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Mohawk

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Mohawk last won the day on August 19

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About Mohawk

  • Rank
    Race Team Owner

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  • Location
    Bristol, UK
  • In My Garage:
    VFR800Fi Y2K, 120hp, minus 30Kg = VFR800R

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  1. Mohawk

    5th & 6th VFR 800 Header build

    Hi Keef, I can’t recall the exact model. But any 42mm OD gasket will do. I prefer the crushable copper ones.
  2. Mohawk

    5th & 6th VFR 800 Header build

    TBR headers are constant diameter, you are correct in your recollection of 38mm OD with 1mm wall, so 36mm ID which was the OD of the Motad header which is a copy of the 98/99 catless header. The Motad has a 1.5mm wall thickness so ID is 33mm, but the exhaust clamp flange weld reduces that internally to 29mm. So Motad to TBR swap changed the ID from 29mm to 36mm & this shows in how the power with the Motad plateau’d at 10500rpm, but the TBR kept increasing to the rev limiter at 12200rpm, with NO losses ! I had a contact in Japan confirm the Ladybird RC45 Titanium HRC copy is 38mm OD with 1mm wall thickness, so apart from being lighter & much more expensive, TBR got the dimensions right. I used Suzuki GSXR750 exhaust gaskets, with the TBR as Honda standard sized ones are smaller than the exhaust port when crushed ! Be good to see the numbers on this new exhaust.
  3. Mohawk

    5th & 6th VFR 800 Header build

    Hi Ken, 5+6th gens have outlets in the same place & the exhaust pairings are the same. But on 5th gen the #1 cylinder (rear left) header runs around the outside of the #3 header, making it longer & accounting for the disparate vacuum readings when balancing the TB’s. On the 6th gen Honda corrected this, by bringing #1 header under & inside #3 header thus making them the same length, but that meant they had to cross the front header pipes to keep the port pairing the same. So 6th gen have crossed front & rear pipes & 5th gen have no crosses. The port pairing on the 5/6th gens gives the best exhaust scavenge effect. But the gains are not great, due to the odd firing order. A correctly sized header with 8th gen port matching should work just as well. Looking at this new header it appears to have stepped or a poor mans tapered header which is all the rage in MotoGP systems. For reference the TBR system on mine added 8hp after a little fuel adjustment, but was good for 6hp without fuelling update. Power went from 112hp to 120hp same configuration, same dyno, all that changed was the exhausts from Motad to TBR. If the 5.7kg mentioned is just the header, then that’s heavy, compared to TBR at 4kg, but lighter than stock, especially if you have a cat exhaust which adds 2kg by itself. YMMV
  4. Mohawk

    Rapidbike Evo And Racing Related Questions !

    You need the Bosch LSU 4.2 for the older MYB or the 4.9 for the new one. The connectors & operation are very different, so you can’t use 4.9 with old MTB. Have a look at the connector on yours, if it was from the group buy or not in the last year then it’s likely 4.2. just match your MTB connector.
  5. Can't recall if I've ever posted these, but here's my old one before & after CBR600 wheel change. It's fitted with Predator 4-1 full stainless exhaust system & made 59Hp on the dyno with 59,000 miles on it, and it as a Hagon replacement shock. I had it for many years before I sold it to buy a CBR600F4. The CBR rear 17" wheel is fitted with a 130/90 section tyre which is 29mm taller than the 110/80 section fitted to the stock 18 inch wheel, thus restoring the stance when moving to the 17" wheel. IIRC the front is a 110/80 which also made the speedo read closer to reality. It may be for sale from the friend I sold it to, as he has not used it for years, I'd buy it back but don't have space for another bike 😞
  6. OK, so they are lighter & more powerful & have better cranking amp rating & they do deliver it. They spin the engine harder on startup which helps compression for primary ignition. They will do it harder for longer than the stock battery (unless you bought the really lightweight racing ones). There is no downside, other than they don't like being drained flat, so if not using for months at a time, charge them & then disconnect if your bike has a live dash with the ignition off. The 5th gen has a silly power drain for the clock !
  7. PS don’t use Lithium batteries, use LiFe ones a smidge heavier, but they don’t catch fire or explode ! Also very tolerant of charging conditions, so will charge on the bike fine. LiFe cells are 3.7volts each, sofour of them gives 14.8v which is just a smidge more than the stock charging systems 14,5v nominal charge voltage.I’ve used them for years with no grief.
  8. Approx 2.5Kg is a noticeable weight. Try carrying that for a few minutes ! Every time you accelerate, corner or brake it will have an effect, on mileage, grip & tyre wear. I’ve removed 35Kg from my 5th gen, a third of that is from the wheels & drive train, it’s very noticible 😎👍
  9. Mohawk

    Pardon The Nudity...

    Cracking job, great write up, good luck with the new vocation, looks like you have the talent for it 👍😎
  10. When you eventually tear it down, clean all the crap out of the inside of the swingarm, then glue some fine SS mesh over the holes in it by the shock this will stop further crud getting inside. Then polish the clamping areas & use some ACF50 or similar on the clamping areas, allow to dry thoroughly before putting back in the swingarm. If you ride in harsh weather especially with salt on the road, then you need to tear down the axle, hub & rising rate linkages annually to clean thoroughly & grease them. If you ride like Larry, then just do what he does. Road salt kills bikes which is why I park up my VFR when the first salt goes down & don't take it out until a few good spring rains have washed it all away again. That's a 5-6 month lay off here in the UK, but I have other bikes to ride in the winter that I'm less precious about 🙂
  11. It should work either way, as gear indicator should NOT modify the stock signal & if after the speedo healer, it should not matter as that only changes the frequency to compensate for the the actual speed , but signal sent out should be the same regardless.
  12. Those diaphragms should be fine, but you can check with the airbox off, engine running, sudden full throttle opening should see the slides lift most of the way. if they do, then its not the vacuum, unless sudden acceleration works, then bike slows down, as slides close ! Use your finger on the slide to ensure it has full movement before starting the engine. There are three things that would generally stop an engine revving out. Lack of air, would be apparent when stationary. Lack of fuel, would be apparent when stationary & poor spark. If the bike revs freely when cold, but not when hot, this is usually down to a failing electrical connector or devices. Coils suffer heat soak, connectors suffer from the same & the ignition advance is in the ECU which also can suffer heat soak, as it passes coil switching power through it. The igniton advance would be rpm specific, with most bikes switching advance around 3500-5000rpm. Just some items to think about.
  13. Mohawk

    Indicators on the Blink !

    Well after a second episode of disco dash which also lead to loss of tail & brake lights when indicating. The VFR was retired until today when I finally got time to dig deep into its wiring. Having stripped the front upper fairing off & checked all the connections & found nothing wrong, but having got random results the other evening, today was time to trace it all out. So removing various fuses, did nothing but prove it was isolated to lights & indicator circuit. Disconnecting various lights did not isolate it. Next up was a possible issue with the instrument cluster PCB, so I removed it & still had the weird lights, so not that. Whilst it was out I traced all tracks with an ohm meter & all were good 😀so that’s some good news. So more digging & I decided after following the wiring diagram to check the earth block in the loom near the reg/rec on the left side under the tail unit. I had this open a few years back when I had another issue & all was good. So untaped it & again it looked good, but for good measure I added a twist to the jump blocks & when reinserted & the issue was gone. So what to do, looks perfect but appears to be the route of the problem. So I decided to remove it & just solder the ends together. So after clipping the block apart to free the connectors for inspection, one of the contact blades fell out of one connector, so that was one fault identified. I then clipped off the crimped on connectors, I stripped the cables back ready to solder & found 2 more faults. Two of the 14 cables were corroded on the skin of their cable strands, one quite badly. So I spread the wires flat on those two & rubbed them with some emery paper to get them back to shine copper, rotated them a couple of times to get all the wires clean. I intertwined those two individually with another clean earth wire, then twisted all 14 together. One is thicker than the rest so I assume that is the primary return to earth wire. Then soldered them all together & heat shrink covered them & finally taped them back against the loom. I checked all earth cables end to end from the solder block, to every lights earth connector and all came out to the same value give or take a couple of ohm’s. I wiggled & moved all wires & the feed stayed good, no more weird behaviour.
  14. Mohawk

    RC51 forks on a 5G questions

    If the axle is the right length & fits the fork bottoms, you can use different bearing to get the wheel to fit ! Just an option. Alternately, if the wheel & axle fit, but the fork bottom does not you can make up shim tube spacers to accept the axle in those forks ! That will give a wider choice of wheel/axle combos, just need the right disc diameter & offset.
  15. Mohawk

    Engine oil recommendations

    New always the best & replace regularly with a quality filter ! YMMV depends on the viscosity of the oil amongst other environmental conditions 🙂
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