chipdalejr Posted June 7, 2014 Share Posted June 7, 2014 I've been wanting to make a fourth gen handle, and make power like a modern bike can. I've already planned out the chassis, but am wanting to coax more power out of the engine while eliminating the troubles of carburetion. My idea is to throw in some high-compression pistons, and convert it to fuel injection through use of a modern system. I have a set of K5 GSXR 750 throttle bodies lying around, and thought that there might be some way to split them in half, fiddle with the electronics for a while, mess with creating my own airbox, exhaust, etc. What I need to know is everything I would need to know to make the electronics function correctly. I love this bike, but just want the refinement of a modern one. I know it will never be an RSV4, but I want a project, from Japan, that I don't have to be afraid to beat on or tear into pieces. Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 7, 2014 Member Contributer Share Posted June 7, 2014 Good luck with the project. I'm looking to FI a bike too, but I'm going to start small, with a VTR 250. If and when I get back to it, that is. You can either go the pricey route of the Motec ECU, or go for the Megasquirt/Microsquirt. Look on those sites and forums, and just start reading everything you can. There's a lot to the conversion. Link to comment Share on other sites More sharing options...
Member Contributer vfr350 Posted June 7, 2014 Member Contributer Share Posted June 7, 2014 What about upgraded carbs? Might be less hassle. Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 8, 2014 Member Contributer Share Posted June 8, 2014 What about upgraded carbs? Might be less hassle. Flatsides are really really pricey. Check them out at Durbahn. The advantage I see in FI is when you're doing a bunch of changes. FI with tuning software will get it sorted faster than messing with carbs. Link to comment Share on other sites More sharing options...
Beck Posted June 8, 2014 Share Posted June 8, 2014 I don't really see the point of changing out the induction system on a 4th gen to FI. It pretty much has the best fueling of any bikes that Honda ever made. Link to comment Share on other sites More sharing options...
Guest Posted June 8, 2014 Share Posted June 8, 2014 I always thought if my '96 had my Y2K engine and linked brakes, it would be a great bike. Or if my Y2K had my '96 handling. Good luck with this project. Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted June 8, 2014 Member Contributer Share Posted June 8, 2014 Could a 5th gen throttle body / airbox / ECU possibly be adapted? A donor bike would also have a fuel pump and other ancillary bits needed. Link to comment Share on other sites More sharing options...
chipdalejr Posted June 8, 2014 Author Share Posted June 8, 2014 What about upgraded carbs? Might be less hassle. I don't want upgraded carbs because even though they're better than stock, they will still have the issues that carbs have due to the nature of the beast. I've torn down so many carbs, so many times, and I'm tired of doing it. Of course, there's also the advantage of being able to extract more power and simplify tuning, which is the main reason why I'm doing it. Link to comment Share on other sites More sharing options...
chipdalejr Posted June 8, 2014 Author Share Posted June 8, 2014 Could a 5th gen throttle body / airbox / ECU possibly be adapted? A donor bike would also have a fuel pump and other ancillary bits needed. I figured that would be the easiest route to go, but that engine doesn't have the sportiness that I am looking for. Gaining 50cc and adding VTEC extracted 3 extra horsepower, and looking at the throttle body diameter, I can see why. They are a 36mm, while the GSXR is a 43mm. That bigger bore is going to flow quite a bit more air at the top of the rev range, where I'm looking for power. Link to comment Share on other sites More sharing options...
Member Contributer vfr350 Posted June 8, 2014 Member Contributer Share Posted June 8, 2014 If using that big of butterflys causes low/mid issues could slightly smaller intake horns be used then? Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 8, 2014 Member Contributer Share Posted June 8, 2014 Bigger is not always better. Too big, and your low and possibly mids will be atrocious, and the rest of the range will be super sensitive. Here's a quick read for ya. http://projectcbr250rri.blogspot.com/ Link to comment Share on other sites More sharing options...
Guest Posted June 8, 2014 Share Posted June 8, 2014 Could a 5th gen throttle body / airbox / ECU possibly be adapted? A donor bike would also have a fuel pump and other ancillary bits needed.I figured that would be the easiest route to go, but that engine doesn't have the sportiness that I am looking for. Gaining 50cc and adding VTEC extracted 3 extra horsepower, and looking at the throttle body diameter, I can see why. They are a 36mm, while the GSXR is a 43mm. That bigger bore is going to flow quite a bit more air at the top of the rev range, where I'm looking for power. Forget a Vtec (6th Gen)... Aim for a 2000 or 2001 Fifth gen donor bike. Then you still have the gear driven cams. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted June 8, 2014 Member Contributer Share Posted June 8, 2014 sheesh . just a turbo.. the FI didnt add much of anything to the 5th gen. and all the top tuners just added wicked cool light parts and ditch the heavy stuff. Link to comment Share on other sites More sharing options...
chipdalejr Posted June 8, 2014 Author Share Posted June 8, 2014 Bigger is not always better. Too big, and your low and possibly mids will be atrocious, and the rest of the range will be super sensitive. Here's a quick read for ya. http://projectcbr250rri.blogspot.com/ Very interesting. I know it will be a challenge, but I think the Microsquirt will make this much simpler, and at a reasonable cost. I figured that the common displacement, and my need for top end power over low end would allow the 43 mm TB to work pretty well. Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted June 9, 2014 Member Contributer Share Posted June 9, 2014 I know I'm in the minority here, but what is the big deal with carbs? I guess I'm just an analog guy in a digital world but other than dealing with ethanol issues (when I am out on the road) I think working on carbs is pretty cut and dried. Granted, I've been doing it for a long time, but with injection you have electricity as a factor to deal with and based on my limited (40+ years) experience that's never a good thing. That's not to say I don't like reading about any kind of technological project people want to do to their bikes (I learn a lot) but once they are dialed in the carbs on a 4th GEN are pretty much bulletproof. Mine gets 40 mpg in town commuting, and has cracked 55 mpg on long runs up to Colorado. I'm a small guy so more performance is not an issue for me, my 97 has plenty for this old guy. ALTHOUGH, I have always wondered about putting a set of 3rd GEN 36mm carbs on a 4th GEN (that has 34mm carbs). Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 9, 2014 Member Contributer Share Posted June 9, 2014 I love the 4th gen specifically for the carbed engine. The 5th gen is more lively, but the 4th just has such a nice smooth operation. I'm looking to do it on the VTR mostly because I've heard a lot of stuff about how any little change to it will throw the fueling way off and it will be impossible to tune back. So an FI conversion might help with that. Link to comment Share on other sites More sharing options...
Beck Posted June 9, 2014 Share Posted June 9, 2014 I know I'm in the minority here, but what is the big deal with carbs? I guess I'm just an analog guy in a digital world but other than dealing with ethanol issues (when I am out on the road) I think working on carbs is pretty cut and dried. Granted, I've been doing it for a long time, but with injection you have electricity as a factor to deal with and based on my limited (40+ years) experience that's never a good thing. That's not to say I don't like reading about any kind of technological project people want to do to their bikes (I learn a lot) but once they are dialed in the carbs on a 4th GEN are pretty much bulletproof. Mine gets 40 mpg in town commuting, and has cracked 55 mpg on long runs up to Colorado. I'm a small guy so more performance is not an issue for me, my 97 has plenty for this old guy. ALTHOUGH, I have always wondered about putting a set of 3rd GEN 36mm carbs on a 4th GEN (that has 34mm carbs). IIRC, the smaller carbs were put into the 4th gen to improve torque values through the rev range. The smaller carbs were then the newest generation "semi-flat slide" carbs as used on the CBR's so it was one instance where Honda definitely did not scrimp on a component for the bike...... I never had any problems with my carbs the whole 19 years I've owned my 4th gen. I think just as long as you are careful not to gas up from questionable gas stations that might have less than good quality, clean gas and a regular use of Sea Foam to keep things clean in the induction system, you will not have any trouble with them for a long time. Heck!, if it turn out that my carbs might need servicing/re-building in the next couple of years, I don't think I can complain after 2 decades of flawless service.... Link to comment Share on other sites More sharing options...
The Phantom Posted June 9, 2014 Share Posted June 9, 2014 I'm all for doing stuff just because you can, but I do agree with the guys above regarding the quality of 4th Gen carburetion... the 4th Gen is right in almost every way and the carbs didn't miss out. It's one of Honda's masterworks. Not sure if it was mentioned earlier but someone was indeed working on putting GSX-R FI onto a 4th Gen, there should be a topic somewhere in the archives. Link to comment Share on other sites More sharing options...
Member Contributer apexandy Posted June 9, 2014 Member Contributer Share Posted June 9, 2014 I too am skeptical of any real significant gains with FI on the 4th gen. The only two advantages I see are avoiding carb gumming up issues (not really a problem for those with a little mechanical sympathy) and tuning, which could be a big positive for someone making a lot of engine changes… but I would think the amount of time getting FI set up and functioning would far outweigh the time spent tuning carbs for engine changes. I love watching other people mod their bikes and know sometimes it's just about the challenges… but in this case I think the end result would be frustrating and disappointing. I love the analog connection I have between my throttle and my engine… there are no surprises or strange issues. Every newer or brand new bike I ride feels like a step backwards when it comes to fueling and throttle control. And how much power is actually gained through the use of FI? Maybe a few horsepower? Even fuel economy gains in bikes with FI compared to carbs seems to be nil. Sorry to sound so negative… Feel free to prove me wrong! But when I hop back on my bike from 1995 after riding any number of newer machines (From Honda, Ducati, Triumph, MV agusta….) and think, man this is so much more sorted, refined and enjoyable I wonder if you'd be happy with the result in the end. Just my 2 cents Link to comment Share on other sites More sharing options...
Member Contributer mk2davis Posted June 9, 2014 Member Contributer Share Posted June 9, 2014 OP, how much power are you hoping to make? Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted June 9, 2014 Member Contributer Share Posted June 9, 2014 Just done 800kms over the weekend, between -2 and +500metres altitude, going up to 230kmh. Not a single surge or hiccup, I love my carbed 4th gen. Ymmv Link to comment Share on other sites More sharing options...
chipdalejr Posted June 10, 2014 Author Share Posted June 10, 2014 I too am skeptical of any real significant gains with FI on the 4th gen. The only two advantages I see are avoiding carb gumming up issues (not really a problem for those with a little mechanical sympathy) and tuning, which could be a big positive for someone making a lot of engine changes… but I would think the amount of time getting FI set up and functioning would far outweigh the time spent tuning carbs for engine changes. I love watching other people mod their bikes and know sometimes it's just about the challenges… but in this case I think the end result would be frustrating and disappointing. I love the analog connection I have between my throttle and my engine… there are no surprises or strange issues. Every newer or brand new bike I ride feels like a step backwards when it comes to fueling and throttle control. And how much power is actually gained through the use of FI? Maybe a few horsepower? Even fuel economy gains in bikes with FI compared to carbs seems to be nil. Sorry to sound so negative… Feel free to prove me wrong! But when I hop back on my bike from 1995 after riding any number of newer machines (From Honda, Ducati, Triumph, MV agusta….) and think, man this is so much more sorted, refined and enjoyable I wonder if you'd be happy with the result in the end. Just my 2 cents I understand entirely, however, this is a bike that I want to screw around with, just to see what I can do with it. I do plan on heavily modifying the engine internals in the long run, too, so the ease of tuning would surely be an advantage. As it seems, the FI bikes can run a higher state of tune, though, which is very important in this situation. OP, how much power are you hoping to make? From just the FI, I'd like to see the power back to 100, assuming it has likely dropped to the low 90's over time. With all the other modifications, high-comp pistons, ported head, possible oversize valves, big cam, stiff valve springs, raised redline, custom exhaust, I'd like to see 120. Link to comment Share on other sites More sharing options...
Member Contributer apexandy Posted June 10, 2014 Member Contributer Share Posted June 10, 2014 I understand entirely, however, this is a bike that I want to screw around with, just to see what I can do with it. I do plan on heavily modifying the engine internals in the long run, too, so the ease of tuning would surely be an advantage. As it seems, the FI bikes can run a higher state of tune, though, which is very important in this situation. That completely makes sense to me. Your goals and expectations seem to be in line with what has been shown possible with these engines and I will watch eagerly :) It's pretty common on the internet to get the types of people who say things like "I'm planning on running a GP exhaust with pod filters on the carbs and slick 50 in the engine and expect at least a 30hp boost." Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted June 10, 2014 Member Contributer Share Posted June 10, 2014 Saw an add on dutch ebay where someone offers VFR800 intake valvesfor the VFR750 that should birng an extra 8-10hp. Oh You need work on the head as well. He claims the exhaust valves can stay as is.... http://www.marktplaats.nl/a/motoren/onderdelen-honda/m813978870-vfr750-f-rc36-motor-tuning-set-vfr-750-f.html?c=be2da871b0d84f75c3056cc6db858f31&previousPage=lr Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 10, 2014 Member Contributer Share Posted June 10, 2014 That's a lot of HP gain for just valves. Link to comment Share on other sites More sharing options...
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