Dunlop D250 180/60R 16 fitted

[hardo]

@colonial Boy

When it is assembled, my first ride will be to a garage who is certified to issue a Warrant of Fitness. This is a 6 monthly safety check. The inspector is a motorcyclist of many years riding who has experience with Pasos and has a fondness for them. His opinion on its handling will be of much more value than mine.

- Indeed, that will be very interesting to hear what the inspector will say, please let us know.

- Since alle these 180 / 60 are done for a different kind of bike (expecially with "heavy backs"), you may lock up the rear wheel much earlier - expecially on a wet road. I am bit afraid of such a behaviour. cf. for instance: http://forums.ducatipaso.org/viewtopic.php?f=2&t=3171

- However, a new 130 / 70 should behave better under heavy breaking.

- One question to this point: "I fitted 10mm longer cap bolts to fit the sprocket but the heads hit the swing arm. To overcome this I deepened the recesses in the sprocket by 3mm, machined 1mm off the back of the screw heads, and another 1mm off the tops. They are now flush with the face of the sprocket." Are you sure that there is still enough stability regarding the rear sprocket when taking some material off?

- Did I get that right: You just turned the front sporcket around and that's it in order to get te additional 10 mm?

- I think your excenter is in the 5 o'clock position. In respect to my calculations, there should be 10 mm left if you use the 6'o clock poistion (and only 7,5 mm if you use the bridegstone and 2,5 mm for the Avon). Is that approx. right? hence, you only get enough clearance if you move the excenter a little bit?

thanks a lot for your help! Hardo

[paso750]

In respect to my calculations, there should be 10 mm left if you use the 6'o clock poistion (and only 7,5 mm if you use the bridegstone and 2,5 mm for the Avon).

to what are you referring to ? What is 10mm ?

G.

[hardo]

"colonial boy" wanted to know the clearance tire / swingarm in the orginal version (here X 59).
on my 906 paso, the minimal distance between tire and swingarm (front of the rear tire / beginning of the swingarm)
is 25 mm (in the 6'o clock excenter position). My Michelin has a diameter of 585 mm. The D 250 F has a diameter of 615 mm, Bridgest. 620 mm, avon 630 mm and - leaving everything unchanged should lead to minimum front clearance of 10 mm when using the D 250. this is only what I measured with my bike, maybe this is not always this way

[paso750]

ok you mean to the front, not to the sides. I had more than 2,5mm with the Avon.
btw did you ever get in contact with "pasoalf" ? He is also in CH and already has fitted 130/70 & 180/60. So I guess he already dealt with the MFK.

G.

[hardo]

thanks, yes we had contact some time ago. He told me that there are still some problems left and he will come back to this forum with alls infos and plans whenever he solved everything.

[Colonial Boy]

@colonial Boy


- Since alle these 180 / 60 are done for a different kind of bike (expecially with "heavy backs"), you may lock up the rear wheel much earlier - expecially on a wet road. I am bit afraid of such a behaviour. cf. for instance: http://forums.ducatipaso.org/viewtopic.php?f=2&t=3171

- One question to this point: "I fitted 10mm longer cap bolts to fit the sprocket but the heads hit the swing arm. To overcome this I deepened the recesses in the sprocket by 3mm, machined 1mm off the back of the screw heads, and another 1mm off the tops. They are now flush with the face of the sprocket." Are you sure that there is still enough stability regarding the rear sprocket when taking some material off?

- Did I get that right: You just turned the front sporcket around and that's it in order to get te additional 10 mm?

- I think your excenter is in the 5 o'clock position. In respect to my calculations, there should be 10 mm left if you use the 6'o clock poistion (and only 7,5 mm if you use the bridegstone and 2,5 mm for the Avon). Is that approx. right? hence, you only get enough clearance if you move the excenter a little bit?

thanks a lot for your help! Hardo

Thanks for the link to the fitting of another Dunlop rear (although not the same type). Why do manufacturers change their tyre designs so often? If each is better than the last they should all by now stick to the road like bugs on a visor!

Locking up under braking is a real concern ofcourse. The bald Metzeler offered no grip at all on my test ride and coupled with low pressure almost put me in a ditch. Even with correct pressure it unsurprisingly locked up readily under braking. On my brief test ride with the Dunlop (on a dry road) I didn't lock it up. As an aside I locked up the rear of my friend's Monster the first time I braked for an intersection - perhaps I apply too much rear brake naturally. The Ducati rear must be quite a bit lighter than my other bikes - and I usually ride them with my wife on the back - so I may have to adjust my style when solo on the 906.

There are so many variables to consider. Yes, the 180 is heavier so may not be so stable on uneven surfaces (due to greater unsprung weight and stiffer construction) but it has a greater footprint to start with and more recent technology in the groove design. My 906 has an adjustible rear damper (see photo) which may provide a way of tuning the damper to suit the different tyre but I'm a novice at this - perhaps someone would like to comment on this damper.


As to deepening the recesses for the cap-bolts on the sprocket, I really don't have a concern for strength there. The thickness remaining is 3mm, which I consider to be the minimum acceptible, but remember there is virtually no side load on the sprocket.

Yes, just turn the front sprocket around to get the 10mm offset.

Here is a photo of my excenter position:


I put the camera under the bike to get this photo of the tyre clearance:


Clearance is 19mm in the centreline of the tyre, and 10mm at its closest point. I also rechecked the chain clearance using an Allen key as a more accurate guage and it has 8mm.

Oh, and to those wondering if this bike will ever get back on the road, my target is 2 - 3 weeks (if I can sneak out to the shed on a regular basis!)

Cheers, CB

[hardo]

thanks for the info

at least her, two dunlops in the size 180 / 60 are availiable (Elite and D 250 F). In one German describtion of all 180 / 60 currently sold here, the D 205 F is the only one that is recommended for "touring bikes", not only custom bikes and choppers. but I am not sure if that means a lot (it is just one scource and mor advertising). I talked to Dunlop regarding the D 205 F and they simply said: "We did not do any testing with that tire and a 906 paso, hence we have not information availiable. In general, these tire is used in the us market for a goldwing 1800"

two points:

- yes you are right, there should be not much side load on the rear sporcket anyway. I think, this is a very good solution

- given your excenter position, I thought there would be more than 10 mm minimum clearance. however, 10 mm should be enough, I heared that 60 km/h will lead to extra 3mm via centrifugal force. Hence, even at maximum speed, I can not think of the tire touching the swingarm. maybe someone can comment on that point with a more profunde knowledge than I have

have a nice day, hardo

p.s. your must be lucky - here we really got snow...it takes two more month till I can ride my nikes again

[paso750]

if a Dunlop at all I`d personally prefer the Elite 3 over the D250 also beause its based on the Sportmax. Just my 2c.

http://www.vw-page.at/pages/trickkiste_ ... echner.php

[Colonial Boy]

if a Dunlop at all I`d personally prefer the Elite 3 over the D250 also beause its based on the Sportmax. Just my 2c.

I guess that other markets will have different tyres available, but the D250 was the only Dunlop my bikeshop offered me as an option.

Summer here Hardo though you wouldn't know it. January was the wettest here for 90 years and February is almost as bad!

[Colonial Boy]

So with a couple of jobs completed on the motor and the exhaust repaired (at last!), it was time to begin final assembly.

I had acquired a chain guard (missing when I purchased the bike) so worked out how much to move it over. It looked to me that originally the front of the guard would have fitted inboard of the mount, but it was enough to assemble it on the outside of the mount and make a spacer for the guide. Remember I'm looking for 10mm so with the guard 4mm thick I made a 6mm spacer about 25mm in diameter. The sequence is mount, guard, spacer, chain guide. If you plan ahead, stick the spacer to the guard with some contact adhesive, otherwise tape it to a rod to get it in position and use a lot of bad language! You will need a 30mm bolt.


For the rear mount I made another 6mm spacer slightly smaller at 20mm in diameter to go between the mount and the guard - with a nice stainless washer and 25mm dome-head cap-screw:


It was after I'd struggled to get the exhaust on for half an hour that I hit a snag. The left hand centre stand bolt was loose and when I tightened it and lifted the stand up, it hit on the chain!


This came as a shock as there was no problem when I rode the bike, but the loose bolt must have allowed the stand to twist away from the chain. I will have to grind away part of the foot to get some clearance.


I ran out of time to do this so it will be my first job on the project in the next day or so (and it may be a good idea to replace the nylon pad too!). Not a big one to overcome, but another thing to take into account.

If you are intending to do this mod, check your chain to stand clearance before you start, so you know how much to alter the stand.

[hardo]

Hi CB

Just a question: do you think the central stand will in general hit the chain and hence something has to be done or was this only caused by the deferment caused by the lost bolt?

By the way: Giving that excenter position, can you still use the central stand / side stand?

Thanks and all the best, hardo

P.S: I talked to the technical advisiers here in switzerland regarding the conversion and showed them everything I have so far. They told me that they had no problems with this kind of conversion; they would also accept the 150/80 combination, but I will go the 180/60 way.

[Colonial Boy]

Hi CB

Just a question: do you think the central stand will in general hit the chain and hence something has to be done or was this only caused by the deferment caused by the lost bolt?

By the way: Giving that excenter position, can you still use the central stand / side stand?

Hi hardo.

I think there is a good chance the centre stand will hit - or run very close. Best to measure your clearance before you start as I'm sure there will be a variation from bike to bike. Anything less than say 13mm clearance with the original chain position and you will have to grind away part of the foot.

Both my stands worked fine when I had the Dunlop rear fitted with the old Michelin up front, but the slightly taller Dunlop front may combine to make them too short. Only time will tell. If so I will first reverse the excenter position so the axle is up and if that is not enough weld some thicker feet onto the stands.

I will report back as soon as she is on two wheels again!

Cheers, CB

[Colonial Boy]

I managed to spend most of my Sunday on the Paso. First I ground away part of the centre stand foot for some chain clearance.


I wasn't sure if this would be enough. When I offered the stand up to the mounts I found there was quite a bit of side clearance so I added a couple of washers to the inside of the stand:

This was enough to give me 2mm clearance on the chain. I figured when I'm sitting on the bike the chain will be higher so will have more clearance. There will be times when you go over a rise and the weight comes off the bike but I will keep an eye on this area to see if there is any sign of contact.

[Colonial Boy]

Next I fitted the front guard. I made up these spacers for the fork brace/guard mount:

They are 12mm diameter and 7mm thick. I used 4 stainless steel dome-head allen screws 6mm x 20mm long. I didn't finally tighten these until I had fitted the axle. I had to file a little out of the curves on the ends of the brace so it would fit up inside the forks where there is no groove for it.
With the Dunlop 130/70/16 fitted there is virtually no clearance on the sidewall inside the mud guard. Thankfully my bike has a mudflap fitted and the speedo cable loop is mounted on that otherwise I couldn't fit it:

With both Dunlops now fitted, I could try the centre stand. By the way, did I mention the battle I had getting those springs back on? More bad language!
The stand worked, but both wheels and the stand all touched the floor together. I reversed the excenter on the rear axle to this position:

With the bike on the stand, the rear tyre just touches but I am able to rotate the wheel so I'll be able to squirt my chain lube on. As for the side stand, this still works and the angle doesn't look too great.
But just so you can work out how much the bike has been raised, with it on the centre stand, I lowered the side stand and measured from the lowest point of the foot to the floor - it was 96mm.
I would add that there was no tank, fairings or seat on the bike. When it is completely assembled, I will remeasure this.

I was hoping to fire her up, but the battery hasn't responded to a charge so looks like I will have to get a new one.

Cheers, CB

[v2barn]

Hello CB, Well done, and thanks very much for the update, the 906 world eagerly awaits the final result / test ride!!
As i mentioned earlier in this thread Dunlop D250's have been replaced by the D419 here in England which is aimed at the cruiser fraternity, i am having real trouble comparing the actual sectional size of this tyre with the D250, i saw a clever chart somewhere on this forum which gave you all the answers can somebody point me please? obviously i need to ascertain that the D419 is the same size dimensionally as the D250 given it is the same size on the tyre wall (180/60/16) otherwise i will be back to square one if the tyre profile is different.
One more thing CB, did you ascertain how much wear was on your chain by adjuster position before you started this conversion? ie was the chain virtually new or approx 1/2 life? i just wondered if the latest position of the excentric adjuster would limit the ammount of chain adjustment available and hence the ammount of miles per chain?
I am afraid i am still hovering awaiting the outcome of your exploits before i get into doing it, as i have a virtually unworn pair of original tyres available but i would rather fit new rubber obviously. Shame you are on the other side of the world otherwise i would pop over and give you a hand. Keep up the good work. Cheers Jon