What exactly was wrong with the VF750?

[Billy Balthorpe]

I know it was the reason that Honda went and built the over engineered VFR750, but what was actually wrong with the VF750? I remember hearing about the old Honda Camshaft lubrication problems, but surely they would have sorted the oiling problem with a re call.

I really fancy one done as the VF750 Rothmans racer from the '86 Transatlantic season. But the ever present danger of the engine eating its own head is not helping my decision to embark on the project.

There seems to be a lot more V45 Magnas about than the VF750, wasnt it the same engine? I'm sure they sold more VF's than V45's (could be wrong), so how can there be so few VF's and lots of V45's still running about? Different heads or oilways that give more cam lubrication, or is it just that the V45 wouldnt have been thrashed as much as the VF?
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M.O.B. Successfully taking the piss since 2014.

[MarJay]

[Kickstart]

Hi

There was the VF750S and the VF750F. Think the S (sort of unfaired thing) had even worse cam and crank problems, while the F had an atrocious . Think Honda did try to sort out the oiling as well as flogging an oil additive.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[pinkyfloyd]

First big bike I was taken out on was a VFR 750, One of the last models before the 800's and I thought it was the bollocks of the doggy.

They improved it with the 800 versions and then they brought out that vtec fugly thing and that new monstrosity they have out is just awful looking.

But thats just my views.

https://pages.cs.wisc.edu/~john/vfr/specs/pics/94-vfr750.jpg

MMMMMMMM

https://pages.cs.wisc.edu/~john/vfr/specs/pics/99-vfr800-corbin-hiright.jpg

More MMMMMMMM

https://www.2wheeltravel.co.uk/Motorcycle%20Hire/USA%20HIRE/Sports%20bikes/Honda_VFR_800_VTEC.jpg

WTF?

https://www.asphaltandrubber.com/wp-content/uploads/2009/06/Honda-VFR-1200-V4.jpg


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illuminateTHEmind wrote: I am just more evolved than most of you guys... this allows me to pick of things quickly which would have normally taken the common man years to master
Hockeystorm65:.well there are childish arguments...there are very childish arguments.....there are really stupid childish arguments and now there are......Pinkfloyd arguments!
Teflon-Mike:I think I agree with just about all Pinky has said.

[Billy Balthorpe]

[Billy Balthorpe]

Pinky,

I found one for my Father in Law 5 months ago, a 96 VFR750 in red with 17,000 miles on it for £1600, lovely nick and felt like new on the ride back to his place, i can see why people rave about them even on that short 40 mile journey.
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M.O.B. Successfully taking the piss since 2014.

[pinkyfloyd]

I was pillion and got a speedo reading of 140mph on the one I was on along a dual carriageway and then went hareing around the twisties was great fun. They have always got a place in my heart after that and I do love the 750 I have pictures with that little black decor on it.
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illuminateTHEmind wrote: I am just more evolved than most of you guys... this allows me to pick of things quickly which would have normally taken the common man years to master
Hockeystorm65:.well there are childish arguments...there are very childish arguments.....there are really stupid childish arguments and now there are......Pinkfloyd arguments!
Teflon-Mike:I think I agree with just about all Pinky has said.

[multijoy]

vf != vfr
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

[Billy Balthorpe]

[multijoy]

Sorry, forgot the internets isn't just for geeks any more!

!= means 'does not equal'.

So, what I meant was 'The op was talking about vf's, not vfr's'
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

[Cheeseybeaner]

[Teflon-Mike]

Well first of all, the VF750 Sabre or V45 Magna, I think, came first, and are different engines. One or both of them are shaft drive, and the cylinder inclination is different.
They are 90Degree V-fours, but pretty sure that the V is more reclined.
On the VF the V is more inclined with teh front pots almost parallell to the floor, rear ones almost verticle.
Maga / sabre have the pots tlited back more.
Internally they are quite different too.
I have a VF1000F of '84 vintage, and it has Magna / Sabre cousins too, and NONE of the internals are interchangeable from research I've done....
so that's that one.
as for the cam-shaft ledgend.....
Here goes!
As far as I can gather OFFICIALLY the first batch of VF750 cams were not properly hardened.
with a bit of guess work, I THINK they were cut on blankd for the sabre engine... (Sabre had been in production for twelve months prior to 'Inteceptor' launch) But the Sabre was much more softly tuned and didn't have the same lift or duration as the Interceptor cams.... so when cut to a wilder profile, more metal was taken off them, and that cut through the surface hardening... but thats only speculation!
According to HONDA it was all fixed in the US (who recieved ALL the first production run) under warranty or by recall.
But there was also an oil feed issue. There are two spray bars over the cams. They are braxed up, and it seems that the pipe work was a tad on teh small side, and revved hard, if the spray bars weren't 'matched' to teh galleries, could starve oil to the cams.
There were three or four successive mod-packs, I believe in the Honda service book for this, which included a different oil filter, drilling out some oil galleries, and I THINK replacing the early cam spray-bars completely.
In Europe, they claimed that the 'original' problem had been cured before any bikes got to these shores, but some of the mod-packs were supposed to be checked or done by dealers......
There is a LOT of 'lore' surrounding teh whole issue, and it SEEMS that the reputation was a little exagerated.
In the US there were afetr-market oiler kits that added an extra oil cooler and external plumbing to give the cams a better supply.
But they got the bike for three model years and got a LOT more bikes than we did.
Big bikes were NOT selling well in the UK at that time, and the press scare over the VF750 didn't help its sales figures at all!
I had up until not long ago, a 1985 copy of Motorcycle & Motorcycle Mechanics with a picture of a silver suited 'robotic dancer' on the front next to a VF750 with the slogan 'Only for Robots', and an article inside asking whether a quad-cam 16valve watercooled engine was just ONE step too far..... and whether the typical motorcyclist, could EVER get to grips with DIY mechanics on something so heniousely complex...... remember, the Triumph Bonnaville was still listed as a 'new' bike back then, and plenty of people bought them becouse they knew they could take them apart and put them back together again....... A Suzuki GSX550 with double over head cams was 'scary' mechanics, for the more experienced DIYer!
Possibly explains quite a bit about the legend.... it WAS a complicated engine...... still is!
But it was just legues away from what people of the time were used to, and rumours of having premature failures was something VERY scary!
People ridiculed Honda Cam-Chains, and the reputation for old hondas to start knocking at 24K either throught cam chain stretch or the tensioner blades giving up, was something that made people steer clear of buying them second hand, as they expected hefty repair bill, or a DIY nightmare to fix them..... an engine that could eat its own head and had twice the number of cam-chains AND a water-jacket round everything was ESPECIALLY scary......
But the MAIN problem was that for all teh engine technology, they weren't a very spectacular bike!
95bhp and I cant remember the quoted weight, think it was about 425lb..... it was under-powered and over weight against the competition.
Bench-mark for it was the Kawasaki GPz750 'unitrack', which was only about 5bhp down on power, and something like 30lb lighter. Had a reputation for being 'unburstable' in the engine room, and a sweet handling bike.... AND cheaper..... why would ANY-ONE want the VF750F, and all the pottential problems it had?
Honda BASICALLY admitted they had completely cocked it up, becouse within months they launched the CBX750F, which had almost the same 95bhp as the VF, without the weight, and went head to head withthe GPz, and fared well.
But the air-cooled four's days were numbered, water cooling was essential if power was to increase much more, so Honda had to percevier, and they were locked into the V4 concept, as market fears were that a water-cooled in-line four would be even wider than an air-cooled four. At the time, a GPz750 could be written off, just falling off its side stand, becouse if the genny cover broke, impacting the flywheel could bend the crank!
ANYWAY....
The here and now is...... is its survived thirty five or more years, without eating its head...... its probably been sorted!
If you still have concerns, I believe that NEW heads are actually still available..... certainly were for the less common VF1000 not long ago.... AND surprisingly NOT that expensive! Think they were only something like £125 each....... mind you DO have to buy two of them!
AND theres the US aftermarket exernal oiler kit.... which I just CANT remember the name of!
So, as a 'classic', it is an interesting one to go for, with a LOT of history to its credit.
As to the Rothmans bikes..... I seem to recall some consternation over those!
Pretty sure Ron Haslam was mixed up in it, & they got a Yank team manager from US Superbike, who had some rather curiouse ideas about the UK Superbike regulations......
Basically, under US regs, ALL they had to use of the stick road bike was the frame and engine cases! In the Easter-Cup series, the ?Yanks were just leaving the brits for dead on the straights, as they had such much more highly tuned motors!
Anyway, this chap from teh states looked at the regs, and decided that the 'key' was in the wording, which said something like 'standard parts' had to be retained, but may be 'modified'..... so set about cutting crank-shafts in half and welding them back together, and melting down original pistons and re-casting them..... which is where I think the ACU decided he had crossed the line!
Think he did pretty much the same thing with the early VFR, which was more awkward to tune due to teh cassette cam-drive, which meant if you skimmed the head to increase thc ompression ratio, you retarded the cams, and due to back-lash ideler in teh cassette, there was oly so much you could take off the head or deck-height.
His mods eventually resulted in the VFR750R 'homolugation special' or RC30 as its more commonly known....
But thats another leap!
Bottom line?!
There were numerouse flaws in teh VF750 motor, from the notoriouse Honda cam-chain tensioner mechanisms, to teh oil feeds to teh cams, to teh cams themselves.
The engine was overly ambitiouse in conception, and rushed into production to stay ahead of the original GPZ600 & 900, and paid the price.
BUT its reputation was also exagerated by a LOT of scare mongering, in an era where its complexity was just a HUGE leap of the imagination.
So, today?
If you find one, and it runs..... no more or no less likely to self destruct than any other thirty five year old bike.
Far more will depend on how well its been looked after.
If you want one as a classic, though, well, its got a lot of classic cudos by way of all that history going for it......
And today? Well its not THAT much more complicated than we've become accustomed to.
ONLY think to note with them is that they have 'thin-wall' pressure die cast cases....... suposed to make them light! (Thats a laugh!)
But becouse the metal section is so thin, when dissassembled you need to handle them carefully as they can crack easily, and on assembly you HAVE to be critical with the low rate torque wrench to make sure that all the cases are pulled up evenly and aren't sistorted by tightening.
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Frost]

Wow, that's much more readable since you've stopped putting a blank line after every time you press enter!

[Nexus Icon]

I thought they were labelled the "Widowmaker" because they became the bike of choice for the mid-life crisis biker of the era. Presumably for their looks rather than their perceived reliability.

[TomCB]

NR750

now that IS a nice bike.

https://www.simonevans.co.uk/v-four/images/nr750.jpg
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Faldo: "Classic BCF. A thread about sky diving is NSFW on post #2."

[Howling Terror]

[Suntan Sid]

[nowhere.elysium]

[Pete.]

The VF750 and VF1000 both suffered from premature cam wear, for the reasons listed above. My brother in law had a 750 which the cams were worn down on, and I had a VF1000 way back and the cams went on that, so I bought a yank interceptor motor to put in it (14hp more power and supposedly 'fixed' of the camshaft woes) - and the cams went on that too!

They didn't call them cadburyshafts for nothing

Shame really coz the 1000 could pull your arms from their sockets without sounding like it was trying to!
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Cheeseybeaner]

[dodsi]

If I had loadsamoney I would buy a NR750 and use it as my winter hack - just to see other bikers faces when they see a mucky - high mile example.

[Teflon-Mike]

[TomCB]

[Cheeseybeaner]

[Cheeseybeaner]

Seems to read 'the result of a decades engineering perfection' 'high technology for the new age' on the rear wheel!