Mohawk

All three 5/6/8 gens top out at 10500rpm, then flatline or decline. We know the restriction is not in the exhaust now, so you might like to try my big air box mod on one of those. When I did mine it added 5hp up top plus it let it keep breathing to the redline ! 🙂

Well done, gents I salute you for having pulled this off. Would I be right in assuming that the mysterious Wade will keep the jigs & after your group buys his contact details will be revealed, so people can order one offs from him ? Obviously the unit cost will be higher, but good for future buyers, or those like me that have no need of another set of headers yet, but may in the future.

Replaced the 2000 Throttle bodies with a modified set of 99 ones. With a manual choke, with 4 hole CBR929 injectors, and a tapered intake modification. It runs, so that’s a start. I balanced the starters & adjusted the idle, now it revs well too. I’ll finish it in the morning 😀😎

Stripped off the silencer & opened it up to reveal most of the packing had left the party. Will order up some more packing material to rebuild it. Pics later.

You will find all bikes lose power at the top past peak power. It’s caused by lack of flow, this can be both inlet & exhaust combined &/or either individually. The primary suspect here is likely cam overlap, as Honda tuned the 6th gen inc Vtec for more torque, which you can see in the graph & people often think it feels sportier due to the kick in power when the Vtec chimes in with the other two valves. But when you look at those overlaid graphs, where 5th gen pulls ahead on power from 6k/rpm. How often do you ride below that rpm when it will matter ? Only when tootling along, so it’s inconsequential. Unless like Honda you are or as they did listened to those lazy riders that don’t know what a gearbox is for & decided to try to add torque. When what the lazy riders wanted was a 1000cc+ Tourers worth of torque from a bike that was a middle weight do it all bike. So a bit like those tourers that ruined the VFR, if you want touring torque for 2 up luggage carrying, then buy a 1000cc+ tourer, if you want flat out high rpm sports ride, then buy an Aprilia RSV4 or some other full on sports bike. If you want a good do it all middleweight that can cover all bases, buy a 5th or 8th gen. My 5th gen has been tweaked to be sportier than most, but still a great all rounder. Clean up the intakes, get the shortest velocity stacks in there, then this new header, a free flowing can & some cams if you really want to push the boat out. But remember to upgrade the suspension to match, to maintain that all round package.

Blimey SP-2 Windmill, looks nice in matching Castrol colours 🙂

Sorry didn’t mean to be harsh but bs is bs. There are direct comparisons with dyno numbers that shows no noticeable difference between stock & de-flapped. But that is with NO fuelling mods. When fuelling is modified to suit, then the de-flapped version makes more power higher up, with no losses. Anyhoo 33mpg is poor, regardless.

OK, so you obviously believe in the helmholtz resonance theory that manufacturers espouse to convince people that they have not restricted your engine to meet noise & emission regs etc. The VFR air box is to small, it’s the wrong shape & wrong material to create a helmholtz reasonance or any meaningful frequency effect. My dyno charts show no losses anywhere with a gutted big air box, with the filter moved to the top & the factory intakes eliminated, that adds about 3L to the intake area volume. Just by moving the filter to the top of the air box it added 5hp to my engine ! So you will have a hard time convincing anyone that the factory setup is best. try keeping your delusions to yourself, unless you have empiracle evidence to back it up.

BS. The air box is VERY restrictive. Check out my threads & mods which prove it empirically, rather than the rants of some armchair warrior. Honda like everyone else has to comply with noise & emissions regs. The 98/99 models had a lower emissions standard applied & gas was cheaper then. But 33mpg (I assume Imperial MPG =4.546L) is bad. I get that from my much more powerful VFR when ridden hard. The guy is not riding that hard. Back to the OP’s issue. Downloaded maps are garbage. Fuel injectors have very different deliveries, so a custom map is the only way to ensure a consistent Air Fuel Ratio & to see how your engine fuelling is performing as stock before a remap. The 5th gen single pintle injectors are simple devices & not prone to blocking unless left for long periods unused. Good luck.

Well the small K&N when moved to the top of the air box in my big air box mod, added 5hp, the filter is NOT restrictive, it’s location is !

Hey doesn’t matter, you have done a great job to date. Stick with numerono & let the tuning wars commence. Maybe after the first production run, variables may be possible. Kudos to Lance & Wade for making this happen. I’m not sure how many VFR800’s of all types have been sold, but in the UK alone there are over 5000 still registered for the road of 5th gen variety & as many 6th gen. On my most recent commute, I used to see 4 or 5 distinct 5th gens during the past year, and a few 6th gens. World wide there must be a goodly number of these in the wild, all with mild steel headers that for 5th gens are at least 18 years old & between 5-17 years old for 6th gens. So there is a huge potential market, just need a means to get them known outside VFRD to improve sales. If everyone does their bit & promotes them outside VFRD on their local or national Honda or VFR forums sales should be good, we need a continuous sales stream to keep them in production for a while ! So people do your bit once production units are ready.

So what Moosemoose said about O2 eliminators is correct, with them in ECU reverts to stored rich map (similar to what the 98/99 uses all the time !). PC3 ZERO map means that NO correction to base ECU injector signal, so the same as running without the PC3 fitted. Regarding a fuel map & why people never generally see the same result with a downloaded map, you need to read this http://www.robsdyno.com/injectors_tuning_massachusetts.html Makes a lot of sense ! Remember YMMV. Have fun.

Yes that is correct, my TBR weighed in at 4Kg complete, a massive weight saving over the stock sytem. Your protype is right there on weight, well done. Re the slip joints, these are supposed to bottom out in the expanded section & a little silicone exhaust paste will seal them I have not had any blow by on mine is 15K miles. Keep up the good work, its nearly there 🙂

Looking sweet & neat, go go go 🙂

Well unless he left the sunny climes of Florida & moved to Keynsham in the UK (where JHS Raicing are based) then that's mine 🙂 Before I had the 300rpm limiter increase to 12500rpm which is a 9% load increase on the rods, its been fine up there on a few track days 😉

Re the crush washers I was just having a tidy up in the garage & one of the things I found was the sample crush washer I had pulled out of the exhaust port when I fitted the TBR. So it was a standard sized crush washer of the round section copper type I prefer. I measured it in it’s crushed state, the OD was 39.5-40mm, the ID was 30mm +/- 0.5mm.

PS on the O2 sensor per header, I think you will find that your guys are living in the old world ! All modern O2 sensors are electronically heated so can operate anywhere in the exhaust system. The old ones were heated by the exhaust flow, so were best placed in the first 10"' of the header to ensure they heated up quickly & maintained an operational temperature. The new ones, can be anywhere in the header & get the same result. Resessing them from the header, so that the sensor tip is flush with the ID of the pipe, actually creates an eddy zone that should in theory make their reading more average, but they are best placed with just the triangular tip section protruding inside the ID of the pipe, being offset to one side they will not cause a full reflective pulse & should not hinder gas flow. But if mounted on a standard bung, they can protrude quite a ways into a primary header, much less so in a secondary or later collector, thus one sensor where mine is has a very minor impact on flow, as the pipe cross section is much larger.

Hi MooseMoose, do you have a link to CR46's dyno charts ? I've been trying for years to get him to do a dyno run, but he always refused unless someone with a stock bike would rock up on the same day to be the standard to measure by on the same dyno, next/previous bike. Perhaps you are confusing these with my dyno charts which have been on this site for years &/or HighSideNZ's from his 825cc big bore !?

Hey Lance, So unless you have a system that can modify the fuel pulse on a per cylinder basis (i.e. a Rapid Bike Racing) then its pointless having per header O2 measurements. The TBR was run & used with a PC3, one fuel pulse adjustment for all cylinders. The extra benefit for per header O2 tuning is negligable unless you have an injector that is way out of spec. So in answer to your questoins;- 1. Yes 2. Yes 3. No 4. I can get this later as I have one in my garage in a box. 5. YES Just run a bike with stock exhaust, then with new exhaust, it does NOT matter how the bike is configured, i.e. airfilter etc, you want to measure does this new exhaust increase the HP, anywhere with no or minimal losses everywhere else !? Let the exhaust do the talking, first run it with NO fuelling mods & see how that goes, only stop if it is dangerously lean. I had an issue with the fuel trims of my very modified bike & Dimsport advised to start with a zero map on the RBR unit, so I did. It ran fine & was only running a smidge warmer than before, so was not critically lean ! Possibly due to the narrow band O2 sensors being removed forcing the ECU to revert to the default rich backup map !

AFAIK, there is NO difference between the US 48 state ECU's & the rest of the world for the 98/99 models. There is a possible difference for the 00/01 models as in Europe we got HECS-3 emissions kit for Euro2 compliance (not sure =if that was included in US models) & HISS ignition chip system for theft prevention. Synchronising your starter valves correctly improves the smoothness of the engine everywhere, especially cleans up the free revving nature of the engine. Gas mileage is hard to improve on the VFR its its one bad point. But on a stock setup 00/01 model you should get 200 miles from a tank, hits reserve around 185, even when ridden in a spirited fashion. When cruised you should get 200 before reserve. My tuned up version hits reserve around 160ish miles, but has reached 180+ when cruised on a eurotour through the Alps.

Hi Mohawk, Thank you for your donation of --. We look forward to improving the forums with your donation. Thanks VFRDiscussion

Unfortunately the electronic support circuits for each version are NOT compatible, so if you have a 4.2 version you have to buy a complete new MTB to get the 4.9 version !

Regarding single point wideband sensor, you don’t need to worry about front rear cylinder trims. The factory ECU map sends different trim values to the injectors already. IIRC the rear cylinders always run a bit richer than the fronts, to compensate for their warmer position and in the airflow. So if you use a single sensor you are adjusting both banks equally. To explain, let’s say at X rpm & Y throttle position the stock ECU sends front value 50 & rear value 55. Your internal or external (on dyno) AFR probe, decides you should have +5 added for the ideal AFR you have set the system for (13.2/1 for Dynojet, adjustable in RapidBike) , so all the injectors get a +5 signal added to the base ECU value, so the fronts now see 55 & the rears 60 ! So the offset trim values are maintained, regardless of which piggy back system you use. Hope me that makes sense.

Do a search for Bosch LSU 4.2 connector and/or 4.9.. The 4.9 is the latest, it uses a fixed reference circuit for a zero mark, where the 4.2 uses fresh air which it rarely sees in an exhaust. The 4.2 zero can drift over time, where as the 4.9 is electronically fixed, and it has a faster response time, which is better for a bike engine. But the 4.9 did not exist when the first MTB was designed ! If if you have a recent MTB which is not old stock it should be on the 4.9, as they were introduced about 2 years ago.

Yes, MyTuningBike (MTB) connected to WideBand sensor. The new MTB support the lastest Bosch 4.9 sensor which is miles better than the older 4.2 that I have. I'll upgrade to one this year as I already have the sensor from when I was manually tuning the O2 before I added the MTB. The nice thing about the MTB is it corrects on the fly, you don't have to add its corrections to the base map, but you can. I did a trackday last year & was to noisy at 109.5db, so had to put a spud in the can, it passed noise testing fine, I was OK with this as the MTB would adjust the AFR to suit the new pipe configuration !