Recipe for dirt monster

[Wadester]

Some years ago, I spotted the Terra Mostro - a Ducati 695 converted to a dual sport machine:


I had always wanted a Ducati - and this was definitely my style. Sadly, I don't have the kind of money they wanted - and apparently they have also stopped the conversions (they didn't answer email asking if they would sell parts, and website is gone now).

Oh well, it's not rocket surgery after all.

So! First ingredient for Dirt Monster is:

A Monster!


I've been collecting information on the Terra Mostro and other successful Ducati conversions, and I'll be posting the measurements and choices as I go along.

[sailah]

Nice, that's my next conversion. I figure you could easily make a better bike than the Terra Mostro for way less.

I want to use the m900...

[Wadester]

Topic of the day: The front end.

Ducati head bearings are 35mm ID x 55mm OD x 14mm ht. This is absolutely true for my Monster, and from what I can tell this is the standard for most Ducatis.

For example, the Fork of choice for many conversions is from a Honda XR650R - a Kayaba 46mm non-USD.
Bearings are 26x47x15 top and 30x51x15 bottom.

Dirt bike bearing sizes are all over the place, but they're all smaller than the stock Ducati. Some adaptation will have to be done. Either a shim sleeve on the XR stem for the lower bearing, or a new steering stem. Looks like there's enough room for either way, but a sleeve will be easier:


The top is a different issue, but a 2 pc sleeve/collet would be a possibility.

The Terra Mostro did something a bit different - check out that top spacer:


That may be more about ride height and head angle than anything, but I'm not ready to figure that out yet.

[sailah]

Why don't you just use USD forks from a CRF450? They have a 30mm stem and the 30-55 bearing is available off the shelf.

I suspect that the reason they needed that large steering head extension is that typically the headstock length on dirt bikes is much longer than a sport bike. In order for the triples to grip the fork tubes in the right spot (on USD forks) you have to lengthen the headstock. I did on my CBR conversion, the Fz1 was minimal.

If you go non-USD forks that isn't the case asyou can probably grip the forks wherever you want. but the stresses from using the bike might be an issue. If you have access to a lathe, it fairly simple to make that extension, weld it on, and then brace it back to the frame. That's what I did at least.

[huzar]

I was wondering when you were going to get around to building the Monster.

[Wadester]

Originally Posted by huzar

I was wondering when you were going to get around to building the Monster.

It's so much fun to ride, I'm gonna have a hard time taking it apart! Meantime, making plans and buying parts. I currently have put almost as many miles on it as the PO did in his 2 years ownership.

[sunset_ryder]

You got my attention. Sally forth!

[Wadester]

Originally Posted by sunset_ryder

You got my attention. Sally forth!

Who you callin' Sally?

[Gummee!]

Originally Posted by Wadester

Who you callin' Sally?

Well, he ain't talkin to me.

Get on with it already! (so I know what to do too! )

M

[Wadester]

I knew I shoulda waited til I was done - but it's too late for that. Repeat after me: patience is a virtue. Patience is a virtue......

Anyways, here's a little triple tree separation comparison - Monster vs XR650R:



My! What long legs you gonna have!

Triple tree offset is not that much different:



So the additional offset of the XR front axle vs the centered Ducati axle will be mostly what I will be dealing with. And the change from 120/60 17 to 90/90 21 will more than make up for that loss of trail. Maybe I won't have to "pitch" the chassis to slack the head angle after all.

But I got one of these anyways:



Height adjusting strut to replace the fixed one - will need a longer center section to match the longer rear shock.

[Wadester]

Getting back - there is a bit of difference between the 160/60-17 and my DR's rear wheel at 130/80-18:



Lot's of room on the sides, but maybe the inner fender needs a little something:



Lot's of clearance at the front - not.



That was with the adjuster almost to the front, but still. A swingarm stretch is needed for clearance, even if I didn't want to balance the front extension.

[Wadester]

Originally Posted by sailah

Are you going to keep the stock swingarm or go longer?

Originally Posted by Wadester

Lot's of clearance at the front - not.



That was with the adjuster almost to the front, but still. A swingarm stretch is needed for clearance, even if I didn't want to balance the front extension.

There's your answer. I've found a couple of 695 swingarms cheap on Ebay ($42 shipped for one of them!) and will be making one out of the two. I need a minimum of 2" for tire clearance, but it looks like this approach would allow up to 5". I'll make my decision based on overall balance of the chassis.

[sailah]

I'm very interested in the swingarm and how you decide to section it up for extension.

I tried this on a cbr swingarm but never installed it in favor of a ktm unit that was set up for the pds system and shock already. Since the ducati needs to mount outboard of the motor the ktm swingarm wont fit.

I've been looking for monsters to do the same project, the 695 looks like a great candidate with quite a bit of power from a air cooled engine and 370#

[donmoto]

subscribed! I figured monsters shouldn't be too difficult a conversion. The only things I've really wondered about are dealing with the low sitting exhaust and if there are already larger tanks available for them.

[Wadester]

Originally Posted by donmoto

subscribed! I figured monsters shouldn't be too difficult a conversion. The only things I've really wondered about are dealing with the low sitting exhaust and if there are already larger tanks available for them.

The only larger gas tank I'm aware of is the California Cycleworks MTT43, at 4.3 gallons (vs stock at 3.6 gallons) and $537:


It does come in natural, so you can see how much fuel you've got left: