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Old 10-05-2011, 03:09 AM   #556
igormortis
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Who's the machinist? I'll need a couple of axle spacers and sleeves at some point.

Regarding the steering stops - doesn't the RS use a nut and bolt through the hole in the stop to limit the bars' lock inside the fairing? Can you do something similar here?

I'll probably end up with a 320mm disc and a 4 piston caliper. Which may be overdoing it. Also, I'll be using the BMW wheel, which will give clearance for a bigger caliper in that position. Maybe look at some slim supermoto setups?

Now about that wheel...
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Old 10-05-2011, 03:22 AM   #557
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Originally Posted by igormortis View Post
Regarding the steering stops - doesn't the RS use a nut and bolt through the hole in the stop to limit the bars' lock inside the fairing? Can you do something similar here?

I'll probably end up with a 320mm disc and a 4 piston caliper. Which may be overdoing it. Also, I'll be using the BMW wheel, which will give clearance for a bigger caliper in that position. Maybe look at some slim supermoto setups?
Sent you a PM.

The GS steering stops have a vertical rather than horizontal hole. Not sure why?

I was originally going to go with a 320mm rotor - I had one on the KTM. But if I use the 4 pot caliper I think it'll be overkill - too easy to lock on the dirt. Also thinking of weight. I've borrowed a Triumph 320mm disc. Massive.
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Old 10-05-2011, 12:29 PM   #558
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Wow theres a lot going on there pal. If it was me I'd transfer all the YZ switchgear, brakes etc over & morph them all. I like misson creep tho
No idea about the steering stops tho sorry.
I hope you're keeping a log of measurements of bushings, sleeves etc as if it all goes well I may look at being a copy cat next year.
great work & very interesting
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Old 10-05-2011, 02:55 PM   #559
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I was in a garage last night looking at a very original R80G/S, hadn't been ridden in about 4 years, nothing wrong with it, the owner had a dozen or so other bikes.

He didn't seem keen to sell it to me though.
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Old 10-07-2011, 02:29 PM   #560
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Originally Posted by BMWRSNUT View Post
Gus's fork upgrade
The steering stem has been modified, with the stem spun down 20mm past the top bearing surface, & a steel sleeve made up & inserted to allow the bearing to be dropped to match the bearing cups on the BMW. A 20mm spacer has been fabricated to restore height at the threaded portion, which was necessary to keep the forks / triples in spec.

I have retained the Yamaha bearings. The top one is the same as the standard BMW one. The bottom one is Yamaha spec. The outside cup diameter is the same as the BMW cup size.



One side effect of this is that either I won't need the Rox Risers, or (more likely) I can go to a lower bar.

No issues with the forks hitting the tank, but I will need to do some modification to the stops to make this work properly - the back of the stops on the triple clamp hit the frame gussets - the front opf the stops don't hit the BMW frame stop.





Next job is to shorten the fork, do the seals, & to put in heavier fork oils. Eventually I'll need to set these up properly with heavier springs, changed dmaping stacks etc, but I just need to get things 'ball park' & 'basically working' at present.

Then I'll need to give some consideration to what I'm going to do with the brakes - I will be retaining the BMW 13mm mastercylinder, given the issues that this would present with replacement. I suspect that the Nissin 2x27mm piston caliper from the YZ F may be too small for the BMW mastercylinder - the Yamaha one is 11mm. The Tokico 4 pot caliper has been good, but may be awkward to get an adapter made for. I am happy with the standard BMW 280mm disc but want to keep this unmolested, so I can sell the front end as a unit. I think that a 300mm disc would be perfect. 320 mm probably too big. The YZ F rotor at 250mm is also too small & lightweight. I would expect huge fade with this even if I could use it.

Any constructive suggestions?

I'll need to re think the dash.

RS's Gearbox
I am going to purchase a replacement rear cover. You'll recall the existing one has a split in the output flange.

Just spent GBP175 + freight getting bearings, seals etc sent across from the UK for a rebuild. Overall the box & gears are in good condition & don't reflect a typical gear wear with this mileage. I have always felt this was a good gearbox & am still confused as to what has caused the split in the output flange - it doesn't appear to have been a wear issue.
Hey looking good there. On the front end that I had, which Vege now has, I shortened the forks by fitting a spacer in with the top out spring. Then cut the same amount from the spring. Shortening the spring stiffens the rate. Rob Taylor measured the rate at .48 which was about the same as the BMW spring. So by taking 75mm out of the spring it went from .43 to .48.
I found the 320mm disc with 4 piston caliper great. Even on dirt. With the BMW master cylinder it felt very progressive. I used a "Braking" supermoto caliper and the first disc was a "braking" disc but it wore quickly in the rivets in the aluminium carrier so i got a ducati disc. I just made adaptors to fit the to the BMW wheel.
Keep up the good work
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Old 10-07-2011, 02:40 PM   #561
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Originally Posted by Phreaky Phil View Post
Hey looking good there. On the front end that I had, which Vege now has, I shortened the forks by fitting a spacer in with the top out spring. Then cut the same amount from the spring. Shortening the spring stiffens the rate. Rob Taylor measured the rate at .48 which was about the same as the BMW spring. So by taking 75mm out of the spring it went from .43 to .48.
I found the 320mm disc with 4 piston caliper great. Even on dirt. With the BMW master cylinder it felt very progressive. I used a "Braking" supermoto caliper and the first disc was a "braking" disc but it wore quickly in the rivets in the aluminium carrier so i got a ducati disc. I just made adaptors to fit the to the BMW wheel.
Keep up the good work
Funny, I was online, researching a lot of this, especially how much was taken out of the fork travel.

Just been rereading Roadsacallin RTW prep trip. Someone there mentioned the 2 piston Brembo worked well with the Sumo rotors, but that they had issues fitting 4 pots with 21" wheels. Good to know that this may not be an issue with the right caliper.
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Old 10-07-2011, 10:36 PM   #562
Phreaky Phil
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This was my setup
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Old 10-07-2011, 10:48 PM   #563
Padmei
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you didn't sell your bm did you Phil? I know you are for some strange reason riding a DR but can't believe you'd give up the BM after all that hard work
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Old 10-08-2011, 12:32 AM   #564
Phreaky Phil
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you didn't sell your bm did you Phil? I know you are for some strange reason riding a DR but can't believe you'd give up the BM after all that hard work
No, its still in thew shed. I sold that front end to Vege when we went to Alaska as i'd brought a new bike for the trip and was going to sell the GS when I got back. But I decided to keep the old girl and sell the new bike. Not sure what I'll do with the GS. I may just keep it as it is but I also have visions of a Richie Moore inspired special. I will see in a couple of weeks how good a DR780 is
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Old 10-08-2011, 02:14 AM   #565
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Originally Posted by Phreaky Phil View Post
I found the 320mm disc with 4 piston caliper great. Even on dirt. With the BMW master cylinder it felt very progressive. I used a "Braking" supermoto caliper and the first disc was a "braking" disc but it wore quickly in the rivets in the aluminium carrier so i got a ducati disc. I just made adaptors to fit the to the BMW wheel.
Phil, I have been thinking of buying the Braking STX 320mm Rotor, but using the YZ250F wheel (much lighter & easier to do tyre changes) & possibly the YZ250F caliper. Now you have sowed the seed of doubt, with your comment re wear you experienced the aftermarket Braking Rotor. How long did that last?

What Ducati Rotor did you end up using. Did you put a different centre into it.
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Old 10-08-2011, 02:54 AM   #566
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Originally Posted by BMWRSNUT View Post
Phil, I have been thinking of buying the Braking STX 320mm Rotor, but using the YZ250F wheel (much lighter & easier to do tyre changes) & possibly the YZ250F caliper. Now you have sowed the seed of doubt, with your comment re wear you experienced the aftermarket Braking Rotor. How long did that last?

What Ducati Rotor did you end up using. Did you put a different centre into it.
After 20000km it rattled like a bastrd. I have looked at the EBC rotors and they have flats where the rotor and carrier meet, so should wear better. I guess supermoto bikes dont clock up big km so it doesnt matter.
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Old 10-15-2011, 05:01 PM   #567
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Progress Update & a Full Stop

Decided to go with the EBC Supermoto 320mm disc (SM6017C), & the 2 x 27mm piston Nissin caliper, to keep the front end relatively stock Yamaha, & avoid ending up with a hodgepodge of parts, especially custom parts. I’ve bought this from Procycle in the US. USD $199+$65 freight.

I’ve had a close look at the wheel & rim, which apart from the bearings are in good nick. But the bearings are considerably smaller than the BMW standard. I am aware that people have converted F650 Dakars to the Yamaha front end. That bike is 193kgs wet. So the wheel / hub combo should be strong enough.



Spent a bit to get ready for the fork work – fork oil ($38), fork seals ($20), dust seals ($39), seal savers ($39), new brake pads to fit the Yamaha caliper, & wheel bearings & seals (the existing ones are well notchy).

I have also bought a new brake lever for the Yamaha Master cylinder, not because I’m going to use this, but to make it more saleable.

There are loads of YouTube & other videos giving basic fork service demonstrations. No information at all (that I could locate) on how to shorten these forks.





Started to pull down the forks. Fortunately the prior owner of the front end had given me a CNC’d fork spanner, for the top nut, & an inner to go into the centre of the top nut, to release the top base value. Unfortunately I’d forgotten he said that this could be used with (I think) the axle nut, to allow a normal socket to free this – I sold that with the remains of the bike.





As it turns out the fork springs are 0.41kg/mm. Even shortened (which increases the calculated rate) I think that the spring rate will be too light. Having decided that, I may be better to sell the springs, & not chop them up.

The left fork seal is stuck fast. Even if I could shift it, I'd need to get a 48mm seal driver before I can replace it. And to change the fork oil I still need to break into the cartridge, which may need a special tool. So it seems more convenient to send the forks off to be professionally shortened, serviced & to have appropriate spings installed. Given the costs of doing so, things will have to grind to a stop here. The Budget is officially blown.

So for the interim (at least) I've put the BMW front end back on, hung the YZF forks back on the wall, & am ready to ride Gus again. And having done all of the above, I'm still mulling over alternatives. I may be better with the BMW hub, & maybe get the wheel rim swapped out for an Excel rim at some later date.


RS'S GEARBOX:
I'm picking the new (old) rear cover up today. The other parts are all in from the UK. Once that is all back together I'll start to work towards getting that back up & running.
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Old 10-15-2011, 06:51 PM   #568
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Great stuff. Are you selling the complete Yamaha master cylinder & lever & keeping the BMW one?
Going riding on my one soon
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Old 10-16-2011, 12:12 AM   #569
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Originally Posted by Padmei View Post
Great stuff. Are you selling the complete Yamaha master cylinder & lever & keeping the BMW one?
That was always the intent. If I used this I'd have to set up a brake switch, & would need to do substantial work to tfr the switch gear from the right handlebar. The Yamaha one is also only a 11mm Mastercyclinder. The BMW 13mm - much more flexible.
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Going riding on my one soon
Thats why I put the original front end back on. Otherwise there was this pressure to get the new one up & running, regardless of the cost. . Mandy didn't approve of that.
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Box'a'bits screwed with this post 10-16-2011 at 10:58 PM Reason: Expanded explanation re mastercyclinder.
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Old 10-26-2011, 02:33 PM   #570
igormortis
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Same forks? http://advrider.com/forums/showpost....&postcount=875
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