Whats the difference ?

I’m rebuilding my 500 F2F and have bought another engine to use as spares. I know the earlier (1985) models had a 2mm smaller inlet port than the '86 ones and this spares engine is the same at 38mm O.D.
However, I’m noticing other differences between them such as the sump oil strainer which is smaller and shorter.
Question - can anyone tell me please what might be going on here ? What are the actual differences between these two engines given the strainers as identification. Are the cams going to be different ?

Not sure what you mean.
The 86 engine has loads of differences to the 84/85. The cylinders heads are completely different for example.

If you are seeing differences between two 86 engines then not sure. Maybe one had been bodged around with.

Thanks Jeremy. I suppose the essence of my question is, are some of the earlier vf500 engine parts interchangeable such as - the crank cases, crank , barrels / bores ( obviously part of the upper crankcase) gear box. The rest I can use from the original '86 engine. I realise I can go and measure all those parts for myself to verify but someone with superior knowledge might already know the answers.

OK. The 86 engine has a lot of differences to the earlier 84/85. I am not entirely sure why Honda made these changes and then only sold the VF500 for one more year but maybe market forces had something to do with it.
The biggest changes are the cylinder heads which were line bored for the 86 engine. The half moon rubber cut outs are the dead giveaway. The camshafts are different and some of the valves are different too. Maybe both exhaust and intake. Valve springs are different as a consequence. The 86 heads are significantly wider but I am told the 86 engine will still fit in a 84/85 frame.
As far as I know the bottom ends are the same but I do not know that for sure. I think the crankcases are the same for all years. The oil pump was upgraded in the 86 and the sump made deeper as you have spotted.
I think the cranks are the same and the camchain tensioners but with Honda you just never know.

You also need to watch out for the timing. This varies from country to country. Make sure the marks on the disc under the clutch cover are the same between engines or your spark boxes will not fire at the right time. Not a disaster as the bike will still run but the advance will be out.

I have three 86 engines and one 84. I try not to mix an match too much. Unfortunately my 84 is knackered as is one of my 86s. Fortunately I have two good 86 engines. Getting much harder to find good examples these days.

That’s a great help Jeremy - many thanks. The bottom line seems to be - don’t use the pre '86 engine parts on later machines unless to check very carefully they are the same. Its mainly the cases I need to swap but the rest can come from the original '86 top end which from what you say should be OK.
Are you in the UK ?

There is much more information about this on the other V4 sites like VFRworld, VFRdiscussion and V4hondabbs.
One advantage of still being obsessed with these bikes is every question you have, will have been asked before.
Not in the UK yet. I work in Ireland but aiming to move back when I retire.

Retirement … I thoroughly recommend it. My son has a really nice NC30 VFR 400. We aim to do some ride outs together on the two machines if my b…y thing ever gets finished.


It will be worth it. I am very fortunate to have other bikes, including a 2016 litre sports bike, but the VF500 is the only bike I have owned that makes me want to actually ride for no reason at all, other than just to get out there.

I know what you mean. For about 5 miles I actually rode the 500 ( before the oil leaks manifest themselves at the cracked cases) and I was smiling from ear to ear. Its the only reason I’m persevering with it. ;D :’( :o