Has anyone on this forum installed or had a big bore kit installed on their bike? I tried the search engine here and found talk about the kits but no actual accounts of someone doing it... I just bought a spare low milage motor for my 98 and am not sure if I want to put it away stock for a replacement if needed or play around with making some more power out of it for sh*ts and giggles. 120 rearwheel hp of of 87 octaine pump gaswould be very nice on 98 if it would not be stressing the motor more than a stock build. Your comments please steven
we have all seen toros charger but if I wanted 160rwp I would buy a liter bike and keep my vfr for commuting on nice days and the occasional trip. Seems to me that it is very difficult to get performance gains from bolt on accessories on this bike and a larger displacement might be what it takes for that 10 to 15 hp that would make all the difference in what this bike could be. The only reason I am concidering this is because I have a spare motor to play with and I just installed a 3700mile in the bike on my current build. I know it is some trouble and $ but I am the kind that likes to tinker on weekends ... Also $800 for a bore kit and a few hundred dollars for machining and gaskets is a lot less than 5g's for a supercharger if you dont have to pay for labor.
any way you go the bikes going to have more power than it does now, start with the cheap easy to do mods then move from there
I promised myself I would not get involved in this....but I don't agree. There, back to your regularly scheduled programming.
In the old days there were some nice kits out there. This was my Honda 500 Four with Yoshimura 605 Kit-Hi Comp Pistons with Chromoly Rings and wrist Pin Buttons, Sleeves, Cam, Valve Springs, K&Ns and Race Porting, Tracy body, Barnett Clutch, Jardine Headers with mods and after these pics, Koni Shocks, Tires, 400F Bars and a few more goodies. The new powerband started at redline and went off the scale. It would just edge out KZ900 Kawsaki's in the quarter mile and walk away top end. It was wheelie machine like the Kaw H2 I had but was 100% Reliable and a blast to ride. Pics suck it was mid 70s circa. Pops Yoshimura knew his shit!
Yeah, back in the day when I (amateur) raced Gixxers, Yosh had "stage x racing kits"; so depending upon the class you ran, you could use a stage 1 kit, which was basically a pipe and a few other parts; then they had stage 2 and stage 3; stage 3 was like this 'full' racing kit, with big bore, cams, rods, pistons, etc. etc.... Whatever happened to that? And how come no one makes something like that for other bikes (like the VFR, OK well I understand why not the VFR, though maybe a European company, since Viffers are so popular over there; like a Walter Koenig tuned bike)?
Yes,I had also thought about doing something like this,but have put it on the back burner for now. Anyway, there is a company in the U.K that I believe still offers a big bore kit for the 5th gen bikes. It goes something like this, you send your completely disassembled engine block to them,they either re sleeve it or do a very big oversize bore,but since these blocks have cylinder walls that are made from a special metaluragical process there are only a few places in the country that know how to successfully bore and re plate the cyl. walls. Now for the pistons,I believe they are custom made by Jans at a price of about a thousand bucks a set,yes they bump the compression about one point and Jans supplies a special ring set with them. Now for a complete reassembly,and while you are doing this now is the time to have the heads freshened up and maybe ported a bit. then for the blueprint and reassembly. So far I think we have spent about $3 to $4 K,so if you really are still interested in this ,I can probably dig up some of the contact people that you will need. eddie
I've heard and read this same comment from several different sources. Lots of time and expense for negligible gain.
I did dig into this once several years ago - there used to be a big bore kit from Dynamo Humm out of Canada, but they are now out of business. I havent check for quite a while but I believe TS performance out of England (name may be wrong) sold a kit that bumped the CC's to 831. I think the price was around $900. (Lot of bucks for 50cc) Then if you were serious about doing it, the block does need to be bored first, then replated, then rehoned. Millenium Technologys in Wisconsin is the expert in that arena. Figure a $800 - $900 to get that done. Then the heads need some parallel machining to match (while your at it, maybe a bit of porting and polish) and while your at consider a valve job to go with the upgrade. Then its the ol' domino effect, maybe cams need to be looked at or retimed and ingition timing too. Get it all together and youve spent and easy $3500 or more..... Yow! ---- Theres an older thread on the whole deal in VFRworld in here someplace. - If I was gonna crack the engine open I think I would mainly stick to head work for the most buck vs result type gains. That may be in some day column, or just say the hell with it and grab a Torocharger. Good luck dude! MD
Thanks for the input guys! Just tossing some ideas around looking for my next project but this seems to be out of my budget on this bike. I think I will go with the upgrades I have and be secure with a spare fresh motor. The VFR is a great bike the way it is and very pleased with her, I was just hoping to give it the ummmff that my previous GSXR had.
I find it kinda funny that everyone is 'poo-pooing' this idea, and trying to figure out the cost... Has anyone ever had their engine really rebuilt like this? Big bore, port/polish, blueprint, balanced, new cam, etc.? If so, what was the total $ & HP/TQ gain, if not, how do any of us know what would happen? Maybe this engine really likes it, maybe it 'comes alive' and turns into a real beast? I asked a question like this, about V4 engine specialist several months back, and got a lot of the same responses. If I had the dough sitting around, I'd do it myself just to see what happens... Maybe when I win the lotto...
I actually plan on doing this to my 4th Gen before I leave Europe in the next 3 years. There are 2 different companies that do this mod, one is below...The other is located in Holland and I belioeve they are called High Performance Tuning or something like that, and that is where I plan on taking my VFR as it is much closer, and the quality/level of work is the same. In the link below you get to see the prices and work being performed. There are a few on this board and over at VFRD that have had this done and have not regretted it. Oh and a 30% performance gain should get you in the neighborhood of around 130 HP, not too bad for the price if you ask me. I've seen full Ti exhaust systems on eBay for this much, and they don't deliver near the performance gain. Holeshot Racing
I wouldnt doubt you could eke 120 - 125 horses out of it, if you could find a TB or Erion header. - Not poo pooing (poing?) it at all. Just look at a gixxer 750, you would think you could at least match that if you worked at it.... MD
