Brisk Bike performance spark plugs - anyone tried them on the xs400?

[XSnoob]

Im looking at these spark plugs and am wondering about them...

Anyone try these? Increase in power or fuel efficiency? Did you have to change any tuning of the bike?

http://www.ebay.com/itm/PERFORMANCE-SPARK-PLUG-Yamaha-XS-400-500-XS400R-XS500-XT125-XT200-XT250-XT350-/160708604797?pt=Motorcycles_Parts_Accessories&hash=item256afab37d&vxp=mtr

 

[LuckyEight]

Thanks for tip. They are from Czech Republic, so easy to find for me I'll try them...

 

[xschris]

I don't know about $40 for a set but if someone want to try them than go for it. I know that going to a set of iridium plugs and indexing them makes a noticeable change from stock so ya never know.

 

[jmd_forest]

Swapped to iridium plugs over the summer and using a 0 ohm plug cap and am happy with the easier startup but didn't see any performance increase. I'm hoping xschris could provide some details on "indexing". Thanks.

 

[xschris]

Indexing is having the open part of the spark plug facing the valves to create and better flow and burn in the combustion chamber. Some plugs will be close without using shims and some will use up to three. I have done this with all my bikes and have noticed better starts and fuel economy. I ran my 79 with stock plugs for 10 years so I know how it felt. After the plug change I could tell the difference, but that me The first pic is non-indexed last is after.

 

[jmd_forest]

Thank you ... never came across that before. I guess I'm never to old to learn something new.

 

[xschris]

Its a old race car hot rod thing. Some people have seen small but crucial power gains on a dyno, witch can mean a race