stuff that's wrong so far...

I haven't had much AF1 time recently as the MBX80 took priority getting it ready for the Stafford Classic Bike Show, you can read about that here.

Back to the Aprilia, after the carburation woes I took it on a shake down ride to see what was going on, I picked up on the following. 1/ the front bake definitely needs bleeding as it was a bit hit and miss on lever travel. 2/ I am pretty convinced the power valve is stuck open, low down is actually bad but is super flat in the mid range with a strong top end rush. 3/ when warm the tick over is to low and stalls.

I pulled the bike apart to see if I could work out what was going on with the power valve. The solenoid was pulled well out the housing meaning it wasn't operating at all and the cable was under tension as well holding the valve open, basically it needs a new cable as the cable fitted isn't the right one. Interestingly I have a spare solenoid in my spares box I got with the bike so i think this problem has been on the bike for a little while un-diagnosed?

According to the manual the solenoid should sit at rest between 7.5mm and 8.5mm out, when it activates it pulls the piston in, pulling the cable and thus opening the powervalve.

NEXT DAY EDIT: 

I changed the cable this morning and checked all functions including the power valve itself. When started the solenoid now actives opening the PV (the manual calls this a self cleaning process), when revving over 2500rpm the solenoid releases closing the PV. A test ride is needed to see if it opens again over 7800rpm, but I am fairly happy this is now working.

the solenoid is as far in as I could get it here, the cable is restricting movement.

I noticed there is a hole in the coolant expansion tank, meaning the system can't pressurise. Thankfully this tank was used on loads of aprilia's so is readily available new. part number AP8101910

holey smoke batman

I found a random plug, anybody know what it is meant for????

what the???

Lastly there are loads of fairing clips missing and the fuel hose was made of cheese. It also has an intermittent rear brake like fault which was fixed by just cleaning the terminals. No doubt there will be more minor issues, but once I am happy mechanically I will then turn to some more fun stuff and make some cosmetic improvements.

Carburettor specifications - all AF1 models

 Carburettor standard specifications - all models Dell'Orto 

My bike - carb issues part 2, fixed

Following on from part 1 of my carb/ running issues I have now re-built the carb to exact Aprilia specifications. For good measure I replaced the spark plug which is a NGK BR10EG and I also had to replace the battery as mine was dead and wouldn't except a charge, I bought a Motobatt 12N5.5-3B from Busters.

With everything back together the bike fired in to life, ran sweetly and most importantly the carb didn't over flow which points to the float weight all along.

Now that I am happy that bike is running correctly I can move on to some more restoration type jobs.

Road test - MCN

 Motorcycle News October 4th 1989, 'Just Seventeen' test, Aprilia AF1 vrs Honda NS125R vrs Yamaha TZR125 vrs Suzuki RG125 vrs Kawasaki AR125

The 1989 AF1 Reggiani Replica

Did Aprilia release any production Type EU Sintesi bikes with a number 6 on the tail piece (Reggiani) or were all bikes number 4’s (De Radigues)?

On Aprilia's own workshop manual it features the Sintesi version 1 (type EH) and the version 2 (type EU), on closer inspection the type EU features a number 6 on the tail unit like the type EH Reggiani relplica.

Image from the official Aprillia workshop manual

Digging a little deeper the number change happened to reflect the changing of Aprilia's sponsored GP riders and the need to sell was being raced at the time.

Making its debut at the 1988 Bologna Motor Show, Aprilia presented the updated type EU Sintesi Replica 125 motorcycle featuring the number 6 on the seat unit, this was to reflect their then sponsored rider Loris Reggiani who ran that number in 1988 season. However, after finishing 13th in the 88 season Aprilia did not renew the teams contract and the rider switched to Honda. For the 89 season Aprilia replaced Reggiani with the Belgian Didier De Radigues. As the new rider came from the 500cc class to the 250cc class he did not have a race number frpm the previous season so was assigned the race number 4. To reflect their new rider Aprilia changed the tail number from 6 to 4 on the Replica model for production versions, however some bikes were sold as Reggiani '6' bikes in the first few months of 1989 but are extremely rare.

This would also explain why the De Radigues Replica bikes are technically in the 88 Reggiani colours rather than the revised 89 colours as at this point the bikes were probably already made or at the minimum some body panels would of been painted ready for assembly. 

1988 Reggiani race bike

1989 De Radigues race bike

If you have a genuine number 6 type EU please leave a message bellow as I would love to see it!

Many thanks to the contributors of the Aprilia AF1 page on facebook and  125 Stadali

UPDATE 06/11/2023

Taken from Practical Sportsbike magazine July 2016

number 6!

image captured from a video at the 1988 motor show

My bike - carb issues part 1

 I noticed when running the bike the carb was over flowing and petrol was poring on the floor, so I decided to strip the carb and see if there was anything obvious going on.

My first thoughts were either the floats were at the wrong height or something was blocked. After removing everything, blowing the jets through and checking the floats I couldn't see anything to wrong so I assembled and left it for another day. 

My next thought was to check the carb settings against the factory set up to see if the carb was in fact set up wrong. I have looked at the settings here: this is what I found.

The idle jet, atomiser and floats were out of spec and the needle was at the incorrect height presumably to compensate for the incorrect atomiser? 

The next thing that confused me was the carb model was slightly wrong, according to the manual it should be a PHBH 28 RD and my had the BD code.

Now the RD carb should be a power jet model, but this isn't referenced in the original carb spec so I am not sure if this is correct. The BD version seems to be a generic 2 stroke replacement carb. 

I ordered the correct parts from Dellorto suppliers Eurocarb to make by BD spec carb exactly the same spec as the manual. I also managed to pick up a RD spec PHBH28 of ebay as a back up plan but the slide is huge and the jetting is odd because of the powerjet so I am not convinced this will be any help.

The next step is to rebuild the carb and run the bike. I am convinced the heavier weight floats will resolve the over flow issue, however the battery died so the test will have to wait for another day!!!

If you have any information on the carb settings for a 89 Sintesi please comment bellow.

 

My Bike - bringing it home

 Fortunately I do have a use of a work van, which is very handy sometimes!