Engine knocking after carb job

[stilkus]

okay I need to know something.
This afternoon I checked for the spark wire boots and I discovered they could be disassembled, findong inside a white stone ???? and a spring.
I want to know the importance of the white piece, and if I remove it will the conductivity of the spark wires increase or what ?

 

[ZackDaniels]

in situations like this it almost always ends with a big forehead slap because it was something routine that you didn't think to check because you were hyper-focused on the complicated stuff. I know I've been there at least!

Well, that was how I got it back running, I thought I would share the results also that was a stupid problem but I totally overlooked the spark strength before :S

Grats and welcome to the club man! I would bet almost everybody has been there at least once.

I can't picture the white stone you're describing... do you have the ability to snap a photo or two of it?

 

[dannymax]

The 'white stone' is the resistor, there is a spring and also a little tiny brass disc....which I believe is to help make good contact between the resistor and spring. And yes, they are necessary.

It's not stone....as you can tell from the weight....it's aluminum with some oxidation on it.

 

[stilkus]

The 'white stone' is the resistor, there is a spring and also a little tiny brass disc....which I believe is to help make good contact between the resistor and spring. And yes, they are necessary.

It's not stone....as you can tell from the weight....it's aluminum with some oxidation on it.

Actually I stretched the spring and removed the stone and I am getting better spark over there. That's what made me wonder why do they even install it there ?? Initially I thought it might be some resistance to delay the spark for a fraction of a second to adjust ignition timing there ( I know my imagination could take me to weird conclusions sometimes ) and that's why I asked the experts

 

[stilkus]

Grats and welcome to the club man! I would bet almost everybody has been there at least once.

I can't picture the white stone you're describing... do you have the ability to snap a photo or two of it?

It was really bad, I took the cam cover off to inspect the valve clearances and totally missed the wiring part. I also discovered that we do have a shim and a bucket valve system which I have never seen or known before. I was standing next to the engine thining we had hydraulic tappets till I went back home and double checked that info online.

about the stone I don't have any pictures of it, but it's easy to picture. a white cylindrical part I would say 1 cm long and diameter of 3 to 4 mm and is placed right behind the spring in the spark plug boot.

 

[ZackDaniels]

The 'white stone' is the resistor

Actually I stretched the spring and removed the stone and I am getting better spark over there. That's what made me wonder why do they even install it there ??

about the stone I don't have any pictures of it, but it's easy to picture. a white cylindrical part I would say 1 cm long and diameter of 3 to 4 mm and is placed right behind the spring in the spark plug boot.

That does indeed sound like a resistor. Resistors are quite an important part in electronics in general. They can fail, and when they do they don't pass electricity effectively which explains your weak spark problem.

I'm not an expert in what they're for in relation to spark plug boots, but they're commonly used in electronics for all kinds of reasons. Including basic energy conversion of electric to heat. If it were my bike I would replace the resistor rather than being content to run without it not knowing the specific purpose of it in Yamaha's design.

It's basic electronics - So if you can't get the exact replacement without buying a new boot from a dealership or ebay you have cheaper options for replacement. A schematic from a manual should give you the important numbers if they're indeterminable from the scorched up and oxidized one you pulled. You can take those and get a replacement from any store that carries small electronics, check out a larger radio shack (the small ones are nothing more than cell phone stores these days), Fry's electronics, or local hobby shops.

Stressing this again:

That's what made me wonder why do they even install it there ??

I don't know but it's not likely to be unimportant. The resistor itself was not a problem, the fact that it is broken was the problem. This is 'fixed' by removing the broken resistor, but it's probably a lot better to replace it with a new working resistor ASAP.

 

[mr.maxx]

the main reason for the resistor is to eliminate electronic interfearance....however it also plays a role in the proper operation of the ignition control module. if it was me id just buy a new plug cap.

 

[stilkus]

Regarding float level....you can't depend on the little circles cast in the carb body, they aren't dependable. Use them as a rough setting but always do a wet level verification.

Let me tell you sir, your advice got stuck in my head and helped me today. I never did one before but it made me doubt my float levels. Well today while I was trying to sync the carbs once more because there's this little vibration, I discovered after I'd finish syncing then it wont go away, so I took the air filter box off and noticed the diaphragm piston action and what I saw was the 2 left carbs would actually spray some fuel droplets up when revving while the two right ones wouldn't. I immediately thought of raising the float levels of the right side carbs and the engine felt way better and the engine power was better distributed amongst the rpm range.

I feel like I am in need of a wet level adjustment
could you inform me of the right amount of gas in each carb. ? metric values would make it easier

I want to make sure as well if the right carb fuel droplets should be there or is this an indication of a rich setting ? I measure everything regarding carbs on a flat surface and the bike on it's center stand.
I'd rather have my bike tad rich than tad lean, I feel like this the engine would live longer., is it right thinking ?

 

[alorio1]

Here is a link that may help you set wet float level in the How to "carb/tuning" section http://www.vmaxforum.net/showthread.php?t=17274

 

[dannymax]

Make sure your carbs are level when you do this.

 

[Rusty McNeil]

In regards to the resistor.


It is to prevent inference to the TCI. heavy EMF's without it.
The stock wires are non suppression wire, just copper wire really.

I've been running mine for several years without the resistor or the factory boot, just regular old 8mm yellow wire and boots, but it's suppression wire and takes place of the resistor.

I tried regular boots and non suppression wire and it would miss fire and act hinky at certain rpm's which I think was EMF's playing havoc with the TCI.

Same as how some electronics ( industrial) will have a sign telling you not to key up a two way radio near them.

Related note; used to have some older two ways at work back when i was in a plant that when keyed up near a GFCI receptacle would trip it, specifically the ones in the lunchroom.

 

[stilkus]

Hi, I have a strange thing going on here and I am trying to link it with the slight engine vibration amongst the rpm range. When I remove the rubber plugs which reveal the carbs syncing ports I find in one of the pistons it suddenly rises the rpm 500-1000 instead of making the engine hesitate as the other 3 would do. I have synced the carbs and I am sure of that. What could that be ?

 

[wildweasel_pt]

Don't do that. You are dangerously leaning the mixture and rising temperature. You can burn your valves and headers...

 

[stilkus]

Don't do that. You are dangerously leaning the mixture and rising temperature. You can burn your valves and headers...

I am not doing it the whole time, I just noticed it today so my question is why are all the pistons causing the engine to hesitate once the sync plug is removed while the piston number 1 has tehe exact opposite outcome which makes the engine rev faster instead of hesitation once the port cover is removed ?

 

[tugla]

rubber plugs carb sync ports? you talking the a/f screws?

 

[DMAN999]

^ He's talking about the little Black Rubber Boots you have to remove to hook up a Sync tool to the Vacuum Ports on the Carbs.
You can see them in the second and third pictures in this thread:
http://www.vmaxforum.net/showthread.php?t=3959

 

[stilkus]

I mean the sync ports.

 

[tugla]

ahhh my bad, sorry......

 

[stilkus]

so, what does this symptom mean ?