How do i tuned motorcycle engine? (F650GS)

Tuning, troubleshooting and the nitty gritty of using rusEFI to make your engine run nicely!
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ReasonX
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How do i tuned motorcycle engine? (F650GS)

Post by ReasonX »

Hello. I have some 1-cylinder 650cm3 motorcycle engine, i want to enhance.
But i dont know how and what to do. Only superficial and divided knowledges.


THE SUBJECT
F650GS Dakar (2002 year).
It is well known Rotax 650 engine. Specs:
Image
43Hp on wheel, ~= 9 transmission losses.

It has EFI from the box, known as BMS-I.
O2 + CPS. Without any phase and load sensing.
CPS is very rude (it only mine thougt). It has 5 or 6 cogs. One long and other short.
Image

It is dirt touring (aka adventure) bike, with rally heritarge. (just model number and engine's basis lol)
I have very long story, why i want to tune this model. Shortly: it is most balanced (include buy and support cost) choice for the my targets. So please lets do not discuss that, i have many debates and no better ways were offered.

The true gold is F650RR. I don't want to get something similar, but i will give references to it.
It build with heavy tuned rotax 650 and has output with 75Hp .
All i know (from current owner of one) is what:
- It has factory team firmware but EFI is compatiable and same. (Still under NDA).
- It is bored to 700cc.
- It has very larger airbox.
- It has two pipes exhaust instead of single in civilian version.
- It has different camshaft and maybe vavles.
And the key one:
- The civilian version with factory team firmware can get 58Hp (NOT CONFIRMED).


THE PROBLEM
- It wants half or full throttle to rip wheel traction off on the dirt, on the first and second gear. (max moment revs is desirable).
On the third gear and higher it practically impossiable.
As in idle revs too.
- Revving-up from idle to max moment revs is really slow and stupid. REALLY SLOW.
You may open full throttle for two-three cycles and get only 500-1000 on neutral gear.
It sounds like engine wants to stall.

The bike is very deforced (my and some people in community thoughts).
It has two civilians firmware "The Old" and "The New". The old is sensitively better.
After the BMW has occured with EURO restriction, "The New" firmware was added.
I have both, but want >a little< (really i dont want racing monster with 100 hours before rebuild).


THE IMPORTANT INFORMATION
As i know, people tried to do something with stock EFI.
They added "power commander", zero filter, extend input air channel (no vavles and cams) and modifyed exhaust.
And have pretty zero result. Noisly 1-5Hp on dyno and some increasing of the throttle response, with any measurements.

I never heared about stock firmware tuning. Seems it never been disassembled. Im have tried too (for the joke) but have no luck due the very simple HC16 disassembler i have (IDA pro).
And zero skills in that of course.

This engine has two sparks head. And i have read some reports that it has some little better lower revs.


THE TARGETS DEFINITION
So, i want to have speed-up revving-up (with load) from lower to mid revs. Not higher. I dont have much care about it.
And have as much moment on it, as i can.
But maybe.. not too much but some little more.

So as i understand, my target is moment on lower revs and throttle response.
Ok. But i have no any thoughts about what to do. What to do first?

My current plan is:
- Add the rusefi.
- Replace air fitler to foam and extend channel.
- Remove catalytic converter from the exhaust.
- Add detailed cranksensor wheel.
- Add phase sensor.
- Setup rusefi.
- Check the goal.
If not reached.
- Add straight-through exhaust (really dont want do this).
- Add two sparks head.
- Setup rusefi.
- Check the goal.
If not reached.
- Replace camshaft.
- Replace vavles.
- Setup rusefi.
- Check the goal.
If not reached.
- Go shoot my self. (really dont want do this).
- Go bore. (dont want do this much more).
- Ask The God for lighter CPG and flywheel. (i have made to many sins for that)


THE QUESTIONS
- If you have experience, i want any of your thought and advice, you can give.
- Does plan steps is correct?
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AndreyB
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Re: How do i tuned motorcycle engine? (F650GS)

Post by AndreyB »

So TL,DR: you are looking for low end torque really?
Very limited telepathic abilities - please post logs & tunes where appropriate - http://rusefi.com/s/questions

Always looking for C/C++/Java/PHP developers! Please help us see https://rusefi.com/s/howtocontribute
mk e
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Re: How do i tuned motorcycle engine? (F650GS)

Post by mk e »

I used to race an H-D XR1000, the big brother to the the XR750 dirt tracker so similar to what you're after. The 750s made 90-100hp, my final road race version at 866cc made about 110, so right around 127hp/l for either version and higher output than you are after..75hp/.7l=107hp/l. ECU tuning played no role because these were carb'd engines and the carbs were for sure a hp limiter, I'd guess another 5-10% more hp with bigger EFI TBs. My franklenferrari with the same rev limit as the XR is going to be around 150-160hp/l, its 4 valve and flows better than the XR heads did with basically the same 450cc cylinders vs the XRs 433cc and EFI on the frankenferrari.

My point here is you will never, ever, EVER hit the race team numbers with an ECU swap and trying is a complete waste of your time and money. The power commander results should be confirming that reality in our mind. When I first started setting up the XR to race I got some time time on the phone with the guy that did all the factory bike head work told told him my plans...he chuckled and said "I don't care if you're Jesus Christ himself, without air you aren't going to make hp".

He was not wrong and I'm now giving you the exact same piece of knowledge.

If you want to make factory race HP you need factory air flow and ALL the parts matter, you can't swap them in and out 1 at a time, they need to match each other and your goals. A programable ECU is a really nice thing to have and I strongly recommend it....but to hit your goals you will need to bore the cylinder (or up the rev limit), flow the head, build custom intake and exhaust that are flow matched to the head then choose a cam to work with the head, intake and exhaust....then tune the ECU to make it run right and I promise you'll be able to hit your goal. Bolt on an ECU and hope and I promise you won't.

Good Luck!
ReasonX
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Re: How do i tuned motorcycle engine? (F650GS)

Post by ReasonX »

mk e wrote:
Wed Sep 01, 2021 12:56 am
If you want to make factory race HP ...
But i dont. My targets are different and not so big.
And i have no target to boost HP at all.
AndreyB wrote:
Tue Aug 31, 2021 10:15 pm
So TL,DR: you are looking for low end torque really?
Yup. And fast revving up from idle to middle-revs. As i understands it is CPG+transmission-mass\torque ratito.
mk e
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Re: How do i tuned motorcycle engine? (F650GS)

Post by mk e »

ReasonX wrote:
Wed Sep 01, 2021 8:35 am

But i dont. My targets are different and not so big.
And i have no target to boost HP at all.

....
Yup. And fast revving up from idle to middle-revs. As i understands it is CPG+transmission-mass\torque ratito.
If you are not interested in factory race HP then why include the information in your post? If you are not interested in HP increase with tuning why did you include the results others have achieved with tuning?

If you want to make an engine to be quicker reving, you can add hp, remove weight, or both….but I suspect you know that which is why you included all the HP data in your original post. I say HP, you are usually using the word torque…HP=Torque x rpm/5252 so the only way to add HP at a given rpm is to add torque. Torque is a function of Brake Mean Effective Pressure (BMEP) and BMEP is a function of volumetric efficiency…..and we are right back to air flow which is why I started the conversation there.

Increasing torque at any given rpm means increasing the mass of air in the cylinder, its just that simple. Making the cylinder bigger can do that, it will be a similar VE to what you had but being larger means more torque...but it will not make (much) more HP, it will make the same HP at a lower rpm. It will hit the max flow at at a lower rpm so the HP ends up basically the same if displace( bore, stroke or both) is the only change.

Again, all I'm pointing out is the things you are talking about wanting to achieve all require physical changes to the engine not an EFI upgrade.....the EFI upgrade just makes retuning for the physical changes much easier.
ReasonX
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Re: How do i tuned motorcycle engine? (F650GS)

Post by ReasonX »

mk e wrote:
Wed Sep 01, 2021 2:14 pm
If you are not interested in factory race HP then why include the information in your post?
Im trying to give the complete information, what i have.
Ive have included factory team data, because i have talked with the guy, which (as he says) have one. And only the EFI switching gives 7Hp boost. I dont know if its true or not or measurement mistake.
And also to mark the realistic performance border.
mk e wrote:
Wed Sep 01, 2021 2:14 pm
If you are not interested in HP increase with tuning why did you include the results others have achieved with tuning?
Because this is very contoversial info and i dont know how to use it right. Maybe someone can extract something usefull from it.
ALSO
Because i think (maybe only due my incompetence), what stock EFI has a very ecological setup and removing ecological setups at all will make some difference.

The reasons for me thinking this way are:
1) With "The OLD" firmware, the BMW has failed to reach the EURO ECO standard (dont know the standard number but only the fact). This has been found by journalists and BMW was forced to make "The NEW" firmware.
2) This two firmwares has sensitive difference, but pretty same dyno curves and the top Hp. It is not only mine observation.
And i assume what is just cognitive errors. =\

As i know, one of the ecological things is an acceleration restriction. Thus i assume that if the bike is at least borderline euro standard compliant, those eco features would affect vehicle performance significantly. Thats why im focusing on EFI at first.
Also because stock EFI is learning one, i would never get the most AFR out of it.

I do not argue, i just tell you what i know and waiting for advice.
And also, again - im not need much more. I just need "a little more". So i dont want to spent 9999$ for "all shit", just because with a big chance im really dont need it. Thats why i want to make it step by step.
And the first target of this tread is to define first steps.
mk e wrote:
Wed Sep 01, 2021 2:14 pm
right back to air flow
Im keeping it in mind always. Small & cheap changes are easy for me (input\output). Cams and vavles is harder but still withing my ability scope.
But big bore is the last thing i want to do, due its expensive cost.
mk e wrote:
Wed Sep 01, 2021 2:14 pm
Again, all I'm pointing out is the things you are talking about wanting to achieve all require physical changes to the engine not an EFI upgrade.....the EFI upgrade just makes retuning for the physical changes much easier.
But what about AFR and angle.
As i know - stock ecological EFI's never give "power AFR".
Yes - this can be changed by powerbox, but it requiers to change angles map. And that thing, F650GS powerbox cant do.
And as i know - good AFR without right angles is a waste of fuel.
Also - stock EFI doesnt have the load sensor not MAP, not MAF. Only the throttle position sensor.
Also - stock EFI doesnt have phase sensor, so seems to work in Simultaneous mode. So it may have more bad mixing. (only mine thoughts).
Also - stock EFI has very crude CPS and this can give bad angle caluclations on slow revs and unexpected loads.

Do you think all of this cant drain significant amount of performance, and upgraiding to the well-setuped EFI with nice phased CPS and MAP sensor, without any ecological features still doesnt give something observable?
mk e
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Re: How do i tuned motorcycle engine? (F650GS)

Post by mk e »

I'm sure a rusefi will make it run better and will be a nice upgrade, you should do it.

I was just trying to caution you to set realistic expectations for what a new ECU can deliver. One have a 1 cylinder so a lot of the little thinks modern ECUs can do to get every cylinder running perfect don't really apply to you. A well done rusefi install will no doubt make it run a bit nicer, smoother off idle and pulling away is what I expect you'll mostly notice.....but its probably not going to make the engine act any different performance wise.

I had a ferrari 308 engine I removed the factory CIS and installed an early aftermarket EFI....it ran fine other than a little trouble getting the off-ilde exactly right, the factory system was better there. The EFI system was relatively privative, 4 magnets mounted to the flywheel, 3 south and a north pole (iirc) and a hall sensor that cold tell the difference so it knew which magnet was for #1 TCD, waste spark, multipoint fuel because it only had 5 outputs and 4 were used for spark so 1 output for all 8 fuel injectors and no cam position so all 8 fired together every rev. It ran pretty well and the off idle issue was mostly fixed when they came out with a FW update that changed the fuel tables from fixed rpm points to adjustable. I have a buddy still running that exact same setup on his 308 to this day.

Some years later I bought a newer ECU that could do sequential fuel, I added a 36-1 wheel and cam sensor and that setup idled must better and seemed snappier free reving. I played with switching from sequential to semi sequential and for sure there was an idle quality change...but I couldn't tell the difference on the dyno.

I also still had the 4 magnet setup and tried that....no difference I could hear free reving, no change on the dyno. When the RMP is changing fast is when you really need more teeth to keep timing right, but free reving a powerful engine it would not really be possible to hear if it had lost 10 or even 30% or its power due to timing issues.....and in gear driving it can't rev anywhere near that quick so it didn't show up as an issue on the dyno.

My whole personal experience is a sample of 1 so clearly your results could be different.

Another data point is the Megasquirt guys in the MS1 days (2 outputs, 1 to the distributor, 1 for all your injectors and 8x8 tuning tables) that tell people anything more was for emissions compliance not performance. they sold 100s or 1000s for those setups.....clearly they were lying and have since joined the world of sequential injection, cylinder tuning, bigger tuning tables, and such.....but they still sell a lot of MS2 setups for V8s because it while not as good it still runs pretty well and for the money it plenty good enough for most projects.

...so just set realistic expectations for this ECU upgrade. Yes it will be better, no it will not be a whole new motorcycle.
ReasonX
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Re: How do i tuned motorcycle engine? (F650GS)

Post by ReasonX »

mk e wrote:
Thu Sep 02, 2021 11:54 am
...so just set realistic expectations for this ECU upgrade. Yes it will be better, no it will not be a whole new motorcycle.
Hey. This is more than i expect. I never think, what only ECU upgrade may do something really better.

But i still have many practical questions.

0) Does airbox size means or i can just make its input channel same size as output and forget about it?
1) How can i calculate needed input (before and after the airbox) diameter?
2) How can i calculate needed airbox size?
3) How can i calculate output resonation frequency and exhaust lenght?
4) How can i calculate needed cams phases?
5) How can i calculate needed vavles diameter and stroke?
6) How can i calculate needed injector throughtput?

There is no guides for this on first view.
mk e
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Re: How do i tuned motorcycle engine? (F650GS)

Post by mk e »

0,1,2

Basically no air box is fine, a bad airbox is not fine. The exact gain with the airbox depends on the engine....a 1 cyl maybe 5%? as much as 5-10 on 3 or 4 cyl. I don't have much experience making a good airbox...H-D engine have uneven pulses so the box doesn't work and V8s to many pulses for it to work. Modern ferrari V8 use 2 4cyl plenums to make the tuning work and my V12 plan is 4 boxes of 3 cyl ech.....but 1st it needs to run. The tuning software I use, Dynomation6 does not do the sir box but EngMod4T does but I've not tried it

I attached a spreadsheet to help but to be honest I don't recall exactly what I was calculating...I'd need to look at it a bit closer but the math is all there.

3) Do a search, there are a lot of thoughts on the right math. PipeMax is a popular software but I found it a bit limiting and use the tools in DM6. Its kind of funny the DM6 treats the engine as 12 1 cyl engines but I'm not sure the tuning really applies to 1 cyl now that I think about it. I say this because I use a fairly complicated header design tuning wise to boost the low to mid range on an engine that wants to be all about top end...its a tri-y with much longer than normal first leg, but you don't have any Ys so.....it principles of are change at distance from cylinder still apply for sure....but maybe look to the factory effort for basic design ideas. A standard header uses the 3 reflection ("harmonic") as does a standard intake manifold but 2 and 4 are also common for headers and my tri-y uses all of them at different rpms so it can be complex and good software is a big help.

4) Software like DM6. You really need a simulation tool to do any cam design type work. The other option is hope the off the shelf options are good for what you're after and adjust the heads, intake, exhaust to make the cam work the best it can.

5) there is no magic valve size, bore or stroke. Stroke is about getting to target rpm without over speeding the pistons....stroke sets redline really but you can certain tune the engine to any rpm below redline.

Valve size is complicated Generally you set the seat or throat to hit give a target velocity, then the valve is generally about 16% bigger for the best flow but there are a lot of exceptions. Sometimes you can't fit a large enough valve so its closer to throat size than idea, or sometime you don't have enough cam duration or lift so you use a bigger than idea vale to help expose more seat area faster knowing the bigger head will recue flow some.

6) there are many injector siz calculator out there, here's one:
http://www.wallaceracing.com/injector-sizing.php
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