Correct plug, Mototrans Elite

[Geordie]

My Mototrans Owner's Manual lists a Firestone F20 EF-S spark plug. Now defunct, I can't find a cross-ref for an equivalent.
The bike came with a new/good Champion L86C but shows rich running wherever I have the carb needle height - UB24 with spec needle/jets as originally fitted.
I am wondering if its a hotter plug needed. Its a '61 engine with big valve head and '1' cam. I don't intend high revs operation.

Any plug equivalent or suggestions gratefully received.

[Duccout]

I think that a B6HS or B7HS is recommended.

[Geordie]

Thanks for that. I have looked for a reference,before asking here but didn't find one. As the current plug is hotter than those two, i'll have to weaken the mixture and try that.

[ducwiz]

The spanish parts catalog for the Mototrans 200 lists a BOSCH 225 (or equivalent Champion, no grade quoted).
The italian catalog recommends a 240 grade for the 200.

cheers Hans

EDIT: I found a spanish user manual on one of my harddrives. It says "F 20 EF-S (240 on BOSCH scale)".

[themoudie]

Aye Geordie,

According to this online cross-reference, linked to below; the Bosch 225 plug, NGK equivalant plug is the B7HS and the Bosch 240 plug, NGK equivalent plug is the B8HS.

Spark_plug_cross_reference_link

At present I am running a B7HS in my '72 450 MKIII, rather than the often recommended B6HS that appeared too hot.

I believe Nigel Lacey runs either B7HS or when possible B8HS plugs in the race engines. He may care to comment?

Good health, Bill

[Paul O]

Hi George,

Mine has a NGK B7 HS, you know the rest lol

[Geordie]

Wow, what a response. Thank you to all. I'll get a new plug and start from there.

[Geordie]

At present I am running a B7HS in my '72 450 MKIII, rather than the often recommended B6HS that appeared too hot

Confusingly, I now find, NGK temperature reference numbers reduce for hotter while other manufacturer's increase!

[themoudie]

That was my problem as well Geordie. Nigel suggested that I should be running B7HS or B8HS, rather than the B6HS that I had gravitated to, as this latter heat range plug was the type recommended in the Champion to NGK conversion tables. I too thought that I was using a cooler plug, whereas in fact I was using a hotter plug and starting to get blistering on the central electrode ceramic insulator.

Good health, Bill

[Ventodue]

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