maybe damage to the pistons resulting in a power failure. Just using lean mixtures at high power settings won't cause overheating. Mixtures either side of peak make the engine cooler,.. assuming no detonation.

Running an LS650 lean is still scary, because it is hard to notice when it is beginning to start detonating. When you actually hear detonation, you are hearing heavy detonation. It is possible for some detonation to be occurring and not hear it, especially with a noisy motor, noisy exhaust, and lot of wind noise.

I wonder how much effort the Suzuki engineers put into how much they were willing to lean the mixtures on the later models. From what I gather here, the early bikes ran a little richer, but then for tree-hugger mollification, they were leaned out some. I would hope the engineers would never adjust the tuning so detonation was a possibility. Maybe they set it up to be close to that point, but not there yet. So,… if you take a stock, say, 2009 S40, and lean it out (in effect) by using a freer-flowing muffler, are you running the risk of detonation?

Title: Re: Running lean and doing damage?
Post by Oldfeller on 08/30/11 at 07:47:05

Mixture too lean

Combined with a high power setting this will result in high cylinder temperatures, possible detonation, very hot or burnt exhaust valves and maybe damage to the pistons resulting in a power failure and a possible off airport landing.

Just read it for what it says -- mixture too lean at wide open throttle will result in higher cylinder temperatures. Detonation is easy to explain when the valves get anywhere near hot enough to burn (cherry red) and aluminum pistons can get soft and blow out in those conditions as well.

It's not like we haven't seen a holed out piston here on the list -- luckily they are pretty rare things.

Damage to piston ring areas (galling coming up the front of the pin bosses up into the ring area) is a lot more common, unfortunately. Most teardowns on high performance engines have this problem.

You make a good point though, Suzuki sets the bikes up pretty lean in all the later years to meet EPA target standards and then we yank off the restrictive stock air filter and exhaust pipe (lowering intake vacuum levels) then run the immortal piss out of the more powerful engines, not realizing that we might be gas starving the engine at full throttle because our vac petcocks were designed to work at the original stock filter intake suction levels.

And that's before the petcock gets old and its performance declines.

You could say rejetting is a performance and reliability enhancer.

Title: Re: Running lean and doing damage?
Post by Gyrobob on 08/31/11 at 05:40:46

0221292B282121283F4D0 wrote:

We’re splitting hairs here, methinks, but,.. to be technically accurate, a lean mixture doesn't raise CHT, it lowers CHT. Since you bring up aircooled aircraft examples, check out Lycoming’s chart:

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Miscellaneous/mixturevscylheadtempo1.jpg

The danger from lean temps is what happens from crappy flame front travel. When the flame front is not smooth and consistent, detonation (an explosion rather than a smooth burn) can cause mechanical damage.

One other comment, if the valves get hot enough to ignite the mixture prematurely, the result is preignition, not detonation. Other causes of preignition: timing advanced too far, and glowing hot carbon residue. The difference between the results of detonation vs preignition is moot,.. they both result in pinging (an explosion rather than a smooth burn) and probable damage if the pinging happens a lot.

Title: Re: Running lean and doing damage?
Post by Boule’tard on 08/31/11 at 07:30:52

202F352E323427252D2334460 wrote:

Wouldn't that be neat,.....a bolt on EFI kit for.........anything, not just our bikes. I have often wondered,....this day and age, why don't we ever see after market EFI. They make everything else !

There's aftermarket FI, just not bolt-on for any particular bike. A couple of guys have converted their DR650s to FI and were asked if they were interested in selling kits.. not interested. It is an expensive proposition for diehard tinkerers who would want to hand-select each individual component (and not pay a middleman) anyway. Anything can be FI'ed with enough brainpower and tenacity, though. I have a friend who built one of those Velocity kitplanes and plumbed up a 6-cyl Franklin from scratch.. ignition, FI, sensors, electronics, full logging.. guy's a genius. Unfortunately the engine crapped out on the plane's maiden flight and he had to put it down in a cornfield.. currently rebuilding.

It is interesting to note in Gyrobob's graph that on the far lean side, specific fuel consumption begins to go back up. It is good to be slightly lean of 14.7 so that there's enough air to scavenge for fuel molecules, but push it too far and the engine loses efficiency by huffing extra air around for no good reason.

Title: Re: Running lean and doing damage?
Post by verslagen1 on 08/31/11 at 07:53:59

Back when the bike was bone stock...
Putting in a 150 jet actually improved mpg.

Title: Re: Running lean and doing damage?
Post by dasch on 08/31/11 at 11:32:55

In europe, Audi/VW came up with (I think) what was called K-Jetronic back in early 80's, in VW golf rabbit. Mechanical fuel injection, no lambda (02 sensor) , no ECU... It can be done... but it takes a lot of trial and error.