M MasonIsGreat35 Member Apr 29, 2023 #1 cant find any info on stock gx390 head valve size in mm and the stock valve spring specs Last edited: Apr 29, 2023
C Compu-kart Member May 26, 2023 #2 You need to call Carlson Motorsports or send him a PM on this forum. Otherwise check the NR Racing website.
You need to call Carlson Motorsports or send him a PM on this forum. Otherwise check the NR Racing website.