Spark plugs totally white

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Nuno

XS400 Enthusiast
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Hello everybody...
the bike: XS 400 DOHC, pods, stock headers with custom exhausts.
The bike doesn't ride too badly but the spark plugs are totally white.
The needle is at the third notch (middle position) and the main jet is a HUGE 160.
The spring has been shortened to make it oppose less resistance and so to make the diaphragm open quicker.
The bike starts fine, run fine (even though my clutch is slipping so I can't test the top speed at the moment...a week ago I recorded 156 km/h on the GPS) but it could run better that's why I'm checking and double checking that everything is fine.
I was previously running with a #150 and needle at the fourth notch (from the top) but felt a lack of response in the middle range so I lowered the needle and at the same moment tried to go up with the mains 'cause I saw the plugs being too clear.

I know these sizes are really big that's why I can't understand how it can be so lean.
I checked for air leaks spring some carb cleaner and see if revs go higher but no...if I really spray a lot of cleaner the engine will start to die instead.

I have to note that the main jets are not exactly like the stock ones as I couldn't find them...I'm using these
http://www.motocarb.co.uk/images/logos/N100.jpg
They mount fine but since the "head" is a bit thicker they sits lower in the bowl....now that I write it I realize this could mess with the fuel level :D

any other idea?
 
Code: 
The spring has been shortened to make it oppose less resistance and so to make the diaphragm open quicker.

By them opening up quicker how does that affect the bike?What exactly are you gaining by doing this?
 
Scorpio1963 said:
Code: 
The spring has been shortened to make it oppose less resistance and so to make the diaphragm open quicker.

By them opening up quicker how does that affect the bike?What exactly are you gaining by doing this?
Click to expand...

quicker throttle response.
 
You are correct after some thought cutting the spring would remove less height and reduce the pressure giving less throttle responce not faster.If anything a longer spring would increase the tension
 
Last edited:
Nuno said:
Well I guess if I asked about tyre pressure you'd have sent a link to Torricelli's biography...
Click to expand...

That is quite the attitude. How do you like this for attitude: next time I won't offer you any input at all. I'm not about to waste my time repeating what has been covered here before.

I though that offering you a link to a thread that includes one of the best sites I've found for tuning carbs would be of assistance. Apparently you want your question answered on a silver platter and fed to you with a silver spoon... :wtf:
 
16VGTIDave said:
That is quite the attitude. How do you like this for attitude: next time I won't offer you any input at all. I'm not about to waste my time repeating what has been covered here before.

I though that offering you a link to a thread that includes one of the best sites I've found for tuning carbs would be of assistance. Apparently you want your question answered on a silver platter and fed to you with a silver spoon... :wtf:
Click to expand...

no. That's your attitude, the attitude of someone who copied and pasted a very neat and vague (I'm sure everything is there, somewhere) link and believe that to be gold or even just an input. Pretty much that's a good one for everybody writing the word "carb" on the forum, isn't it?
I detailed every operation I did on the carburetor and your attitude suggested I needed a link about "anything carbies" because you're very smart and have no time to waste while everybody else is really dumb and is not able to find yet another step-by-step guide on internet. Or, similarly, since it has already been covered from now on let's just post link to past posts and be happy ever after....

I've never asked for any ready answer on a silver spoon but maybe there is something I'm not seeing even if it's right under my eyes...a discussion like "Hey, have you tried .... ?" is what I was looking for.
 
Did you even bother to follow the link to factorypro.com and read the carb tuning guide? It is very detailed about how to determine what jets are required.
 
Scorpio1963 said:
Guys chill attitudes arent helping anybody,correct facts and information does.Im not cutting springs only to ruin my carbs
Click to expand...

Nobody told you to but if you talk about facts then don't talk about cut springs 'til you tried...no? Also "ruin my carbs" for a mod that can be reverted with a few dollars/euros (92081A) doesn't seem quite factual.
I was skeptic too when I tried this mod, suggested me by the classic someone "who should know better" and then never does :D but truth be told, it works. I had another pair of springs ready so it was not a big deal to try.
 
16VGTIDave said:
Did you even bother to follow the link to factorypro.com and read the carb tuning guide? It is very detailed about how to determine what jets are required.
Click to expand...

did you bother to read my post or you just had the link ready to paste? we can go on as long as you want, you were the one without time to waste (but somehow feeling you had to answer...)
 
So you cut springs and yet you the know it all carb speacilist cant figure out why your plugs are running white:wtf:?If your so smart then you should know cutting springs shortens then reducing tension.Maybe this is the cause to your problem.:shrug:
Another thing you had an extra pair of springs on hand so incase you screwed up by cutting springs you can just drop in another pair of springs and go.Well I dont,Also your bike is setup completely different than mine jetting so no 2 bikes are going to run the same after this mod unless the 100% identical Correct yes or no?
 
Last edited:
Scorpio1963 said:
So you cut springs and yet you the know it all carb speacilist cant figure out why your plugs are running white:wtf:?If your so smart then you should know cutting springs shortens then reducing tension.Maybe this is the cause to your problem.:shrug:
Another thing you had an extra pair of springs on hand so incase you screwed up by cutting springs you can just drop in another pair of springs and go.Well I dont,Also your bike is setup completely different than mine jetting so no 2 bikes are going to run the same after this mod unless the 100% identical Correct yes or no?
Click to expand...

Can you show me exactly when I told YOU to cut your springs? Do whatever you want but please think before writing "ruin my carbs". It's the same as buying a new pair of jets: does a wrong sized jet ruin your carb? No. Want to try this mod? Buy a new pair of springs. What's the difference?
Moreover, what does it mean "no 2 bikes are going to run the same after this mod unless the 100% identical". No bike is identical to any other, not even using the same air filter and same exhaust will lead to the same jetting. So what? What's the point here? The final setup of a bike (actually, of pretty much everything outside the digital world...) is a combination of factors, each factor having it's own effect. Your setup might be different from mine, I agree, but doing the same mods will lead to the same effects: it's the amount of change that will be different but you can't really expect a whole different effect...
...or should we consider everything random since every bike is different?
 

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