Aprilia Content

Picked this up yesterday:

'96 Aprilia RS250 in Biaggi colors.   Motor freshly done w/weisco pistons, nikasil, VHM heads. Set up to RGV250 kit specs with a 1.4mm base gasket and whatever VHM insert made the squish right (seller was a long time 2 stroke guy - I own a chainsaw and a weed wacker). Race ECU. Tyga billet power valves. Brembo radial brake master cylinder. I have some OEM stickers. Stainless steel brake lines (stock?)


He had only run it through a few heat cycles when he jumped on an RG500 that became available so I have some tuning ahead. It runs OK, but (I think) pretty rich, and it hesitates as it crosses 8krpm into the powervalve region. Smokes more than I think it should (running pre-mix - I have the pump but he pulled it) and I'm surprised at how quickly oil accumulates on the muffler exits. I put a quick 40km on it this morning. I'm not expecting the smiles and waves I get from the neighbors on my Vitpilen. 

Sweet! Great handling machine! Hope you get it tuned right.

Very nice; looks like a ton of fun! I've lusted after these bikes since they were new.

Been playing with this quite a bit.  Two rounds of leaner jetting and a needle change so far.  Tyga shipped me some "quieter" mufflers.  I guess they're quieter...

I have a dyno run scheduled next week.  Not a full round of tuning, I just want to be sure I'm safe before I go any leaner on the jetting and see where I am with power.   If everything is perfect, these little guys can put 70hp to the wheels.  280hp/L!  The factory advertised them as 72hp (maybe 65 at the wheels?) but I think the marketing team came up with that number.  It feels like a ripper to me but that might have more to do with how the power hits than how much it actually makes.  I scoped the front piston last week and I haven't ruined it yet, so that's good.  

I am jealous. Very nice acquisition!

That's a spectacularly cool bike! Congratulations!

I have about 220 miles on it now and ran it on a local dyno at a Harley-specific shop.

The guy running the dyno didn't seem to understand how flat slide carbs work or maybe they behave differently on a 1500cc Harley that peaks at 6000rpm.  You can't go WFO at 4000rpm in 6th gear and expect it to accelerate on a 250cc motorcycle with giant expansion chambers.  It just bogs lean.  The only time I'm ever at 4000rpm is coasting down the hill from my house so I don't annoy my neighbors.  Eventually, he started the run at 5000.  Next time I'll suggest 6.

I was lucky I did it.  It was crazy lean.  Like 16:1 on the right cylinder at 10.9k.  The left was right off the chart but I'm attributing that to something weird with their equipment.  It was bad enough that he didn't even run to redline, shutting down at 10.9k rpm and 50hp. Yikes.  Torque hadn't peaked yet.  :)

Scoped the other piston and it looks good, so I haven't ruined anything yet.  

I should point out that the bike feels like it rips and will indicate 200+kph at, um, my Mexican test site.  I was not expecting the results I got.  I've since brought the mains up two steps and it's clear that it is still lean.  At WOT at 9 or 10k, rolling a bit off the throttle improves acceleration (restricting the airflow brings the AFR towards the good).  Oops.  I should have had that test in my repertoire. 

So, it continues to entertain me.  It's just ridiculous fun to rip through a bunch of gears like Biaggi at Mugello and end up at ... 80mph.  I think.  The speedo is small and in kph. 

If I recall correctly those bikes weren't sold new in the US, but a few sneaked across the border from Canada and somehow got titled and licensed.

In reply to stuart in mn :

You are correct.  I found a sticker inside the fairing from a shop in St Petersburg FL.  They must have been the original importers but no idea from where.  It would not have been EPA-legal at the time but it was titled in MD by the time I got it, so it's 'legal'.

Now that they're 25 years old, there's a robust business of Japanese market 250cc two strokes coming across.  Unfortunately, they've become really expensive and shipping is also through the roof.  I should have restarted my motorcycle addiction 2 years ago!

mfennell said:

Now that they're 25 years old, there's a robust business of Japanese market 250cc two strokes coming across.  Unfortunately, they've become really expensive and shipping is also through the roof.  I should have restarted my motorcycle addiction 2 years ago!

There was a Japanese market only 250cc version of the original Suzuki Katana that I would like to have (I used to own a 1000cc Katana.)  I just think the idea of a four cylinder 250 is cool.

I think some of the Aprilias were sold in the US for racing use only, and then one way or the other ended up with titles for street use.  Yours could have been one of those.

You're correct about the race bikes but they came later.  This one has always been a street bike.

Coincidentally, a buddy has a '97 that was one of a dozen that were imported as demo bikes for an Aprilia Cup series.  It has a 15 digit VIN and came with race bodywork but all the street wiring so it's fairly straightforward mechanically to make it a street bike but much less so to get it titled.  The later Aprilia Cup bikes were the next generation (Mk2) and did not have full wiring harnesses.

There's a bunch of info about the Cup bikes here:  https://www.apriliaforum.com/forums/showthread.php?338213-RS250-CUP-production-numbers

My cousin had one in the early mid 2000s that I rode more than he did. Pretty sure it was a Cup/Track bike that had seen some sort of backdoor titling. But it had a title, and was a HOOT. That bannana swingarm is still a thing of beauty.

Cool!  I spoke with a guy in PA who has a converted cup bike.  The story seems to be that he titled it by adding two zeros to the 15 digit VIN.  You can't make this stuff up.  

I went back to the main jets it had when I got it.  The ones that seemed so blubberingly rich.  That had oil dripping out of the pipes and even getting it on the license plate, leaving a blue trail everywhere I went.

And now it rips and feels like it carburates cleanly almost everywhere.  Minimum launch RPM is down to around 3500rpm and I'm not paranoid letting it idle at a light for a minute or two.  I clearly don't know anything about anything.  Stuff that has changed since I got it:

• I put the stock ECU back in.  Different timing curve and power valve management.  I had a race ECU that is optimized for race or avgas and supposedly optimized for a particular set of pipes.
• Needles dropped one slot.
• 250 miles of breaking in (new piston but well seasoned cylinders w/new Nikasil - how much breaking in does it actually need?).
• I've run a bunch of gas through it.  Who knows what was in it when I brought it home.

Scoped a piston this morning and I still haven't ruined anything.  Score!  Put the bodywork back on and I'm just going to ride it around a bunch and keep my tools off it.

Winter is project time. 

I put about 1200km on the RS250 this year.  It's a great 30min bike.  Fire it up, buzz around, bang some gears, arrive home with a smile on your face.  The only problem I encountered was a dead battery.  I was out riding and the bike quit rolling up to a light.  Dash was dead.  Huh?  I stared at it for a minute, then thought to turn the lights off (Euro spec bike so the lights have a switch).  The dash came back on.  Ah hah!  Lesson learned - a dying battery doesn't reveal itself so obviously when you have a kickstarter.

I put a used Ohlins on my Ducati mostly-track-bike last summer.  The improvement was so dramatic, I found myself coughing up for a Penske double adjustable for the Aprilia.  A proper spring for my weight, which is light-American but not 17yo-Italian-teenager probably made at least as much difference as the proper valving.

So, first step was fork seals and a spring I purchased from The Tuning Works in the UK.  Advertised as 15% stiffer, it seemed to get my sag right in the 20-25% range depending on pre-load.  Fork oil in the right leg (which does the damping) was really low.  I (arbitrarily) decided to put 12.5W in vs 10W.

Next up is re-installing the oil injection pump.  Pre-mix drives me crazy.  Compared to the pump, it means way more smoke at idle (because the pump is variable) and the air box coated with oil, which seems to get everywhere.  The pump also feeds the main bearings directly, which seems more better to me.  Also, pump volume is tied to the powervalve controller, which means when you close the throttle at high rpm, oil volume stays high until RPM go below 8500.   A great way to seize a two stroke is high rpm overrun, where you're at zero throttle and very little oil is coming in but the engine is still spinning at 10000rpm.

I had the pump but I'm missing a few installation pieces, which are on order from a shop in the Netherlands, of all places.  One of the cylinder fittings is broken.  Fortunately, they're available.  It's actually a check valve.

The old school turn signals look ... old.  I picked up a set of LEDs from Tyga in Thailand.  

I bought a set for the Bimota too.

Finally got this thing properly tuned.  Speedwerks in Dover, Delaware set it up for me.  I installed a Zeeltronic ignition/powervalve controller first to give them extra tuning options.  The Zeel has an input for a quickshift, so I asked them to install it for me.

And .... 67hp at the wheel on pump gas.  Out of 250cc running  a safe main jet.  That is not bad!  A stock 693cc 701 Vitpilien does about 70.  My understanding is 57 was a typical number stock.  It runs a lot better at low rpm too.  It's clear I didn't know what "right" felt like.  Sounds really crisp on part throttle.  It used to be unable to pull past 8000rpm in 6th gear.  I had to rev it to 9 before shifting.  Now it will (gradually) accelerate through.  It also powerwheelies in 1st.  Banging through the gears with the QS is incredibly satisfying.

A friend of mine gave me a few pieces of race bodywork from his Aprilia Cup bike.  I filled out the rest from a company in Germany and signed up for a "small bike" day with the NJMP club, reserved for Advanced/Expert riders.  I'm considering getting it painted and stickered up like the stock Biaggi replica bodywork.

Awesome! Incredible results from the tuning, and the trackday sounds like fun!

I'm not sure where this falls on the smart-dumb spectrum but an old Aprilia Challenge Cup bike showed up on craigslist last week at a price some of the guys on the WERA board thought meant 'scam'.  I got in touch with the guy, showed up last night with money, and took it home.  This kind of stuff just keeps hapenning to me...

So, it's a '99 Cup bike.  It was pretty obviously raced and has been in in the gravel a few times but the current bodywork has only been down once (best guess).  The rear brake master is seized, the coolant sight tube disintegrated, the radiator didn't warm up as we ran it (though it started on 1st kick), the windscreen is trashed.  However, it came with a complete disassembled engine in a transit case (with a bad trans but still...) and spare wheels.  It's the MK.2 version, which has a wider front wheel and better forks.  

You never know what the real backstory is.  Amused to find mis-matched tires from '03 and '05 on it, clearly just thrown on to make it roll.  The tank has T4 ethanol-free gas in it, which is $120/5 gallon pail.  The seller had a sweet RVF400 in his b-i-l's garage and an NS250R in the loft of his townhouse.  Woodcraft clip-ons and rearsets.  If it's a good runner, it was a fabulous deal.  If the trans is wrecked or whatever, I'm still probably even.  I called Steve from Speedwerks while I was looking at it to ask about the cold radiator.  "Dude, just berkeleying buy it.  I'll buy it from you if you don't want it."  :)

Must.  Avoid. Distraction.  I think I'm going to swap a tire on my 848 to keep that moving forward.