moneybags Posted November 1, 2007 Report Share Posted November 1, 2007 I am looking to make my 421 cub motor faster. So far I have come up with the folowing ideas. Drag port the cub cyclinders. Duneable tranny Smaller domes for where I ride (4000 eve) Swich to alky Freshin up the top end Is their any case mods that have to be done to install a duneable over ride? Are thay much differents then installing a normal tranny? If and when I go for the overide. I will be wanting to install it my self. Has anybody elce installed one? Anybody elce have any go fast ideas? Current mods are in my sig. Quote Link to comment Share on other sites More sharing options...
00tbanshee Posted November 1, 2007 Report Share Posted November 1, 2007 (edited) I am looking to make my 421 cub motor faster. So far I have come up with the folowing ideas. Drag port the cub cyclinders. Duneable tranny Smaller domes for where I ride (4000 eve) Swich to alky Freshin up the top end Is their any case mods that have to be done to install a duneable over ride? Are thay much differents then installing a normal tranny? If and when I go for the overide. I will be wanting to install it my self. Has anybody elce installed one? Anybody elce have any go fast ideas? Current mods are in my sig. as for installing the dunable override its the same as putting a stock tranny in but you have springs that go in between the shifter forks.go for it i love mine and do the neutral down its only like 15$ more and its nice to have and for the alky also its great i will never go back to c12. great power gain Edited November 1, 2007 by 00tbanshee Quote Link to comment Share on other sites More sharing options...
J-Madd Posted November 1, 2007 Report Share Posted November 1, 2007 You may be able to bump up you timing a little, especially if you go to alky. I went from what you have now to what's on your list (besides changing the domes and drag porting), and it is night and day. Dropped 4 tenths or so in 300ft. Don't forget to gear up a little if/when you go to alky. Quote Link to comment Share on other sites More sharing options...
badassbanshee479 Posted November 1, 2007 Report Share Posted November 1, 2007 where is your compression at right now?? these things love timing!! I have my plate maxed right now! on alky of course. drag port it switch to alky and crank up the timing! Quote Link to comment Share on other sites More sharing options...
moneybags Posted November 1, 2007 Author Report Share Posted November 1, 2007 Right now the compression is at 175 psi in both cyclinders. That is at sea level. If I add more timing will that take away from my top end? I love top end power. so that if I have to. I can run people down on the mountion. (I love doing that :biggrin: ) Quote Link to comment Share on other sites More sharing options...
badassbanshee479 Posted November 1, 2007 Report Share Posted November 1, 2007 I dont think I would change the domes. The cubs seem to like around 170-180 psi of compression. Yeah it may take alittle off the top but it will come out of the hole super hard!! Quote Link to comment Share on other sites More sharing options...
moneybags Posted November 1, 2007 Author Report Share Posted November 1, 2007 Will I have to get new domes When I make the swich to alky? Herd people talking about having alky domes. (???) The 175 psi is at sea level. I ride at 4000 to 4700 evevation. So I was thinking that my compression would be around 140 up their. Thanks Quote Link to comment Share on other sites More sharing options...
J-Madd Posted November 1, 2007 Report Share Posted November 1, 2007 Will I have to get new domes When I make the swich to alky? Herd people talking about having alky domes. (???) The 175 psi is at sea level. I ride at 4000 to 4700 evevation. So I was thinking that my compression would be around 140 up their. Thanks I didn't change domes when I went to alky. I've also heard about alky domes, just don't know the difference...and you'll need to actually test the compression, and not go by the chart. Quote Link to comment Share on other sites More sharing options...
moneybags Posted November 2, 2007 Author Report Share Posted November 2, 2007 I have tested the compression my self, at sea level. (175psi) Quote Link to comment Share on other sites More sharing options...
J-Madd Posted November 2, 2007 Report Share Posted November 2, 2007 I have tested the compression my self, at sea level. (175psi) OK. BTW, 175 seems a little low for 19 cc domes; I've got 180 with 20 cc domes on my 421 Cub...but every motor is different, and even different testers will yield different results (so I've heard). Quote Link to comment Share on other sites More sharing options...
moneybags Posted November 2, 2007 Author Report Share Posted November 2, 2007 OK. BTW, 175 seems a little low for 19 cc domes; I've got 180 with 20 cc domes on my 421 Cub...but every motor is different, and even different testers will yield different results (so I've heard). I was thinking the same thing. Thats why I menchened freshing up the top end. My 06 stock cyclinder 4 mill has 20cc domes with 180psi. Maby I will go do another compression test. Quote Link to comment Share on other sites More sharing options...
black sunshine Posted November 2, 2007 Report Share Posted November 2, 2007 IDK I have 20cc and 160psi@900ft which is pretty much right on with the chart on the Noss website :shrug: Quote Link to comment Share on other sites More sharing options...
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