White deposits on spark plug ground strap.

[JZ05220r]

My plugs have been looking like the are very hot ever since the rebuild where the engine was what I would say is fully modded. The white is uniform so no random specks on it. It also has a texture of like 1200 grit sandpaper where the white is. I have all the good stuff from FRP in conjunction with the RB mods. I’m running a br8es but thinking maybe the br9es will help in my situation. Not sure if that is the right train of thought but if I had to bet this spark plug is definitely getting alittle too hot.

[SS109]

Are you running pump gas? Sometimes it will make the ground electrode white. As long as the porcelain is the proper color, don't worry about the ground electrode unless you start seeing little tiny silver specs.

[JZ05220r]

Are you running pump gas? Sometimes it will make the ground electrode white. As long as the porcelain is the proper color, don't worry about the ground electrode unless you start seeing little tiny silver specs.

The upper half of the porcelain is always pretty white with a slight tan hue to it.

[SS109]

Upper portion really doesn't mean much. Have you read John_S's thread about reading plugs? If not, check it out here: viewtopic.php?f=105&t=21813

[KDXGarage]

The plug should look like hot cocoa.

What octane are you using?

[JZ05220r]

The plug should look like hot cocoa.

What octane are you using?

I am using 93

[JZ05220r]

The plug should look like hot cocoa.

What octane are you using?

Just revisiting this as the consensus from other people is that I am running the bike too lean in general. These are some pics of what I am talking about. This plug had a couple of hours on it. My jetting for the rb carb is 40 pilot, dek needle 2nd clip, and 155 main. I feel it ran best on the 2nd clip because when I try the 3rd their is some slight hiccups. I think If I go to a 150 main, I can bring it back to the 3rd clip. I’m still very confused on why it keeps looking this way every time I have taken the spark plug out.

[KDXGarage]

wow
too lean

richen up something somewhere :-)

[KDXGarage]

Here's a Vespa plug pic off the internet. It should be pretty close to this after some hours.

[bufftester]

Start with the pilot and get the right one in there, that'll richen up the entire band, then work through the rest of the jetting guide

[JZ05220r]

Start with the pilot and get the right one in there, that'll richen up the entire band, then work through the rest of the jetting guide

Throttle response got better when I backed out the air screw to 2 turns out so I don’t think I should go up on the pilot from the current 40 jet I have in.

[John_S]

I still think the engine could be getting hot. A bad radiator cap on mine gave no other symptoms other than the temp rising way too fast. Even long half throttle runs with plenty of air flow didn’t cool it down. Didn’t boil over or smell like coolant but the temps were 200+. Try a mounted temp gauge or one of those laser pointer temp guns from Home Depot for $30.

When it comes to throttle response from the air screw, the best way to tell if it right is a full throttle test believe it or not. With the engine fully warmed up roll along in first gear at a walking pace with the engine at idle speed and whack the throttle wide open and back to zero quickly. 1-2 seconds is all it takes.
If it bogs like its out of gas it’s lean.
If it bogs then wants to take off it’s still too lean but getting there.
If it stutters and then wants to take off it’s too rich.
It should INSTANTLY start pulling the front wheel or be shredding grass or dirt with no bog or stutter. We’re talking idle to on the pipe like that quick. Keep one finger on the clutch so it doesn’t get out of control.

All that can happen within 1 turn of the air screw if you have the correct pilot jet in there. For example 2 turns out bogs lean, 1 turn out stutters rich, and somewhere in between is instant response. Make 1/8 turns at a time and give the engine a minute at each setting before you try the full throttle test. It’s quick and works every time. 0-1/4 throttle response feels great at multiple air screw settings even when it’s too lean. Thats why I do the full throttle test. Whatever happens there gets exaggerated in higher gears like if you’re in third gear lugging out of a corner and quickly hit the throttle to 1/2 or full.

The porcelain of your plug should definitely not be white after a few hours of run time. I’m guessing the pilot is lean or it’s very hot (or both). Especially if you’re running that #7 slide you mentioned. I finally got mine situated this weekend. Went from a 4.5 slide, 40 pilot, 1.5 turns on the air screw to a #7 slide, 48 pilot, 1.25 turns out on the air screw. 1.5 turns out now will lean bog at full throttle.

I had 2 1/2 hours of run time this weekend starting with a new plug and the whole porcelain is wet cardboard colored. The max engine temp was 188 with plenty of lugging and on the pipe riding and it used barely over 1 gallon of gas in that time. Keep at it.

[JZ05220r]

I still think the engine could be getting hot. A bad radiator cap on mine gave no other symptoms other than the temp rising way too fast. Even long half throttle runs with plenty of air flow didn’t cool it down. Didn’t boil over or smell like coolant but the temps were 200+. Try a mounted temp gauge or one of those laser pointer temp guns from Home Depot for $30.

When it comes to throttle response from the air screw, the best way to tell if it right is a full throttle test believe it or not. With the engine fully warmed up roll along in first gear at a walking pace with the engine at idle speed and whack the throttle wide open and back to zero quickly. 1-2 seconds is all it takes.
If it bogs like its out of gas it’s lean.
If it bogs then wants to take off it’s still too lean but getting there.
If it stutters and then wants to take off it’s too rich.
It should INSTANTLY start pulling the front wheel or be shredding grass or dirt with no bog or stutter. We’re talking idle to on the pipe like that quick. Keep one finger on the clutch so it doesn’t get out of control.

All that can happen within 1 turn of the air screw if you have the correct pilot jet in there. For example 2 turns out bogs lean, 1 turn out stutters rich, and somewhere in between is instant response. Make 1/8 turns at a time and give the engine a minute at each setting before you try the full throttle test. It’s quick and works every time. 0-1/4 throttle response feels great at multiple air screw settings even when it’s too lean. Thats why I do the full throttle test. Whatever happens there gets exaggerated in higher gears like if you’re in third gear lugging out of a corner and quickly hit the throttle to 1/2 or full.

The porcelain of your plug should definitely not be white after a few hours of run time. I’m guessing the pilot is lean or it’s very hot (or both). Especially if you’re running that #7 slide you mentioned. I finally got mine situated this weekend. Went from a 4.5 slide, 40 pilot, 1.5 turns on the air screw to a #7 slide, 48 pilot, 1.25 turns out on the air screw. 1.5 turns out now will lean bog at full throttle.

I had 2 1/2 hours of run time this weekend starting with a new plug and the whole porcelain is wet cardboard colored. The max engine temp was 188 with plenty of lugging and on the pipe riding and it used barely over 1 gallon of gas in that time. Keep at it.

Thanks for taking the time to provide all that info. With the temp gun where are you getting your readings from? Also your probably aware of my idle issues at this point. I’m not sure where to start, whether its checking the engine temps with a temp gun, or sorting out my my pilot jetting. Also I remember the plug looked just like this after a couple hours when I was running the bored 36mm with a 48, 3rd clip, and 158 main. Thanks

[John_S]

I would shoot the temps on the cylinder and the top of the radiators to see what you’re getting. I’m guessing the top of the radiator is more accurate. The last time I had a plug that looked like yours was on my Honda that also needed a radiator cap to fix. We were on a long ride and I looked down at the temp gauge and it was 253. Ouch!

The main thing is to try to eliminate one more variable and know that it’s not getting piping hot. Don’t worry about the idle until you know for sure the pilot jet and air screw are correct with the test above. A good idle usually comes right along with it being set spot on. This weekend mine was idling like yours (sometimes up sometimes down) while I was messing with it. Or it would idle fine and then I’d gas it a little and it would hold a high idle for about 5 seconds and then come back down.

[JZ05220r]

I would shoot the temps on the cylinder and the top of the radiators to see what you’re getting. I’m guessing the top of the radiator is more accurate. The last time I had a plug that looked like yours was on my Honda that also needed a radiator cap to fix. We were on a long ride and I looked down at the temp gauge and it was 253. Ouch!

The main thing is to try to eliminate one more variable and know that it’s not getting piping hot. Don’t worry about the idle until you know for sure the pilot jet and air screw are correct with the test above. A good idle usually comes right along with it being set spot on. This weekend mine was idling like yours (sometimes up sometimes down) while I was messing with it. Or it would idle fine and then I’d gas it a little and it would hold a high idle for about 5 seconds and then come back down.

I was able to try the first gear test you described. A few of the times it pulled with little hesitation. A couple other times when I really stabbed it to wot from just off idle it definitely bogged pretty bad. I don’t know if I just twisted to quickly or what but yea their was definitely something going on. I was also using a step colder br9es plug. I have already replaced the cap in the past so I don’t think that is an issue.

[JZ05220r]

I would shoot the temps on the cylinder and the top of the radiators to see what you’re getting. I’m guessing the top of the radiator is more accurate. The last time I had a plug that looked like yours was on my Honda that also needed a radiator cap to fix. We were on a long ride and I looked down at the temp gauge and it was 253. Ouch!

The main thing is to try to eliminate one more variable and know that it’s not getting piping hot. Don’t worry about the idle until you know for sure the pilot jet and air screw are correct with the test above. A good idle usually comes right along with it being set spot on. This weekend mine was idling like yours (sometimes up sometimes down) while I was messing with it. Or it would idle fine and then I’d gas it a little and it would hold a high idle for about 5 seconds and then come back down.

I was able to try the first gear test you described. A few of the times it pulled with little hesitation. A couple other times when I really stabbed it to wot from just off idle it definitely bogged pretty bad. I don’t know if I just twisted to quickly or what but yea their was definitely something going on. I was also using a step colder br9es plug. I have already replaced the cap in the past so I don’t think that is an issue. Oh and glad to hear your got your bike dialed. These 2 strokes aren’t as easy to get right as I thought, especially when I did every mod I could with the 220. I just swapped out the 40 pilot for a 42, and also replaced the jet block gasket. The jet block gasket can be alittle tricky but I think I have it seated well.

[John_S]

No such thing as twisting it too quick. Just richen up a little at a time until you get it.

[JZ05220r]

No such thing as twisting it too quick. Just richen up a little at a time until you get it.

Gotcha. Wasn’t sure, I know on older 4 strokes without accelerator pumps that can be an issue. I rode for about a half hour with the colder plug. Did ride quite as hard as I typically would have but thought I’d share the pics I took. Looks like this is actually may the correct heat range based on the strap. But the ring around the threads has basically no color at all which would tell me it’s still lean. Ignore the messed up threads

[KDXGarage]

That's a bit too dark. Years ago, I struggled with a 9 in my '94. My jetting was not perfect, but I went from daily fouling to monthly fouling with going from a 9 to an 8.

[JZ05220r]

That's a bit too dark. Years ago, I struggled with a 9 in my '94. My jetting was not perfect, but I went from daily fouling to monthly fouling with going from a 9 to an 8.

Yes I think I’ll go back to the 8. I’ll test it with a bigger pilot and see how that goes. I’m hoping that makes a difference in how clean/white the plug was in my first pics.