An RZ350 gets dirty.

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tHEtREV

An RZ350 gets dirty.

Postby tHEtREV » Sun Aug 23, 2009 8:32 pm

Having nothing better to do this weekend I decided I had better start on my bike for Pezz's scrapheap ride.

I'm planning on taking my time on this one so it may be a while between updates.

Anyway on Thursday morning I went out to pic up the donor bike for the project, an old (86 model from memory) RZ350 rolling chassis that I picked up a few years ago and promptly did nothing with...
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Then I spent the night and Friday night stripping down to the frame.
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Saturday dawned to another trip out the iDIOT cAVE to collect some suitable suspension.
I wanted to keep it all Yamaha in the hope that it may minimize hassles in making parts fit, so that limited my choices to three bikes.

An old XT that was well past it's used by date, my DT that I have plans for, and the most suitable, an old WR200 that I picked up for a couple of hundred with the intention of rebuilding it.

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I had decided a few months ago that the WR wasn't worth the rebuild.

It was a pre compliance model so I couldn't get it registered, there was some severe bending and rust in the subframe, and the old owner was a completely incompetent when it came to maintenance.

So it lost its wheels, swingarm and front end, all to to aid in the creation of the two stroke dirt monster.
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And they were fitted up for a test fit.
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As expected there were fitting problems, but nothing major.

The shock mounting point is about 100 mm lower than it needs to be, so I have fitted a shock from a BMW 650 Dakar, that is the correct length for what I need, but the spring is so hard I could only get it to move a few mm by sitting on it and jumping up and down on it.

The swing arm is also a 10 or 20 mm thiner at the mounting point than the original, but it doesn't look like anything a few strategical placed spacers wont fix... And it will help with sprocket alignment anyway...

And the front end is going from ball bearings to roller bearings so the usual problems are there.

But it was a good start.
Today I was back out at the olds place to grab the original inspiration for the build...

My old bike build in a weekend bike, the RZ.
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And thats about as far as I got so far.

Hopefully I will get time to see if I can get the steering stem bearings during the week, and I'll start stripping to RZ's motor to give it a good clean.

I'm really looking forward to this. :twisted:

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Pezz_gs
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Location: Hills District - Sydney

Postby Pezz_gs » Sun Aug 23, 2009 9:58 pm

Gee tREV

Strewth that's putting the acid on . . . . . .

I wonder if I can find CRF450 Front end . . . . . .

Just put he 400 up on the stand to start puling the carbies out and do a compression test
Pezz :)
I'm not a complete idiot -- Some parts are missing

Visit www.scrapheapadventureride.com.au

Whitey
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Joined: Sun Dec 23, 2007 7:41 am
Location: Central West NSW

Postby Whitey » Mon Aug 24, 2009 12:53 am

I do admire you folk who have the skills and patience to rebuild a bike from not much more than a frame and two wheels. No way would I even attempt it.

Carry on... maybe I learn something.
8) 8)
Graham
'08 KLR650, '16 CRF1000L
My Pics

tHEtREV

Postby tHEtREV » Wed Aug 26, 2009 8:58 pm

Looks like I have the front steering stem bearings, but I have struck another potential problem.

While playing around with the swing arm I took to it with a tape measure to have a look at the rear wheel travel.

With the BMW shock in place I have an estimated 140mm travel.

total travel without a shock is only 180mm.

Does this sound like its not enough to anyone else or am I to used to seeing 300 mm wheel travel?

tHEtREV

Postby tHEtREV » Wed Aug 26, 2009 9:35 pm

Sorry, got interrupted before I could finish.

I was thinking 140mm may not be enough for a bike that has the potential to do 180+ Kph.

The main focus of this bike will be gravel roads and I doubt I'll trying much single track or jumps (besides the occasional cattle grid).

I'll have a look at the linkages to see what I can come up with, but I think it may require some surgery.

But just for reference, the standard RZ has 100mm travel, the KLE500 has 200mm, and the 650GS (the single, not the twin) has 160mm.

I'm not sure on the accuracy of those figures, I just did a quick search.

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Pezz_gs
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Joined: Fri Jul 17, 2009 11:54 am
Location: Hills District - Sydney

Postby Pezz_gs » Wed Aug 26, 2009 11:16 pm

tREV,

With Linkage suspension, Its simple maths but its not that simple.

I was corresponding with OldDog about ratio's on the rear swingarms of his Duc.

Its on the office computer. I will find it and post it here.

A twin shock setup would be much easier :wink:

Dont know where I could find a XL500S front end with 23" front wheel?
Pezz :)
I'm not a complete idiot -- Some parts are missing

Visit www.scrapheapadventureride.com.au

tHEtREV

Postby tHEtREV » Thu Aug 27, 2009 7:14 am

By looking at the linkages and seeing what I could come up with, I only meant the mounting point (where it mounts to the frame.

That seems to be what is holding it up.

If I take the shock out and let it sit at the lowest position it sits at about the same hight as a standard RZ (about 100mm more travel to go before anything interferer's with the rear wheel).

If I can move the mounting point back then (with the right shock ) I should get full travel.

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Pezz_gs
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Joined: Fri Jul 17, 2009 11:54 am
Location: Hills District - Sydney

Postby Pezz_gs » Thu Aug 27, 2009 9:49 am

There are two Ratios to take into account and 3 to 1 seems to be the magic number.

Spring ratio:
This is used to get spring rate correct. For Bills Ducati the 600mm swing arm and the 220mm bottom mount. Which was fine.

Dampening Ratio:
This is the ratio of the axel travel, 250mm in this case, and the shock shaft.

This needs to be less than 3 to 1, or the shim stack will struggle to keep up.

In the end Bill had to have his shock built 9mmm longer in the shaft travel to work effectively.
Pezz :)
I'm not a complete idiot -- Some parts are missing

Visit www.scrapheapadventureride.com.au


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