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Are the new Bosch WR8AC plugs Compatible with a Tiger CDI?

Are the new Bosch WR8AC plugs Compatible with a Tiger CDI?

These plugs have a suppression resistor and I am afraid to use them with a Tiger CDI.

Stock number 7902. Part number WR8AC.

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It links down to this, Mallory, MSD, Crane and Accel and others produce a high output CDI system (these should not be confused with a marine style CDI). For an automotive high output CDI system it is imperative you consult that manufacturer for plug specifications for their system. Some high out put systems specify the use of resistor plugs, while others will fry the internal plug resistor turning its 5k ohms into 60k ohms.

As a rule, performance is in no way impaired by resistor spark plugs. The only exception to this may be some models of high output CDI (exclusively for racing application) specify non-resistor plugs.

My Note: all of this makes me paranoid to use these plugs with my Tiger CDI. Any help is appreciated!

Reply to
Jim Ed
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Not entirely sure what brand of plugs I had with my Tiger, but they where of the resistor type. The only mod I had was the rotor with the resistor removed.

I would say nothing to worry about. The very worst that could happen is a fried resistor in the sparkplugs.

Wait for a few others to chime in.

J.

Reply to
P.J.Berg

If that happened, would the engine stop running, or run with a loss of power? TIA!

Reply to
Jim Ed

I was using NGK B5HS plugs and Bosch W8AC plugs with no noticeable problems. Did these plugs have resistors in them? TIA!

Reply to
Jim Ed

The NGK's resistors have an R in the code like NGK BR5HS if my memory is not gone toast, they are very hard to come by up here as the importer no longer stocks non resistor plugs. I cannot remember whether Bosch uses an R in the code to identify a resistor plug. You will however find both NGK, Bosch and Denso charts on the net breaking down/explaining all aspects of any particular plug. One peculiarity is the fact that NGK's heat range runs opposite of most others. 9 is cold and 6 is warm, 5 I have only seen recommended for old premix Vespa scooters(me thinks).

J.

Reply to
P.J.Berg

A qualified guess would be neither, it would run as a non CDI equipped car, the CDI module making up for the increased resistance of the plugs. In real life it would mean starting would not be as instantaneous as with CDI and healthy plugs.

Take a peak at Mallory's or MDS's pages, I can not recollect any warnings regarding plugs. Equally, look up the Mallory unit at Aircooled.net Mr. Connolly would give it straight.

J.

Reply to
P.J.Berg

Today I ordered a set of NGK B6HS plugs from Advanceautoparts.com to play it safe.

I will just put the set of Bosch WR8AC on the shelf for now.

Reply to
Jim Ed

You can buy plugs with capacitors built into the plug. Said to make the energy in the spark greater. If the resistor fries and goes open circuit it forms a capacitance!!.. I suspect the 20-30 KV from any ignition system would jump across the gap from a fried resistor. Actually I alsways wondered re the capacitor. How the hell can introducing any component that is intrinsically "lossy" increase energy. Probably at least as efficicient as putting magnets on the fuel line....................... John

Reply to
John

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