[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked)

Bentou, thankyou very much. Very interesting, great drawings. I am happy.

bentou, how lubrication of the engine?

A classic oil pomp was used, with 6 output or rather 3 double output.
one for the bearings on the crankcase (like the kawasaki H1 or H2) and one on the air intake (shown on C_Wolf picture)

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the lower arrow shows the output of the oil pump.

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The other picture is one of the two survival prototypes, one comes back home from USA, you can only see one banjo and its bypass for the bearing lubrication.
The oil is then projected in the crankcase and is mixed in the air, passing thu the ports. the second part is directly injected in the air duct, just to lubrificate the rear part of the piston (as there is no reeds, "la jupe du piston ouvrant et fermant l'admission a besoin de lubrification" I wrote in French, I'm not sure that the french word used "skirt" can be used about a piston )

Marc, Jan or Frits, if you thinks that is really "Hors Sujet", could it be possible to move this on another place ?

bentou a écrit:

Marc, Jan or Frits, if you thinks that is really "Hors Sujet", could it be possible to move this on another place ?

I am fine with it, Bentou. Subjects always seem to go off-topic whenever I am involved. Usually I am the culprit .

Thankyou, this is most interesting.

Uniflow,

Is there any particular reason you don't use the ignition side in the Link? Wouldn't that simplify things a little? Or is the Link you are using a fuel only computer?

Michael

Frits Overmars a écrit:

michaelten a écrit:

I am not sure if the Aprilia used a detonation sensor...

You are now, Michael:
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hello

thanks, but someone can explain to me how such a sensor works and get installed??

manuel

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Frits or Jan – In the earlier photos of the RSA, the detonation sensor was attached to the power-valve cover and here it is attached to the cylinder head stud – what was the reason for the change?
Can you see any problem with attaching a detonation sensor to the cylinder base studs?

Thank you for your answer.

michaelten, the Ignitec was already running with the Lake Injector ( mechanical injection )and opperating the sliding rotary valve housing, before the EFI idea came along. So I just set it up side by side. The link can run ignition, has data loging, can run power valves etc but I'm only using it for fuel. The next version up can run knock sensors and electric throttle also. The new engine I'm building will run all of this from only the one link computer. The F9 in just a "test hack" ( that I happen to race in VMX ).
The EFI CR500 that was shown earlier in this thread had issues with the computer ( not link ) having trouble with counting the trigger teeth at low speed ( start up ). The ignition would go off at the wrong time and bust things. I side stepped this problem by accident, not using the Link for ignition.
I am going to have to be aware of this problem with the new engine. I'm sure there is a way around this issue.

uniflow a écrit:

michaelten, the Ignitec was already running with the Lake Injector ( mechanical injection )and opperating the sliding rotary valve housing, before the EFI idea came along. So I just set it up side by side. The link can run ignition, has data loging, can run power valves etc but I'm only using it for fuel. The next version up can run knock sensors and electric throttle also. The new engine I'm building will run all of this from only the one link computer. The F9 in just a "test hack" ( that I happen to race in VMX ).
The EFI CR500 that was shown earlier in this thread had issues with the computer ( not link ) having trouble with counting the trigger teeth at low speed ( start up ). The ignition would go off at the wrong time and bust things. I side stepped this problem by accident, not using the Link for ignition.
I am going to have to be aware of this problem with the new engine. I'm sure there is a way around this issue.

I had trouble with this too with my Microsquirt. Using a drill and timing light to test the system and spin the engine over the timing would always be right on. As soon as the kicker was used it was anyone's guess as to what the timing would be. I was using a Hall sensor at this time to pick up the trigger wheel. When the engine was kicked the engine would reverse at the end of the kicker stroke if the piston was near TDC due to the build up in compression. When the engine reversed the sensor and ECU got lost. Once the engine was running I had some sporadic timing logs as well with the Hall sensor. I found that by switching to a VR sensor this virtually eliminated the problem. The VR sensor tip was much closer in size to the trigger wheel teeth than the Hall sensor so I believe the VR sensor was able to pick up my trigger wheel better than the Hall. I had to experiment a lot with the missing tooth location as well to insure the ECU would pick up the tach signal and that I would get a spark every time I kicked the engine over. I'm not sure what the CR500 engine is using for sensors or ECU so I don't know if we have had the same troubles but this is what I have found.

Uniflow, this is kind of what I had in mind for port injection
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Isn't it interesting, same set up as I have planed for the YZ 250 accept I'm fitting the injectors to the rear two ports. Same injecting down on to up comming air. I'm waiting on my drum throttle body housing to arrive back from Heat Treatments ( cast in CC601 ). I'll post a picture if you like.
What charging system are you using, how many amps, at what rpms?

michaelten a écrit:

What problems did you have?

Mine had the piezo sensor epoxied onto the end of an L-shaped bracket that was clamped under the plug. The problem was setting the sensitivity, since a little too high and it registered continually, a little less and not at all. Possibly because the bracket resonated.

The HRC sensors put the piezo under the seat of the plug, so they directly measure variations in the pretension of the plug due to pressure variations inside the chamber.

I didn't try the stud mount types, since it wasn't too obvious where to mount them.

BTW, are you using a VHM etc head, or you cut a standard head with Frits's profile? With the Yamaha head, mounting any sort of det sensor under the plug requires you to cut a chunk out of the outside of the head, because of the recessed seat (and buy special extra-long plugs).

GrahamB a écrit:

michaelten a écrit:

What problems did you have?

Mine had the piezo sensor epoxied onto the end of an L-shaped bracket that was clamped under the plug. The problem was setting the sensitivity, since a little too high and it registered continually, a little less and not at all. Possibly because the bracket resonated.

The HRC sensors put the piezo under the seat of the plug, so they directly measure variations in the pretension of the plug due to pressure variations inside the chamber.

I didn't try the stud mount types, since it wasn't too obvious where to mount them.

BTW, are you using a VHM etc head, or you cut a standard head with Frits's profile? With the Yamaha head, mounting any sort of det sensor under the plug requires you to cut a chunk out of the outside of the head, because of the recessed seat (and buy special extra-long plugs).

Hi Graham,

I have the m8 stud sensors mounted to the stud that holds the cylinder to the case. It looks like they don't offer the type of sensor you had anymore. I put one nut off each cylinder in the lathe and machined the flange thinner and machined a little off the hex side of the nut, that gave me enough exposed stud to screw the sensor on. I was going to convert the cylinder heads to studs but I was concerned that the nuts would strip. The bolts screw into the cylinders approx 25mm, where as a nut is only about 8mm at the most. Have you seen anyone convert the heads to studs?

I had a HRC counter on my 125, it never gave any trouble. If I had to use the HRC sensors I was going to cut the top of the head down the thickness of the sensor so I could continue to use the standard plugs. The short plug caps and long plugs are too expensive!

I am using standard Yamaha heads. I cut 2 sets, one at 9.8cc and one at 10.3 just in case the first didn't work (spark plugs in, so add 2.25cc for the plug). The 9.8cc head worked a treat! At the end of the day I thought I was probably about about 2 jets rich ( from memory of how the 125 revved on elf124), I couldn't do plug chops and didn't have time to pull the heads so I was being conservative. The bike bike would rev nicely to 12500 then slow as it reached 13000, just like the 125 so I thought I was pretty close. I pulled the heads when I got home and there was basically no carbon on the pistons, it was so rich the fuel was washing it clean. I think I am probably 4-5 jets rich at the moment. If it continues to improve like it did all day it is really going to go well, it's really going to rev! I was scared of the unleaded thinking I had to be right on the money for the jetting, it actually seems the opposite. I know if we tried to run the elf124 that rich it wouldn't of ran at all. I'm very happy with the unleaded so far.

Not sure we should continue this here... oh well :-)
What model do you have again? On the 2003 the heads are held on with studs stock, so it's possible :-)
My concern about using the cylinder studs is that you are starting to get away from the source of the detonation. There must be a point where the detectors are too far to work.

The Denso long plugs were not so bad for price last time I bought some, but that was a while back... and they worked with ordinary caps.

Mine is a 2001 and they use m6 bolts, the 2003 uses m8 studs (same as Honda). There is not enough meat in the cylinders to drill out the m6 to m8 unfortunately.

I think the cylinder studs should be ok for the sensor mount, cars have them located on the block, not the head. I said to Mike (April Systems) that I was intending to mount it there and he said that was the usual location for TZ's. I will find out on Feb 9-10.

Frits or Jan, have you ever done experiments with uniflow style twostrokes?
Or has this already been asked?

uniflow a écrit:

Frits or Jan, have you ever done experiments with uniflow style twostrokes?
Or has this already been asked?

No, I never did.

michaelten a écrit:

I was going to convert the cylinder heads to studs but I was concerned that the nuts would strip. The bolts screw into the cylinders approx 25mm, where as a nut is only about 8mm at the most. Have you seen anyone convert the heads to studs?

If you pair the strength grade of the nut to the same or higher grade than the stud, you can load the stud to the yield point. For example, stud 8.8, Nut 8 or stud 12.9 nut 9. Now if you can load the stud to yield, it doensent really matter what lengt of thread you had in the aluminium, since the stud itself will be the limiting component.

EDIT: Speling an gramar.. doh

michaelten a écrit:

Mine is a 2001 and they use m6 bolts, the 2003 uses m8 studs

Don't think so, pretty sure they are m6. However the sealing system is different, the 2003 has a rebate for an o-ring at the base of each stud, whereas the earlier models just use a copper washer under the bolt. If you just install studs you'll leak water via the threads.

The Honda has the studs mounted outside the water jacket seal, which simplifies life.

Hi Guys

We tried this . . . . Bosch knock sensor linked to April Systems det counter.
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We could never get it to work well. I think the sensor isn't very good mounted at 90 degrees to the bore. Far better to be mounted on a cylinder head stud in line with the axis of the bore and closer in.

Also the wire was just soldered to the pins on the knock sensor and covered in shrink wrap. The wire broke after a couple of uses.

We had great problem adjusting the sensitivity, but perhaps this was due to a poor knock signal.

I think they have improved a bit now, and you can get an iterface so you can use the HRC det sensor
linked in to the April Systems counter (or straight to the logger if you don't need the counter).
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and then linked to an analogue 0-5V channel on an AIM logger with a "blue-flash" indicator.
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Having said all that the full HRC kit is by far the best, most rugged and totally plug-and-play if you aren't on a tight budget.
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and again you can buy a cable to connect straight to an AIM logger
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Best Regards

Ian

hi
my name is Danny are appassionated of two stroke engine, I want make an question, why the radius down of exhaust duct of the cilinder follow the radius of piston dome? what is the function in that configuration? sorry for my english
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Frits or Jan:
Hello. In designing the exhaust ports why did you raise the main port opening to 202° instead of raising the sub exhaust ports to the same height of the main exhaust port and/or squaring the sub exhaust ports instead of a triangle shape to get more blowdown angle area? Which leads me to ask why are the sub exhaust ports in a triangle shape?
Thank you. Jeff

Hi I recently registered here very motivated by the warm and most inspiring participation of Frits and Jan,and have to say it's been a pleasure and very elucidative reading,just finished 1st part.
I'm also hopelessly addicted to the smell of 2 stroke oil fumes seasoned with the sent of burnt rubber on asphalt and clutch dust, very early in cold sunny mornings
Excuse me,I also can only write in Eng but usually get the gist of Fr sentences.
I'm an electronic technician and am building a deto detect, test showed very strong signal with this very simple arrangement and a wide band automotive Bosch sensor,even got the sensors picking up signal from the opposite cylinder,but is important to have good surface contact,be the closest to the comb chamber and no inclination (0 deg) and in my case the sensor is seeing all the head nut torque which I could keep "low(er)" thanks to "o"ring sealing instead of head gasket
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Please excuse the off topic,I also would like to ask things about the Aprilia and Frits and Jan time there,but I respect if they are tired of so many questions and can't reply,plus I have yet to read many pages and might be revisiting subjects.

Mr Frits and Mr Jan I trust you were present at the track on race or practice sessions close by to other competitor teams,did you interact with them?Was there a friendly atmosphere between teams? Was there anyone caught trying to spy or suspect to steal secrets?

Why is the RS carburettor mirror polished?If it's to aid flow why not do the same to the engine internals,or the purpose is another?
Why was Porsche design the gearboxes if they're a car company,when clearly there are motorcycle manufacturers in constant development that should do better?
In the pursuit for the last Hp, was the rider's feedback quickly passed to you(s) when a change was track tested?
Did you ever have conflictive results like the rider saying "worst" and the machines saying "better" in face of a new change?If so how was this decided?

since I'm here Just 1 more very quick off topic (for me to anyone with sound knowledge):
dealing with a wet clucth in road racing is it worth to polish the clutch basket surface to reduce oil drag?

Thank you All this is great!!Keep it going forever

Hey guys, i understand perfectly your addiction but, please, only one question at a time!

genna900 a écrit:

hi
my name is Danny are appassionated of two stroke engine, I want make an question, why the radius down of exhaust duct of the cilinder follow the radius of piston dome? what is the function in that configuration? sorry for my english
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The radius of the exhaust duct does NOT follow the piston radius!
Instead the volume of the exhaust duct was reduced as much as possible.
This improved flow, as seen on the flowbench.
And above all, it improved blowdown!
Improving blowdown without raising the port height is, of course, a very good thing!
Reducing the exhaust duct volume also gives stronger pressure waves.