Cubshee421 Posted February 3, 2015 Report Share Posted February 3, 2015 What cc domes are people running on there 421 cubs on race gas Quote Link to comment Share on other sites More sharing options...
Cubshee421 Posted February 3, 2015 Author Report Share Posted February 3, 2015 300 ft drags at sea level Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted February 3, 2015 Report Share Posted February 3, 2015 I'm sure most wouldn't share a secret like that if there the least bit competitive Quote Link to comment Share on other sites More sharing options...
Nightmare Posted February 3, 2015 Report Share Posted February 3, 2015 That's for you to figure out bruh. Quote Link to comment Share on other sites More sharing options...
BUILDER Posted February 3, 2015 Report Share Posted February 3, 2015 Only answer you are going to get on that one is probably from a builder Quote Link to comment Share on other sites More sharing options...
SlowerThanYou Posted February 3, 2015 Report Share Posted February 3, 2015 On our race gas 443 cub we ran 20cc & 21cc domes. The quad was competitive with a heavy stock frame (320 lbs.) & a heavy rider (210-220 lbs.), it ran low 3.90s & was faster with a lighter rider. It was run on Q16 race fuel the majority of the time. It's first & only time at Gilbert, LA. It made the semi-finals in 426-525cc heads-up class against chassis/alky bikes. It also, made the semis in the bracket class & went a bunch of rounds in an index class. Quote Link to comment Share on other sites More sharing options...
Cubshee421 Posted February 3, 2015 Author Report Share Posted February 3, 2015 Thank for giving me a honest answer. Im just local river racing we tape off 300ft Quote Link to comment Share on other sites More sharing options...
possum Posted February 4, 2015 Report Share Posted February 4, 2015 (edited) I would go with 19s or 20s. on a 4cub. Driveline domes on ebay or hit up bansheehp, and dont look back. Edited February 4, 2015 by possum 1 Quote Link to comment Share on other sites More sharing options...
camatv Posted February 7, 2015 Report Share Posted February 7, 2015 cc isnt as important as squish. you could run 30cc and have .30 tho squish clearance and it will smoke all the time.. try a 20-19cc dome flat top profile in the bowl, 8-9mm squish band and at least 48 tho of clearance. id personally step it up to 52-58 and or even 60 on gas. if you can try a set of differnt squish. the higher squish will let it rev to the moon and run all day on lesser fuels. but i like motors that stay together. not just dyno stars 1 Quote Link to comment Share on other sites More sharing options...
SlowerThanYou Posted February 7, 2015 Report Share Posted February 7, 2015 cc isnt as important as squish. try a 20-19cc dome flat top profile in the bowl, 8-9mm squish band and at least 48 tho of clearance. id personally step it up to 52-58 and or even 60 on gas. if you can try a set of differnt squish. the higher squish will let it rev to the moon and run all day on lesser fuels. but i like motors that stay together. not just dyno stars camatv brings up some good points! While dome cc is important, there are other factors as he has brought up. We ran our cub with squish tighter than camatv's recommendations. Our 7mm revved to the moon, stayed together, wasn't a dyno star, but didn't run on lesser fuels. The OP stated race fuel, there are many different ways to set the domes up for that. Does that make camatv, or I, right or wrong with our opinion. We both use what works for our applications. Many different ways to skin a cat. IMO, your best bet is to have a known builder design/machine custom domes for your application. 1 Quote Link to comment Share on other sites More sharing options...
Cubshee421 Posted February 7, 2015 Author Report Share Posted February 7, 2015 I had someone measure my cubs and they said the port timing were factory. So it runs pretty hard but is just cleaning them up going to help that much. Or should I have someone bump the exhaust transfers up for me? Quote Link to comment Share on other sites More sharing options...
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