Yamaha TRX850 Enthusiasts Forum

Hey... I'm not too sure about this, and searching here brings up nothing...

Has anyone heard of Yamaha using 'Selective Engineering' for the TRX?

As it was explained to me... the pistons, head, etc (basically all the close moving parts) were specifically picked and matched from parts with the closest matching tolerances, hence providing an overall matched motorcycle. This means that when something like the bottom end going happens, you have essentially two choices.... repair, or replace the entire engine as chopping and changing the major parts therein whilst it will work, will still be a backwards step from the previously 'perfectly/harmoiously' matched bike you had.

The guy I've been talking to is great, I really trust him... and he used to race TRX's, so he certainly has the knowledge... just find it odd that no one else seems to know and/or care about it.

Just wondering what other obscure knowledge is out there, and if anyone here has encountered any problems as a result of this selective engineering process?

Cheers.

as with any motor and system, if you rebuild one part of a major system, it puts extra pressure on the unimproved residuals.
for example, overheat your car-blows the radiator top tank:then fix the tank but dont replace the thermostat which is now been heat stressed=trouble.
reco the head=extra pressure on the older bottom end.
in essence, think of separate systems throughout the bike, and try to maintain a service harmony within them.
braking systems, cooling systems, drivetrain systems, electrical systems etc.
upgrade your lighting without relays=trouble.
you'd never renew only one side's bearing of a wheel eh.
food for thought.
cheers
fung

Selective engineering? Never heard of that one!
I`ve heard of many motorcycle manufacturers checking tolerances on components prior to using / fitting them together though.
This is simply good engineering practice but I would be very surprised if the Yamaha factory actually did that at assembly stage for the TRX.
An engineering tolerance can be quite `wide` to allow for expansion of materials, end float, clearance etc and when components are made you may have some parts at the upper end of the tolerance limits.
If you then use that part with another at the same upper end of tolerance you`ll have built in greater clearance from the beginning.
Standard practice is to `aim` for middle to top tolerance between components.
I take it you`ve heard of blue printing?



Blueprinting is the re-machining of components to tighter tolerances to achieve better balance.

Ideally, blueprinting is performed on components removed from the production line before normal balancing and finishing. If finished components are blueprinted, there is the risk that the further removal of material will weaken the component. However, lightening components is generally an advantage in itself provided balance and adequate strength are both maintained.

The above lifted from this Wiki page:

http://en.wikipedia.org/wiki/Engine_balance

I think your friend is talking about what he believes the Yamaha factory did, I`m not so sure.

I wondered if his friend was his friendly motorcycle shop proprietor.

buzzboi wrote:Hey... I'm not too sure about this, and searching here brings up nothing...

Has anyone heard of Yamaha using 'Selective Engineering' for the TRX?

As it was explained to me... the pistons, head, etc (basically all the close moving parts) were specifically picked and matched from parts with the closest matching tolerances, hence providing an overall matched motorcycle. This means that when something like the bottom end going happens, you have essentially two choices.... repair, or replace the entire engine as chopping and changing the major parts therein whilst it will work, will still be a backwards step from the previously 'perfectly/harmoiously' matched bike you had.

The guy I've been talking to is great, I really trust him... and he used to race TRX's, so he certainly has the knowledge... just find it odd that no one else seems to know and/or care about it.

Just wondering what other obscure knowledge is out there, and if anyone here has encountered any problems as a result of this selective engineering process?

Cheers.

I don't believe that for a second - for any motorcycle manufactuiring process (let alone the mass produced TRX)

What was that...oh sorry thats selective hearing..been around Janet all day

Did they select some tolerances to allow for burning of oil in certain bikes?

i am totally bamboozled with this burning oil problem so often spoken about.

never known it, an uncomfortable 3rd gear whine in my1996 --.90,000 kay ,early model motor made me change to a 99 model motor from a writeoff machine with low kays...all serviced with first a Castrol , a Penrite, and recomended Motul1500 10w 40-50 to all those oils and serviced around every 2 to 3.5 thousand kays...speedo showing 158,000 kays at the moment and going like the clappers...no fuel leaks from the origional fuel tap and no oil useage..quality fuel and upper valve lube mixed,...even though i service regularly, i would notice SOMETHING...eh?

What i am saying is, the motor that i have,.. should be what these detonating ones are as well...!
The TRX motor is NOT to blame..

Hi Alex

Don't get upset mate.

I was just pointing out, hopefully humourously, that a number of owners report some oil usage and if Yamaha had blueprinted, matched or hand picked parts for the trx engine then this may be less so.

Your defensive rant may help prove my point as it highlights a wide variation in oil usage in individual engines of all ages and mileages possibly suggesting a wide range of tolerances between parts from new.

Just a thought

Love and peace

Andy

That`s it right there, gaffer tape around the piston rings and a drip feed of WD40 for upper cylinder lubrication, that`ll stop your oil consumtion problems.
Mine burns oil on the overrun, she didn`t when I first got her but I tend to find the induction roar from the FCR`s to force my right hand to twist that throttle more often!

andyaber wrote:Hi Alex

Don't get upset mate.

I was just pointing out, hopefully humourously, that a number of owners report some oil usage and if Yamaha had blueprinted, matched or hand picked parts for the trx engine then this may be less so.

Your defensive rant may help prove my point as it highlights a wide variation in oil usage in individual engines of all ages and mileages possibly suggesting a wide range of tolerances between parts from new.

Just a thought

Love and peace

Andy

Hi there Andy...possibly a better use of Smiley needed by me...i wasnt cross..[ your direction to me correct]..however i am very stressed to hear of the problems people are haveing due only to neglect..[much to anyones reaction to a pure bred pet being seen beaten.]...cheers

[Hi there Andy...possibly a better use of Smiley needed by me...i wasnt cross..[ your direction to me correct]..however i am very stressed to hear of the problems people are haveing due only to neglect..[much to anyones reaction to a pure bred pet being seen beaten.]...cheers[/quote]


Hi Alex are you saying that neglect is the only cause of oil usage in the 5 valve motors and therefore owners experiencing this are guilty of neglect?

Is the trx (and we all love it) a pure bred pet or parts bin special and does that make any difference to how well it should be treated?

Just a thought

Love and peace

Andy

Mincehead wrote:built in greater clearance from the beginning.
Standard practice is to `aim` for middle to top tolerance between components.
I take it you`ve heard of blue printing?



Blueprinting is the re-machining of components to tighter tolerances to achieve better balance.

Ideally, blueprinting is performed on components removed from the production line before normal balancing and finishing. If finished components are blueprinted, there is the risk that the further removal of material will weaken the component. However, lightening components is generally an advantage in itself provided balance and adequate strength are both maintained.

The above lifted from this Wiki page:

http://en.wikipedia.org/wiki/Engine_balance

I think your friend is talking about what he believes the Yamaha factory did, I`m not so sure.

With my previous years of engine rebuilding experience, I was always lead to believe that to "BluePrint" any engine is to follow what the original design specification that is set out in the blueprint design of the engine. Modification of any component from this , would not be following the manufacturers "blueprint"..........

Stankflapper wrote
"With my previous years of engine rebuilding experience, I was always lead to believe that to "BluePrint" any engine is to follow what the original design specification that is set out in the blueprint design of the engine"

egggzactly.

blue printing is just an exercise to ensure that every part of an engine (or any mechanical device for that matter) complies precisely with the original design, no tolerances allowed.

Always made me giggle that rev heads brag about having an engine 'blue printed'. in 90% of cases it means nothing. in some it can improve things and even in some cases detract from an engine.

Given the spread of tolerances nessecary in modern manufacturing (invented by Henry Ford of the T model fame) you will get most engines out of a factory in perectly standard servicable form and you will get some below standard lemons and also a few cherries where the tolerances stack up exactly right to make an engine that is above standard.

"Blue printing" dont mean shit.

Tom R