Yamaha TRX850 Enthusiasts Forum

This is not finished, but ive had some time to start work on it in a "serious" way.
Please note that this engine is STOCK in every way except 2 major things. There is not 4UN computer module, i have fully taken over spark control, along with dynatek coils and iridium spark plugs, and now the EFI throttles.

The throttles are off a TDM900 and have been taken out to 41.2mm and flowed to make them nice. I suspect similar "bolt on" performance to FCR41s. Ive left the headers as STOCK, and everything else about the bike, engine performance wise is "stock". Ive not put in the bits yet as im getting a baseline to work off.
The cyl head is stock in every way except for being perfectly cleaned, and new iridium plugs, and a slight shave to ensure its flat. The shave was so minimal i dont think it would even bump the compression up.
Anyway. Here are some pics to show whats going on. This is more a "preview" of what post i will make some time next week when the bike is up and running. This is the last "major" stage which is installing my fuel pump. I originally had a inline GPX1100 unit, it was much like a soda can, but it was a bit cactus and not consistant. So since i had this Hayabusa ('zuki GSX1300R) sitting there, thought i better use it. For those that saw, this is the fuel pump with a fuel level sensor, which i wrote some code for to work with my computer. So now i have a bike with a digital fuel gauge

Anyway, Ask away, but ill just dump some pics and post a full report (with video !) at a later stage once the bike is up and running. Providing i dont get any more obstacles. Enjoy.

Nice

Looking forward to seeing this running!

Impressive as always mate. Be interested to see the baseline figures you come up with before further mods.

yup. I DONT have any "stock" dyno chart, but thats been fairly well documented. With some EFI and spark tuning, would be interesting to see what it yields. I suspect slightly higher than normal FCR41s. Probably identical to a FCR + TPS mod.

Next part will be custom making a huge flowing exhaust and then dyno that. At some stage ill be bolting on the modified head, then prolly do the full engine. 907cc and 12.5:1 comp. Should prove interesting. But thats a few months away.. Its taken its time, but its slowly comming together now.

For the record, i WONT be keeping this EFI setup. They will be sold / given out / whatever.. I asked on the TDM forum, not huge interest for them. Problem with TRX guys is having to mod your tank and get some sort of computer for EFI.. I suspect i can make a harness for a PC3. But thats WAY WAY off... anyway. Ill post more stuff later when i get some info. As i said, ill do a full write up on EVERYTHING involved.

I can assure you, its no easy task. Theres been sooo many obstacles and weird things its retarded. Even the throttle cables dont fit properly, the TDM ones are about 30cm longer, and thats minor compared to many things.

Interesting bottom pic - at first glance it looks like you've sawn through the top r/h frame tube

Well,, here it is. Should be fairly self explanatory. Ill add a write up later as im going to bed.. Please feel free to ask as much as possible, and anything you want. Theres no such thing as a stupid question.
It HASNT been dyno'd as yet. I need to get some filter pods on there before i do anything adventurous. Not been for a ride on it yet either.

Quan-Time wrote:

Well,, here it is. Should be fairly self explanatory. Ill add a write up later as im going to bed.. Please feel free to ask as much as possible, and anything you want. Theres no such thing as a stupid question.
It HASNT been dyno'd as yet. I need to get some filter pods on there before i do anything adventurous. Not been for a ride on it yet either.

Oy....you got way much time over...get a job mate!!

I was desperately looking for the beer bottle, it took some time, but...

Awesome, thanks for sharing! I will definitely come back with questions later on!

HansJ wrote:I was desperately looking for the beer bottle, it took some time, but...

Awesome, thanks for sharing! I will definitely come back with questions later on!

Sorry but, questions on what?? Are we going anywhere NEAR what this master fabricater have done??

...oy mate, just kiddin....any info is gooooooood info!!!

OK.. just finished another shift, and got a few hrs before im back out again.. So here goes.. Ill try to cover what i can.

Obviously megasquirt is the computer.. Im eagerly waiting on the 3rd gen upgrade which ill mess around with and do some serious hardware hacking on that. I was tying in with the dev's and requesting some features but they have gone in the CAN direction. I personally wanted I2C, but struck out. Did some digging around on the hardware specs which were made available, and i found out what i can do. So ive already designed a hardware hack (physically altering pins and traces on the CPU and associated board) before i even saw it.. I know what i gotta do, but need to physically grab one.. Ill do that in the next 3 weeks or so. The guy who wrote Megatunix is hosting the video on youtube.

Id also like to quickly add that megatunix has a win32 port which works great. I was testing that with him for a fair while too, but i run linux on this machine (laptop) so much of that dev has stopped currently.

It will allow MUCH more options. Im planning on implimenting what i call "conditional" tuning. I want to add a linear (telescopic) gauge for the front forks. So it can measure when the front wheel is off the ground. When the gauge is at full extension, obviously your doing a wheelie.. When its at full compression, your braking REALLY hard. Useful for anti wheel and launch control. That matched with about 5 other sensors should yield some interesting results.

Wiring is a nightmare. I started doing it clean, and just gave up cos i had to alter quite a few things. Ill be making a nice clean harness which will hide quite well.

The throttles.. Ugh.. They gave me some shit.. Turns out, the head HAS been modifed. The bolt pattern for where the adapters bolt on, i had to build up some weld, then drill and tap a new hole. Other than that, it is indeed stock.
I had to remove the IAC.. Idle air contoller. Thats the thing which brings the revs up when the bikes cold.. "Auto choke" if you will. Its a solenoid which opens up a bleed hole to allow air in UNDER the butterfly. More air = more revs. Simple. The computer knows to put more fuel in too while its in "warm up" mode. All controlled by the stock temp sensor which im reading off.
The throttle cable on the stock TRX WILL NOT FIT.. For anyone who has looked at their carbs, notice the cables pull from the front of the carbs ? Well, the TDM throttles pull from the BACK side. Im currently using FJR1300 cables. Couldnt find any TDM ones. All yamaha share the same style throttle cables. The FJR one is like 120mm longer. Im currently only using the "accel" side of the cable, its all i need with the way i set it up.

My idle is a touch high atm, not sure why. I have a few ideas, but not had a chance to investigate any of them.

My left cylinder (cyl 1), STILL gets hotter faster than cyl 2.. No idea why.. Its just one of those things i guess. I honestly thought EFI and spark control would remove it. Weird.. May look into it one day.

O2 sensor is a nice "wide band" model. It returns an actual ratio rather than a "too rich" or "too lean" signal.. It tells you by how much. Great for tuning.

IM going to fabricate an alu airbox at some stage. Ill settle for pod filters in the mean time. Im going to investigate the effects of "ram air" thru the head stock. Gonna be some huge ass fibreglass fabrication but nothing i cant really handle. Getting the ducts in may be an issue, so may end up re-doing the front end of my bike.. And by that i mean "cut off the head stock and fabricate a new one".. Will also be good for trialing different trail angles. Big project, but not really to complex. Just time consuming.

I think with a nice exhaust (which ill fabricate) and the mods ive done.. I may be able to hit 90hp.. Or around that mark. With cam and what not, obviously more. Wait and see.

Whole thing so far has cost me ~$1500 AUD. That money includes:
MS2v3 ECU + 4bar MAP sensor
Throttles (TDM900) and FJR1300 cable, alu slug to make the trumpets out of.
Rolls of wire (5 colours) and a bunch of crimps.. Already had solder + iron.
WBO2 sensor
2 Iridium spark plugs, coils + leads (silicone doody whats-its..)
Cyl head + cleaning, lapping paste, valve spring compressor, etc.. Technically theres a cost in the parts and what not.
Sundry (few new stainless screws, orings, etc..)

This price DOESNT include my labor costs. But if you could do most of it yourself, and you KNEW what to do, you could get away with it for around $1100 AUD id expect. Depends how much you can scam free things via mates. Incidently the water blasting on my head was free, the plugs i got at cost price (mate works in the shop), as were most of the sundry parts, including FJR cables.

Summary is this: Am i happy with the result ? Partly.. It needs MUCH development and i need to redo HEAPS of it.. Whole subframe, whole wiring harness, make a proper airbox, etc.. Happy that it runs and "works", annoyed that i have to do stacks on it to be satisifed. Incidently, im not easily satisifed. But you guys / gals prolly knew that.

Was it easy ? Mostly yes. There were some bitchy parts which sent me insane, such as why a relay needed to be "flicked" to work (fuel pump).. Turns out it was a dud flash on the ECU.. Triple checked EVERY connection from the battery, and manually connected the battery to the pump, etc.. 2hrs later i learnt the flash i used was screwed. Most annoying. Incidently i submitted a bug and got it fixed (Megatunix / DJandruczyk - the creator). I dont find this stuff hard at all. Obviously is my job (to some extent.) So its more "time consuming / tedious" than anything. Trying to maintain a family (i have 2 kids now, one is 7weeks old as of this post) its why i had a huge ass delay,, etc.. Plus doing crazy work stuff. No submarines anymore, im now onto power station turbines and boilers.. Ugh..

Would i do it again ? Only if someone paid me. Now that i know what im doing, no biggie.. Would I provide a "kit" ? yes. If there was a need. Im not in this for profit, im in it to share knowledge and help others who want.

Am i insane ? Not sure, ask my wife / therapist.

QT wrote:Am i insane ? Not sure, ask my wife / therapist.

Insane, yes, but in a good way. Awesome work mate. I would like to say I understand more of it but I'll just settle for appreciating it instead.

Stu99 wrote:

QT wrote:Am i insane ? Not sure, ask my wife / therapist.

Insane, yes, but in a good way. Awesome work mate. I would like to say I understand more of it but I'll just settle for appreciating it instead.

what this guy says - havent a clue what you are at - but i know it is awesome!! hats off to you!!

This is incredible, but I'll stick with these



and this



I'm in total awe of anyone who understands how electronics work

That's brilliant! Seems like a lot of work for 90HP though... Still very cool.

I suspect it will also alter the way the engine behaves, & how it gets the power down substantially?

Which wideband sensor did you use? (I'm looking for a Bosch LSU4.2 at the moment for an air fuel gauge project, don't know where I could pick one up for peanuts do you?)

Cheers!