www.motorfahrrad.eu

I'm nervous about the NGK BP4 recommendation because here in America it isn't a resistor plug.

I have used a new NGK plug called an XR4 which is a resistor plug. It works very well.

CDI ignition is rare here in the US. I understand that a resistor plug is required so it can "read" the spark. I once made the mistake of trying a special "hot" sparkplug for a chainsaw that didn't have a resistor and the CDI box died. After that, I only use resistor plugs.

Yes, the spark plug...
I can't understand why people make experiments with this part.

The NGK B6HS has a longer thread than it should have. The consequence is, that after some time oil coal will fill the first part of the thread near the electrodes. This acts as Loctite ultra-tight when you turn the spark plug out. The aluminium of the cylinder suffers a lot.

NGK XR4IX and NGK XR45IX should be available in the USA as well as in the UK.
I don't know whether the Bosch WR10FC is sold everywhere.

I'm not sure about the effects of the resistor in the spark plug. Most of us drive with open CDIs, which do not restrict the rpm. There are rather strong and large capacitors inside, which can endure stronger pulses than the capacitors in the ignitions from stock.

Cheers

Dieter

Threads of a NGK B8HS (on the left) and a NGK XR45IX
Click to enlarge

Hi

1 off our dutch members uses the NGK XR5IX Iridium spark plug for his engine. Be aware these 1,s arent very cheap.
Right, i don,t use this 1 myself. But he said he drove manny miles with it. And it did function perfectly.

http://www.automedia.com/Iridium_Spark_ ... 010101ds/1
http://www.importtuner.com/tech/impp_08 ... index.html
http://www.spark-plugs.co.uk/pages/tech ... _plugs.htm

http://www.amazon.de/NGK-XR4IX-Z%C3%BCn ... B000HDDBWE
Iridium NGK XR4IX plug, around 12,50EUR

http://www.globaldenso.com/en/products/ ... 037_4.html
Cross-reference for NGK BP-4 -> DENSO W14PR-U, does not give an iridium equivalent.

http://spark-plugs.co.uk/index.php/cont ... ts.iridium
Link given earlier by yoekio, claiming the entire denso line is superior to the basic NGK (XR4IX) iridium plug.

BP-4 W14PR-U - -
BP4E W14EX-U - -
BP4EA11 W14EX-U11 - -
BP4EFS T16EPR-U IT16 VT16
BP4ES W14EP-U - -
BP4ES W14EX-U - -
BP4ES11 W14EX-U11 - -
BP4ES-L11 W14EX-U11 - -
BP4EY W14EX-U - -
BP4EY11 W14EX-U11 - -
BP4FS T14PR-U ITF16 -

Gives an iridium plug from denso equivalent to NGK standard plug, only for the BP4EFS and BP4FS NGK plugs.
http://www.ngksparkplugs.com/techinfo/s ... berkey.pdf

E indicates '19mm, 3/4" Thread reach', and FS 'Tapered Seat 10,9mm (.460")'

Can anyone make sense of this?

Is this XR4IX a resistor-plug? Some concerns were raised to protect the CDI's generally, the plug should be a resistor-type.

It's necessary to know this before picking up another plug and for the amount that an iridium plug costs. ~13EUR.

BP4 vs B6HS update:
It (the motor) went back to BP4 as the B6HS made no noticeable difference - without having seen the previous helpful thread comment first, i think it was by dieter-k - it was noticeable when comparing the two out of the engine, how much longer the B6HS is, and the intuition was to not want to damage anything inside the firing chamber by having the plug extended further than necessary into the engine. Plus as has been mentioned, the BP4 should fire better.


Transmission fluid:
Since someone brought up transmission fluid: could that be a reason for the high pitched momentary whining noise when letting-go of the throttle? A low transmission fluid level? The vehicle is moving normally, then the clutch disengages with a release of the throttle, and there is a momentary whining noise. I have not yet been able to check the transmission. I just started using the regular bicycle instead, until friday, when there is more cash for such things (iridium plug, transmission fluid, parts order).

Hi

I cant give any further info about this spark plug cos i aint using it myself, Got this link from the duth spartamet forum. And he,s claiming it works perfectly.

The XR4IX is a resistor type. All NKG Iridium spark plugs are resistor types.

This model is luxus for people who love their Saxonette and money doesn't matter.
For normal users the Bosch WR10FC is the first choice.

Dieter

Well, thanks dieter.


We'll see if one is available from the local chop-shop (TIP AUTOMOTIVE)

If so it'll be ordered. RE/AW:LOVE: It's not 'love', it's about best ignition, cleanest running:

E.G. Had an older woman the previous day put her paper wipe up to her nose while the bike was on an island, idling, and the exhaust was going to her.

Plus, the xR4IX, being a resistor plug, should technically work better with the CDI.

I have hopes. Also I will be able to check the transmission fluid and report back.

Many thanks again.