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sportstu

Endurance Racing VF500 build.

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Ok. I am going to build a VF500 endurance race bike for an upcoming classic endurance race. I have bought a US import VF500 interceptor in non running condition and I have a plan to have it stripped and rebuilt by sometime in early 2017. The VF500 is a daft choice for this but I like daft choices so I'm going with it! The rules of the race mean that it will be a F2 racer running alongside early VFR750's, early GSXR750's as well as any pre 1986 2 strokes. We will be down on power but we will also be lighter so there is hope that we can make a reasonable showing on the day.

These bikes do have a little bit of race heritage. Back in 1985 in the UK we had the VF500 cup single bike series which ran as a support class to the bigger races and actually got some TV time which can be found on google. My bike will be based on the US style AMA superbike styling, no full fairing, but I will have clip-on style bars rather than the high bars favoured on the VF750.

So, the plan is:

Strip to bare parts

Powder coat the frame etc

Bin all the road kit

race loom, keyless

CBR600 41mm forks

alloy yokes top and bottom

cbr600 rear wheel

520 chain

under-slung caliper

bespoke exhaust 4 into 2 

new linear linkage

new adjustable shock

NC30 calipers and discs

complete engine overhaul

skim heads

polish ports

full carb overhaul

close ratio gearbox

lightened flywheel

bespoke rearsets

lose as much weight as possible

plus lots more as it unfolds.

 

I am aiming at a genuine 70rwhp and less than 180kg wet.

If anyone is interested I will try to post some pics and up-dates, if not I will just post up when the thing is done.

So far I have stripped everything, the frame has gone of to the painters, the motor is split and I have all the new bearings, cam chains, tensioners, gaskets etc ready for the re-assembly. I have to re-furb the top casing as it's a bit rough and then we are ready to start.

 

 

 

vf500.jpg

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There are ceramic bearings. If you area really serious into blowing money into this, then I would look into them. There's also a company called Microblue that puts some coatings on their steel and ceramic bearings, but not sure if there's been any real testing. I think most race teams use ceramic where possible.

 

I'd be interested to know what you do with the pistons if anything. Impossible to get, and the closest piston that would fit is from a Ninja 250, but would need a bore on already thin walls.

 

Biggest concern is the frame. There's not a whole lot of...frame.. to it. Bigger forks might not work all that great.

 

But keep posting away :beer:

 

:lurk:

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Hi. there are a few suppliers of exotic stuff but the plan with this build is to keep roughly period and within the spirit of the regulations. The chassis is what it is in terms of rigidity, it's never going to be anything else. The 41mm fork conversion is pretty standard, it's not going to twist the rest of it out of shape but they do offer rebound damping which is absent from the standard set up. Pistons look Ok as do the rings so I don't plan on anything other than honing the bores and cleaning up. 

 

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Congrats!!

 

 

"The Dutchy" here on VFRD has a VF500 set up for racing and could chip in shortly :-)

 

 

Me? This Dutchy has a VF500F2 and no interest in racing it, but will gladly follow your progress! :beer:

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A few pics of the progress so far. The sump was full of petrol from a faulty fuel tap vac hose, carbs had previously been split and remounted to the base plate incorrectly, bending it out of shape and making the mechanism very stiff. The motor had been painted in situ so everything was covered in engine paint. It all came away surprisingly well though, few sheared bolts and rounded heads.

Image000.jpg

 

Most of what is in this picture is now in the skip. Wheels, forks, yokes, exhausts, stands etc etc.      

Motor ready for stripping. Ace paintwork on the cam coversImage001.jpg

 

Image008.jpgCases split. I couldn't find anyone willing to strip and repaint the casings so had to do it myself.Image014.jpgCovered in paint stripper. It took an age, probably 5 applications followed by wire wool and wire brushing.Image015.jpgMasked up ready for paint

Image018.jpgFinished and cleaned up.Image020.jpgImage021.jpg

 

 

So now I have everything for the bottom end rebuild. I've bought all new bearings from CMSNL as well as new slippers, guides and cam chains. The gearbox is ready to go in but having looked at the casing I am slightly worried that it will be too large because of the different ratios. Time will tell!

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51 minutes ago, sportstu said:

So now I have everything for the bottom end rebuild.

Conrods and pistons balanced?

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Why would you put the exhaust and forks in the skip? Are they  farked? :unsure:

 

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and while you have the engine split, put in a new seal for the clutch rod.

 

So you donot have to get creative at a later stage.....    :-)

 

IMAG3550-768x1358_zpslniydpur.jpg

 

 

IMAG3552-1024x1811_zps6suaplrm.jpg

 

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1 hour ago, Dutchy said:

and while you have the engine split, put in a new seal for the clutch rod.

 

So you donot have to get creative at a later stage.....    :-)

 

IMAG3550-768x1358_zpslniydpur.jpg

 

 

IMAG3552-1024x1811_zps6suaplrm.jpg

 

Yep, and the output shaft seal.

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1 hour ago, Dutchy said:

Why would you put the exhaust and forks in the skip? Are they  farked? :unsure:

 

The forks were knackered and the collector and headers were gone. Silencers are OK but there's no market for them as far as I know.

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20 minutes ago, jeremyr62 said:

Blimey. I hope your valve gear is in good nick. I'd hate to see all that work rewarded with a dropped valve.

So do I!! The heads are being rebuilt once the bottom end is assembled.

 

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Basic stuff from screwfix, on the plus side it didn't damage the alloy.

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Subscribed.

 

Very nice thread, keep plowing ahead.

 

 

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I concur, good to see the progress....

Sent from my HTC_PN071 using Tapatalk

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Well, there's a bit of a hold up with the engine rebuild while I get a but of machining done to try to fit the NC30 close ratio box. There are a few issues that stop it being a straight swap over but hopefully with a bit of imagination and time in the machine shop it can be done.

The main issue is that the output shaft on the nc30 box is slightly longer, presumably because the chain line for a wider tyre dictated the final dimensions. The cluster sits within the same space and the selectors line up but the output bearing is further down the shaft meaning that the locating groove does not line up with the crank case. The second issue is that the second gear output sprocket on the nc30 is straight cut (nearly) but on the VF500 it is tapered to clear the casting. The NC30 2nd gear is a 39 tooth whereas the VF one is 40 but it still fouls the casing very slightly so I have to have it ground to suit.

Sorry about the blurry pics.Image027.jpgVF500 output shaft measured from 2nd gear to the locating groove.Image028.jpgSame measurement applied to the NC30 boxImage026.jpgVF500 also uses a wider groove in the bearing                you can just see that the NC30 bearing sits a little further from the gear. There is no thrust washer and the bearing can't be moved so the only option is to re-groove the bearing or the crank case.Image032.jpgNC30 2nd gear straight cut, VF500 2nd gear tapered to clear an internal casting.Image019.jpg Meshed up in the top casing with the shift forks fitted so I'm confident I can make it work.                                                        Anyway, the components are now off at the speedy machine shop and I don't expect them back for a week or so and there's nothing else that I can do to the motor until I get the gearbox done.

Hopefully the frame will be ready to collect from the powder coaters tomorrow and I can start the chassis assembly while I'm waiting.

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What year VF is that the 84/85 bikes have a habit of dropping valves if used at high rpm a lot, so endurance racing fits that !

I had an 86 F2 for ages, ragged the guts out of it & did the high pressure oil feed to the head mod.  At 60K miles I had it dyno tested & it was putting out 59whp, this was with K&N & a Predator stainless system which is not the freeest flowing exhaust in the world.

 

Just remember they are already an overbored & tuned VF400 motor, so if you manage to get better than 65hp out of it you will be doing well.

I'd concentrate on the intake & exhaust, shorten the intakes stacks to the minimum you can manage, then replace the airbox with a full surround maximum volume, ramair fed one, like an RC30 HRC one, you'll have to make it, or maybe modify an NC30/35 one.  I can't remember the carb size, so compare to NC30/35 or add cheap chinese flat slides even !

 

A custom exhaust is the only answer, make it flow as good as possible, you will need an internal diameter around 30-32mm for maximum exhaust flow.

 

On the brakes, get a set of CBR600RR/F4/929/954/SP1/2 Nissin four pots & a CBR master cylinder for the most awesomw period correct (ish) brakes :)

 

Have at it & it will be good to see how it goes.  Where in Devon are you ?

 

Edited by Mohawk
typos :(
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Good brake suggestion Mohawk. If you go that path, the 41mm forks from a VTR1000F will work well with those calipers with minor grinding for clearance. I prefer the 954/SP2 brake combination for the best master cylinder and caliper piston size mix.

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Interesting, Looks like you know what you're doing. 

 

Yes, the dreaded VF500 dropped valve scenario. 

 

Best to scrutinize that area closely before assembly. 

 

Maybe there are other model Honda valves you could use with thicker stems? Mod the valve guides to suit? A millimetre extra might just buy you all the insurance you need? 

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Changing the valve stem thickness would change all manner of characteristics of the dynamic behaviour of the valve train. The weight of the valve would change so you would need to adjust the springs etc etc.

I admire the OPs ambition but as a VF500 owner I question his sanity :-)

 

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Cheers for the advice all. The forks are 41mm cbr ones but I am using NC30 lowers that will allow me to bolt NC30 4 pot calipers on. They are period and work great. I did this mod on an old steelie that I raced for a while and it works well. The bike is an 85 interceptor. Carbs are the 32mm, the later US and the UK ones were 30mm. The inlet stacks are pretty much flush with the base plate on these bikes, the airbox is a weird round thing with a the intake facing back so I intend to find a way to get a bit more volume but that's a job for later. I won't get a NC30 one under the tank and I can't cut the tank because we need as much fuel capacity as possible. Exhaust is going to be a 4-2 custom one along the lines of the VF750 AMA racers, offset cans to keep the pipe length the same from front and rear pots.

Reliability is going to be the Achilles heel. These do have a reputation for top end woes but all I can do is make it a good as it can be and keep my fingers crossed. I am keeping the motor standard with a view to reliability so any tuning will be purely through breathing mods and fitting a much lighter flywheel to help it spin.

Frame is ready for collection tomorrow so I will start the chassis build next week.

 

 

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6 minutes ago, jeremyr62 said:

Changing the valve stem thickness would change all manner of characteristics of the dynamic behaviour of the valve train. The weight of the valve would change so you would need to adjust the springs etc etc.

I admire the OPs ambition but as a VF500 owner I question his sanity :-)

 

Haha, yes, so do I, there are easier bikes to prep.

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13 hours ago, Mohawk said:

What year VF is that the 83/85 bike have a habit of dropping valves if used at high rpm a lot, so endurance racing fits that !

I had an 86 F2 for ages, rathed the guts out of it & did the high pressure oil feed to the head mod.  At 60K miles I had it dyno tested & it was putting out 59whp, this was with K&N & a Predator stainless system which is not the freeest flowing exhaust in the world.

 

Just remember they are already an overbored & tuned VF400 motor, so if you manage to get better than 65hp out of it you will be doing well.

I'd concentrate on the intake & exhaust, shorten the intakes stacks to the minimum you can manage, then replace the airbox with a full surround maximum volume, ramair fed one, like an RC30 HRC one, you'll have to make it, or maybe modify an NC30/35 one.  I can't remember the card size, so compare to NC30/35 or add cheap chinese flat slides even !

 

A custom exhaust is the only answer, make it flow as good as possible, you will need an internal diameter around 30-32mm for maximum exhaust flow.

 

On the brakes, get a set of CBR600RR/F4/929/954/SP1/2 Nissin four pots & a CBR master cylinder for the most awesomw period correct (ish) brakes :)

 

Have at it & it will be good to see how it goes.  Where in Devon are you ?

 

Exeter. Pop in and have a look if you're in the area

 

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