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Mohawk last won the day on November 11 2016

Mohawk had the most liked content!

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About Mohawk

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    Motorcycle Racing Legend

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

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  1. Interesting Fuel Stats.

    OK, so the issue here it that there is NO SUCH THING as Premium fuel. Fuel comes in various octane ratings & there are generally 2 used in the world just to confuse people. MON in the American influenced world & RON in the rest of the world. MON87 roughly equates to RON95. The higher the number the more the fuel when mixed in the correct AFR resists detonation, this is normally linked to compression ratio, and as a general rule the higher the compression ratio the higher the octane rated fuel required. BUT The BUT being most manufacturers confusingly state the engines static compression ratio, this is if you set the piston to BDC, then closed the valves & forced the piston to TDC. But as we all know, valves are never closed except at ignition time. So what you really need to know is the DYNAMIC compression ratio & for most well tuned engines designed to run on normal octane fuel (MON87-RON95) that will be around 10.5-10.9-1 ratio. Even the CBR1000RR & various other 1000cc sports bike quoting 12+ or 13-1 ratios only manage 10.x dynamic compression due to valve overlap to allow maximum rpm's to carry power higher up the speed range. The upshot of this is that "premium" or rather higher octane fuels can NOT produce more power or better mpg, the energy content of a set volume of fuel is fixed, so regardless which you inject the amount of power out is more a factor of the AFR than the fuel octane. In theory if our cylinders were working perfectly at the ideal 14-1 AFR then they would burn 0.0000273cc per cylinder per cycle. MPG or MPH is a determined to a large extent by the engine speed, acceleration & riding style plus load applied to the vehicle. So a bike travelling at a constant speed below 50mph will have significantly better mpg than one reaching 100mph & back to 30mph randomly on a track, mostly due to revs and speed of acceleration. You can run your own numbers, but efficiency is a combination of power required & where any engine sits in the rev range relative to the road speed required. So a big engine at idle can often be more efficient than a mid sized engine below/above peak torque rpm, where as a small engine running at peak torque rpm will often be more efficient than either of the others, but then you won't have much speed or power in reserve. On my euro tours, I often got 200miles from 17L of fuel or 53mpg, at motorway speeds commuting to work I can't get 170miles from 19L, or 40mpg (UK gallon=4.546L), on a track day I can push that close to 30mpg, due to running in low gears at high rpm all the time. So run some numbers for a VFR at say 5000rpm constant & 11000rpm constant & you will find that whilst fuel flow at higher rpm is reduced due to cylinder filling time reduction, the amount of fuel applied is only slightly less, depends on the volumetric efficiency of the engine in each rev range..
  2. Handlebar Muffs

    I'm now a convert to electrical heating. I've been riding 50miles each way to work in 0C (32F) temps over the last few weeks & the heated jacket & gloves are brilliant. It's nice to not have to dress up like an astronaut to keep warm & still use your fingers normally.
  3. Winter cooling improvement project

    The problem with stock water pumps is they can't be efficient at all revs, as their speed is linked to engine speed. At idle after a hard run they don't pump enough fluid & at high revs they cavitate a lot, so are actually closer to ideal than you might think. I replaced mine with an electric one, it has the advantage of operating at a better Lt/min rate ALL the time, so at speed its just right & at idle it to much, which is great for helping to dissipate the heat, plus as its rigged to a relay from the ignition, when you stop, you can leave it running with the engine off if the bike/air temp is really hot.
  4. RC36.2 (4th Gen) Fuel Injection discussion

    I can confirm that the 5/6th gen rubbers are the same, but the TB's are different, with different injectors. Not sure on the 8th gen, but its 6th gen motor retuned, so should be the same. No idea on the carbed ones.
  5. Performance Mods rap up

    Now that's a classic :)
  6. RC36.2 (4th Gen) Fuel Injection discussion

    Simpler to use GSXR TB's, they are seperate units on the late 90's ones, mounted like carbs on a rail, so would be better suited to fitting as replacements.
  7. 5th Gen Engine Modifications

    So imagine my 120hp VFR :) at 205Kg wet, its a blast :)
  8. 5th Gen Engine Modifications

    Sort that top end fuelling out & you have another 3-5hp for free ! :)
  9. Replace '97 with a '01????

    I know Ken & he is very anti electronic safety aids & I don't particularly disagree, why have a 200hp bike that can't be ridden without the electronics by the average jo ? But adds 50% to the cost said machine. Why is it late 90's/early 2000's 1000cc models weighed <170Kg with 150Hp & no electronics, but todays 1000's boast 30-50hp more but weigh in at 30-40Kg more ? All down to electronics & the heavy protective shells they need to survive the bikes limited protective capabilty & more arduous environment. I'd rather have a CBR954RR weighing 125Kg wet, than a YZF-M1 weighing 200Kg wet, that extra 75Kg will be there always, it will over work the tyres, it will limit your corner speed, it will do many bad things just by existing. The current tech race will lead to un usable bikes in the future, which go into limp mode, when abs sensors rings for traction control etc fail, as they age or corrode over time. I'd rather have ABS for the one time I might need it, than not have it & crash. But as Ken says EVERYONE pays for it, but only a tiny fraction ever use it. When you walk on the rim of a tall building you are very cautious, when you walk on the same rim, with either a safety net below or safety harness to stop you falling you are less concerned & less cautious, this is just a human reaction trait. YPYMATYP
  10. 5th Gen Engine Modifications

    Blimey, and I thought it must be vapor ware :) Get it in a bike & get it running. Check out my mods since this first started, up to 120whp with induction & exhaust mods. I went with an electric water pump, much simpler.
  11. It's the piston area, so the number of makes a difference or the area to be exact. The crf rear caliper piston is 22mm driven by a 10mm M/C for a 4.84/1 ratio. The RVF rear is 1x25mm & 1x27mm giving a ratio of 13.5/1 ratio, so will need a lot more throw to develop any pressure.
  12. He Chris,


    I wanted to get your thoughts? I broke down, having white connection block between stator and rectifier melted, if soldering would be the best option?



  13. TPS random fault ?

    OK been a while & this kept happening intermittently, to the point it was at least once a week. So I had to change the clutch plates a couple of months back, so bypassed the Rapid Bike ignition pickup. I looped the Rapid Bike connectors together & put the igition pulse output back on the original ECU connector. It has not happened once since so the error appears to be with the Rapid Bike unit. I'll ask Dimsport for some support next week.
  14. Programming a blank HISS key

    Assuming the 2014 & later work the same as the earlier ones, try this video, you need to make a programing lead, but its just 2 wires, one with a resistor. Have fun.
  15. I used to get 130mph indicated out of my 1986 one, no GPS back then :(