Jump to content


  • Content Count

  • Joined

  • Last visited

  • Days Won


BiKenG last won the day on December 6 2017

BiKenG had the most liked content!

Community Reputation

113 Great

About BiKenG

  • Rank
    World Superbike Racer
  • Birthday 08/26/1952

Profile Information

  • Location
    Surrey, UK
  • In My Garage:
    Montesa 4RT
    Triumph ThruxtonR

Recent Profile Visitors

5144 profile views
  1. BiKenG

    5th & 6th VFR 800 Header build

    Interesting reading for sure, but something is not adding up. I am not interested in max power figures, except for comparison purposes. In that Honda doc, they state the 5.2 makes 106 PS and the provided graph, while not including any figures shows the 5.2 making quite a bit more than the 5.1 they show for comparison. In fact from that Honda graph, a very rough estimate would put the 5.1 at no more than 100 PS. Yet figures I have for the 5.1 state 110 HP. Now I realise that PS are slightly bigger than traditional HP so the number would be slightly lower, but certainly not 10%. Those 5.1 figures are not from Honda literature, but from some press info. However, it is almost certainly simply copied from Honda's own literature at the time. So either I'm missing something here, or someone's being economical with the truth. BTW, Honda's figures for the Gen 6 are 107 PS max. So certainly same ballpark. The 8th Gen dropped to 104.
  2. BiKenG

    5th & 6th VFR 800 Header build

    Pretty sure I see HISS there, so he will probably find an O2 sensor here as well... Yes I can see the HISS module as well. It's even advertised as a 2000, so that makes it a Gen 5.2 and the same as my bike. Oh well. I'm still available.😀
  3. BiKenG

    5th & 6th VFR 800 Header build

    That's all good to know,. So I need a 5/6 Gen collector and rear downpipes, with 8th Gen fronts. Simples.
  4. BiKenG

    5th & 6th VFR 800 Header build

    I am still trying to establish how Delkevic can use the same collector for 5 and 6 Gen systems. Is the outlet angle and position the same on these bikes with just a different link from there to the low can of the 5th Gen or the high level stuff under the seat of the 6th Gen? As I said, I'm needing the splayed front pipes of the 8th Gen with an outlet suitable for the 6th Gen's high level and although modification of the pipes to suit may be necessary, the less needed the better. So just trying to understand what might be required. Anyone know for sure about the outlets?
  5. BiKenG

    5th & 6th VFR 800 Header build

    Well I am in the UK, but down south:-( However, I have a good trailer and a suitable bike and the time :-) Also, I'm very interested in this whole issue so would be prepared to truck the bike up there, especially if it got me a system to use. Then I just need to buy one more. I've started to make contact with Jeff to take this further. I'll update you all when I know more. Two more things. My bike is a Gen 5.2, i.e. with cat. So ideally need to source a regular system for comparison. Anyone got any Gen 5.1 headers kicking around we could borrow? If international shipping becomes an issue with this or anything else, I am prepared to accept items delivered here on behalf of members and ship them on to the final destination. I don't have any special deals with shipping companies and the original supplier may well be able to do it better and cheaper. But if for some reason they won't offer Int. shipping, I would help, obviously only at whatever cost the shipping company charges. You could even make your own arrangements and just have it collected from here. Anyway, just offering in case it helps anyone get hold of the VFR parts they want.
  6. BiKenG

    5th & 6th VFR 800 Header build

    The Delkevic system is often dismissed for its poor collector joint internals, but has anyone actually tested on a dyno? Ideally a bike with standard system, then swapped for Delkevic to get a good comparison on same dyno, same day etc? It would be particularly interesting to see this for their 8th Gen system as they use the same L&R merging of earlier Gens rather than F&R as Honda use for that model.
  7. BiKenG

    5th & 6th VFR 800 Header build

    I hadn't noticed that the 8th Gen uses a Fronts and Rears merge style, but it does indicate how the different merging affects power and torque. Personally I'd be more interested in healthier mid range torque than top end power and if that's the effect of a F&R merge on a 180 crank, then it shouldn't be dismissed out of hand. Although for those wanting the max. top end power, L&R merging remains the more desirable. So many options :) For mid range torque then, the Lextek may well be ok. Anyone want to try one and put it not the dyno so we can see the result?
  8. BiKenG

    5th & 6th VFR 800 Header build

    The way exhaust pulses are combined can have a very significant effect on the power of the engine. For the 2000 FireBlade (CBR929RR) Honda used a (cast Titanium) combiner valve that joined 1+4 and 2+3, or 1+2 and 3+4 under different conditions specifically because to maximise power under all conditions required the different merge styles. It was their first exhaust 'power valve'. So the way the pulses are combined can make a big difference and the pulses from a 180° and a 360° V4 occur in a different pattern which Honda (and other exhaust engineers) have found require the different merging for each of the crank designs in order to maximise power. Let's face it, the way they merge Lefts and Rights on the 800 is much more complicated than Fronts and Rears, with more pipework required etc. They wouldn't do that if they didn't think it necessary. Using the wrong merge style isn't going to make the bike unrideable, or even be particularly noticeable to some riders, but on a dyno it would be very noticeable and with the main thrust of this topic being to source a good high quality, high power replacement to the TBR system, going the other way to something that makes less power than stock is probably not what people here want. This exhaust tuning should not be dismissed. When Honda were racing their multi cylinder 4 strokes back in the 60s, current thinking was that a separate pipe for each cylinder allowed freest gas flow and gave the most power. It has since been discovered that combining the pulses in the right way means one cylinder's pulse can help scavenge the exhaust of the other(s). This is one of the main reasons for the huge increase in specific power output of modern race engines. I cannot help but think that anyone who tries to tell you that a Fronts and Rears merged system works well on a 180° crank 90° V4 is trying to sell such a system that they made because it was the cheapest way to do it and I'd need to see dyno comparison charts to convince me otherwise.
  9. BiKenG

    5th & 6th VFR 800 Header build

    Just had a chat to the seller of that Lextek system on eBay UK. I asked if the picture was of the actual correct system as the Fronts and Rears merging is really for a 360° crank motor and not the VFR800 which is 180°. To cut a long story short, he knows nothing about it and just sells them. Apparently Lextek say VFR800s run ok with it and it didn't need changing (from what though). Looks to me like they used an existing collector and bodged it to fit the VFR800 and as it does actually run (which it would of course) didn't look into it any further. While I think spending loads of cash to try to extract every last hp from a VFR is probably a mug's game, actually saddling it with a fundamentally badly designed pipe system is equally daft. Everyone can make their own choice of course, but IMO the Lextek system is to be avoided at all costs.
  10. BiKenG

    5th & 6th VFR 800 Header build

    Thinking further on this merging issue, Honda merge the Lefts and Rights and then merges the resulting Left and Right (as does the TBR) on all bikes I've checked that use a 180° crank (VFR750 and VFR800), but on the bikes with 360° cranks (RC30, RC45, NC30, NC35) they merge Fronts and Rears and then Front and Rear. I think this gives a clear indication of what is the best for the bike under discussion here, i.e. the VFR800. Which rather leaves a question over the Lextek system. Unless the picture is actually of a 400 (or RC30/45) system. Again, do we have any idea about BW's intentions regarding this? As far as I'm concerned, the CSK system is way out of reach pricewise. It appears they do fantastic work, but even at the regular price indicated by Louis it's not appropriate for me and let's be honest, if you're that keen on spending money to get a fast V4, buy the Aprilia, or Ducati, or Norton. For my purposes the Lextek price makes more sense. That's not to denigrate CSK in any way. Fabulous looking work and Louis has jumped in here and been very accommodating, but it won't be for me.
  11. BiKenG

    5th & 6th VFR 800 Header build

    I think this is something that needs to be settled. Honda pair the Lefts and the Rights as did TBR and Erion before that (same guy I think). Although the Tuono is Fronts and Rears paired, that may not be relevant to our requirement. The Aprilia has a different cylinder angle and I've no idea what the firing order, nor crank angle is. So what works best for Aprilia V4 power may not work for the VFR. So I would tend towards thinking the original Honda merge style would be best. Everyone holds up the TBR as the system to copy and that's what they use so does it not make sense to stick with that? Has this been discussed with BW? Any idea what their intentions are with regard to this aspect?
  12. BiKenG

    5th & 6th VFR 800 Header build

    As far as I can make out, you +1'd JZH's comment about Black Widow, but then commented on the Delkevic which indeed seems to have their 8th Gen rear slip joints backwards. It does seem wrong to me, but in reality, does it actually make any difference. Not to the flow as there is the same small gap in the otherwise smooth internal bore. Where that gap then leads is surely incidental. Also, would it affect potential sealing of the joint? Since static pressure is going to be exerted in all directions equally, the only difference would be due to the movement of the gas and like the flow, I don't see how the direction the gap takes could make any difference. Indeed with a perfect seal, it could make no difference. As I said, it does seem wrong to me, but is that in fact just a misguided concern.
  13. BiKenG

    5th & 6th VFR 800 Header build

    Seems to me this is crucial for any prospective manufacturer. The problem is always going to be cost of design/manufacture vs size of market and since in this case it wouldn't impact on performance, modularity just HAS to be the way to go. I could do with some clarification though. Is the collector outlet the same on the 5th Gen as the 6th Gen? Obviously completely different systems downstream, but is the collector actually interchangeable? The reason I ask is because my requirement for such an exhaust is to suit an 800 special I'm building which will have the 6th Gen high level rear end, but as a naked bike will need the front rad of the 8th Gen and hence the wide spaced front downtubes. Seems to me from what Seb says, this could be done by piecing together Delkevic parts. But how do they use the same collector, unless the outlet is actually the same for the 5th and 6th Gens. Or do they use the same actual collector but have different outlets that can be attached?. Hence my question. Actually another thought. Why do Honda cross the pipes over. Since they cross both front and back it doesn't change the merge order, so why do it. I can't see any obvious reason. Anyone?
  14. BiKenG

    5th & 6th VFR 800 Header build

    Oh yes. No question. But that doesn't necessarily mean it works any better.
  15. BiKenG

    Gear Indicator

    Yes, those are the sensor and bush to which I was referring. If the later sprocket cover that accepts the sensor will fit the earlier bike (highly likely) then you're home and dry. Otherwise, you could modify an early sprocket cover to allow the sensor to be mounted onto it.

Important Information

By using this site, you agree to our Privacy Policy.