Yamaha TRX850 Enthusiasts Forum

hi every one, I have done the cylinder head crankcase of our beloved TRX on solidworks in my effort to draw all the bike in this awsome mechanical software. For me this is one of the parts harder to do on solidworks and I´m happy to get finished. I have done other parts of my Tixie but this is the part that has cost me more work to make it. I´m taking sketches now from the camshaft and the rest of the head parts to complete assembly. I hope you like it. http://thetrxproject.blogspot.com/2009/ ... -on-s.html






P.D. Excuse my english here and on my blog.

DrSlumper wrote:hi every one, I have done the cylinder head crankcase of our beloved TRX on solidworks in my effort to draw all the bike in this awsome mechanical software. For me this is one of the parts harder to do on solidworks and I´m happy to get finished. I have done other parts of my Tixie but this is the part that has cost me more work to make it. I´m taking sketches now from the camshaft and the rest of the head parts to complete assembly. I hope you like it. http://thetrxproject.blogspot.com/2009/ ... -on-s.html






P.D. Excuse my english here and on my blog.

Amazing! Very well done!

Awesome

Very well done

Bob

Hats off to this gentleman..I can appreciate someones time and effort to the understanding of the fine tuning of such a wonderful piece of engineering in the TRX..

Excellent work, what a magnificent effort

I work as a design draftsman and do a fair bit of 3D modeling as part of my job. Unfortunately it's all heavy industry and not the cool mechanical stuff like motorbikes etc. I know how long it takes to model stuff up and to see the amount of detail you are putting into this project is impressive to say the least. Much respect to you Doctor. I looked through your portfolio and you obviously have a talent and passion for it. I know it's the last thing I feel like doing when I get home so I get the comments on being to tired to do it.

I see you make mention of the 5 valve head. Others here have commented that it's less efficient than a 4 valve head. What are you comments on this?

Again, top work on the modeling.

devlin wrote:I work as a design draftsman and do a fair bit of 3D modeling as part of my job. Unfortunately it's all heavy industry and not the cool mechanical stuff like motorbikes etc. I know how long it takes to model stuff up and to see the amount of detail you are putting into this project is impressive to say the least. Much respect to you Doctor. I looked through your portfolio and you obviously have a talent and passion for it. I know it's the last thing I feel like doing when I get home so I get the comments on being to tired to do it.

I see you make mention of the 5 valve head. Others here have commented that it's less efficient than a 4 valve head. What are you comments on this?

Again, top work on the modeling.

I second that, pure amazing!
....5valve, isn´t it only fuel efficient....??

devlin wrote:I work as a design draftsman and do a fair bit of 3D modeling as part of my job. Unfortunately it's all heavy industry and not the cool mechanical stuff like motorbikes etc. I know how long it takes to model stuff up and to see the amount of detail you are putting into this project is impressive to say the least. Much respect to you Doctor. I looked through your portfolio and you obviously have a talent and passion for it. I know it's the last thing I feel like doing when I get home so I get the comments on being to tired to do it.

I see you make mention of the 5 valve head. Others here have commented that it's less efficient than a 4 valve head. What are you comments on this?

Again, top work on the modeling.

A lot of thanks for all your comments and about my opinion I think that 5 valves its better than 4 valves because use better the surface of the combustion chamber and better mixture air/fuel but this number of valves had his negative thinghs, like more mobile parts, expensive machining/verification/mounting/maintenance than 4 or minus valves, and maybe more oil consumition. But I think that the principal reason for the manufacturers to do or not 5 valves engine is the costs of manufacturing. But this is my opinion.

Written this I remember one book where talk about this.



Multivalve engines from Gert Hack/ Fritz Indra. I have a Spanish edition of this interting book where I can read this: (Translated to english for me)

"...at the begin of the 40´s of the past century the catedratic Eberan von Eberhost , old builder of the Auto Union race cars , was working around the number of valves in a scientific research of the technic university of Dresden (Germany). Then the conclusion was as follows: from a geometric theoric point of view 4 intake valves and 3 of exhaust (7 valves) use the better form the surface but in a trial done in a test banks reveal that the 3 valves for the intake and 2 for exhaust offers the better results...."



This texts and others that I read in others books, forums or with a friends are the reason because I prefer 5 valves than 4, 3 or of course 3.

You remember the 90´s state of art engineering bike from Honda the NR750 with oval pistons, two spark plug78 valves per cylinder







Thanks a lot again for everyone and I apreciate a lot your comment Devlin.

Yep,remeber it well,saw it raced quite a few times too,showed lots of promise but it was prohibitively complex and expensive to manufacture and keep running reliably.
Sounded great though!
The 5 valve thing?
It`s got it`s good points,efficiencies and such like but the inline fours and v8`s in moto gp and formula one give the casting vote,if 5 was better than four they would be using it for sure.

Mincehead wrote:Yep,remeber it well,saw it raced quite a few times too,showed lots of promise but it was prohibitively complex and expensive to manufacture and keep running reliably.
Sounded great though!
The 5 valve thing?
It`s got it`s good points,efficiencies and such like but the inline fours and v8`s in moto gp and formula one give the casting vote,if 5 was better than four they would be using it for sure.

Surely you are quite right, but this kind of race engines had a higher rev range of work.Maybe I think that perhaps influenced by my love of "strange" engines (I love the Wankel engines, the Desmodromic engines from Mercedes and Ducatis, the boxers from BMW bikes, subarus or porsches....). Other reason because Moto GP or F1 don´t use 5 valves engines can be that to get high compresion ratio the 4 valves distribution helps the shape of the combustion chamber better than a 5 valves. Regards.

P.D. Excuse again my english for my is a hard work write in english.

No need to apologise DrSlumper,it`s a darn site better than my own feeble attempts at any language other than English,I`m certain we`ll all understand fully.

My TRX cylinder head on solidworks has been selected to the top ten models of the week 32 on 3dvia.com If you want know more click here.... http://thetrxproject.blogspot.com/2009/ ... p-ten.html.

Very impressive and well done for the top 10, now for the number 1 slot.

Dave E

devlin wrote:...you make mention of the 5 valve head. Others here have commented that it's less efficient than a 4 valve head. What are your comments on this?

Empirical testing might give an answer; but for the time being armchair reasoning will have to do! What is the rationale of the five-valve head? Well, typically, in both two-valve or four-valve heads, the inlet valves are bigger than the exhaust valves, for the obvious reason that exhaust gases exit easily under pressure, whereas, unless the induction is pressurized (by a supercharger, turbocharger, or even simple ram-air), the fresh fuel/air mix is drawn in by a partial vacuum.

An engineer chooses four valves rather than two for dual advantages: (i) better volumetric efficiency; and (ii) higher revs are possible (and therefore more power is available) if the reciprocating valves weigh less. BUT, since the inlet valves are bigger than the exhaust valves, it is the higher mass inlet valves that limit maximum revs...

Enter the 5-valve head. With three inlet valves and two exhaust, not only should volumetric efficiency be good; but also, since all five valves have similar (small) size and mass, the maximum rev limit (and maximum power) should be greater. Small valves are not only shorter than bigger valves, they have a shorter travel, and the cams are smaller; and all this means that the valve gear can be more compact. The argument for a five-valve head seem impeccable; and even if it is marginally more costly than a 4-valve head, this expense is a small proportion of the cost of the whole bike.

The 5-valve single engine in the Yamaha XT660 and the MZ Skorpion shows that the concept works well and reliably. Just one thing: if really high revs are not the ultimate aim, and if mid-range power is the target, then why not settle for a 3-valve head? A 3-valver has a ratio of inlet valve area to exhaust valve area of 2:1, which is better than the 5-valver's ratio of 3:2. Ducati, having introduced first the ST2, and then the ST4, finally abandoned both for the ST3 that provided a sensible compromise of performance, reliability, and cheapness. It follows that the TRX could probably have done almost as well as a 3-valver!

In another context, I used to have a Citroen Xantia 1.9 with 2 valves per cylinder; and I upgraded to a 2.1 Xantia with 3 valves per cylinder (both turbodiesels). The 2.1 litre engine has 15% more power and 25% more torque than the 1.9. QED?

Finally, I read in a recent Motor Cycle News that a firm claims to have perfected the rotary valve design, resulting in better volumetric efficiency, better fuel/air mixing, an escape from the reciprocation of poppet valves, and a VERY compact cylinder head. BMW, who have just announced a 4-valve dohc version of its boxer twin (!) might have done better to use such rotary valves and reduce the engine width by eight inches or so!.