Weird jetting!
 

So i took my carb off today to verify what i had in my notes because the jetting values i had were no were near what everybody elses are.

My bike is a 2011 ec 300 that i think is all stock but the jetting i have is 145 on the main and 38 on the pilot. I have no idea wich needle is in there and cant see any writing on it. The slide is a number 7.

The bike runs good, smokes only a little and the plug is actualy pretty dark.

Any ideas as to why my jetting is so different?

The main is too small, the bike will be asking for more fuel. I run a 40 pilot and # 2 from top for the needle. I'm about 5hr from you.

Theoreticly it should i know. But it definatly is running good.

Just wondering what could make it need such a small main jet.

Are you actually riding hard enough to get on the main jet? The main jet is mostly controlling the mixture past 3/4 throttle and you've got to be riding with the throttle almost pinned to see what effect your main jet has.

A small main would require a needle with a very small bottom diameter.

Are you sure it isn't a 175 main?

If you don't see any markings on the needle it may be a jetting kit where the markings were removed to keep someone from copying it. e.g. old LTR jetting kit. This is a keihin needle.

If you don't know which needle it is - I would pick up a needle suggested elsewhere here - e.g. "suzuki needle" or "yamaha needle"...

With all replacement (improvement) needles - you typically run a richer pilot jet and reduce idle setting to better separate the carb circuits (high/low). My experience (which is a bit dated) is that you should see a 42-45 pilot - maybe a 40 - but definitely not a 38 if things are set up "well" (given conditions are not extreme).

jeff

Weird jetting!
 

https://uploads.tapatalk-cdn.com/201...db2167cf18.jpg

You can see it pretty good in the pic but in real life it's even more clear that it's a 145.

And no I don't tend to reach above 3/4 throttle except on the rare occasion.


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Weird jetting!
 

https://uploads.tapatalk-cdn.com/201...b42264e3d8.jpg

Here's a pic of the needle.


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Is it a 36mm carb? Some 2011 models came with them.

No it's the 38, I was just looking it up to see which one I had.

I have a left over 42 sj from my kdx220 but I'm kinda having a hard time seeing if it's compatible.


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Perhaps your 145 main has been bored out? If the needle is modified the main could be too.

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FWIW, some of the bikes to land in Canada were "Euro Spec" and came with really weird needles and jets. If this is the case you proved that they would run. I was never sure if the bikes would blow up instantly with that set up so I pulled it out and put proven needles and jets in them before they were delivered to customers. Sounds like you have one of those EU spec jetted bikes.

Well I'm the third or fourth owner and I know it's been jetted just don't know how.

They may have only changed certain circuits.

Do you by any chance remember what you might have put in a bike like mine?

This is the best way jetting is explained that I have read so far. very good Jeff

Double check and compare the "145" against a known 170 to see if it has been drilled. In a pinch I have drilled jets but I grind off the original number to avoid confusion.

So i'm back to riding after knee surgery. I haven't put any time into jetting the bike yet but I have recently fouled 3 plugs from riding with my kids.

The temperature here has been quite high for the past few weeks witch could be one reason for the plugs fouling more than usual (fouled only 1 in the first two years).

Since I usualy ride with my kids now I rarely go over 1/2 throtle.

Yesterday, after some normal kid speed riding we stopped at the truck for a break but I took off down the dirt road to try to ''clean up'' my bike. It runs great at WOT. After that the silencer smoked for a while, Im guessing the heat caused from WOT running was burning up the excess unburnt gas and oil. It ran better after doing this and for the rest of the ride I hung out at the back of the group and let them go for a while before going to catch up, this allowed me to run at higher speeds with more throtle. The bike definetly likes been riden that way. I also noticed that there was some spooge running down the outside of the silencer for the first time since I've had the bike.

Would I be wrong in thinking at low speeds and 0 to 1/2 throtle i'm too rich?

Where is your idle screw set? Is it dialed all the way in to the point of being "coil bound"?

jeff

It almost is screwed in all the way yes. However it is idling a bit high and holding that speed without stalling.

I looked this up for like 30 mins and didn’t find anything that convinced me, would anybody know if next 220 jets are from the same series as what is in the as2. I have some left over jets (42 pilot and 145 main) from my previous bike that I could do a comparison with.

Here’s some pics of two 145 jets side by side. Can’t see much but the one in my bike definitely hasn’t been bored out.

https://uploads.tapatalk-cdn.com/201...35656699d1.jpg

Here’s a pic of the nameless needles top. Notice the dab of dark blue colouring.

https://uploads.tapatalk-cdn.com/201...2c52cd0cbb.jpg

I’m gonna go ahead and order some Necw and nedw needles. What main would be recommended to go along with them?


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The needle in the pic is a JD_blue and its a very good needle, probably one of the best.

Which bike is it, model year and which carb? (Keihin 36 or 38).

Assuming its a 300 with a 38 Keihin start with PJ 42, MJ 172, JD_blue clip #2 (as you said its hot). Set AS to 1,75 turns out. Make sure your idle is super low so that the bike stalls from time to time.
High idle settings negatively affect the idle circuit...

edit: seen its a 300/11 Dunno what the factory set up was, so above said is valid for the new models. You could ask JD which MJ he recommends, a 145 seems to lean for my understanding but might work on a 2011.
The needle is worn and that leaves room for assuming that the needle jet may be worn too. You need to check that.

So last time I rode i noticed a change in engine sound near the the end of the ride. The idle was also hanging a bit when i would let off the throtle. Put the bike away till this week. It started on first kick then died. Started on 2nd kick but you could tell something was going on and then died. No more starting! Changed the plug and started 1st kick.

This has happened to me 4 times in the last year and I doubt i i've put over 300 km on the bike in that year. What else could cause plugs to suddenly crap out (other than rich jetting)?

I also got a crap load of jets in the mail the other day. Every main between 165 and 185 plus a 40 pj. After changing the plug I tried the 165 main (from the previous 145) and noticed that the bike could easily lift the front Wheel at low RPM's compared to before. This was only a short test around my house with a cold engine but I liked the feeling and am looking forward to trying it out in a full ride.

I had a racebike with a marginal ignition that used to eat plugs.
I grafted on a cr ignition and problem went away. Coil and plug cap might be a good start.

Some 2t oils are worse for leaving residue on plug...and vary on spooge produced

I use Amsoil interceptor.

The only change that happened not too long before plugs stated fouling was the installation of an aftermarket voltage regulator.

I?ll be doing a test with the new jetting soon

Thanks for bringing that up. It has been simmering for a while but i'm gonna look into the ignition coil. I looked at the coils on my kids bikes (kx65 and 85) and both fit onto the gasser. Both have big bike plugs in them (br9ix and br10eg) so would I be wrong in thinking they should work on my bike if I want to do some testing?

I recently unpluged my voltage regulator as that was the last change I had done to the bike before it started fouling plugs. Fouled a new plug within a 1hr ride anyways.

Today I cleaned up the power valve as it was sticking a bit, i doubt it wil change the fouling plugs but i'm looking forward to see how the power will be affected. I want to change things by process of elimination so that know exactly what is wrong. Next up on the list is checking/replacing the reeds and changing the needle as someone had pointed out that it might be worn out. I also realized the gap on the plugs I have been buying from my local Honda dealer was way too small so I will now be keeping a eye on that and setting to the right spec (0.6).

I dont think my rh crank seal is leaking because the trans oil stays clean and the level doesn't budge.

I dont get much riding done these days for one because of the long winters and I just got back from 2 months in Latvia. I know riding with my kids at lower speeds might be one of the causes for fouling plugs and that just riding faster and at higher rpm might fix it, but I still need to figure out why plugs are sudenly craping out on me.

Any other ideas?

Ign coil from kx will work fine complete with cap.

After that the stators don't last forever and can fail slowly and are hard to test definitively. See other current threads on stators.

If using Motul 800 it can foul by slow riding.
Are you still using the 40 pilot jet?
What ratio of fuel to oil mix are you using?
How many hours on the bike? Maybe replace the exhaust packing as well?

Isn't this a Lean condition?

Can?t remember if I actually put the 40 in there. But yeah I?m also thinking I?m a bit lean compared to every ones jetting recomamdations. I?m running intersepror at 50:1 and I don?t know how many hours it has but I did do the packing a while ago. It might have 15-20 hours on the packing.

Are you sure that's a genuine Keihin Main Jet?

Are you sure it's a genuine Keihin PWK38 carb?

Sorry, I don't mean to sound rude, but there's a lot of fake Keihin PWK carbs on the market.

145 Main Jet sounds very lean at WOT, I mean dangerously lean. :eek:

All the best, Dave.

The main is now a 165 that I bought from Rocky Mountain.

And I can?t be sure it?s a genuine keihn carb because it?s what was on there when I got it. But i doubt it?s a fake. Previous owners were not the kind of people who cheaped out.

Soi took the carb of to see if I had changed the pj and to confirm witch position the needle clip was in.

Turns out it was in the middle clip, so I moved it to the top clip.

But I also figured since the carb is off why check on the reeds, and this is what I found. Two of the reed petals have small chips in them.

https://uploads.tapatalk-cdn.com/201...7d91df2add.jpghttps://uploads.tapatalk-cdn.com/201...a9ab52f765.jpg

So I’ll be changing those out before going any farther.


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The reeds aren't the reason why it fouls plugs.

Try a correct and brand new spark plug. When did it start to foul plugs? What was the last change/last maintenance you did before ut started to foul plugs.

I assume the air filter is clean. How old is the fuel in the tank? Which kind of gas are you using?

I?m not sure what you mean by correct spark plug. Every time I foul a plug I put in a brand new ngk br8eg plug.

Gas is fresh and air cleaner is clean and oiled.

As you mentioned the two different spark types of your kids bikes I assumed that you run those for testing and they fouled. But BR8EG is the correct spark. If it fouls the problem lies somewhere else. Did you change the oil type recently?

My GP fouled at least 1 plug per hour until JD advised me not to use Amsoil Saber anymore. I didnt believe him and changed all components of the ignition system. All! Including stator and ECU. Nothing helped. After talking directly with Amsoil I changed the oil and it never fouled a plug again in the next 80 hours. Strange things can happen... That's why I asked plug, gas and oil type.

I use pump gas, always use supreme which is 91 octane if I remember correctly. It?s mixed 50:1 with amsoil interceptor( have been running this in every 2stroke I own for over 10 years)

When I mentioned the other plugs it was only because I figured if the coil from those bikes were strong enough to power them it should be able to fire the plug on my bike. Once the reeds comes in going to test it out with a new clip position and donor coil.

Change the reeds now before they get worse is good idea but not bad enough to notice, yet.

1 position on needle can make quite a difference depending on the needle so you have to trial

Interceptor is perfect, its not the oil. If you said Saber I'd suggested to change it.

Yop, got it now. The coil will work with no problems. I also tried one from a KTM and it worked.

Good luck! Pls keep us informed.

So, i swapped in the new reeds, changed the needle from a jd blue to a NECW and lowered the float level a bit (i know I said i'd change one thing at a time).

The throtle is very response from 0 to 1/4 and the power is smooth and steady throughout the powerband. I tried it in the woods at first but since hunting season is at our door i did not want to spend too much time out there and decided to hit a small private track we have acces to. Since I always ride with my kids, the woods is usualy slower speed stuff. I found the transition of going from +/- 1/4 to wot was slugish when done with a quick snap of the throtle but if I slowly (2 seconds) roled onto it it was fine. It sounded similar to when the engine is first started up and still cold.

Once we got to the track I did not have to follow my kids, I could go my own speed (wich isnt that fast), the engine ran great the whole time and i did not foul a plug. I had a little bit of spooge on the inside edge of the muffler at the end of the day.

So my current setup is 40 pj 165 mj and NECW 3rd clip. I did not play with the airscrew. I'm thinking of going up one clip position on the needle.

On a side note, my oldest son (12 yo) is having a freaking blast on his recently purchased 2014 kx 85. It is simply amazing seeing him blast through the trails with that thing and pop wheelies or make small jumps off of everything he can. I alway thought those little bikes where not made for trails but he is proving me wrong and it wont be long until I cant keep up with him anymore. His little brother (8 yo) inherited the kx 65 and is learning to cope with using the clutch in the woods, not an easy task but it wont be long. He wont even look at his KTM50 anymore.

Cool
Glad it is getting there. Try clip position/s then adjust idle mixture for best, decide if need to try different pilot.

Steep long uphills should tell you if the float level is too low. If no problems there it's ok. If it falters you are low on gas at an angle in high load.

Then think about wide open. 165 is quite small so I'd want to try size up and see if it's better wide open. If so, size up try.

That's what I'm thinking from above too. If going WOT early feels flat/lean throw a bigger jet in it.