250R Build and Dyno Charts

[Buttermilk]

Hi. I thought I'd share some of my dyno charts of my 1987 Honda TRX250R, even though it's old school and no one really races them any more.

None the less, I thought I'd share.

Some of the Particulars:
*1987 250R
*OEM '87 cylinder supposedly ported (tear down months later revealed very little if any porting). So since I had to replace a sleeve (broken sleeve skirt on intake side) I decided it was time to do my own porting. I'd been wanting to for some time anyway.

So, I set the porting to the specs below:
*Exhaust timing was ~ 190 degrees.
*Transfer timing was ~ 133 degrees (new sleeve had the ports there already, otherwise I would have went lower on the tranfer timing....).
*Blowdown was ~28.5 degrees (less than what I wanted, but it was what it was.
*Keihin 38 mm PWK A/S carb running a 178 Main Jet, DDJ needle in middle clip postion, with a 55 Pilot Jet.
*Stock Airbox and stock airbox boot with K&N filter.
*'98 CR250 intake with '98 CR250 reed cage setup with my variation of a high tension reed setup using carbon fiber reeds.
*Wiseco Pro-Lite '86 style piston at 66.0 mm.
*+4mm crank with a 130.3 rod (commonly known as the Long Rod...) - making the stroke 76mm.
*Pro-Design Cool Head with a 19cc dome (actual measured volume was 18.8cc) for an Un-Corrected Compression Ratio of ~ 17.9:1
*Spacer plate 0.200" thick running two 0.020" base gaskets to set the deck height to zero (when combined with the 4mm crank and the '86 style piston...)
*Sparks TT pipe and ESR silencer.
*CR ignition timed "straight up".


Dyno Run 008 shows what the little 265 motor put out after my first attempt at porting my own cylinder. I was a bit dissappointed, to say the least. I'd ws hoping to be in the 48-49 range, with maybe a stretch to 50 hp.

[Buttermilk]

After some time, I decided I needed to change some things.

Dyno run 011 shows what effect changing the BD to 32 degrees has. I accomplished changing the BD to 32 degrees by changing the exhaust height.

*198 degrees Exhaust timin. (more than I wanted, but a slip of the porting tool and after smoothing... that's what I had...).
*134 degrees Transfer timing. (some smoothing made the change from 133* to 134*).
*UCCR changed from ~17.9:1 to ~15.6:1 by changing the dome volume from 18.8cc to 21.5cc and going with a narrower squish band.

All other parameters stayed the same.

That resulted in a shift of the power curve to the right. Average area under the curve really stayed about the same as run 008.

[Buttermilk]

Run 022 shows what effect changing the pipe from a Sparks TT pipe to an ESR TRX5 pipe has.

No other changes were made.

[Buttermilk]

After dyno'ing the ESR5 pipe, some more changes were in order.

I switched pipes to an ESR TRX11 Centermount pipe and silencer.

No other changes were made.

Note that the ESR11 pipe with the same jetting runs richer than the ESR5 pipe and still makes virtually the same power.

Dyno run 022 is the ESR5 pipe with a 180 main jet.
Dyno run 030 is the ESR11 pipe with a 180 main jet.

[Buttermilk]

After installing the ESR11 pipe, I remembered that the CR ignition could be advanced by slotting a mounting hole. After slotting, I estimated that there was ~ 5 degrees advance on the timing.

I also changed the main jet out to a 168 main.

Also (I almost forgot) I changed the reed cage out to a V-Force3 reed cage.

Dyno run 030 is the same as above. Run 041 shows the effects of a main jet change and advancing the timing ~ 5 degrees.

[Buttermilk]

I still wasn't too happy with the overall output since I'd really wanted to get to 55 hp after I started this project.

I decided my port timings were perhaps on the high side and contacted a local machine shop to make me another spacer plate to lower my port timings.

After having this plate made, it was installed on the engine and the cylinder lowered to set the port timings to the following:

*193.5 Exhaust
*128.5 Transfer

Since my deck height was now changed from zero, I also had to have a dome cut to accept the pistom coming out of the cylinder.

The dome volume was kept the same at 21.5cc (net) but the squish band was changed from 7mm to 11mm.

Also, compression ratio was at 15.9:1 UCCR, since the cylinder was now at 67mm bore.

Dyno run 054 shows the effects of those changes. While peak HP went down a bit, the average hp/tq numbers (area under the curve) went up and the quad was faster on a track.

Dyno run 041 is the same as previously posted.

[Buttermilk]

I had finally managed to locate a Dyno FS programmable iginition for the CR ignition.

That was installed and another trip to the dyno was scheduled.

Another change that was made was adding an additional base gasket under the cylinder, raising the cylinder by ~ 0.010". This would accomplish 3 things for me:

1. Raise my port timings ever so slightly, but not by much (something just under 1 degree). Exhaust timing is now ~ 194.5 degrees. Transfer timing is now ~ 129.5 degrees.
2. Drop my compression by a very slight amount (UCCR went from 15.9:1 to 15.2:1)
3. Raise my squish by a slight amount (there are reasons for doing this which I won't go into here......)

Dyno run 059 shows the effects of these changes.

The Dyna FS was ran in the stock setting, with no programming (that will come later, hopefully....)

[Buttermilk]

The latest changes involve the installation of a taper bored Keihin PWK 41.5 mm carb.

I had also planned on doing some programming of the Dyna FS, but it was not to happen. It was discovered that the axle bearings were shot while on the dyno. So the dyno session came to a end sooner than planned.

Run 071 shows the effects of the larger carb (run 059 had a 38mm A/S)

Later while at home, I discovered that I had ~ 1mm mis-match between the bigger taper-bored carb and the intake boot. I fixed that with my porting tool. I now need to get to the dyno again to finish dialing in the carb and trying some programming on the ignition timing.

I also have some needles ordered to fix the lean condition on the needle taper. As you can see by the long lengthy drop in the AFR, from 6500-7500 RPM, I need some more fuel in the middle. I expect those needles to be in this week.

Now I feel like I getting somewhere with this little motor. :) Now, I just need to get some programming on the ignition. I've got the axle bearings fixed, and smoothed out the transition from the bigger carb to the intake boot......

:) :D

[Buttermilk]

Run # Avg HP Avg TQ
Run 008 30.8 21.6
Run 010 30.5 20.9
Run 022 32.5 22.2
Run 041 35.8 24.8
Run 054 37.4 27.3
Run 059 37.7 26.3
Run 071 39.1 27.6

[GPracer2500]

That's a lot of well documented tuning/building info there. I only glanced at it but will come back to it another time when I can really focus on it.

For now I just want to recognize the effort you've put into sharing your hard-earned information. Thanks.

[8686]

Yeah I second that. Very nice.

[Buttermilk]

Thanks! I just wish I could have gotten on this 250R project about 6-7 years ago when the 250R was still the quad to race.....

At the least, I am having fun tinkering and learning. I now have my son on a 450R, so I get to play with the 250R......

I plan on going with a big bore cylinder some day....

I just hope that I can get similar horsepower per cubic inch.....

Regards,

Rog

[wilkin250r]

This might be my new favorite thread.

Not to be nitpicky, but is there a reason you have a few different scales? All the information is there, yes, but it makes the comparison a bit more difficult.

[Buttermilk]

No reason, other than that's the default scale when I load each run in the Run Viewer.

I can post the graphs on the same scale if you like. Just let me know which runs.


I've got the Dyna Programming Kit on order. As soon as I get it, I plan on making another trip to the dyno..... Gotta try some different ignition timing maps to see if I can get some more power...




Regards,

Rog

[Buttermilk]

Here's a chart showing the HP for sevaral runs that represent each stage of the "development" of this motor.

[Buttermilk]

Torque chart for the same runs as above.

[wilkin250r]

Can you post up Run_011 and Run_022 on the same graph.

I'm usually not a "best pipe" kind of person, but that one is interesting.

[Buttermilk]

Here is run 011 and run 022 on the same chart.

As you may recall, run 011 is the Sparks TT pipe, and run 022 is the ESR TRX5 pipe (std mount).

Motor setup was exactly the same for each pipe (same port timings, same carb, same intake, same ignition timing, even the same jetting - both with 180 main jets, and a DDJ needle in middle positon, with a 55 pilot jet). Even tested on the same day on the same dyno, back to back, without removing the quad from the rollers.

[wilkin250r]

Originally posted by Buttermilk
Here is run 011 and run 022 on the same chart.

As you may recall, run 011 is the Sparks TT pipe, and run 022 is the ESR TRX5 pipe (std mount).

Interesting information. Your porting is obviously much more in-tune with the TRX5 pipe.

However, it would have been very interesting to see how the Sparks pipe behaved out to 10k. The TRX5 pipe didn't have a lot of over-rev. It hit it's peak, and fell off directly afterwards. From the looks of the graph, although the Sparks pipe didn't have quite as high a peak, it looked like it would rev out much better beyond the peak.

[Buttermilk]

Here's a chart showing the Sparks TT pipe with a bit more rpm's on the graph (run 010).

You are correct that my porting seems to like the ESR5 pipe better than the Sparks TT pipe.

I forgot the chart.....

see below...

[Buttermilk]

Here's the chart I meant to post above.

[Buttermilk]

This chart shows the Sparks TT pipe setup with different port timings and different compression.

Run 008:

Sparks TT pipe
Exhaust timing of ~ 190 degrees
Transfer timing of ~ 133 degrees
Blow Down of ~ 28.5 degrees
Compression = 17.9:1 UCCR (~250 psi on the guage)



Run 010:

Sparks TT pipe
Exhaust timing of ~ 198 degrees
Transfer timing of ~ 134 degrees
Blow Down of ~ 32 degrees
Compression = 15.6:1 UCCR (~209 psi on the guage)

Everything else was the same.

[Buttermilk]

This chart represents what I had over a year and a half ago vs. what I've got now. Run 008 shows what I had after my first porting attempt. Run 071 shows what I've got now after months of tinkering.....

[wilkin250r]

Originally posted by Buttermilk
This chart represents what I had over a year and a half ago vs. what I've got now. Run 008 shows what I had after my first porting attempt. Run 071 shows what I've got now after months of tinkering.....

Do you still have the porting specs from your first attempt?


Beyond just port timing, what else did you change?

[headache]

Wow what a great thread! I'm a two stroke man myself and im glad to see 56hp from around a 250cc motor. Great job.

[Buttermilk]

Originally posted by wilkin250r
Do you still have the porting specs from your first attempt?


Beyond just port timing, what else did you change?

I've copied this from my first post in this thread (this applies to run 008):

Some of the Particulars:
*1987 250R
*OEM '87 cylinder supposedly ported (tear down months later revealed very little if any porting). So since I had to replace a sleeve (broken sleeve skirt on intake side) I decided it was time to do my own porting. I'd been wanting to for some time anyway.

So, I set the porting to the specs below:
*Exhaust timing was ~ 190 degrees.
*Transfer timing was ~ 133 degrees (new sleeve had the ports there already, otherwise I would have went lower on the tranfer timing....).
*Blowdown was ~28.5 degrees (less than what I wanted, but it was what it was.
*Keihin 38 mm PWK A/S carb running a 178 Main Jet, DDJ needle in middle clip postion, with a 55 Pilot Jet.
*Stock Airbox and stock airbox boot with K&N filter.
*'98 CR250 intake with '98 CR250 reed cage setup with my variation of a high tension reed setup using carbon fiber reeds.
*Wiseco Pro-Lite '86 style piston at 66.0 mm.
*+4mm crank with a 130.3 rod (commonly known as the Long Rod...) - making the stroke 76mm.
*Pro-Design Cool Head with a 19cc dome (actual measured volume was 18.8cc) for an Un-Corrected Compression Ratio of ~ 17.9:1
*Spacer plate 0.200" thick running two 0.020" base gaskets to set the deck height to zero (when combined with the 4mm crank and the '86 style piston...)
*Sparks TT pipe and ESR silencer.
*CR ignition timed "straight up".


Dyno Run 008 shows what the little 265 motor put out after my first attempt at porting my own cylinder. I was a bit dissappointed, to say the least. I'd ws hoping to be in the 48-49 range, with maybe a stretch to 50 hp.


Dyno run 071 has the following changes:
*ESR TRX11 center mount pipe/silencer.
*Less compression (15.2:1 UCCR now vs. 17.9:1 then) with a different dome configuration - bowl area and squish band has been revised.
* Port timings of 194.5 degrees Exhaust and 128.5 degrees Transfer - port timings revised by running a thinner spacer plate and running the piston out the top of the cylinder, and a custom cut dome to accept the piston.
*V-Force 3 reeds
*41.5mm PWK taper bored carb.
*Advanced timing on the CR ignition approx. 5 degrees or so.
*Dyna FS programmable ignition, but with stock programming.

I think thats all the changes between the two runs.

[witech]

Thanks for the dyno files . no luck on the files you requested yet.
I must say you have done an outstanding job with the power curve on that engine . It looks more like a four stroke than the peaky short powerband most have come to expect .
here is a comparison with my latest stock engined ported Dale.
That really is amazing . Good job .

[Buttermilk]

Thanks. It still isn't quite up to the level that the 4 strokes are, even your 'dale. Those built four strokes have an amazingly broad power spread.

Here's my 250R compared to a very well built stock bore/stroke 450R that belongs to a friend.

[witech]

This is the only dyno file I found with an esr pipe all the rest are fmf and lrd. He must not have hooked up the tach lead so torque readings are not available and therefore useless for comparison.Sorry

[Buttermilk]

Thanks.

[jasonex]

how fast can it go

[mxduner]

Originally posted by Buttermilk
Thanks.

no man... thank you! that is just amazing!

[Buttermilk]

Thanks for the props! I've still got some more work to do yet to the little 265R. It'll take a few more weeks before I get around to it, but it's coming.....

Hoping to get a 2-3 hp increase.....

Then I'll try some different fuels in it like E85 and Methanol.

After all that, a big bore Puma Cylinder will be next.

:)

[gimmie11s]

great documentation!

you are doing all of us 250r guys a major service with this thread! Keep it coming.

how does the bike ride? what does it feel like?

I've been wanting to build a 55hp OEM cyl-based 250r and now i know where to start...

[Honda 250r 001]

how do you tell when you need to change the taper or length of the needle. is that only able to be read on the dyno?

[Honda 250r 001]

Originally posted by Buttermilk
Thanks for the props! I've still got some more work to do yet to the little 265R. It'll take a few more weeks before I get around to it, but it's coming.....

Hoping to get a 2-3 hp increase.....

Then I'll try some different fuels in it like E85 and Methanol.

After all that, a big bore Puma Cylinder will be next.

:)

im hopein to have my motor set up about the same way. are you runnin race gas? if not u should try a 200 pounds of comp or even more and run race fuel and see how much she jumps.

[Buttermilk]

Originally posted by Honda 250r 001
how do you tell when you need to change the taper or length of the needle. is that only able to be read on the dyno?

The area on the dyno chart from 6500-8000 RPM is where the needle taper is too lean. Shows on the AFR portion of the chart.

Also, racing at the track has confirmed the lean needle taper.

Regards,

Rog

[Buttermilk]

Originally posted by Honda 250r 001
im hopein to have my motor set up about the same way. are you runnin race gas? if not u should try a 200 pounds of comp or even more and run race fuel and see how much she jumps.

My previous postings show that I'm running ~ 209 psi, and Track Tek TT111 racing fuel.

I've ran higher compression (as high as 260 pis on one build....), but the motor runs better with where it's at now.

Regards,

Rog

[Buttermilk]

This may well be my final update on the little 250R.

At one of the last races, the motor "popped" coming out of the corner (lean acceleration pop) and put a small concave impression in the top of the piston, and cracked the cylinder again (it had broke previously due to the base nuts loosening up ever so slightly..... welded it back and it held, and would still be holding if it hadn't "popped"....)

The cylinder started losing coolant and I've decided that this particular cylinder is toast. There was enough coolant getting into the combustion chamber somehow that was killing the spark at 8000 RPM and above. Seems the coolant was only leaking when the motor was at operating temps and being ridden.

I was really dissappointed, since I still had plans to squeeze 2-3 more HP out of the cylinder. I still had a couple of things to test yet, and I still hadn't programmed the dyna fs cdi..... :( But such is the way things go at times....:)


On to bigger things now.

Regards,

Rog

[slamdak8782]

Dont give up grab another cylinder. You know exactly where to go, dont want to see this one end great thread!!

[jcs003]

any updates?

[Buttermilk]

No updates. Long story, but I've sold the 250R and moved on.

[honda400ex2003]

man sorry for the bump but wow what a great thread for us 250r owners. congrats and great work on the testing there!

steve

[headache]

I agree. this is a great thread for 2 strokers in general!