nmrichardson Posted March 13, 2017 Report Share Posted March 13, 2017 hey all I'm working a bit backwards on this build haha I've picked up a new cool head with 19cc std bore domes, I also picked up a new std bore cylinder/piston kit now I need to source a crank..... question is, now that I have std bore cylinders, std pistons and std domes am I limited to a std crank? or is there a way to make a 4mil crank work with my other bits? I realize this isn't the best way to tackle a build but the other bits came my way at a good price and now i just need to decide which crank will be best ... Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted March 13, 2017 Author Report Share Posted March 13, 2017 To make a 4mil crank work, you need to make sure you run the correct parts. Will the 4mil be long rod or short rod? If long rod, you will have to rig up some shit. It isn't worth it to try to make shit work together. not sure on rod length as I don't have a crank yet so I guess could be either at this stage so standard crank probably best here ? 50mm stroke , 110mm rods ? Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted March 13, 2017 Author Report Share Posted March 13, 2017 doesnt the spacer affect port timing? Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted March 13, 2017 Author Report Share Posted March 13, 2017 yes, but running a 4mil on stock cylinder without porting isn't good either. im thinking Std crank and some porting will be best ? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 13, 2017 Report Share Posted March 13, 2017 doesnt the spacer affect port timing?Yeah, but at least you got a great deal. Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted March 13, 2017 Author Report Share Posted March 13, 2017 so what would be a better setup? 4mil crank and spacer or Std crank no spacer Quote Link to comment Share on other sites More sharing options...
Ducman Posted March 13, 2017 Report Share Posted March 13, 2017 so what would be a better setup? 4mil crank and spacer or Std crank no spacer If you want to run a 4 mil crank you will need cylinders ported for the extra stroke or you are kind of wasting the money on the crank. If you go with a port job on the cylinders to go with the +4mm stroke then you can get them ported for use with a spacer plate under the cyliinders and use standard domes, or I would recommend a port job that uses stroker domes (no spacer plate), but that would mean you would need a new set of domes. If you run a +4mm stroke +5mm long rod crank then you would need 795 series pistons which lower the wrist pin in the piston 5mm to acount for the longer rod. Since you said you already have the pistons you would want to go with a stock rod length which most would not recommend. All that being said, the way most builders do a +4mm stroke long rod set up on stock cylinders is to do the 795 series pistons and stroker domes so you would need to takes 2 steps backwards on your parts list. 2 Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 13, 2017 Report Share Posted March 13, 2017 At this point you're about saving money so just find a standard stock stroke crank with 110 rods. At a minimum, find a quality used stock crank, have it trued and welded, and replace outer bearings. 1 Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted March 14, 2017 Author Report Share Posted March 14, 2017 All that being said, the way most builders do a +4mm stroke long rod set up on stock cylinders is to do the 795 series pistons and stroker domes so you would need to takes 2 steps backwards on your parts list. So you can can get stroker domes ? I looked on Pro Designs web site and it only mentioned Std bore and big bore domes in different volumes, no mention of stroker domes, I'm guessing this dome allows the piston to travel 2mil over the deck ? I'm not emotionally attached to my std Pistons and as they are part of a cheap Chinese (probably) kit maybe not a bad idea get a set of 795 Pistons and stroker domes and 4 mil crank I guess the question is would the 4mil crank, 795 Pistons and stroker domes be much better than a Std crank, Std Pistons and Std crank ? Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted March 14, 2017 Author Report Share Posted March 14, 2017 At this point you're about saving money so just find a standard stock stroke crank with 110 rods. At a minimum, find a quality used stock crank, have it trued and welded, and replace outer bearings. You have a very valid point , I'm only a Std crank away from having a running motor , 4mil crank will add more costs than just the crank.... Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
Ducman Posted March 14, 2017 Report Share Posted March 14, 2017 So you can can get stroker domes ? I looked on Pro Designs web site and it only mentioned Std bore and big bore domes in different volumes, no mention of stroker domes, I'm guessing this dome allows the piston to travel 2mil over the deck ? I'm not emotionally attached to my std Pistons and as they are part of a cheap Chinese (probably) kit maybe not a bad idea get a set of 795 Pistons and stroker domes and 4 mil crank I guess the question is would the 4mil crank, 795 Pistons and stroker domes be much better than a Std crank, Std Pistons and Std crank ? Sent from my iPhone using Tapatalk Usually you have to have stroker domes custom cut, not off the shelf. Yes the piston goes 2mm above the deck. You can get more power out of a +4mm stock cylinder with the proper porting, I'm guessing about +5 more hp and a little more Tq but like was mentioned above, your a stock crank away from a rebuilt with the parts you already have. Quote Link to comment Share on other sites More sharing options...
nmrichardson Posted April 22, 2017 Author Report Share Posted April 22, 2017 so i was a std crank away from a running motor, but wheres the fun in a std motor I've ordered a 4mil long rod crank, ill get 795 pistons and ill cut my domes for the stroker, doing some case matching and porting ordered some Vforce reeds too thoughts on racing ignition systems/CDI ? I'm thinking of using the Electrex? Quote Link to comment Share on other sites More sharing options...
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