ESE's works engine tuner

[dmcca]

Peak power of the 250 kart engines was around 10600 and reved to 11600 if needed.
Big ends didnt last long but who cares, plenty of National titles.

What engine were you using as a base for this? Assuming 66.4 x 72 or did the mods include squaring things up?

[wobbly]

Early 2000 CR250s were the most used - before Avgas and Methanol were stopped by the wise men..
Stroke is way too long, but as I said we reved the tits off the things and replaced the cages regularly.
The early KTM had a shorter stroke and went very well, but needed a huge amount of porting and welding to make it work.

[2T Institute]

What a funking lemon. Just started to strip the top ends. Only got as far as removing the barrel on the bottom cyclinder to find 3/4 of a piston and a completely shaged bore. At that point I gave up and am now having a beer thinking of how I should proceed with what is now turning into a complete engine rebuild.

Did you remember me saying this a few pages back?

You can get 65hp with just bolt on bits and an ignition. However, you will run into the problem of the shit RGV piston which at 65hp is at their limit. The pin boss will disintergrate and take out the cylinder on the right that or the tang between the arch will break off.

Another reason not to flirt with the old kit set up, (unless you have a VJ21) a programmable allows you to split the timing between cylinders. ALWAYS happens on the bottom cylinder

[richban]

Did you remember me saying this a few pages back?



Another reason not to flirt with the old kit set up, (unless you have a VJ21) a programmable allows you to split the timing between cylinders. ALWAYS happens on the bottom cylinder

I think this was more a case of 40000k's and no love.

I have finished the head drawing and dropped them of to be machined. New cylinders on the way and pistons after that. Frame mods should be done next week. So end of the month bike will be ready for the track. We will see how that goes but thats the plan. Oh and ignitech also on the way.

[dmcca]

Just thinking aloud here (which i usually end up regretting)... been pondering variations on the exhaust dam idea and whether or not theyd be of any benefit, initially considered a horizontal divider across the exhaust port positioned at the height of TPO and what effect that would have on pulse strength and short circuiting... but what about the concept of a powervalve flap on the floor of the exhaust port that raises the floor up to the level of the transfers as revs increase... could this widen the power spread? If i was really clever id think of a way to incorporate a 6th transfer port in this floor flap that opened to give more transfer area at high rpms.

[Frits Overmars]

Just thinking aloud here (which i usually end up regretting)... been pondering variations on the exhaust dam idea and whether or not theyd be of any benefit, initially considered a horizontal divider across the exhaust port positioned at the height of TPO and what effect that would have on pulse strength and short circuiting... but what about the concept of a powervalve flap on the floor of the exhaust port that raises the floor up to the level of the transfers as revs increase... could this widen the power spread? If i was really clever id think of a way to incorporate a 6th transfer port in this floor flap that opened to give more transfer area at high rpms.

I am all for raising the exhaust duct floor, but why do it only as revs increase?

[kel]

If i was really clever id think of a way to incorporate a 6th transfer port in this floor flap that opened to give more transfer area at high rpms.

re the port under the exhaust port, how would this port be orientated?
My crude flow testing of the auxiliary transfers shows the hook at the rear of the port drives a stream underneath the main flow and towards the exhaust port. This would seem (on the surface) to drive the residual burnt gases towards the exhaust port aiding in cylinder purging. If a port was added under the exhaust port floor would this not work against this perceived effect?

[Yow Ling]

might help with the imaginary 2 stroke in our heads

[TZ350]

Attachment 284436

I have been playing with EngMod simulating the Ball Valve and trying different scenarios.

Attachment 284438

I have been looking at how the 24mm throttle body will go with the Ball Valve.

Attachment 284440

And found that the Ball Valve on its own was likely to be better than with the plenum.


Attachment 284439

Then I had the bright idea to simulate the Ball Valve 24mm throttle body combo with a Boost Bottle.

Attachment 284437

Red Line is the Ball Valve and 24mm throttle body, Blue line is with a Boost Bottle. It looks like something worth checking out in real life on the dyno.

Attachment 284449

I wouldn't get to hung up on the hp numbers, the real thing to take notice of, is that EngMod2T is pointing out that a Boost Bottle with the Ball Valve is a worthwhile direction to explore.

Ok, making a bit of progress with setting up the EFI systems throttle body.

Attachment 284965

The original idea was to run the 32mm Ball Valve inside a plenum feed by a 24mm carb equivalent, but things change and now I am going to try it with a 24mm insert first.

Attachment 284966Attachment 284967Attachment 284969

The 24mm venture insert is going hard up behind the Ball Valve. I am not sure exactly where reversion will accour but it looks like it will be a reasonably short inlet tract.

The insert has an aerofoil shaped leading edge and the trailing edge is a 14 degree (included angle) divergent cone, in fact it diverges at 14 deg more or less all the way out to the rotary valve face.

Attachment 284968

32mm Ball Valve with 24mm carburetor equivalent throttle body venture behind it.

Attachment 285027T

Took a sneaky peak at TeeZee's special inlet, just to see if it was actually 24mm.

It will be interesting to see how he fits a boost bottle in there, looks a bit tight.

Making a bit of progress.



My mission at the moment is a boost bottle, it took me two - three weeks just looking at the problem to even see how I could fit one in, and have the bottle and piping all pointing down hill and get the gear box and clutch cover to seal around the pipe.

Normally I would not bother with such things as boost bottles, they traditionally being a carb tuning aid but Engmod said it might be a good idea and it should boost torque everywhere.

When you look at the restricted inlet I have to work with, there maybe something in it.

In my new engine the 24mm restriction in the inlet is only 25mm away from the rotary valve face and I have been able to fit the 12mm id boost bottle tube between the restriction and valve.

When you look at it, its easy to imagine the motor drawing air from the boost bottle and the 24mm inlet at the same time, then the boost bottle being re charged when the rotary valve closes.

The class rules restrict me to a 24mm carb equivalent. The area of the 24mm inlet is 4.5cm2 and boost bottle tube 1.1cm2. So the boost bottle represents a 25% increase in area or equivalent to having a 26mm carb. Not much maybe or even a perfect comparison but it looks like something to try.

I am anxious to get this BB thing sorted and the engine re assembled so I can get on with the much more interesting job of getting it to run with fuel injection.

[Flettner]

Thank you for the update, we all eagerly await progress reports.

[cotswold]

Check this lads race bike, It's built for 50cc racing in the uk...

details:

Wheelbase 43.5", Head angle 26 degees, trail 3.75". Weight (wet) 47kg. Undamped forks. 90mm drum brakes. Constructed from 1.5 mm, ERW steel tubing and mild steel sheet.


He has used a ty50 motor and the wheels are from a Tomos moped, he is off racing for less than $800

[F5 Dave]

I was reading Practical Sportsbikes magazine, specifically the AR50 100MPH project and noticed that the ESE thread was mentioned! I hope that they don't mind me posting this, it's advertising on their behalf so I doubt they will, but see the attachments for some sneak peaks.

It's a good build and I hope they achieve their goal, actually, it's a great magazine with lots of stink wheel articles and builds. We've just subscribed to the magazine too.
. . .

Attachment 281658Attachment 281659Attachment 281660

Well I'd been looking out for the latest issue to see how they are doing (mag takes months to get to NZ so we're out of date - yeah yeah)

Ran to 106mph on the dyno at 12,000 which I think was well past their peak power. Net result so far; 87mph but unable to hold 6th gear. They had jetted down a step to try improve (where they got 87) & it nipped up. Apparently was just getting too hot between runs & not jetting fault.

I'd argue that aircooled bike is petrol cooled & it has to run that bigger than optimum jet.

Either way they are cleaning it up & rechecking on the dyno so we have to wait another month (unless we get a spoiler from overseas guys). They will try gear it down if they can't pull 6th this time. Frankly I think it was crazy they didn't have a range of gearing for a top speed attempt on a Tiddler.

I still predict 92mph. I am not trying to knock them, it is a good effort & the bike looks great for what it is, true to the original idea rather than a liner attempt (they drafted a kid to ride it). I just think a bigger carb & some more revs would have helped their cause somewhat.



[edit] July issue, just looked on site & Aug issue advertised so we're not that far behind, but no mention of it in blurb.

[TZ350]

I'd argue that aircooled bike is petrol cooled & it has to run that bigger than optimum jet.

Yep ... totaly agree, found many times that what was best hp on the dyno was to lean on the track. Wob made some good points about finding the optimum exhaust temp on the dyno then replicating that on the track. Interesting stuff.

[F5 Dave]

Even then you might want to throw in some fudge factor for aircooled bike, unless you purposely went out of your way to get the plot particularly hot on the dyno (he says from a position of ignorance of not trying it). Guess he would have tried that on a KT.


Is it time for a beer yet?

[TZ350]

Even then you might want to throw in some fudge factor for aircooled bike.

Yes I think your right, probably adapt Wobs idea. So after getting close on the dyno, note what exhaust temp works well on the track and then jet for that on any given day.

Wobs exhaust temp idea is all about being able to reliably jet for different days and changing conditions to get the best out of the bike.

But how to measure and record exhaust temperature ....