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Author Topic: Yamaha SR250 Power and Temperature Testing  (Read 11196 times)

Offline sbruton

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #90 on: Nov 30, 2016, 22:07:51 »
Badass.  As an engineer, I totally dig the thought process and mechanics of your testing procedures.  It will be very cool to analyze the results once you've had a chance to put your theories to test!

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #91 on: Jan 11, 2017, 16:19:12 »
The exhaust thread in the head of the Jadus Test Mule 1.0 finally gave out  :(  Swapping headers around and bolting down the clamp flange a few times did it.  If you look closely at the hole you can see the old bolt is actually still there - in the middle of where the new thread should have gone.  But sadly, the muppet that did this repair job failed to extract it and then just decided that a new M6 tapped hole, 3mm to the right at a 15 degree wrong angle was good enough.  Same person that bolted in a wood screw remember!  Gah. 

I took it as a sign.  I am going to do a full rebuild of this engine eventually and make a separate build thread of it.  I'll get that exhaust thread repaired properly with the head off - hopefully even welded up and re-tapped in the correct position.  I have lots of ideas for the build... Cam, high comp piston etc.  It's gonna be a killer.

In the mean time, plans go ahead to complete the testing on the Jadus Test Mule 2.0  ;D

Offline Tune-A-Fish©

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #92 on: Jan 11, 2017, 17:14:49 »
If you made a drill jig to bolt to the other hole and went slow you could get a timesert in that head.


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Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #93 on: Jan 12, 2017, 15:35:31 »
If you made a drill jig to bolt to the other hole and went slow you could get a timesert in that head.

That was my original thought too, but unfortunately, the new threaded hole is so far off centred and crooked that it has removed a lot of meat where the timesert would nead to go  :-\  So I think I will extract the bolt that is there and try have it welded up - def a job for a pro.  The jig is an awesome idea for the new hole though.

Btw, pros and cons for Timesert vs Helicoil?  I have used both and didn't quite evaluate if one was better than the other  :o

Offline Tune-A-Fish©

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #94 on: Jan 12, 2017, 16:23:14 »
Helicoil is like a thread spring, sub par but will work. Timesert is a solid part and installed with a roll form tap that sets the od threads in the tapped hole with a shoulder to both stop it and provide a perfect opening for alignment.

I got a set that provides a four step process... drill, shoulder cut, tap and driver/thread roller.

Really better than new if installed in aluminum.








Sent from my iPhone using DO THE TON
"I didn't come here and I ain't leavin"  Willie Nelson

"love hard, live fast, die fun" Kacey Musgraves

"Like a Wreckin Ball!" Eric Church

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #95 on: Jan 13, 2017, 12:56:26 »
Ah sweet, that definitely looks like the way to go!  Have just read a bit more and it looks like these are the ticket for cylinder blocks and things too - perfect :)

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #96 on: Jan 14, 2017, 05:37:53 »
One of my favourite shows on Youtube (after MCM and Roadkill ;D) Engine Masters have done some pretty awesome tests with exhaust systems - both collectors, inch size and mufflers.  Although slightly different, a lot of this stuff is applicable to bikes too.  I have been inspired by their methods and love their enthusiasm! 


Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #97 on: Mar 01, 2017, 16:27:12 »
Incase anyone missed it, here are what the cooling engine covers look like on the other Jadus bike...

I will continue to conduct testing on them as summer (e-ven-tu-al-ly) rolls around here in Sweden.  But the testing will be carried out on the orange Jadus test mule.  I will swap over the sump oil temp set up and the head temp set up, but probably won't bother with the oil galley set up.  Even though if I wanted to, I could just swap the whole engine case over ;)

Online stroker crazy

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #98 on: Mar 02, 2017, 01:02:49 »
Too many fins are never enough!

Crazy
“Ride like the Wind” W.H.

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #99 on: Mar 25, 2017, 16:16:39 »
Here was the jetting options I accumulated leading up to the last dyno session, which happened around 4 weeks ago now.  I am going to add some pretty lengthy posts here summing it all up :)

I also decided to become a reseller for Keyster carb kits too, because they are amazing!  I ordered a couple sample kits and had the chance to test out the jets on the dyno day as well.  They are spot on.  The kit includes all the things that usually wear out or break on the SR250 carb.  But I think my favourite things included are the different jet needles.  What we found during both dyno sessions is that moving the needle clip position up and down does not very often put the mixture where you want it.  But with these different needle diameters, it really does wonders to evening out the air-fuel ratios :)

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #100 on: Mar 25, 2017, 16:52:37 »
Jadus dyno session 2.0

I'll start by saying this, the day was a mix bag of feelings - sometimes stoked, sometimes gutted.  If you were looking at numbers alone, things are not that impressive - gutted, but, as with what most dyno sessions show and tuners say, it is a relative thing, i.e.. what did you start with, and what did you end up with?  In this case, the graphs and the gains were strong and I was pretty stoked.

Right off the bat things didn't go to plan.  The rear tyre was out of round and bounced on the dyno drum and the stock suspension on these sr’s is shit so the thing was bouncing pretty bad and giving pretty bad readings.  This makes the power curve bounce a bit at the top and affect clear readings on how the carb should be adjusted.

Once we got things somewhat sorted - tightened straps, established which gear to do our pulls in (in contrast to last time where we just did 5th gear pulls all day) and then did some roll ons from 30kph-105kph in 3rd.  Plus some gear ups - throttling hard all through the gears.

I had made a spreadsheet with columns to fill in for jetting settings and a full days test plan - with exactly which tests I would do and how.  It went like this:

Test 1:  Completely stock - 2 pulls to confirm

Test 2:  Add Jadus header and silencer - stock everything else, tune to strong AFR’s, get reading

Test 3:  Add K&N filter to carb - remove airbox, tune to strong AFR’s, get reading

Test 4:  Remove K&N filter and add Jadus intake bellmouth and foam filter, tune to strong AFR’s, get reading

Test 5:  Add Jadus ignition advance brackets and tune to strong AFR’s, get reading

At this point, it is possible that this could be the final Jadus kit, so best power could/should be achieved at this stage. 

Test 6:  Swap carb (with same jetting) to one with the butterfly shaft mod, tune to strong AFR’s, get reading

Test 7:  Swap out cam sprocket and install with 4 degrees advance, tune to strong AFR’s

Test 8:  Adjust cam sprocket so it has 8 degrees advance, tune to strong AFR’s, get reading

Test 9:  Add Jadus harmonic intake, tune to strong AFR’s

YEAH, NAH.  That didn't happen and became apparent within the first half hour that this is not how things work.  It is just such a time consuming process to do the tuning and swapping of parts that this plan went right out the window! 


Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #101 on: Mar 25, 2017, 17:10:59 »
It turns out there are huge differences in dynos, not only in the way they measure but in the accuracy and the results too.  It also turns out lamda is only good up until a certain point - to get you in the near zone.  Then it is a bit of an experience/feeling thing to dial things in according to what just that motor/engine needs. 0.8-0.9 (AF 11.5-13ish) for example seems to be a sweet spot for the SR and this was the same with the last testing too.

Anyway, after doing these tests we established a baseline of 12.55kw at the engine, 10.4kw at the wheel with 16.5Nm at the engine.  Which is almost exactly what all of the period tests found - if you go back through the thread you will see the different dyno charts.  Even the power curve and torque curve graphs looked like the period ones.  Great, on track, but meant we had a long way to go.

The next step was to swap headers.  We did that and did some pulls, good increase, not amazing - got up to 17Nm and 14kw at the engine - around 10%, to be expected I guess.  Then we tried the k&n filter, no change to power or Lambda (believe it or not), then the Jadus intake bell mouth, also no change to power or Lambda , then even the carb with the shaft mod and nothing made a difference, we were stuck on these numbers.  This somewhat lines up with what I was finding back in Autumn last year when I was testing all these different settings with the O2 sensor and A/F ratio gauge installed - nothing on the intake side seemed to make a difference to power or A/F ratio.  Really weird.  The conclusion?  Something I already suspected/knew/is obvious...

An engine is just an air pump and can't suck in any more air than it needs.  The best thing you can do then is to make that flow in and out as easy and as smooth as possible and remove any restrictions in the system - in the SR's case, the header is the restriction, not the air box.  But in saying that, if you like the look of a pod filter and want to ditch some extra weight, getting rid of the air box is not going to affect your max power or torque or even it's delivery in anyway, not even the A/F readings! 

Right around this time, the clutch started slipping - as it did last time.  So it was out with the old springs, in with the new!

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #102 on: Mar 25, 2017, 17:17:42 »
And onto the results...  Here is the before and after curves comparing stock to the set up with the Jadus header and repacked silencer, plus a foam filter (although as mentioned, any changes to the intake side did diddly squat).

What you can see is an increase in both torque and power, plus a longer power curve - extended by around 1500rpm.  You can also see the flat spot in the stock SR's torque curve completely cured. 

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #103 on: Mar 25, 2017, 17:36:21 »
Then we swapped out the foam filter and stubby bellmouth (which did nothing) for the harmonic intake tube, and did some pulls.  Results were immediately promising - even with the same jetting.  We decided to throw on the advance brackets too, before adjusting the carb and there was a slight pick up in torque low down without any adverse affects up top.  This actually gives the engine a bit more time to burn its fuel if you are running rich in the midrange but think the engine has more to give - rather than leaning out the mixture.  We fluffed around with jets for a loooong time and realised that the power really falls off after 7000rpm - we checked this when shifting too - the dips etc.  What became clear was that if you shift quickly between 7000 and 7500, you get a good torque curve through all gears, if you leave it too late, the engine doesn't recover well and come back on the power as hard.  So best power was from 5000-6500 and best torque was 2500 to 4500.  Anyway, the jetting settings we ended up with were almost exactly the same as the previous bike on the previous dyno sessions.  This harmonic intake must really do something special because the carb settings end up way different to what one would expect.  For example, the main jet ends up being a 115 - much smaller than the stock 122.5 and way smaller than the 135 that we used when tuning with the foam filter and stubby bell mouth.  I think this makes the engine run much more economical and get a much cleaner burn and more complete combustion.

The graphs speak for themselves - dotted lines stock, next lines Jadus header and silencer, final (top) lines, Jadus full kit (so to speak).

So why did the harmonic intake do so much?  I still think the harmonic tuning has something to do with it, the engine benefits from both a 3rd and 4th harmonic at different points in the rpm range with this particular length and this shows.  However, after working with water flow in my day job for the last few months, I am now also convinced that the longer intake tube smooths out the flow A LOT and gives incoming air a chance to get some laminar flow before it goes through the carb and picks up fuel droplets - meaning a really nice mixture.  Neither a pod filter nor the stock air box can provide this nice smooth straight shot to the carb - the air is still very turbulent and non-laminar.  At work, through simulations and testing, we have found some crazy stuff that water does as it navigates though a plumbing system and pump, but of you give it a long enough straight section after a bend, it evens out again.

Offline JadusMotorcycleParts

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Re: Yamaha SR250 Power and Temperature Testing
« Reply #104 on: Mar 25, 2017, 18:04:23 »
One thing that really bothered me through the latter part of the testing was the results from the previous testing - where the hell was this 22hp at the wheel business?  No where to be seen!  I asked the tuner about that and he reckons the other guys were either wrong, pulling my leg, or I misunderstood and it must have been power at the engine.  Even still, this bike didn't make nearly that even at the engine!  He then also explained to me the variations in quality and measuring accuracy of different dyno machines and the different costs for different set ups - the more expensive, the more accurate.  Anyway, this left me convinced that I needed to return the the other mob and speak to them and also get a run down in standard trim with the other bike - to be able to have a comparison figure.  I would just bolt that damn stock header on anyway I could - even if it meant re-using that bloody wood screw!!!  Ha.  Since this days test I have been back to get the figures in stock trim (just last weekend actually) - more on that in another post.

Comparisons…  We will take at the engine first.  Stock vs Full kit.  Check the graphs too - red vs red is stock rwp (kW) vs Jadus kit rwp, blue lines are power and green lines are torque - both at the engine, before and after pretty obvious.

From 12.5kW to 15.2kW at the engine is a 21% increase

From 10.4kW to 12.6kW at the wheel is also a 21% increase

Torque went from 16.4Nm to 19.6Nm at the engine for an increase of 20%, but look at the area under the curve, it is chunky!

Then if you want hp instead of kW, here are the conversions:

Hp at engine went from 16.7 to 20.4 - a 21% increase.  I guess you could say, wow, the engine now actually makes what Yamaha claimed it did from the factory haha.

Conclusions...

The thing is, as mentioned earlier, carb settings make things vary quite a lot if the actual modification has done something to the engine.  To test every detail as much as I wanted to would have taken daaaays.  We were at it from 1pm to 9:30pm straight - no food or smoko breaks either, just head down get on with it.  That's over 8 hours straight of testing and fluffing around.

I will close in the same way I opened these posts, looking at the numbers, not so impressive, right?  Looking at the graphs and the percentage gains?  Pretty damn good.  I thought anyway.  And do you think a 20% increase in both power and torque is felt in the seat?  You bet ya.  I rode the bike home with the mods in place and the thing rips.  It certainly feels 20% faster.  But it doesn't end there, the throttle response and crispness is really nice, the power comes on sooner with that chunk of torque and pulls right up to 6500rpm before the power really starts to fall off.

These mods and these power gains are what could be considered 'the low hanging fruits'.  With just bolt on parts, modifications to the intake, ignition and exhaust, we have gained 20% power.  If I/you wanted more from this engine, it would entail head work - valves, porting, springs, etc and a big bore kit.  I think there is potential there, but I will save that can of worms for another development project when funds are available again and if any interest arrises. 

Oh yeah, I didn't get time to test the cam advance mod.  I'll have to do that on my own sometime and test by the seat of the pants or some timed runs somewhere  :D