February 7, 201412 yr comment_677064 Hey everyone, So I blew my 4k up today... :'( I was wondering if someone could give me some input into wether or not to build a new 4k with a 3k head, 5k or 7k? Thanks in advance, Kieran Report
February 7, 201412 yr comment_677081 What did you blow up? What is damaged?? What condition was it in beforehand?? Are you talking a rebore, crank grind, head job, new bearing throughout, new cam chain and tensioners, new valves.. what needs to be done? What modifications would you do at the same time? Cam grind? Lighten flywheel? New carbs? Balance job? This might be the time to do everything you can while its stripped. Report
February 8, 201412 yr Author comment_677094 What did you blow up? What is damaged?? What condition was it in beforehand?? Are you talking a rebore, crank grind, head job, new bearing throughout, new cam chain and tensioners, new valves.. what needs to be done? What modifications would you do at the same time? Cam grind? Lighten flywheel? New carbs? Balance job? This might be the time to do everything you can while its stripped. I snapped the cam gear and bent some valves, she was a pretty old motor anyway at 300,000 kms.. I would be talking a full rebuild, balancing, cams, port work, probably a bore.. Just not sure on which motor to choose. I want to keep it K power and would be buying a new motor either way because the 4k I have is pretty old and tired anyway and was going to replace it when it died.. Report
February 8, 201412 yr comment_677118 Ah- pretty serious rebuild then. 5K would be a good start if you're going to buy a motor, but if there are none around you could bore the 4K to 5K pistons. Read the Wiki here- http://www.rollaclub.com/wiki/index.php?title=Tech:Engine/K_Series/How_to_build_a_tough_K_motor Pretty straight-forward stuff, what you build depends on what bits you can buy. I'm running SUs, but the next one will be bike quad carbs or maybe a single DCOE Weber. Make sure you lighten the flywheel and get it all balanced, then you can do your own head porting & skimming. Report
February 9, 201412 yr Author comment_677153 Ah- pretty serious rebuild then. 5K would be a good start if you're going to buy a motor, but if there are none around you could bore the 4K to 5K pistons. Read the Wiki here- http://www.rollaclub.com/wiki/index.php?title=Tech:Engine/K_Series/How_to_build_a_tough_K_motor Pretty straight-forward stuff, what you build depends on what bits you can buy. I'm running SUs, but the next one will be bike quad carbs or maybe a single DCOE Weber. Make sure you lighten the flywheel and get it all balanced, then you can do your own head porting & skimming. I was planning on running twin side draughts or bike carbs. How much do you have I bore out to get the 5k pistons to fit? Do you think this setup would have alright power for a 4k with a decent cam, port job and skimming to make higher compression Report
February 9, 201412 yr comment_677160 How much money do you have? The answer to this question will be the major deciding factor in which route you take. Report
February 9, 201412 yr Author comment_677162 The answer to this question will be the major deciding factor in which route you take. Money doesn't really bother me, just want to build the best k motor I can Report
February 9, 201412 yr comment_677164 Do you think this setup would have alright power for a 4k with a decent cam, port job and skimming to make higher compression Its the best you can do- You'd need to have a good idea of bhp per buck to sort out the fine things.. Do you get a vernier cam drive wheel so you can dial the cam in where you want it? Do you spend money on the crankshaft getting it lightened before balancing. Do you see if a larger oil pump from an RA40 Celcia can be made to fit? Rocker gear machined to make up for the cam grind and head skim? Do you go chasing Fiat valves to get them 1mm larger in diameter? Filfredrick has already built the ultimate K motor- http://www.rollaclub.com/board/topic/51097-4k-twin-cam/ I think if I were you I'd grab another 4K to drive around with and use as a test bed while working up the various systems. Maybe get the short block completed and swap it in to use for 6months while you build the top end. A motor like this can't be done in a month. Report
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