ESE's works engine tuner

**FastFred** · 23rd May 2016, 09:47

Originally Posted by TZ350

Attachment 321586 Well I got to try the small low speed injector in its new location. Totally changed things, it ran absolutely rat shit. Had to double the map numbers to get it to run at all at the low end. The injection-end timing had to be totally different too. A bit of re mapping work to do now, hopefully it being so different is a good thing.

Click image for larger version.

Name: EFI TPS Throttle Body Injector.JPG
Views: 42
Size: 242.3 KB
ID: 321797

Gave TeeZee a hand over the weekend with testing the new injector position, well its no magic bullet. But we did learn a lot about how critical timing the injection event is. Having high and low injectors in two completely different places with one timed to the transfer ports and the other needing to be timed to the inlet looks like an insurmountable problem, for now anyway. It still runs Rat-Shit.

Back to the drawing board. ...

**chrisc** · 23rd May 2016, 10:45

Originally Posted by lodgernz

Please forgive me if this post is too far off-topic for this thread.

I may be misreading things, but it seems to me that the 125GP class in NZ is dying a slow death due to the increasing cost and difficulty of maintaining the engine of the only competitive unit, the RS125, long since abandoned by Honda in any useful context.
There appear to be no foul-strokes that can make the grade, even given their huge capacity advantage under the current MNZ rules, and no competitive 2-stroke alternatives are jumping out of the woodwork.
As far as I know, the only 125 2T left in current manufacture is the KTM SX125. I'm wondering, would it be possible to coax the 45 or so HP required to make this engine a viable substitute for the RS125 if developed sufficiently and shoe-horned into the RS frame?
If a 2T substitute is not found soon, I can see corrupt FIM legislation will eventually trickle down to NZ and we'll be stuck with a poxy 4T class, inevitably of 250cc and dominated by Honda.
Are there any competitive kart engines that could be modified to fit the RS frame?

Opinions?

Misreading? I'm wondering where you're doing your reading at all lodger? I don't blame you though, most racers in NZ shoot down 125GP without trying to understand the class.
When I started racing 125GP in NZ a year ago, everyone tried to talk me out of it here in Auckland saying that it was a dying class. I pressed on anyway because I knew it's what I wanted to do, knew how much it could teach me compared to racing a production 250 or 650 diesel. It has been the best decision I've ever made for my racing and I've come so far in 1 year I can barely believe it. What an incredible experience! Even doing both the spannering and racing. Thank you so much to this forum and to the incredible people around the country who are so willing to give guidance.

What I found when I started was a class with very little to no communication, virtually no media or technical support in a class that sorely needs it, running on word of mouth and hearsay. No WONDER the class gets such crap thrown at it. Every barrier to entry of this amazing class was 10 metres high, with no clear avenues for new riders to join the class or ways to support it. Between myself and my friend Chris Malcolm (also Auckland 125 rider), we've really started to turn it all around, hell it's growing!!! In the last year, Auckland has gone from 1 part time 125 rider to SIX full time 125 riders. That's massive considering 125s have always been driven strongest from the south (hence up until recently, the string of south island national champs). Steve Ward in the south island does an incredible job of flying the 125 flag super high and has also had a spike in interest down there. He's flat out. There is renewed national interest in the class and we've been able to get bikes dragged out from sheds. We now get frequent messages of interest to join the class and we're even looking at getting bikes the USA to people have bikes to ride. At a Taupo practice day recently we had 4 125s, at a Hampton Downs practice day this weekend we'll have 4 or 5 125s, 2 weekends ago at Levels I was there and we had 5 125s (would have been 6 if not for an injury). 2017 nationals I'm expecting a marginal growth due to new riders getting comfortable with bikes but the following year, we're expecting a proper 125 presence.

Engines. As Wob pointed out, the stock NX4 RS125 is hardly an impressive engine by todays standards and we could do far better if we wanted to chase power. Do we need to change this? I don't think so. They're for sure fast enough to embarrass much larger bikes with the right rider. Also they're pretty straight forward and reliable engines. Bikes in the class currently are mainly stock which I see as a very good thing! Closer racing and more time understanding the in's and out's of the bikes rather than throwing $ at aftermarket parts and starting an arms race. Even worse, a missed opportunity for the rider and mechanics to learn the core fundamentals this class brings: preparation, precision and consistency. The worst thing for this class would be to further over complicate an already relatively (to 4t production bikes) tech heavy class. Yes the engines are no longer manufactured which does mean eventually, when all the worlds supply is wasted, the class might stand a chance of "dying". I'm willing to wager however that much like classics out there, reproduction parts will be created to meet demand. I do believe we have many years left in this class and I urge those to take advantage of it if you get even half a chance.

Cost. I honestly, truly believe that running a 125GP bike is not very expensive. I'm 26, no sponsors, no mechanic, all self funded obsession. Racing the nationals in ANY class is expensive, running the 125GP bike itself is very affordable. A 125GP bike is not a production 250 4 stroke and what you learn on a 125GP bike is far greater than what you learn on a 250 4 stroke. So yes, a 125GP bike is more expensive to run than those water pumps. A 125GP bike is also not a 600 super sport. You want expensive, try the tyre bill on a 600! Tyres on a 125 last forever and you can sell them back to bucket racers and regain most of the initial outlay. Fuel, oil, parts are all available and affordable if you use your head. The pistons we run through the nationals only end up doing 1/3 of their useful life so we use them again for club racing the full rest of the year. Do you even need to run a new top end every round to be competitive at the nationals? Nope. If you're a good rider do you even need brand new tyres every round of the nationals to be competitive? Nope. Seriously. Can you do that on a bigger 4 stroke? Nope. What we have is this brilliant class for mechanics and riders to learn fundamentals of racing with a reasonable cost. If only more people understood that. Where will that happen if this class disappears? Definitely won't happen in the introductory 250 classes and most don't have the wallet to compete in 600s.

As you can tell I have a massive amount of enthusiasm for this class which has given me so much in such a short period of time. We're putting a great deal of energy into making sure new riders find bikes and are all set up ready to race. So far the reception has been incredibly positive and I hope we can change the conversion to align with what is actually happening where it counts, on the race track. Want to know more about 125s? Either contact me directly or ask on the 125 facebook page: www.facebook.com/groups/125GPNZ

Note, photo from last round of NZSBK 2016 and doesn't include a large portion of the fleet of new riders coming through now. We also had 2 injuries in the south island meaning they didn't come up for this round.

**crbbt** · 23rd May 2016, 15:24

Wob: I had thoughts of using a CR cylinder on the RS as it would be a cheap powervalve cylinder a few years ago. I was promptly told that this was a silly idea

given that the CR's generator isn't 12v. do you have to run total loss ignition?

I can only echo chrisc points. similar position (27, no sponsorship, own mechanic) deterred away from the 125's because "they're expensive" by everyone with a passing interest in bike racing. ASBK have just split the 125's into a separate class over here. the running costs of a production Moto 3 honda is about 3 times that of the 125. only thing I find a struggle is getting good advice cheaply. must be how Italian do business

**wobbly** · 23rd May 2016, 16:08

All the CR ignitions from about 2002 onward are 12v to drive DC ignitions and powerjets ,TPS and powervalves ( 04 ) so these will bolt
straight onto earlier models.
The later RS125 kit engines with PV and the short ( 800mm ) pipe with 200* Ex are easily replicated using the 04 CR cylinder as it had a cable
PV as standard - the only model that did.
It has reverse transfer stagger like an Aprilia, a really nice small oval Exhaust duct exit, and could easily be ported to make well over 50 Hp.
And with the PV in place it would jet past any bog RS125 out of every turn, due to the gearing enabled by the great overev.
Here is a dyno sheet ( rear wheel Hp ) of a well tuned customer Honda, a B kit, and Azuma's A kit with PV - I know what I would be trying to replicate.

**chrisc** · 23rd May 2016, 16:58

Isn't that is a carrot in front of a crowd of stink wheel fiends if I've ever seen one. Thanks for posting that Wob!

**lodgernz** · 23rd May 2016, 18:04

Brilliant reply Chris, and don't get me wrong, I love the 125GP class. Nearly won it myself once upon a time. It's the only pure racing class left in NZ outside of buckets and sidecars.
I've just been concerned to see the numbers dwindling, and to hear that parts are getting harder to find, with no obvious successor to the RS.
Your enthusiasm is obviously already rubbing off on new riders, and that is exactly what is needed. The stronger the class becomes numerically, the easier it will be to find sponsorship.
I wish you and the class well.

Thanks also Wobbly for your comments. Clearly faster 125s can be built without horrendous expense, but I'm inclined to agree with Chris that the class is more attractive to a newcomer as a pseudo one-make class, for the moment anyway.

**wobbly** · 24th May 2016, 09:40

Yep, it would be impossible to compete against an engine that had the same power at 13800 as a well tuned stocker has at 12200.
As i say, the CR cylinder is well capable of being tuned to even above this level, is cheap and available.
Add a long 110 rod from say Samarin with a plate and you have what won the last 250GP championship.
Slap on an Ignitech, a modern fat pipe, a VF2 and you are well into the 50Hp zone cheaply with ease..

**chrisc** · 24th May 2016, 10:09

Are you able to comment on the CR125 cranks and how they'd take the abuse in a road racer vs MX bike Wob? The service interval on the NX4 crank is 2,000 kms, how would they compare.

It'd be a fun exercise to build a NX4 into a superlite/F3 class beating 2 stroke with an engine you described Wobbly!

**2T Institute** · 24th May 2016, 12:46

Originally Posted by lodgernz

Please forgive me if this post is too far off-topic for this thread.

I may be misreading things, but it seems to me that the 125GP class in NZ is dying a slow death due to the increasing cost and difficulty of maintaining the engine of the only competitive unit, the RS125, long since abandoned by Honda in any useful context.
There appear to be no foul-strokes that can make the grade, even given their huge capacity advantage under the current MNZ rules, and no competitive 2-stroke alternatives are jumping out of the woodwork.
As far as I know, the only 125 2T left in current manufacture is the KTM SX125. I'm wondering, would it be possible to coax the 45 or so HP required to make this engine a viable substitute for the RS125 if developed sufficiently and shoe-horned into the RS frame?
If a 2T substitute is not found soon, I can see corrupt FIM legislation will eventually trickle down to NZ and we'll be stuck with a poxy 4T class, inevitably of 250cc and dominated by Honda.
Are there any competitive kart engines that could be modified to fit the RS frame?

Opinions?

Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now de rigueur in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4 rebuild. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.

**wobbly** · 24th May 2016, 13:09

The CR125 crank parts are same same as RS125 quality wise and last forever over 12,000 rpm in a SKUSA engine.
I think Lozza has looked at putting a HotRods CR125 crank into the RS as it has higher inertia, and revs on better ?

**seymour14** · 24th May 2016, 13:28

Originally Posted by 2T Institute

Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now de rigueur in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4 rebuild. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.

It's not dead...just looking for other challenges.

**Frits Overmars** · 24th May 2016, 22:22

Originally Posted by bjorn.clauw.1

Hi Frits, so when we take the piston out to turn this radius, would it be wise to make a small radius on the bottom of the piston skirts? Found in a book this helps to keep more oil on the bore wall (in that the sharp edge of the skirt acts as an oil scraper).

Yes, the idea is to make the piston skirt 'water ski' over the oil film instead of scraping the oil off. You don't really need a radius there, a 5° chamfer will do fine.

Originally Posted by wobbly

... the Aprilia RSA125 didnt handle as well as the RSW125 due to the engine having to be moved back away from the front tyre to increase ~~carb~~ header clearance.

Corrected that for you Wob.