Member Contributer Mohawk Posted June 14, 2013 Member Contributer Share Posted June 14, 2013 As per title, not interested in comments unless you have actually done this & can tell me what the results were & what's required to get a suitable finish ! Thanks Link to comment Share on other sites More sharing options...
reaper7767 Posted June 15, 2013 Share Posted June 15, 2013 your not going to find too many ppl have done this mod, the best place to start would be to talk to TTS performance over in the UK they could answer your questions far fast then the forum since they where doing them just a few years ago Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted June 17, 2013 Author Member Contributer Share Posted June 17, 2013 Thanks Reaper, Managed to get a sensible answer from the CBR forums, they rebore the Honda MMC (Aluminium Ceramic) liners & Nikasil coat them with no problems ! Winter Big Bore project looming if I can afford it ! :) Some VFR -V- CBR929 pistons, from 72 to 74mm = 825cc, 12.5/1 comp, more stomp everywhere ! Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted June 17, 2013 Share Posted June 17, 2013 I talked to Superbike Mike down in south florida about doing this. His planned route involed going through a company called Millenium Technologies, He said they would strip the block down and submerge in a nitric acid solution that would remove the metal matrix liners. He said that would get you a 3mm over bore and then they would coat the cylinders with an aluminum-nickel-sil coating (that you mentioned already) that is so hard that it will literally break the tip off of a carbon steel knife if you tried scratching the coating. After the cylinders were done he would have JE pistons make a custom set of vfr800 75mm pistons for a resultant 848 cc displacement. He said this was all basic stuff and would not be a problem. He also strongly discouraged using strock pistons out of the cbrs as the valve reliefs on the top of the pistons would not be in an optimun location. He also advised against boring through the metal matrix liners. Mohawk I recommend that you call these guys up and pick at their brains a little before making any big desicions. Superbike Mike Engineering (954) 484-6969 2928 NW 17th Ter, Oakland Park, FL Millenium Technologies 1 888 779 6885 http://www.mt-llc.com/ Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 17, 2013 Member Contributer Share Posted June 17, 2013 I believe Flyguyeddy was (past tense) working on the CBR929 pistons for the 4th gens. He had to do some machining to them and some work on the dome. So swapping pistons is not a straight forward job. Link to comment Share on other sites More sharing options...
flyguyeddy Posted July 18, 2013 Share Posted July 18, 2013 i believe the 929 piston is a lot closer to the vfr800 design tho. Link to comment Share on other sites More sharing options...
Member Contributer spinalator Posted July 18, 2013 Member Contributer Share Posted July 18, 2013 I talked to Superbike Mike down in south florida about doing this. His planned route involed going through a company called Millenium Technologies, He said they would strip the block down and submerge in a nitric acid solution that would remove the metal matrix liners. He said that would get you a 3mm over bore and then they would coat the cylinders with an aluminum-nickel-sil coating (that you mentioned already) that is so hard that it will literally break the tip off of a carbon steel knife if you tried scratching the coating. After the cylinders were done he would have JE pistons make a custom set of vfr800 75mm pistons for a resultant 848 cc displacement. He said this was all basic stuff and would not be a problem. He also strongly discouraged using strock pistons out of the cbrs as the valve reliefs on the top of the pistons would not be in an optimun location. He also advised against boring through the metal matrix liners. Mohawk I recommend that you call these guys up and pick at their brains a little before making any big desicions. <snip> Wow that is a ton of work for a 50cc bump. I love to tinker, but less than a 10% boost in displacement for all that? Yikes! Link to comment Share on other sites More sharing options...
timmythecop Posted July 18, 2013 Share Posted July 18, 2013 Wow that is a ton of work for a 50cc bump. I love to tinker, but less than a 10% boost in displacement for all that? Yikes! took the words right outta my mouth. and dont forget to add after it is all done and your wallet is smaller that a singularity, you are completely in the unknown. Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted July 19, 2013 Share Posted July 19, 2013 There's not a lot of room in the VFR800s engine to hog it out. You're not gonna get 1000cc's nope. Link to comment Share on other sites More sharing options...
wera803 Posted July 19, 2013 Share Posted July 19, 2013 Wow that is a ton of work for a 50cc bump. I love to tinker, but less than a 10% boost in displacement for all that? Yikes! Not sure which book is really correct (I didn't go through the math to figure it out), but the 5th gen book says the engine is technically a 781cc and the 6th gen book says it is a 782cc, so you would get a little more than just 50cc's. Still less than 10% though as you pointed out. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted July 19, 2013 Author Member Contributer Share Posted July 19, 2013 Hi CandyRed, thanks for the info, but the guys in lala land. The MMC is made from the same grade alloy as the upper crankcase, so immersing it in acid, would erode the whole crankcase ! So no thanks to that one. I have it on good authority from an RC45 tuner that the MMC can be bored like any iron liner, but needs a diamond hone like Nikasil. Regarding the cc to bang ratio, the whole is worth more than the sum of its parts. VFR750 4th gens make an average 90rwhp, but bored to 837cc (+87cc) they put out 133rwhp (+43hp or 47%) . If we look at the percentage ratios for this, it's a 11.6% cc increase, so 750/90=8.33cc per hp, so 87/8.33=10.4 extra HP, but the 837cc makes 47% more power ! This is achieved with NO other tuning ! So taking the 800 (actual is 782cc) to 74mm bore = 825cc is +43cc (5.5%), or to 75mm bore = 848cc is +66cc (8.44%). So if we assume that similar gains to the 750 would be seen on a bigger 800, then using the same 47% power increase for the 750 & extrapolating it to the 800 with a base 95hp, would be as follows;- 750+87cc=837cc=+47% hp =133rwhp 782+43cc=825cc (87/43)= +23% hp = 117hp 782+66cc=848cc (87/66)= +35% hp = 128hp Or based on my existing tune of 107rwhp & using the same percentages above, then I'd expect to see 825cc=130hp or 848cc=140hp. Now that would be impressive :) I have a few tweeks planned for the existing tune to bring it up towards 120hp. If I could pull that off then those tuned figures should certainly be attainable. All hypothetical until I actually cut metal, roll on the winter :) Link to comment Share on other sites More sharing options...
Member Contributer vanion2 Posted July 19, 2013 Member Contributer Share Posted July 19, 2013 I say do it and be sure to include dyno graphs and costs once your project is complete. I always love seeing someone boldly going where all the nay sayers have never gone before. Your bike. Your rules. Link to comment Share on other sites More sharing options...
snake Posted July 21, 2013 Share Posted July 21, 2013 according to the factory service manual oversize pistons are available it lists two sizes 0.25mm over and 0.50 over I wonder what the 0.50 would bring the 800 up to oh this is in the 800 6th gen manual Link to comment Share on other sites More sharing options...
Member Contributer spinalator Posted July 21, 2013 Member Contributer Share Posted July 21, 2013 <snip> Or based on my existing tune of 107rwhp & using the same percentages above, then I'd expect to see 825cc=130hp or 848cc=140hp. Now that would be impressive :) I have a few tweeks planned for the existing tune to bring it up towards 120hp. If I could pull that off then those tuned figures should certainly be attainable. All hypothetical until I actually cut metal, roll on the winter :) That would be impressive and makes more sense. Keep us posted! Link to comment Share on other sites More sharing options...
Guest Posted July 22, 2013 Share Posted July 22, 2013 What happened with this?. Has anyone tried this? Can the heads on a 5th gen have larger valves. If so off what?. I know you can"t shave the heads so how did honda get 160 odd hp out of the rc45?. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 22, 2013 Share Posted July 22, 2013 I am pretty sure that the valve sizes on the vfr's are way beyond more than adequate. From everything that I have read so far, the vfr800's have the same size valves as the rc45, the 929 and the 954. I would put big money on all the power being held back by the tiny 36mm throttle-bodies/(and even smaller velocity stacks), the mild camshaft specs and the puny exhaust header primaries. These are the main differences in the rc46 versus rc45. (besides redline and 360 degree crank) Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted July 22, 2013 Author Member Contributer Share Posted July 22, 2013 according to the factory service manual oversize pistons are available it lists two sizes 0.25mm over and 0.50 over I wonder what the 0.50 would bring the 800 up to oh this is in the 800 6th gen manual 792cc with .5mm overbore. What happened with this?. Has anyone tried this? Can the heads on a 5th gen have larger valves. If so off what?. I know you can"t shave the heads so how did honda get 160 odd hp out of the rc45?. Still in the tech discussion phase, as I'm working away from home permanently at the moment, so can't actually do any work, but I did just get another 3 x 75mm CBR954 pistons to go with the 4 x CBR929 ones I have :) That gives me options. I'll probably get another set of crank cases to experiment with on the boring/honing side ! No need for larger valves, the RC45 used these sizes & never ran into breathing problems. Even HRC's head porting only takes a tiny amount out of the ports. They got 160+hp by revving the engine to 14,500rpm+, They used larger throttle bodies & longer duration cams & high comp pistons to boost the power in the high RPM's, my VFR makes more torque/power than a lightly tuned RC45 everywhere up to 10K/rpm, when the 45 steals ahead & revs out to 13,500rpm ! Link to comment Share on other sites More sharing options...
Member Contributer spinalator Posted July 22, 2013 Member Contributer Share Posted July 22, 2013 242 revolutions per second is really quite fast. I have difficulty counting that fast in one second. Link to comment Share on other sites More sharing options...
Guest Posted July 25, 2013 Share Posted July 25, 2013 Right who will do the re-boring? I have made some inquires here in Australia and they say it can't be done?. I would also like to know as what to do about the throttle bodies. Can you bore them out?. Cbr 600 2010 have 40ml . Can you cut them? do they fit? Bigger bore more air /fuel more power. Quiet interested as i wish to create more hp for the bike Honda wont make!!!. Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted July 23, 2014 Member Contributer Share Posted July 23, 2014 I've just found a workshop that will take on the boring of my 5th Gen case to 74mm dia for fitting CBR929 pistons. They are quite happy in doing this, just the set up cost will be higher due to the unequal angles from the crankcase faces to the cylinder bores. Just waiting on my pistons to arrive and it will all be off to the boring bar. I'll keep everyone posted as to progress. Cheers Phil Link to comment Share on other sites More sharing options...
Member Contributer Rush2112 Posted July 23, 2014 Member Contributer Share Posted July 23, 2014 I've just found a workshop that will take on the boring of my 5th Gen case to 74mm dia for fitting CBR929 pistons. They are quite happy in doing this, just the set up cost will be higher due to the unequal angles from the crankcase faces to the cylinder bores. Just waiting on my pistons to arrive and it will all be off to the boring bar. I'll keep everyone posted as to progress. Cheers Phil Sweet!!! Honda manual states the liner can be machined as long as temperature is controlled... :cheerleader: When I contacted APE in the US they stated they could bore it out also... Link to comment Share on other sites More sharing options...
VFR4Lee Posted July 23, 2014 Share Posted July 23, 2014 Wasn't there a kit from Dynamo Hum or something? Not to say there still is one being made. Got a spot that gets me hot, but you ain't been to it. Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted July 23, 2014 Share Posted July 23, 2014 -Yes there was. -No there isn't. -I don't wanna know. Link to comment Share on other sites More sharing options...
VFR4Lee Posted July 24, 2014 Share Posted July 24, 2014 But, the spot... That's my scantily clad backup singers line. In case that changes your mind. Link to comment Share on other sites More sharing options...
The Phantom Posted July 24, 2014 Share Posted July 24, 2014 Dynamo Humm is defunct and there's - so far - been no sharing of the ip that Brian Law had/has regarding big bore VFRs. However, people are still chasing this elsewhere and some good leads are emerging. Link to comment Share on other sites More sharing options...
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