The ground up yz/wr/xt/tt adventure build

[yamahaman]

So I got home and put the back end together and was putting some thought into the fuel tanks??? yeah I got a rear sub tank and I was messing around with the set up of the bike and I put the ex-army main tank on the bike and it looked absolutly terrible! SO BAD I DARE NOT POST PICTURES. I started to mess about with some wr tank shrouds and I think I am going to make my own tank out of aluminium (this is my vanity) using the shrouds to make it look pretty.



Yeah its a pretty poor representation of what im going to do but computers are not my speciality



Here is the rear end set up for the big girls long distance rig any input for the tank setup would be appreciated

[a1fa]

[andyhol]

this mate is way TOO SEXY for its own good. i wish i had a bike this when i was working up north chasing cows through the bush............

[PhiSig1071]

Your work up to this point looks amazing, but I have to ask, what's with the exhaust can mounted pointing up like that? I've seen it on Rally bikes, but I would think it would create problems. To me it would be more prone to collect water, harder to expel water and it would have a lot more bends in the mid-pipe, which would reduce exhaust flow. What am I missing? Obviously there's a reason for it.

[mtothef]

Originally Posted by yamahaman

Here is the rear end set up for the big girls long distance rig any input for the tank setup would be appreciated

go on, run a low pipe, you know you want to!

[yamahaman]

Originally Posted by PhiSig1071

Your work up to this point looks amazing, but I have to ask, what's with the exhaust can mounted pointing up like that? I've seen it on Rally bikes, but I would think it would create problems. To me it would be more prone to collect water, harder to expel water and it would have a lot more bends in the mid-pipe, which would reduce exhaust flow. What am I missing? Obviously there's a reason for it.

The exhaust is here because when it is more parallel to the ground it is very vulnerable to crash damage, when it is here and you lay the bike on the ground and it contacts the ground in a more even manner



When the pipe is low and parallel to to the ground to clear all of the swing arm and pivots it protrudes ou too far and the end of the pipe is way past the rear axel. Just looks weird, wobbles heaps and is vulerable to damage


Oh and I like the way it looks!


Off to see crowded house tonight at rod laver arena

[PhiSig1071]

Gotcha. I figured there was a reason, just couldn't figure out what it was.

[BIG ED XT FAN]

[trackhead]

Originally Posted by mtothef

go on, run a low pipe, you know you want to!

When people do the low pipe thing, does it change engine tuning or back pressure dynamics at all?

[mtothef]

Originally Posted by trackhead

When people do the low pipe thing, does it change engine tuning or back pressure dynamics at all?

there's a lot of variables in response to your question. ideally, the pipe routing shouldn't make much of an impact on pipe tuning at all. theoretically, a straight pipe with no bends at all in it will be the most efficient at getting exhaust from the valve to the other end of the tailpipe, but if the bends are done without kinks or sharp changes it has been proven that some mighty twisted spaghetti bowls do a fine job as well.

header pipe diameter has a huge impact on tuning - larger headers generally allow better wide open throttle behavior, but usually at the expense of lower rpm power and throttle response. smaller headers, within reason, do the opposite. total length of the pipe also has some impact on tuning, as does how much the pipe widens or constricts at the muffler end of things.

my reasoning for going with a low pipe was purely about looks. if anything, i have lost some power, and am in the midst of jetting it back into the right ballpark.

[yamahaman]

So a bit of a set back with progress due to my teething daughter but nevermind I wouldnt have it any other way!


I Have mounted the rear subframe leveled and trued it to the frame so it is at 90 deg to the frame. I cut some strips from a sheet of 1.9mm mild steel sheet to make the lower mounting tabs for the sub frame. I shaped them and bent them to suit the first contact point on the frame. Once this was done I tacked the first contact point on the top and bottom of each tag. Then I heated up the tags cherry red and with a small hammer dollied them around the tubes to match them with the frame.




So now I have also tacked the top tube where the top bolt mounts to the frame.

The whole rear end is tacked in it final place and nearly ready to have some permenant welds done.



When I put the seat on this is very stable and the seating position is quite comfortable.

The other thing I compleated was the mount for the Future navigation tower I bent Some more 1.9mm sheet and then ran it through the mill to make sure the whole fitting was parallel because benders tend to stretch the sheet and in order to make sure all is good a quick pass in the mill has done the trick. I have only just held it in place with one rivet so I can get it level vertically then I will tack it. When I go to do the final weld I will clamp a straight edge to the top tube and use an engineers square to make sure the front of the bracket is flat across the front of the bike to mount the future hedlight assembly.



I plant to fit ferrules to the holes in order to increase the bolt area maximising stength in the vertical plane

[a1fa]

What kind of geometry is that?

[yamahaman]

Originally Posted by a1fa

What kind of geometry is that?

Not sure of the question but I think what yor asking is to do with the correct rake and trail of the fork and the angles of the linkage and the shock relationship.

If the fork is too steep this will make the bike awsome in the single track (slower speed & tight and windy) But it will make it unstable/suseptable to head shake at higher speeds. On the otherhand if you have the fork raked out (like a chopper) to much it will make the bike stable at speed but turn like a boat at the slower stuff. Hence a happy medium must be found to make the bike complient in a range of terrains

The other part to all of the geometry is the shock, swingarm and linkage ratios. If you change all of this too much you may have a situation where the rear wheel progression through the stroke will be affected. This will change the leverage on the shock causing problems with the valving in the shock. Solution Copy somthing that works already. All points were transfered across from another bike.

[yamahaman]

I was out walking my crying, drooling, teething daughter and I walked past a small bike wreckers and I spotted a tank hanging up in the window so I went back today and took the rolling frame to shop to check for a rough fitment and low and behold it is not to bad. Forked out the cash (bit too much) went back home to cut an old tank bracket off and play with some fitments. Turns out this acrebis tank is no longer made and as rare as hens teeth not to mention that it is brand new and never been fitted.



The red is not my first choice of colour but this just means that the bike will end up with a red/white or a red/black colour scheme. Any surgestions?

Apparently this tank is 4.1gal/18 l can anyone give me a clue as I am finding conflicting info as to its capacity?



A front end like this and we should be all good

[yamahaman]

Well I was at a mates place and we got talking about the dr650 back wheel and how it is very close to the ktm wheel and we sumised that the dr wheel had to fit the yz rear end so off I went to find a suitable set of bearings.

First hurdle the closest bearing to put the yz axel into the dr hub is an odd ball 47mm OD and a crazy 7/8 inch ID this puts the metric ID at 22.22
This is more than a loose running fit, not acceptable, so I had to fit some brass shim to take up the slack this worked ok for now.

I then had to make a few new spacers to put in the wheel no worries. Fitted the wheel up and low and behold the dr wheel is only 3mm narrower from inside disk to inside sprocket than the yz wheel, so if I make the internal spacer again 3mm wider and trim some off the two outer spacers the wheel will fit up to the yz rear end with no problems. If I get a dr wheel to run as a cush rear for this project (heaps cheaper option) I will re-lace with an 18 inch and change the offset to suit the whole setup

Can anyone help with a metric bearing 47 x 22 x 14 this bearing is not listed here at my bearing wholesalers but it has to exist I just know it does