My already tired F3 engine suffered through a big overheat this past weekend (radiator failed) and it may be time to look inside and freshen it up. I'm not looking to put big bucks into the engine but I would like to get some information from you guys .... Any problems with a 2mm over bore? Wiseco, JE, or other? Any history of stock rod failure with the bigger pistons? Stock cams or other? Who does good head work (and is currently familiar with F3's)? Does everyone run stock radiators? Ignition options? Any "must do" stuff while I'm in there? Thanks in advance!
No problems w/2mm at all.But you could also do a 618 and leave yourself a next time.Stock rods,no problems.I always had weisco's.Dont know about JE. Keep the ram air and stock carbs.No flatslides. I sold KMC a motor that I thought surely needed freshening up till I took it and had a leak down on it.It was to late I had already commited to selling it to him.It was a KWS motor built in 98.It was a 637 w/weisco's stock cams,nice head work and stainless valves.It was built and then sat for years.It probably has 5 seasons on it and it still lays down 106 atw or better.We call it the magic motor.Still purs like a kitten and has never been touched.Only amsoil changed.Hell it still has the same plugs in it. Steven Isenhower,I believe is his name(screen name VFR-something)dont know,he is in Texas and has a great deal of knowledge about these bikes and I believe will build u one. Whats interesting is FTZ racing,which builds these motors for little race cars or used to kinda has a different take on the heads.They have tons of r&d on these motors.Years ago one of the guys there was nice enough to talk to me awile about them.He said stock cams were best.Instead of going bigger on the headwork they sell these plates that fit in the intake that reduces the opening and thus increases the velocity.He said that the F3 would eat an F4i alive because of its torque and ability to get out of the corners.He said the flatslides they sell for the motors now are to big and all they did was chase them.He said the older smaller ones were perfect.If u ever see an FTZ head or motor on ebay,which I have seen both before,that would be a great snatch. U can also search motorman or break in secrets and this guy also talks about F3s and reducing the intake size and explains why this is better.Interesting read. My old bike supposedly had an HRC radiator,but Gypsy said it looked like a Zx7 rad.I never had any overheating problems though. If I had to do it all over again,I would just take a good bone stock motor w/full exhaust and a jet kit and just keep my suspension fresh.The 637's get out of the corners a little better.A stock one u just have to ride a little differently.When u get to tracks w/long straights just add U4.It takes a lot of money to build a 618 or 37 these days.Just my take on it. And just FYI,F4 cams are the same as F3 HRC cams. Also for all the F2/3 guys.KMC just sent me some forks that his sponsor did for him,totalracingsolutions I believe,his name is James.He does a bunch of ama motors and stuff but he also used to race these back in the day.I dont know if he would do more but whatever he did is amazing.They feel almost stiff but there not.These forks completly changed the bike.Have never ridden anything like it.I just did a t-day at Barber sunday on old tyres and ran my first 36 there with a bone stock motor.I was'nt having to wrestle the bike like the Barber race a month ago or so.It would go where ever u wanted with no effort.Changed the braking,rock solid in the corners and made braking bumps non existant.I have ridden these since 03 and like I say have never felt anything like it.:up:
Stay as close to stock as possible. Big pistons make more torque but stock ones will last for years and years. Same goes for the stock rings, aftermarket rings are inferior by a large margin. Mill the block deck to achieve a squish number (including the headgasket thickness) of less than .75mm but over .50mm. Mill the head just enough to make it flat, perhaps .004/.005. (if the head is warped or eroded more than that toss it and snag a used head to build) Use stock valves as the stainless will NOT last as long. Send the head to Cooper Performance (they ROCK) and buy new valve springs. Dial the cams, many will offer numbers, I am sure. HRC numbers were 100/100 but I prefer a wider spread myself like 101/107.. Of course all new bearings and if you can find a source, micro polish the journals. (if you do, extra care must be taken to clean the polish grit out of the oil passages!)
Ive had both and they lasted about the same length. The stainless are really good. And that motor Melch is telling you about is the shizzit. Thing is fast as hell. Melch and KJ are both pretty knowledgable on these bikes. SO I followed some of theyre advice a couple years ago when building my son an f2/3 and we did most everything stock except the head and it was close to a hundred and ran pretty strong. Gypsy may remember running again the kid. But those guys know there stuff. My brother who built the bike for my son with Kj and Melch's advice said send it to him or call him and yall talk some $s and he would build it for you. The guy has built every race bike we have raced in the last 5 years including my son's 04CBR600RR and ask Melch its pretty fast.
Thanks for all the input. I don't need anyone to build the motor for me ... I worked in bike shops most of my adult life and moonlighted assembling NHRA engines for a shop years ago. I'll enjoy being able to put the time in to carefully build my own engine but there's no need to reinvent the wheel as far as finding out what works and what doesn't for these engines. :up: FYI, I remember stainless valves being slightly harder and heavier than stock and consequently harder on valve seats. So, I guess I would defer that decision to the "head guy". What about ignitions?
Stainless is not harder than stock, it is lighter and (the main reason people use them) cheaper. I find stainless, if a good brand name, work ok in lower rpm engines, but tend to pound out in high rpm applications. Nothing is stronger or more durable than stock Honda valves, nothing. They could use a better shape, flow wise, but the reliability is top notch, peroid. If you plan on opening the engine after the season and checking how things look, buy any brand you like (even black diamond-yuck-) but if you want to screw it together and forget about it for four or five years,go with stock Honda parts throughout.
just what we need, another superbike on the grid do what everyone else (read me) does throw some jb weld on it and come out and play and hope that it doesnt blow up...
It's highly unlikely that I'll build a superbike. I live in Louisiana .... I need the money so I can buy gas just to get to the track!
Where the hell have u been for the past 5 yrs.with this wealth of F3 knowledge??Do tell.I could never get anyone to give me degree #s or sweet #s rather.I know it makes a hell of a difference but if u gain it down low do u lose it up top?I saw Sticks bike after someone put some sweet degree's on it and it would want to stand staight up pit out in the 1st three gears. Will a stock motor(bone stock) see any gains if the cams are degreed???And does this affect the longevity of the motor?Do share more please.Cams,overheating issues,carbs,yada?Tell us your history with this sweet powerplant.
Basic stuff like making sure the bores hold tolerance under .001 and doing a perfectly concentric (to the guides) valve job apply to all fast four strokes. So does running the squish as tight as your level of calmness will allow. Cam numbers on four valve engines are not much of a secret, but spending the time to dial your numbers to match your head casting shape/s, valve job, exhaust primary diameter and length, airbox (if any) resonance, just takes hours and hours of your life and dyno time, and AGAIN testing each change. First step is to measure where your stock cams are set, but do it AFTER the engine work is done, so you can compensate for the material removed from the head and block deck. Your factory installed lobe center numbers will probably be different from any other given factory installed stock lobe center numbers. Your's my already have a low intake number, but then again it may be 114 or some other off the wall setting. The track/s you run will dictate what numbers you choose. If you ONLY run Daytona then you need top end, if you run little Taladega, you need low rpm torque. If you run a mix of track layouts, then you aim for the middle ground. I've been around, but not many guys open their engines anymore, so I'ts sort of a lost art. In addition, new designs are built much closer to the limit, so the days of rooting around and finding free HP are drawing to a close.
