markzx7 Posted May 10, 2005 Report Share Posted May 10, 2005 ill give you a liitle history on this i got a local builder to build my 4mm motor when i got it back it never really ran that good, my stock port stock stroke cpi piped bike almost beat it. my setup was 4mm longrod 795 pistons .20 over timing plate advanced %6 cpi in frame 34mmpjs drag ported 14/41 gearing hemi head with cut domes. best times in the 1/8 mile was 8.8s tryed to gear higher but it wouldnt pull it. talked to the builder and he said i needed diffrent carbs and pipes. he said i needed 35.5ftz mikunis and out frame drag pipes. well i got the carbs and grr suicide pipes and try it and still no help. well i took it to anther biulder to look it over and come to find out that the port was for a stock stroke crank. so i sold the cylinders and got another set and had them ported for a 4 mill and went .80 over with blaster pistons. well here is my problem the bike runs better it will leave out in second where it wouldnt think of it before but still i wont runn less than an 8.8 in the 1/8 ive tryed everthing jetting is on tried diffrent timing tried diffrent gearing dont know what else to try. im just wondering if it is in the porting again is there any way to compare my specs with any others so i can rule this out, or any suggestions of things to try Quote Link to comment Share on other sites More sharing options...
superchicken Posted May 10, 2005 Report Share Posted May 10, 2005 if you have got the right port work done this time,try putting a 17 tooth front on and if you dont see a difference theres a problem some were else in the engine Quote Link to comment Share on other sites More sharing options...
Koolguyson Posted May 10, 2005 Report Share Posted May 10, 2005 Cant really compare your porting over the internet because there is a lot more to porting that a camera or words cant describe. If you must send the entire motor to a reputable builder and see what they say. Quote Link to comment Share on other sites More sharing options...
PassionRE Posted May 10, 2005 Report Share Posted May 10, 2005 ill give you a liitle history on this i got a local builder to build my 4mm motor when i got it back it never really ran that good, my stock port stock stroke cpi piped bike almost beat it. my setup was 4mm longrod 795 pistons .20 over timing plate advanced %6 cpi in frame 34mmpjs drag ported 14/41 gearing hemi head with cut domes. best times in the 1/8 mile was 8.8s tryed to gear higher but it wouldnt pull it. talked to the builder and he said i needed diffrent carbs and pipes. he said i needed 35.5ftz mikunis and out frame drag pipes. well i got the carbs and grr suicide pipes and try it and still no help. well i took it to anther biulder to look it over and come to find out that the port was for a stock stroke crank. so i sold the cylinders and got another set and had them ported for a 4 mill and went .80 over with blaster pistons. well here is my problem the bike runs better it will leave out in second where it wouldnt think of it before but still i wont runn less than an 8.8 in the 1/8 ive tryed everthing jetting is on tried diffrent timing tried diffrent gearing dont know what else to try. im just wondering if it is in the porting again is there any way to compare my specs with any others so i can rule this out, or any suggestions of things to try 367392[/snapback] Did your builder give you any specs on the porting he did...one mans drag port is another mans chainsaw....Jim Quote Link to comment Share on other sites More sharing options...
markzx7 Posted May 10, 2005 Author Report Share Posted May 10, 2005 Did your builder give you any specs on the porting he did...one mans drag port is another mans chainsaw....Jim 367456[/snapback] he didnt give me any specs but pretty much every 4mm motor he does runs in the 6s in the 1/8 last i heard he ports fredy sanfords cylinders in nc and they have some pretty impressive stuff Quote Link to comment Share on other sites More sharing options...
markzx7 Posted May 10, 2005 Author Report Share Posted May 10, 2005 he didnt give me any specs but pretty much every 4mm motor he does runs in the 6s in the 1/8 last i heard he ports fredy sanfords cylinders in nc and they have some pretty impressive stuff 367465[/snapback] the motor wont pull the 17 Quote Link to comment Share on other sites More sharing options...
PassionRE Posted May 10, 2005 Report Share Posted May 10, 2005 If your cylinders are ported the same as what you mentioned running 6's and everything else is the same, Id start by looking at either your ignition, or possible sheered,woodruff key, cracked reeds possibly. Is everything else the same?...lock-up, over-ride etc? Quote Link to comment Share on other sites More sharing options...
markzx7 Posted May 10, 2005 Author Report Share Posted May 10, 2005 If your cylinders are ported the same as what you mentioned running 6's and everything else is the same, Id start by looking at either your ignition, or possible sheered,woodruff key, cracked reeds possibly. Is everything else the same?...lock-up, over-ride etc? 367475[/snapback] that is one diffrence in them they run overides i didnt want to go with the over ride cause we drag in feild and just mess around alot and i was told they only take a few tenths off of your et when i redone it put in new shift forks modified shift star and a shift pro. it shifts like a dream Quote Link to comment Share on other sites More sharing options...
wayfst Posted May 11, 2005 Report Share Posted May 11, 2005 pull the head, move the piston all the way down, if the opening to the transfer port is above the piston u don't have the right porting for your crank. Quote Link to comment Share on other sites More sharing options...
markzx7 Posted May 11, 2005 Author Report Share Posted May 11, 2005 pull the head, move the piston all the way down, if the opening to the transfer port is above the piston u don't have the right porting for your crank. 367616[/snapback] thanks for the help you all Quote Link to comment Share on other sites More sharing options...
fastbanshee4u Posted May 12, 2005 Report Share Posted May 12, 2005 ill give you a liitle history on this i got a local builder to build my 4mm motor when i got it back it never really ran that good, my stock port stock stroke cpi piped bike almost beat it. my setup was 4mm longrod 795 pistons .20 over timing plate advanced %6 cpi in frame 34mmpjs drag ported 14/41 gearing hemi head with cut domes. best times in the 1/8 mile was 8.8s tryed to gear higher but it wouldnt pull it. talked to the builder and he said i needed diffrent carbs and pipes. he said i needed 35.5ftz mikunis and out frame drag pipes. well i got the carbs and grr suicide pipes and try it and still no help. well i took it to anther biulder to look it over and come to find out that the port was for a stock stroke crank. so i sold the cylinders and got another set and had them ported for a 4 mill and went .80 over with blaster pistons. well here is my problem the bike runs better it will leave out in second where it wouldnt think of it before but still i wont runn less than an 8.8 in the 1/8 ive tryed everthing jetting is on tried diffrent timing tried diffrent gearing dont know what else to try. im just wondering if it is in the porting again is there any way to compare my specs with any others so i can rule this out, or any suggestions of things to try 367392[/snapback] Boy that builder sure likes to spend your money, and is full of sh!t .It does not take those carbs and pipes to make a 4 mm run good. I built my buddy that same set up with 30mm carbs and Pro Circuit pipes and I seen it run with some bikes that had alot more than him.Good luck Quote Link to comment Share on other sites More sharing options...
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