Newbie on site - Had VFR750 for 13 years though - fuel cleanout question/s

Hi Guys,

I’ve got a 1993 VFR750FP which I bought in 1996 with very little K’s on it and have had ever since – it’s become a bit of a family heirloom. My history before was a mixture of Kawasaki road/trail bikes then bigger road bikes then a series of BMWs mostly late 1980's K-100RS and once even an old ex-police RT I went touring around some of the country on. I bought the VFR because my BMW at the time was getting old and rattly and looking like needing very expensive repairs somewhere down the line and there were no replacement BM’s about for a realistic price – then almost by accident I test rode a VFR for a mate who was interested in buying it and I got sold on the VFR. At the time I got a job in the city too so the narrower and more nimble VFR suited the mission and it became my daily commuter for a few years until I changed jobs and then got moved out of the city again. It has been a very good bike for me and despite my long-running love for BMWs in the past I have found it hard to justify a replacement bike for pure “bang for your buck” as well as performance balanced with usability that the VFR has offerred. And it still looks great, too. Even now that its’ a 16 YO bike I can still park it outside the shops and get one or two onlookers – albeit sometimes ex-bike riders saying “I used to have one of those – should have kept it” or “You don’t see many of those anymore - most of them have been smashed/thrashed/gone to the wreckers by now!”
Still, parked beside a modern sportsbike the VFR does not look too dated unlike some of the more radically styled machinery you see now which will just look rakish in a few years’ time – IMHO at least.

I did most of my own work on the bike, balancing the carbs with vacuum guages and changing oil and filters mostly. I’ve had it in for a service a few times though to do some of the more finicky work and each time they’ve checked the valve clearances its’ been unchanged so I haven’t bothered with that for a long time. The thing just ran and ran, was fairly cheap to keep on the road if I did most of my own servicing and I ran up almost 50,000km on it without any major hassles except for a couple of electrical problems and some modifications I made to make the bike a little more useful “in service” as I call it:

1) The voltage regulator cooked itself (common on VFRs due to engine heat transferring along the frame) which I fixed by replacing the reg and mounting it on an aluminium baseplate with a little air gap between the frame and the baseplate to help reduce heat transfer.
2) The stupid “always on” headlights – (stipulated by the numb-nuts legislators who run the traffic laws in my state :crazy:– I guess they’re like that everywhere) - would drain enough current out of the battery when the ignition was turned on at winter on a cold morning to prevent it starting easily. I fixed that by isolating the headlight circuit at the fuse box and fitting a little toggle switch with a rubber boot over it (from a boat shop!) onto the inside fairing trim to allow me to switch the headlight off for starting. A neat installation that did the trick and didn’t require splicing into wiring looms and altering handlebar setups etc - it was a practical and simple mod and almost invisible.
3) I hated the standard VFR grips and threw them away and replaced them with slightly thicker, more grippy generic black “superbike” grips (which were actually the cheapest and surprisingly the best in the shop) and were much more comfortable on my hands not turning them into cramping claws after a long ride.
4) I unbolted the standard pipe off the bike and had a Tingate straight-through racing exhaust made for it with a restrictor on the end to quieten it a bit (and give some back-pressure for low-rev running – this was a daily runner not a racer strictly speaking) - and had a similar ball-knuckle joint to the original fabricated to allow the pipe to be swung out of the way when changing a rear tyre. This meant I could use the original again if I needed to rather than cutting the original exhaust pipe off and fitting a “slip on” pipe therefore voiding the chance for the original exhaust ever being re-useable.
5) Despite the restrictor (!) the Tingate gave me a headache on trips of more than ½ hour so I took it off and fitted a single stainless steel “colander” baffle in it midway down the pipe (i.e like a coffee plunger full of holes) - and that quieneted it down to an acceptable level – still a lot louder than original so car drivers heard me approaching and gave very good low-down response from the bike due to more back-pressure - so I was very happy and it didn’t seem to make much if any difference to top-end power though I think it must have taken some – it was still many times better than the original exhaust and at full throttle you’re doing well over 200kmh anyway and I don’t do that very often!
6) I’ve cranked up the rear spring preload a fair bit because I am 6ft 2” and weigh 93kg and used to carry pillion passengers a lot but have left it like that and tightened up the little adjustment screw in the rear shock most of the way to assist in making it stiffer as the rear shock had become a bit soggy over time. It still handles pretty well but lighter riders whom have ridden it have thought the rear end was too hard. It works for me.

So the bike was a regular runner during the week. That changed when my wife and I had two kids and I was then dropping them off at creche, school etc before work - so for the past 6 years’ the bike has had very little running – I’d get it out on the weekend every now and again and top up the tank, give it a run to blow out any cobwebs then cosset it back in the garage under a dust sheet out of harms’ way.

Last month I did that and – horror of horrors – it started OK but then after a few minutes riding I grabbed a handful of throttle and it lurched forward then propped, nearly dropping me on my *rse in front of oncoming traffic which was disconcerting to say the least.

I rolled the bike off the road and restarted it – which it did fine – but it seemed to run a little rough at anything much past half-throttle from then on. I had just topped up the tank with fresh fuel and always stored it with most of a tank so didn’t expect water in the fuel or anything – I thought perhaps one of the vaccuum diagphragms had failed as I had had that happen on a bike once before with similar results. My Dad, whom is a retired bike and car mechanic, said I was wrong and all I’d done was fill it with a batch of rubbish fuel and that had drawn through the carbs causing the problem.

So the other night I took the fairings and seat and tank off, and took the top off one of the carburettors to check the diagphragm - it looked brand new so it was unlikely that any of the others may have perished so I put it back together again very carefully after taking out and replacing the slide inside the carb for a look inside – it all looked clean and with a finger gently down each of the carb throats to move the slides back they all appear to be moving smoothly and sliding back into their correct positions too.

Then seeing as my Dad had told me fuel was the issue I drained one of the float chambers and – the fuel came out quite clean, - but it was a horrible dark brown colour. The fuel has gone off ! The fuel I had been using was 98RON premium unleaded and I have since read that this stuff goes stale much faster than conventional unleaded if left in an unsealed tank. I have also read that these bikes should be run on standard unleaded not the high performance stuff – does anyone know if there’s any truth in that ? I thought the high performance fuel would start better and be cleaner inside the engine and also give more power, burn cooler in the cylinders and prevent carbon buildup or knocking / pinging in very hot weather which we sometimes get over here in Austalia - Oh yeah I'm an Aussie - forgot to mention that. No - I don't have kangaroos in my backyard - but I did manage to hit one once !

Anyway I stuck the sample in a clear plastic container to get a good look at it and see if it would form varnish on the surface of the container – after a few days it doesn’t appear to have done so.

My concern now is varnishing etc, inside the carbs as I don’t want to dissemble the lot to clean it up again if I can avoid it – I am time limited nowadays. It looks clean inside from my inspection down the throats of the carb slide etc and the butterflies look clean too so I hope that it isn’t gummed up with varnish etc inside the carbs. I have actually come across a fuel additive that claims to dissolve varnish so I was going to replace the spark plugs while the tank is off, clean the air filter and put it back then drain the tank, check the fuel filter and fill it up again with a new tank of fuel and the fuel additive and hope that does the trick in flushing the fuel system through.

Does anyone have any other suggestions ?

Also while on the subject, once I’ve run the new fuel with the additive through the engine I was going to replace the engine oil, coolant and other fluids (i.e. brake fluid) while I was at it and was also considering replacing the fork oil which I have never done on this bike myself.

I have a US-published Clymer manual that says the fork oil on this model bike is (I kid you not) ATF ! - as in plain Automatic Transmission Fluid rather than bike fork oil ! Is this correct ? Other model years such as later 1994-on models it says use fork oil. I thought ATF was pretty nasty stuff to use on anything other than automatic transmissions. Why would you use it as fork oil and does it provide any better life or assist with fork seals or something ? Can anyone answer this one please ?

Also coolant – does the VFR use Glycol coolant or not ? The manual just seems to refer to coolant from what I read but when trying to buy the stuff it seems I need to know if the cooling system is designed to use glycol or not.

Many thanks in advance for any help – I only found this site recently and this really is a cool site.

Cheers DC