Reading the Spark Plug Color

[panmil92]

@2stroketerry If I remember correctly both cylinders had the same number and the same heads ( the 3BN type with the non-flat squishband ) . Now regarding the markings on the crankshaft cover I think they were a little different ( something like Y-1 , and Y-2 ? I’m not sure about this I need to call my brother to check as the donor engine is on a different town )

[panmil92]

I found a pic, the crankshaft cover on the 1997 bike reads ( 3BN03 )
----------------------------------------------------------------------------- ( Y-1 )

and from the donor bike it reads ( 3BN03 )
--------------------------------------------(Y-2)
What the second code means anyway ?

[2stroketerry]

@panmil92 The number on the cover has nothing to do with engine types years or models as even the latest 4BL engines have 3BN03 Y-1 on the cover.

[panmil92]

@2stroketerry Ok , so how i know if the stroke of the cranksaft is the same in both engines. *** And on that note, if it was different what would happen ? With the exception of bogging at WOT the engine works OK ( i think.., keep in mind this is my first 2-stroke bike and my first bike overall ) .

Also DAMN that's a squeeky clean engine you have there !

[Calum]

The DTRE/X used 210 main jet also.

My RE, with newer electrics, definitely had problems with no battery. YPVS wouldn't operate properly.

[declan]

@Calum my bike won’t operate ypvs with battery dead I was forever leaving the ignition on so when it came to riding I’d have to give it an extra long warm up so it had enough charge for the pv

[panmil92]

UPDATE – First of all, yes a working battery gives the bike a lot more torque after 5-6k rpm, I think as well that the YPVS servo is not working correctly without a steady 12v source, or / and , the ignition is not working correctly ( thus the loss of torque ) .

Secondly, the 240 main jet was a disaster , it was like pulling the choke after ¾ of throttle , nevertheless I took a pic of the sparkplug after 15 secs at WOT :

Now I have fitted a 210 main jet. I run some tests and this is what the spark plug looks after 10 mins casual driving and then 15secs at WOT :

I noticed that now approaching 4/4 throttle I had some cuts that I think it was misfire ( it sounded like an interruption of the normal sound for a split second, it had a muffled note not metallic or pinging ). This may be due to the spark plug being fouled from the previous over-rich condition. Still, going from 3/4 to 4/4 seems like you are still holding ¾, there is no more ( or very little ) acceleration and the note of the engine gets a tiny bit more “ heavy”. It does not bog like it did with the 240.

[panmil92]

Another update ( kind of ). I was driving home at night , it was cold ( 15 C from 29 C in the midday ) and the bike had the most responsive throttle response I’ve seen :face_with_open_mouth: . It was like a rocket revving from idle till WOT with no problems at all. I guess it was the temperature ? One change i also made before the drive was i emptied the oil tank ( it was almost empty anyways ) and filled it with Motul 710 2T. I’ll make more observations in the following days…

[finnerz89]

Engines love cold air, just wait until you're riding on a nice crisp, foggy morning then it'll really sing!

[Calum]

@finnerz89 Used to notice it a lot on my little 50cc Aprilia RS when I was kid coming home from a late night!