Inconsequential ramblings of an Old Git

[mangocrazy]

On the basis that the shed roof was frost-free for the first time in nearly a week when I looked out this morning I decided that some shed time was in order. Unfortunately my normal routine of wheeling the LC outside so I have more room to work on the VFR was stymied by it starting to rain the second I walked out of the house. So instead it was a case of trying to contort myself into shapes that really didn't befit an Old Git.

Bit of a re-cap; the reason I need to fit different exhausts is that the currently fitted exhaust collector box sticks out rearwards about 50mm more than it should, meaning it's impossible to remove the rear wheel without dismantling the rear suspension. This is clearly a nonsense; if I ever get a puncture while out and about I would be completely unable to fix it.

The reason why the collector box is misplaced is because I fitted a set of Motad stainless downpipes to replace the OE steel ones that were nearing the end of their life. Replacement OE systems have been NLA for 10-15 years, so when I bought the Motad downpipes I thought I was making a smart move. Unfortunately I didn't buy the matching Motad collector as I already had a couple of OE ones squirrelled away. But as I later discovered, the Motad downpipes do not play nice with the OE collector. By the time I'd discovered this Motad had very inconsiderately gone bust and ceased trading.

In the longer term (assuming I keep the bike) I will need to get a replacement collector box made up (preferably in stainless) that has an overall length reduced by 50mm from OE. But as this will take some time and I have a spare aftermarket exhaust cluttering up the shed, that's what will get fitted. But first I need to remove the current exhaust system back to and including the collector box. This is what the RH side of the exhaust system looks like:

DSCF3941.JPG (465.11 KiB) Viewed 539 times

And this is what things look like at collector box level:

DSCF3949.JPG (492.62 KiB) Viewed 539 times

And with the RH can removed from the collector box, here's a close-up of the ridiculously small current clearance between tyre and collector box - there can only be about 10-15mm tops.

DSCF3951.JPG (457.22 KiB) Viewed 539 times

Before I can get the collector box off I'll need to remove the swingarm to linkage bolt, so I can lift the rear wheel up and give enough rearward clearance between tyre and collector box. And for that I really will need to punt the LC outside and have room to swing a cat (or a skylift). Maybe tomorrow?

[Supermofo]

Is that a very old school way of tyre warming

[mangocrazy]

Is that a very old school way of tyre warming

It's close to being a friction warmer...

I'm currently reading up on tyre 'fling'...

[Demannu]

2 things may help, and they're related.
Adjust the chain to give more wheelbase or fit -1 sprocket, and fix that tight gold link!

First time spannering in IoM, rider comes in after EMP moaning that the bike is a bit loose at the back. Had a quick look and there was a gouge all around the tyre centre and rubber sprayed over the shock and linkages.
Checked the tyre pressure and it was 8psi!

[Rockburner]

Can't you shave 50mm off the downpipes? (Once it's all apart)

[mangocrazy]

2 things may help, and they're related.
Adjust the chain to give more wheelbase or fit -1 sprocket, and fix that tight gold link!

First time spannering in IoM, rider comes in after EMP moaning that the bike is a bit loose at the back. Had a quick look and there was a gouge all around the tyre centre and rubber sprayed over the shock and linkages.
Checked the tyre pressure and it was 8psi!

The chain is currently about mid position in the adjuster slot in the swingarm, so the wheel has about 60mm clearance to the swingarm. But I will have a good look at that gold link. It's quite possible it was fitted with excessive pressure and it's tight as a result.

With the (rusty) OE Honda downpipes fitted, everything lines up and the collector box sits where it should and doesn't protrude rearwards. With the replacement Motad downpipes fitted the collector box sticks out past the swingarm by about 50mm, giving me major clearance problems. It also means the centre stand can't be fitted, as the collector box occupies the space the centre stand should when not in use.

[mangocrazy]

Can't you shave 50mm off the downpipes? (Once it's all apart)

The downpipes on the VFR are an absolute twat to fit or remove, being a V4 layout. The rear downpipes are especially twattish. The front and rear downpipes on each side merge underneath the engine and then plug into the collector box. This is an ebay listing for the left hand rear downpipe for my MY of VFR750:



So there is no scope to shorten the downpipes as everything has to fit together in some Frankenstein jigsaw puzzle. The only way to get around the problem is either to fabricate a shorter collector box or fit a different system. I'm intending to do the latter. But may also need to do the former...

I have made progress today; the collector box is now off the bike, but I had to make creative use of the Skylift along with using a ratchet tie-down round the subframe and through the rear wheel to take the load off the suspension linkage so I could remove two of the linkage bolts and allow the swingarm to pivot freely.

It's all back together now (sans collector box) but torquing all the bolts up can wait for another day. Getting all that done in a small shed with two bikes in it was an exercise in frustration and bruising.

[mangocrazy]

Finally got round to making the trip to the welders with assorted pieces of aluminium tube and this was the result once Chris had done his thing:

DSCF3957.JPG (637.64 KiB) Viewed 636 times

And here's a closer view of the welded bits:

DSCF3963.JPG (499.78 KiB) Viewed 636 times

Next step is to head off to the platers/coaters and get them Xylan coated in satin black.

[Supermofo]

Surely you're missing about 8 inches off them risers for you (as the bishop said to the actress)

[mangocrazy]

Surely you're missing about 8 inches off them risers for you (as the bishop said to the actress)

Hah! These ali bars are basically a clone of the steel ones I'm currently using, so I can test which material offers the best vibration resistance. Here's the current (steel) bars and the much-maligned MT-09 risers:

[Mr. Dazzle]

I strongly suspect any difference will be in your head.

Which, TBF, isn't a bad place for it to be, 'cause that's the bit where you feel annoyed about vibrations too.

[mangocrazy]

I strongly suspect any difference will be in your head.

Which, TBF, isn't a bad place for it to be, 'cause that's the bit where you feel annoyed about vibrations too.

I'm reasonably sure any difference (if indeed there is any) will be felt in my hands and forearms.

If my head is in contact with the bars something has gone seriously wrong.

[Skub]

Shirley the heavier bars will dampen the vibez best? Or is it more complex than that?

Or maybe it matters little which material the bars are made of,because bar end weights will do the dirty work.

[mangocrazy]

Shirley the heavier bars will dampen the vibez best? Or is it more complex than that?

That would be my guess, as well. But the ali bars are made from heavier gauge tube (i.e. more material) so that may have an impact. Or not.

Or maybe it matters little which material the bars are made of,because bar end weights will do the dirty work.

Nail head, meet hammer. I've had to modify both bars so they will accept the OE Aprilia bar-end weight system (discussed at length somewhere on here, not in this thread) so that will probably make the major difference.

I'm also going to check throttle body synchronisation, just to rule that out.

[mangocrazy]

After my customary January/early February hibernation I've (sort of) woken up and started doing stuff. In a lazy, rather disconnected way of course. The object of my attentions has been the VFR. It was ferried back from France last October for a good dose of looking at the front end and clonking issues. I'm hopeful these have been resolved (time will tell) so now I need to do something about the exhaust collector box being approximately 50mm rearwards than it should be. I've resolved this problem by the simple expedient of taking the fucking thing off, pending surgery (of it, not me).

One of the benefits of being a hoarder is that stuff that I stopped using 30 years ago is still lying around somewhere. This is/was the case with an aftermarket exhaust system I had fabricated to fit the VFR (same model, different model year) that I had in the mid-90s. It was somewhere in the loft of spiders but was still in remarkably good nick and (better yet) still fitted pretty well. It completely dispenses with the collector box (yay!) and just has one pipe and one (carbon) can per side. It also sounded pretty good, if memory serves. Here's the RH side of the bike with the old/new zorst fitted and the bike on the Skylift:

DSCF3967.JPG (642.96 KiB) Viewed 560 times

And a closer look at the carbon can. It's survived remarkably well and still looks pretty good to my eyes. I'm pretty sure I got the system made up in 1995 so for a 29 y.o. can it's not too shabby. But it was made at a place that also fabbed F1 exhaust systems (Parallel Motion, unfortunately no longer in business) so that would possibly account for its longevity. I have had to get db killers made for them though - the V4 open pipe wonderfulness isn't appreciated by everyone, especially MoT testers...

DSCF3971.JPG (596.41 KiB) Viewed 560 times

But removing all that silencing restriction and back pressure does bring its own set of complications. Hondas of that era (in fact most Hondas) are famous for running as lean as possible and today's petrol is vastly different to that of 30-odd years ago, so I think I will need to richen up the mixture somewhat. I'm debating whether to take a stab at it myself and bung some bigger jets in, or take it to a dyno and get it done properly. Are there any 'old skool' dyno operators that know how to fanny about with jets rather than just do it all on a laptop? All recommendations welcome.

Here's what faces you when you take off the seat and tank on a 1988 VFR750...

DSCF3970.JPG (504.61 KiB) Viewed 560 times

[Skub]

Drunken Ferret Repairs get a good name among the classic boys,I think the shop is around Portsmouth.

[mangocrazy]

Drunken Ferret Repairs get a good name among the classic boys,I think the shop is around Portsmouth.

Cheers - it's a bit of a trek from Sheffield but I might be able to fit it in on the way to France. I normally sail from Portsmouth.

[mangocrazy]

Having thought about this for a bit, I messaged Dave Whattams (the guy who dynoed my LC with excellent results) and asked him if he was prepared to dyno a diesel and this was his reply:

I don't do 4 strokes, my extraction system isn't able to handle it without being fully cleansed of old 2T oil etc - its a major fire risk for me as 4 stroke exhaust gases are way hotter than 2T's

The only guy I would recommend is John Warrington in Malton, tell him I put you onto him, he will sort it for sure - his number is 01653 698258

So I rang John up and I'm booked in for Monday 25th March. John used to race VFR400s (NC30s) back in the day so knows all about jetting V4s. He's based in North Yorkshire (between York and Scarborough) so not too far to go. Looking forward to this.

[KungFooBob]

I'd have given Swinton Motorcycles a call, they have a rolling road and tune for at least one BSB team. They're local too.

I've no idea how hot they are with carbs tho'

Edit:

https://www.swintonmotorcycles.co.uk/

Lol, they only do carbs in winter!

[mangocrazy]

I'd have given Swinton Motorcycles a call, they have a rolling road and tune for at least one BSB team. They're local too.

I've no idea how hot they are with carbs tho'

Edit:

https://www.swintonmotorcycles.co.uk/

Lol, they only do carbs in winter!

Bugger, wasn't aware of their existence! But trying to get booked in before end of Feb would probably have been a no-no anyway.

I do understand what they mean about 'carbs only in winter', though. Changing jets or needles on a VFR is a complete PITA. It's seat/tank off, airbox off, plenum chamber off, then try and wrestle the banks of carbs off fighting 35 year old carb rubbers and no space. And a hot engine. Only then, with the bank of carbs on the bench, can you get at the jets/needles. Then it all has to go back together for the next dyno run.

Compare that to making a few fuelling changes on a laptop...