NBT- My Aprilia UXB!

Discussions and updates on your new bike, your new build, your wishes, wants and desires
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Tricky
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NBT- My Aprilia UXB!

Post by Tricky »

The (almost) last thing I currently need is another bike as truth be told, space is getting a bit tight and I probably have too many ( if of course that is possible- I’m still not convinced that it is :think: )

Anyway, Iccy’s “ You’ve got £5k “ bike thread got me thinking, and I ended up buying the bike I linked to in that thread- at the time (last week) I was away on a mini-break in Lanzarote, so perhaps that had something to do with it, but with the Pembrey weekend coming up and a two-dayer at Cadwell at the end of this week, I thought it could be just the bike for these sort of tracks and an occasional bit of lunacy on the B-roads, so I decided I’d phone the seller, see what I thought of him/her and decide then.
So I phoned him from Lanzarote last Monday, he came across well, telling me where he bought it and answering every question I had so we agreed a deal and sent him a small deposit, on the understanding that I could collect as soon as I got back home on Thursday so I could take it to Pembrey, and that’s what I did, and this is what I bought

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They are not a particularly common bike, for good reasons I guess, but for anyone that doesn’t know, it’s a 550cc V-twin, with perhaps the lightest and most compact 4-stroke 550 motor ever made, and were produced purely to win Supermoto and road races ( irie on here owned a couple and raced at least one of them for a few years not long after they came out IIRC, and I think perhaps @Jody too? ) with race-engine type maintenance and component replacement schedules- they produce 70-80 rwhp and weigh in at only 120-ish kg as you see it there with all the road kit on, so as you can probably imagine it’s quite a lively package.

This particular one is one of the early 2006-7 ones which had one fairly major problem and to a very large extent gave them their reputation for having exploding engines.

The problem came from the type of sealant they used for the crankcases on the early ones, which basically didn’t, meaning that water and oil got to mix, and, well, ka-boom!

This pic illustrates how compact the motor actually is, and relatively speaking how little surface area there is.

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There were a number of other issues, including a starter motor that wasn’t really up for the job and fairly regularly burned out (not surprising when it’s the one off their 50cc peds I guess :roll: ), pretty poor fuelling on the early ones, but the story went that when they were running they were crackers.
I am a massive fan of light bikes and love most Italian bikes and am a long-time big Aprilia fan, so one of these was always on the cards at some point I guess, even though it’s probably one of the most impractical bikes you could buy- unless you’re a committed SuperMoto racer, and of course the class you race in permits twins- I think non-singles were quite quickly banned in the main US SM series back in the day due to the SXV’s then dominance

Anyway, although this is one that suffered from the crankcase sealing issue, it was addressed fairly early on its life with a receipt to prove it and has apparently been running faultlessly mechanically-wise ever since in the approx 1.5k miles ( out of a total of 2.5k ) it’s done since.

So bleary-eyed I trundled down to Surrey in the van on Thursday morning- it’s got a few relatively minor scrapes here and there so is by no means immaculate but was pretty much as described, seemed to run OK with no nasty noises or moke or oil/coolant leaks and all the paperwork checked out so I paid the man the money and chucked it in the van.

I got it home and set about giving it a decent once-over, as I was off to Pembrey with it the next day.
It all seemed as though it had been well maintained, with clean oil at the correct levels ( engine is a dry sump with 1.2 litres capacity and gearbox oil is separate, holding 0.5litre ), recent new chain/sprockets and pair of Conti-SM tyres, and the latest fuelling map loaded.
I checked the suspension settings, which were all pretty much at standard apart from the low-speed compression damping on the rear shock which had been wound right in so I put that back to standard.
The only other thing that I could see had been changed was the forks had been pulled through the yokes by approx 15mm, which seemed like a lot to me, particularly for something that has a reputation for being quite quick steering anyway, but I left that as it was, and thought I’d see how it went, and I took it for a short 10-ish mile blat around the lanes near me just to check all was OK before putting it back in the van.

First impressions were of a very strong motor that accelerates like an absolute bastard! It’s one of the quickest revving and angriest sounding motors I can remember, easily wheelying off the throttle in 2nd (and probably 3rd and maybe 4th if you tried) and the joke of an LCD revcounter really can't keep up.
I saw 110ish really easily on the speedo, which I thought was plenty as it was getting quite twitchy and flighty at that speed, suspension seemed very long travel and soft, but front brake was a cracker, so no big concerns at that stage other than likely having to firm it all up a fair bit before trying to use all it’s performance on track

So it went back in the van, I chucked the ZX6 in too, and off we went to Pembrey Friday afternoon ahead of the Saturday track day.

Saturday morning came, and although there had been some rain overnight, it wasn’t raining when we got to the track and the awful weather that had been predicted hadn’t materialized meaning the track was pretty much dry so after winding the rear pre-load up 20mm or so, I took it out for the first session.
And I have to say, it was pretty disappointing overall. :thumbdown:
The engine, gearbox, and brakes were great, but it’s so soft with far too much travel that I wasn’t comfortable riding anywhere near a reasonable pace - I was all over the place, and being overtaken by people/bikes that I could pass with ease anywhere I chose on the ZX6.
I could have got the spanners out again and I have no doubt that I could have made some level of improvement, and that is what I would have done if it was my only bike there, but I had my old faithful ZX6 there and I knew that whatever I did to the SXV with just spanners the ZX6 would still be better, so I ended up spending the rest of the day on that.

As for the SXV, well, I’m currently not sure. I’m debating whether to bother taking it to Cadwell this week, current thoughts are probably not as although I reckon I could get a great mountain picture on it, to really enjoy riding it I think I need to re-spring it.

And then that leaves the question of if I don’t use it on the (very few these days) track days that I do, am I likely to ride it on the road?
I think the answer to that is that as long as I have the Tuono (which is a real keeper), then the SXV realistically isn’t going to see much, if any, use.

That doesn't matter that much to me as it would be in good company in that respect, and It is very pretty IMO with some lovely and unusual engineering touches - it is also absolutely brilliant at doing what it was designed for and I just love the angry sound of it 8-)
I don’t for a moment regret buying it, but I’m just not sure whether those things alone warrant me hanging on to it when I am currently at pretty much full capacity, so the jury is out at the moment, we will see….. :think:
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Re: NBT- My Aprilia UXB!

Post by Bigyin »

I remembered Iries race one as it had race number 60 on it for his birthday at the time at a snetterton meeting

Bonkers bikes and a throttle like an on/off switch. The racket yours made in the paddock didnt sound as bad on track when you passed me and cant have been that bad as the rest of us were running a book on how many laps after the sighting laps you got before being black flagged :mrgreen:

IMHO you can never have too many bikes as long as you have somewhere to put them which is why i am on only 2 ;)
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Re: NBT- My Aprilia UXB!

Post by Jody »

I did have one, In fact I still have a huge box of spares that I bought from British champion Christian Iddon.

The thing with the SXV, it was OK out the box, but really, it needs, a shortened swing arm and a change of triple clamps to make it great.

As opposed to say a KTM 530, which is pretty good, out the box, but gets even better with suspension upgrades.
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Re: NBT- My Aprilia UXB!

Post by Le_Fromage_Grande »

I remember seeing them in World Supermoto rounds in 2005, the 550s were fantastically fast in a straight line, at a wet, muddy, Namur they were sideways the length of the straight.

Would I own one, probably not, given my ability to destroy the engines of off road bikes it wouldn't be a wise choice for me, but I do think they're a fantastic bike,
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Re: NBT- My Aprilia UXB!

Post by Screwdriver »

Very interesting write up and so glad I didn't buy it when I saw the link in the other post. I did have a similar type of hyper fragile machine, the old Husky SM570R but that's a young mans game.

But WTF is going on with that cylinder liner? Does it form the inside of a water-cooling jacket? How many hours between comprehensive tear down?

Oh and if you have second thoughts about selling it, drop me a line. I might be having second thoughts about buying it.
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Re: NBT- My Aprilia UXB!

Post by Tricky »

Screwdriver wrote: Tue Aug 15, 2023 7:33 am Very interesting write up and so glad I didn't buy it when I saw the link in the other post. I did have a similar type of hyper fragile machine, the old Husky SM570R but that's a young mans game.

But WTF is going on with that cylinder liner? Does it form the inside of a water-cooling jacket? How many hours between comprehensive tear down?

RE the liner, yes it does- in the above pic the liner isn't in it's correct place and the O ring isn't installed - this pic shows it better how it actually is

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Re teardowns/re-builds, as with all things, it, of course, depends on usage but if you're not racing it then recs are full inspection every 3k miles, and pistons, bearings etc replacement every 6k- this is probably comparing oranges ( :D ;) ) with apples , but KTM recs for piston replacement in my 2003 525EXC are every 90 hrs- feck knows what mine has done as the clock stopped working 8 or 9 years ago but it's certainly well (well) in excess of 500 hours and the motor has still never been apart
Anyway, as I said, I guess it's probably not that relevant as I'm comparing a good old KTM RFS motor to an Aprilia SXV, but as far as I can gather, the consensus seems to be that if they are built right, then they are not particularly mechanically fragile
Oh and if you have second thoughts about selling it, drop me a line. I might be having second thoughts about buying it.
Well, I've decided it's not going to Cadwell with me this week, so if you are serious, let me know and I'll ping you my number so we can have a chat if you like
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Re: NBT- My Aprilia UXB!

Post by Screwdriver »

Sadly, I am not that serious, I actually do have too many bikes. All in a million pieces. About a dozen of them iirc.

I have to force myself not to buy anything else though I may reward myself if I ever nail one together and sell it.

When/if that ever happens it will be something like the SXV though I am still looking at the Superduke 990R. Neither of which I have any conceivable use for!
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Re: NBT- My Aprilia UXB!

Post by Le_Fromage_Grande »

My road oriented Husky SM610S was supposed to have a major engine rebuild every 6000 miles, that meant new cam chain and new piston, so 3000 miles for a race engine is pretty good, Screwd probably knows the rebuild mileages for an SM570R.

My 610 did shit itself, but it wasn't cam chain or piston, it was a cam roller bearing giving up and distributing itself through the engine, fortunately after I'd sold it, I told the buyer it was due an engine rebuild and the price reflected that.
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Re: NBT- My Aprilia UXB!

Post by A_morti »

Screwdriver wrote: Tue Aug 15, 2023 1:07 pm Sadly, I am not that serious, I actually do have too many bikes. All in a million pieces. About a dozen of them iirc.

I have to force myself not to buy anything else though I may reward myself if I ever nail one together and sell it.
Do I remember right - was it you building a cagiva mito special?
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Re: NBT- My Aprilia UXB!

Post by Screwdriver »

A_morti wrote: Thu Aug 17, 2023 6:24 pm
Screwdriver wrote: Tue Aug 15, 2023 1:07 pm Sadly, I am not that serious, I actually do have too many bikes. All in a million pieces. About a dozen of them iirc.

I have to force myself not to buy anything else though I may reward myself if I ever nail one together and sell it.
Do I remember right - was it you building a cagiva mito special?
Yeah. It's still sitting in a corner of a garage. Not seen it for some time but I expect it looks a bit like this with a bit more dust and rust.

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