Weird jetting!

[muddertrucker]

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.

 

[(F5)]

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.

 

[barossi73]

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

 

[muddertrucker]

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

 

[muddertrucker]

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.

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?

 

[(F5)]

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.

 

[Pygmygod]

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?

The idle was also hanging a bit when i would let off the throtle.

Isn't this a Lean condition?

 

[muddertrucker]

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.

 

[Davehuge]

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.

All the best, Dave.

 

[muddertrucker]

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.

 

[muddertrucker]

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.

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


Sent from my iPhone using Tapatalk

 

[Doc Brown]

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?

 

[muddertrucker]

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.

 

[Doc Brown]

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.

 

[muddertrucker]

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.

 

[(F5)]

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

 

[Doc Brown]

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.

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.

 

[muddertrucker]

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.

 

[(F5)]

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.

 

[Jakobi]

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.