backwoods yamaha

[Anonymous]

where is our combustion engineer and our heavy mechanic?

they are letting us down LC

Re: the range of movement of a spring. my source does spend a lot of his weekdays with professional dirt bike riders. but he is not an engineer and i did say the info was sus. his passion for dirtbikes sometimes exceeds others reality

[Anonymous]

Moto wrote:

Quote:

:huh:

i’ll explain with your bike and a stick in the dirt on our next ride

[Anonymous]

Its basically explaining the pulse tuning and scavenging effect that I talked (argued) about before with Ktmrat. I posted the :huh: as it went off at a tangent to the discussion of springs etc.

You have since followed that up by stating that your friend appears to have the ability to halucinate without the use of drugs. I therefore surmise that maybe what he saw was the shock movement from a parrallel universe where everything is in fact the opposite causing, in this case, the spring to expand radially as opposed to compressing vertically :laugh:

Hopefully in said parallel universe things are the opposite and TB isn’t a jibbering, post whoring mole and women don’t wear bra’s

[Anonymous]

a few weeks ago i visited a spring manufacturer. i wanted a spring made for the thumpstar. while i was there i took to opportunity to ask some long unanswered questions about springs. they could not anawer them. “duh we just copy the ones the customer supplies”

i took my business elsewhere

[Anonymous]

That’s because there are people who just copy springs and then engineering companies that deisgn and make springs. You visited the first in pursuit of a spring for a pit bike.

I resited the urge to put another :huh: in this post :p

[Bruce CurtisMember]

Champo has fairly well hit the nail on the head with 2T pipe design, a 2T without a tuned for purpose pipe is a whipper snipper, even racing chainsaws get tuned pipes, all old hat now, champo match the longer stinger with a shorter silencer and your power will come on sooner and with a better torque taper/curve.

4T pipe design is childs play in comparison, think to a chev small block, the most coomon 4T performance enhanced engine in the world, short primary tubes with a larger I/D give more help to the upper rev range but at the expense of throttle response in the lower portions, we used to call these “extractors”
Longer primary tubes with a smaller I/D meeting into a collector (powerbomb is just this) then into tuned length pipes give better throttle response through most of the rev range increase torque in the lower 3/4 of the rev range and are more expensive, we called them “headers”, the only time this really becomes moot on a non 2T is on Rotaries, where the engine is really a 4t, but reacts to exhaust pulses like a 2T as it has ports and no poppet valves. I would be interested to see Mr TB sir if the old 2T GM engines and double knocker commer motors would have responded to a tuned exhaust.

What yamaha has done here is not new technology at the basic design, they and others have done this before on race and road bikes, but it never filtered to dirtbikes as a buying public we don’t accept change as well as the other discliplines do. the shock maybe prone to over heating issues with the exhaust but like the old RZ500s of the 80’s (yes I owned a few, whaddya reckon I’m a 2 Stroke bloke just recently!!) heatproof wrap keeps it under control.

I believe yamaha has gone back to 4 valves may be a backwards move in overall performance potential as the 5 valve heads tend to help with the “electric motor” power delivery most is their 4T signature style, but maybe there were gains enough in other areas that suited the 4 valve layout, maintenance wasn’t much of an issue as the 5 valve layout came out in the late eighties on the streetbikes and they last longer than the honda Hi-Po 4 valvers.

I will be trying to get a test ride on one as soon as I can sweet talk the local (moneyprinter) dealer into it when they come in, as I am actually quite excited about this and the Hussy layouts.

BC

[GregMember]

Moto wrote:

Quote:

You have since followed that up by stating that your friend appears to have the ability to halucinate without the use of drugs. I therefore surmise that maybe what he saw was the shock movement from a parrallel universe where everything is in fact the opposite causing, in this case, the spring to expand radially as opposed to compressing vertically :laugh:

Just the fact that Champo put the post up about the spring leads be the believe champo is using what his mate isn’t :laugh:

TB

*I in no way think champo takes any sort of drugs illegal or other wise is a joke :laugh:

[Anonymous]

I want a shorter pipe for little KTM200 to imporve the bottom end. Tyne needs it be really snappy and torquey :laugh:

[Anonymous]

Moto wrote:

Quote:

I want a shorter pipe for little KTM200 to imporve the bottom end. Tyne needs it be really snappy and torquey :laugh:

no, tyne would want a longer pipe for more power at lower revs

[GregMember]

champo35 wrote:

Quote:

Moto wrote:

Quote:

I want a shorter pipe for little KTM200 to imporve the bottom end. Tyne needs it be really snappy and torquey :laugh:

no, tyne would want a longer pipe for more power at lower revs

I think thats what the :laugh: was for Champo

TB

[Anonymous]

Re: springs. i have 3 shocks with evidence of unwanted spring flex. the shock bodies have marks on the where the spring has contacted due to flex. i reckon this can happen on my elsinore just due to riding over rough ground. the springs in the elsinore forks would be in constant contact with the walls. also give your bike a rev in the garage and watch the spring. unwanted spring flex exists

therefore i’m not going to join in and accuse my mate of any dishonesty or stupidity. he does not work with yamaha or james stewart. and i don’t think that yamaha would do a press release on this. so his information is chinese wispers.

but i do reckon that if you had and exhaust too close to a spring, it is possible for contact.

i like what yamaha has done

on topic but in a new direction.
i hope the seat on the yamaha does not get too hot for wr use

[Anonymous]

Trailboss wrote:

Quote:

champo35 wrote:

Quote:

Moto wrote:

Quote:

I want a shorter pipe for little KTM200 to imporve the bottom end. Tyne needs it be really snappy and torquey :laugh:

no, tyne would want a longer pipe for more power at lower revs

I think thats what the :laugh: was for Champo

TB

i think so too. but people may read this and get confused by that.

[Bruce CurtisMember]

Now you’ve confused me Moto (easy to do, it’s the Scots in me) you want your dearest and most cherished significant other to learn on a bike that has “instant” throttle response that becomes a nightmare in S/t for the novice… or am I getting it wrong and it is YOU that wants it to be snappy and crisp, or the smileys are going over my bald dome and it’s all tobgue in cheek?

Look at the pipe design on an enduro 2t versus MX 2T, especially the Gas gas versus say a SX250.

BTW how did a thread on a most innovative 4T become a discussion on anything but?

[GregMember]

champo35 wrote:

Quote:

Re: springs. i have 3 shocks with evidence of unwanted spring flex. the shock bodies have marks on the where the spring has contacted due to flex. i reckon this can happen on my elsinore just due to riding over rough ground. the springs in the elsinore forks would be in constant contact with the walls. also give your bike a rev in the garage and watch the spring. unwanted spring flex exists

therefore i’m not going to join in and accuse my mate of any dishonesty or stupidity. he does not work with yamaha or james stewart. and i don’t think that yamaha would do a press release on this. so his information is chinese wispers.

but i do reckon that if you had and exhaust too close to a spring, it is possible for contact.

i like what yamaha has done

on topic but in a new direction.
i hope the seat on the yamaha does not get too hot for wr use

Hang on compare apple V apple, how thick is the spring on your twin shock 1975 honda against the thickness of a late model single shock spring Chalk and Cheese and the lack of preload on the springs of your 1975 bike would be half of that on a shock for a late model single shock bike of course they would vibrate when rev’ed with half the preload, remember we started talking about a late model single shock Also all long fork springs contact the tubes, all of them I am told, they dont have the tension, support, or size that stop them from doing it

Its Chinese whispers alright and you need to relax no one accused your mate of any dishonesty or stupidity just make a joke about it and the posting of it champo its all good, healthy chit chat

TB

[glennMember]

I`m first to admitt i dont know the front of a bike to the back of one, so maybe someone can help me here,, I notice the yz cutaway shot of the tank shows the internal fuel pump I think,, how would this hold up to the rigors of motox and trail riding??

[Author]

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