Friday, January 8, 2016

Other projects

Click to go to the NSR250 Forum

Well this project is pretty much a done deal.
Currently I have 2 other projects on the go:

1) I am building up a NSR300 engine using two NSR150 barrels with custom conrods and pistons.
It is not just a simple TYGA NSR300 kit. I hope to improve on that significantly.
I am blogging this privately until I have made reasonable progress. Then I shall open it up to the public.

2) I am building up an NSR250 MC21 SP engine with 2004 CR125 barrels.
This is being documented over at

Tuesday, September 16, 2014

F3 PGM-II ??

Here is a link to a NSR250 Forum.

I recently got hold of what is supposed to be an F3 PGM-II.

So I took the plastic cover off 3 different PGM-II's and took a photo:
One of these things is NOT like the others

OK, so the codes on the back are like this:
Top: CI550C 8.N 241
Mid: CI580A 8.D 271
Low: CI580A 9.1 201

The photo below is of the supposedly F3 PGM-II

I have no idea if this is just a different revision circuit board or actually something more significant?
Possibly it is the PGM2 off a Honda RS250?
 Also, I got two 12mm wide collars made to space out the header pipe. Cost $40.

So I will be heading back to the dyno soon.
Hopefully the pipes will still fit on with the 12mm spacer.

One day later:
I fitted up the pipes with the 12mm spacers.
The pipe that exits on the RH side fitted OK. In fact it actually fitted a bit better than without the spacer as that pipe no longer hits against the RH Bottom head studs.
The Pipe that exits out the LH side of the bike was not such a good fit as I could not quite get the bolt hole at the bottom of the frame to line up with the pipe mounting point. (about 3-4mm of misalignment) But for now I have just put an M4 bolt through and attached the muffler clamps.
The muffler clamps do not do up tight onto the mufflers, so I will need to get a strip of packing rubber to make it tight.

I attached the PGM2 of unknown origin and tried to start the bike.
The bike usually starts REALLY easily. Sometimes I have started it from cold just cranking the kick start over with my hand.
After about 10 solid kicks the bike did not start and gave 2 large backfires out of the RH muffler. So I am thinking that the firing order is incorrect for my bike. I wonder if the firing order or pick-up locations on the RS250 is different to that of the NSR250R?

Sunday, September 14, 2014

Dyno Run and TYGA pipes

Friday 12th September 2014

I took the bike to Lincoln Shaw's Dyno in Dairy Flat (Northern Auckland NZ).
It is a Dynojet 168 with load control.
I had the bike in fairly standard trim: 128 main jets. (standard except for all the mods mentioned in this blog).
Embarrasingly the fuel used was 8 month old 98 RON. The oil is Castrol "Power1" TTS coming from the standard oil pump set as per Honda manual.

I had drilled two 20mm holes in the airbox lid but had them blocked off with Duct Tape.

The Blue line shows the horsepower with the two airbox holes blocked off.
The Red line shows the horsepower with the 2 airbox holes open.

Then I chucked on the TYGA MC18 pipes. They fitted straight on.
One pipe was hitting up against the RH barrel, but basically fitted,
The pipe sticking out the RH side basically stuck out at a bit of an angle and I will need to bend the stinger pipe a bit to get it to look right.
The Blue Line is standard pipes with both airbox holes blocked off.
The Red line is TYGA pipes; unfortunately, due to a slight misunderstanding, the LH airbox hole is blocked off and the RH airbox hole is open.

In the above dyno chart the Red line shows the MC18 R6k with both airbox holes blocked off with the TYGA pipes fitted.
The Blue line shows the result from a very sweetly tuned RS250.

So, this is all very interesting. It would appear that the rear cone (diffuser) of the std pipes causes the power to sign off around 10,500 to 11,200 rpm.
I am tempted to try a 12mm spacer between the head of the pipe and the header spigot to try and shift the TYGA pipe HP graph about 500 revs to the left.

It cost me NZ$200 for these 4 runs.
Also approx 6 hours travel and another $100 in travel costs.
I would have loved to have fitted EGT's (which I had available) and been able to play with different carb settings but just did not have the time available.

It was enjoyable to get the thing on the dyno. Thats for sure.

Pipe purchase details:

> Products
> -------------------------
> 1 x .Set, Exhaust Chamber, Side By Side Type, Stainless Steel, MC18 (EXCS-0003) = $586.44USD
> 2 x Silencer, Carbon, Two Stroke, Assy. (EXSL-0003) = $252.16USD
> 1 x Exhaust Hanger Stay, Pair, 1988 NSR250 MC18 (BPSY-0130) = $23.40USD
> ------------------------------------------------------
> Sub-Total: $861.99USD
> SAL Shipping (SAL Air Shipping Zone 8): $82.06USD
> Total: $944.05USD
Plus money conversion fees of NZD$29.92
Note that the 1988 MC18 R2/4J hangers are of course not needed for R5/6k.

 I will hopefully get the info on the weight difference between TYGA and standard pipes posted up soon. The TYGA pipes are probably about 3 kg lighter overall at a guess? Oopps,... see below 

Crappy video. Sorry my multi-tasking wasnt the best. Above std pipes. Below TYGA pipes.

But Weight, there's less:

To save you reading any further: the Tyga pipes and mufflers save a total of 6.5kg (14.5 lbs) compared to the standard Honda items.

Extended blabbering: The Tyga pipe and carbon muffler for the LH Top cylinder weighs 2070 grams including the header spigot, spring clamp and springs.
The Tyga pipe and carbon muffler for the RH bottom cylinder weighs 2015 grams including the header spigot, spring clamp and springs.
Thats a total weight of 4085 grams for the pair of pipes and mufflers.
My standard Honda pipes that have been caustic cleaned inside and out about 500kms ago have shortened cabon/kevlar Tyga mufflers attached that weigh roughly the same as the Tyga carbon mufflers on the Tyga pipes. Actually my mufflers weigh 440g and the Tyga carbon mufflers weigh 439 grams, so thats the same in my book.
The LH top set of pipe and muffler weigh 4510 grams
The RH Bottom set of pipe and muffler weigh 4695 grams
Thats a total of 9205 grams.
Hence a weight saving of 5120 grams, just in the pipes, NOT including the mufflers.

But if you take into consideration that the standard Honda mufflers weigh 1150 grams each compared to 440 grams each for the Tyga mufflers, then you are actually saving another 1420 grams.
So that makes for total weights of  4085g (TYGA  set) and 10625g (std Honda set)
Hence a total weight saving of 6540g.
Lets call it 6.5kg or about 14.5 lbs.


So very basically, overall, for your USD$950 you get an extra 2.2hp but with massive improvement on over-rev past 11,000 rpm and a 6.5 kg weight loss.
[Straight pipe swap with airbox holes blocked off: 61.77hp - 59.55hp = 2.22 hp]
I think it is a bit unfair to just bolt them on, run them, and then claim only a 2.2hp gain.
In reality, to be fair, you need to experiment around a bit to unleash the pipes true potential.
I have not had time to do this.
Also, I haven't actually ridden the bike yet, but I am expecting it to be a massively improved bike from about 10,500 through to [cringe] 12,800?

I would like to thank Matt at TYGA for doing something that he didn't really need to do, and doing it well, at a price that seems pretty reasonable given the amount of work that goes into designing and making them.
The two stainless steel pipes are made up of about 35 parts for one pipe and 45 parts for the other.
These pipes look excellent, function well, and fit well. Good job done!

Sunday, March 31, 2013

Another Track Day

I did 2 x 20 minute sessions on the bike at Hampton Downs on Wed. March 20th.
The bike ran well and the 41 tooth rear sprocket was perfect in terms of just reaching 12,000 rpm at the end of the main straight. Very enjoyable!
Paul seemed to think that the bike didn't sound all that crisp anymore.
I was clocked at 1 min 22.4 seconds for a lap.

I did 1 x 20 minute session on the blue fairing NSR250 that is shown in some of the pics on this blog.
It is an MC21 engine in an R2j frame running PGM-1 ignition. (no battery required).
I was pleased to be able to notice that my bike was noticeably quicker than the blue bike.

I want to pull the heads and barrels of my NSR and maybe give the barrels a very light hone and fit new rings.
I also want to get the thing on a dyno, and get a horsepower reading.
This will have to wait though as I have other priorities.
Am heading into winter now, so,..   may go into hibernation for 6 months.

Wednesday, March 13, 2013

A look up the exhaust ports

I took the pipes off to have a look up the exhaust ports.
OK, well this doesn't look the best.
I did have a few high speed "clutch in" moments during the first 300kms.

I am fairly sure that this was due to the petrol tank breather not working properly.
This meant that a slight vacuum built up in the tank and hence petrol flow into the float bowls may have slowed down to a dribble or less and resulted in a lean condition after a while at high revs and max throttle.
I fixed this problem before my first track day and it seems to be running pretty good now at prolonged high revs/throttle.

Sadly it seems that the LH Cylinder in particular may have come quite close to seizing at some stage?
I am hoping that it will survive the next track day. Then I will pull the heads off and check this out properly.
Looks like I will probably be taking the barrels off as well.
Bloody fuel tank breather!!! Argh.
RH Cyl

LH Cyl

RH Piston
LH Piston


41 tooth Rear Sprocket

In order to get the gearing right for Hampton Downs racetrack, it seems that gearing of 15 tooth front, 41 tooth rear is going to be about right.

I ordered a couple of 41 tooth rear sprockets from TYGA Performance.
Including freight they cost NZ$179 or approx NZ$90 each.
I ordered them on Friday and they were at my door 8:30am Tuesday, from Thailand.

The TYGA 41 tooth rear sprocket weighs 293 grams Made from a type of aluminuim called Duralium? and anodised for hardness.
The standard Honda 42 tooth rear sprocket weighs 830 grams.
So, a nice way to save half a kilo.

When I went to fit the sprocket I found that my 110 link chain was too long and I had to shorten it to 108 links.

110 links works for 15/42,.. just. If things wear/stretch a bit, there is little or no adjustment left at all.
110 also works for 16/42.

Monday, March 11, 2013

Link Plates, Gear Shaft Extender, Radiator Bracket

Today I fitted the "compromise" rear shock Link Plates. (see previous post)
I also fitted a proper gear shaft extender so that the gear change mechanism no longer rubs on the frame.
I also fitted the little bracket that bolts on to the bottom head and holds the bottom pin of the radiator.
"Compromise" rear suspension link plates fitted 01
"Compromise" rear suspension link plates fitted 02
 I plan to do another track day in approx 10 days so it will be interesting to see if I notice much difference.