Stock TRX850 head data *caution LOTS of pics*

[Quan-Time]

That side radiator thing is actually a really good idea. Ive thought about it for the TRX. Hows the heat i wonder ?

Id like to see still 850cc, but shorter stroke and bigger bore. So like a ~900cc piston, but shorter stroke to bring it back to 850cc total. Could reduce the height of the motor, thus aiding sparkplug fun. Im torn over 5v VS 4v heads.. Could go either way. EFI obviously, 6 speed box, USD forks, nice swingarm (YZF braced version) and maybe a slightly bigger wheel, but its honestly quite good for what it is.

I like the twin exhaust how they are, BUT id probably make them much shorter and smaller. Similar to the suzuki's current after market stuff.. Twin pipes, but more "tidy" looking.
Obviously still naked.
Nice big single headlight, not a huge fan of the twin style.. Ram air if possible, nice tacho / dash setup.
If your going to have a huge ass rear end, make the glove box a useable size ! Else try to stream line that sucker and make it sleek. I like how bobtrx / stu99's look. Quite clean and tidy.

Magnesium rocker cover and side covers, id try to lighten the internals a bit, bump HP up to around 100ish. With a shorter stroke it will rev to ~12000rpm but still have a nice bark / twin thump, but get a real nice scream going on.

Id also fix the "useless" stock mirrors and give it something decent, and put indicators in those too. Plenty of technical other stuff, but arrivisto fairly much nailed it honestly.

[slow codger]

Ok Quan, as the technical guru, aka clever sod, chain drive, or shaft driven? I accept weight gain for the shaft drive.

Dave E

[Quan-Time]

belt drive anyone ? HD / Buell..

Shaft is REALLY cool imo. Maint side of things you just cant beat it. Yes it takes a bit more power from the drive line, but realistically, thats not a huge deal on a 150+hp bike that weighs 200kg.

Chain is obviously lighter and really good on maintenance side of things, service wise. Saying that, they need more of it in comparison. Chain tech is fairly much at its limits on what it can do. Break strain, flex, weight.. etc. Take a Motogp bike chain for example.. They weigh 2kg (4.5lb ?) and have around 4 ton break strain. Flex is awesome and they just cant get em any smaller. Different pivot pins provide some shear strength, and the thickness of the side plates add to rigidity + more strain. Many experiments have been done and its hard to develop much further.
To my knowledge the only real development going on now is different shaped seals to trap oil in longer, which helps service life. The speed these things rotate at, it flings oil / grease out REALLY fast.. So different seals to try and hold it in without sacrificing total power potential.

Belt drive is old but damn effective. Screw blowers on top fuel drag cars still run belts, not gear or chain. These guys wrestle over the SMALLEST power gain and lash, so there has to be something in it if these guys use them. OBviously rules play a part, but rules can change easy enough if ppl all vote on something.

I believe shaft is hugely under rated. Not sure how well it would go in a "power" bike, like a hyper sports, etc..

Saying all this, Ducati asked what people wanted on the 1098, the huge resonating answer was "single sided swinger".. And they did it. Took quite some research im told to make it "good", but its possible. Now imagine if your favourite motogp rider came out with shaft drive, wouldnt everyone start bitching and complaining to manuf's to get it ? Big-bang yammy's anyone ?

The 2 biggest issues today, in my mind, is front suspension, and rear swinger setup. In that order. MANY people are setting up and taking note of hossack front ends, and im not surprised it wasnt tested in moto2 tho.. A few teams made bikes with it, none got in. Even the old Tony Foale was approached for making a frame, he made one, and it was quickly abandoned as it wasnt a twin-spar setup. Yes there is a few trellis frames in moto2, but its more "stick with what we know works"..
Id rather see a development class, thats the whole point of prototyping !. Hossack front end, new style swinger / shaft drive, etc.. would really shake things up.
Vyrus anyone ? How about a Britten ? Motocycz ?
These are companies which think out side the box and REALLY started going places, and got shut down by big business.. Sure britten got up there, but he struggled like anything to do it.

Its hard to convince main stream to change if they dont see their favorite racer winning on it. Imagine if stoner / pedrosa / rossi were given a prototype front end from ohlins, which was "different".. but they got a podium finish.. Think others would start investigating in that area ? you bet my white ass they would. BUT if they loose (which inevitably they WOULD for a few races) everyone would laugh and say "stick with what works"..
Tele-forks have had 50+ years of development in top end racing. People stick with what has data / info..

Id try a shaft, only because i think its a freakin awesome design. You can make them surprisingly small too.. Would look trick if you wanted.

[arrivisto]

I'd try a shaft, only because I think it's a freakin' awesome design.

Historical note: it can be a freakin' awful design too! The Sunbeam S7 & S8 bikes had shaft drive with a worm-gear at the back axle. Yes, a worm gear, as used in steering boxes because its main characteristic is that it is happy delivering power from the worm to the cog, but not vice-versa. So every time the Sunbeam was on the overrun, the cog would grind away at the worm. When you changed the oil, it was full of bronze particles in suspension. Obviously, no one would dream of using worm drive today; but how did Sunbeam's dreadful design ever get beyond the drawing board?

Great though shaft drive is for low maintainance, I'd prefer either to stick with chain or to try a belt. (My TRX has done 13,000 miles and I have only had to adjust the chain once; so for me a chain has been entirely satisfactory. I spray lube it before each major trip, and the chain gets lubed constantly when riding. But I am going to modify the hugger to put a wall between the wheel and the chain. A hugger should not merely keep the yellow spring pristine, it should also keep road crap off the chain).

Belt drive is old but damn effective.

A Kevlar-reinforced toothed drive-belt can be almost as compact as a chain, and would do the job cleanly, quietly and efficiently. The Hesketh V1000 had a very good feature: the drive sprocket was concentric with the swing arm pivot. This prevented rear suspension squat when accelerating; and, being freed from tension variations, the drive chain could be somewhat smaller. Assuming the drive-belt is an entire hoop (without the equivalent of a chain's split link) the swing arm would have to be designed to allow easy fitment and removal; otherwise, in case the belt snapped whilst on the road, one would have to carry a split spare. A belt is more susceptible to cuts from road debris than is a chain.

[slow codger]

Simple answer for the Sunbeam, it was cheap and the S7/S8 put out about 25 - 30hp!!
Look at other british designs, as well as BMW's.

Lets be honest though , an S7 deluxe, balloon tyres and all day to get somewhere. (Yes the shaft drive could give problems, the brakes were useless, and lucas prince of darkness messed up the electrical components) still looks the business.

You forgot the Zenith gradua belt system with pulleys that could be widened and narrowed by winding a lever, bit like Daf used on their automatic cars in the 60's and 70's.

One other thing, if the drive to a shaft breaks up, it just makes a mess, If a chain snaps..................Crankcases, Ankle, crash!!

If the belt snaps.....................apparently its a fetish

Dave E

[arrivisto]

Lets be honest though , an S7 deluxe, balloon tyres and all, still looks the business.

True! I had a light green S7 with a Steib "rocket ship" sidecar. It looked fabulous!

Look at other British designs, as well as BMW's.

Another crazy British design was the Douglas Dragonfly: lovely air-cooled flat-twin (rather like a BMW R69) and ideal for shaft-drive .... and then they turned the output shaft through 90 degrees and gave it chain drive!

One other thing, ... if a chain snaps......Crankcases, Ankle, crash!!

I've never had a chain snap; but twice I've had a split-link come undone. (Moral; always carry a spare split-link!) No drama; the chain just gets dropped on the road and you end up with no drive. Why should a broken chain exit any other way, when all its momentum is fore-and-aft? Dirt bikes have a steel "horseshoe" in front of the drive sprocket to protect the crankcase in the event of a chain coming adrift. It wouldn't hurt road bikes to do the same.

[lenny]

Any updates on your head porting adventure Quan-Time? Would sure like to know how its going. What are your thoughts on the standard valve sizes. How far can you go before the standard valves become a limiting factor.

[Quan-Time]

Ah huh.. Theres is progress and much data

More info later when im available to post some info.. so maybe wait a week or so.. You may need to nudge this thread again at a later date. Ill get some exact numbers on the old head (stock) to show you what its physical limitations are in a "perfect" world. Ill have pics and stuff.

I may even show you whats possible.