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YB6 front fork steering lock rubber bumper rings (41.7 mm)

 
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Tue Sep 08, 2015 2:47 am    Post subject: YB6 front fork steering lock rubber bumper rings (41.7 mm) Reply with quote

Hi all, I need to replace the rubber steering lock bumpers on a a YB6 with 41.7 mm Marzocchi forks, or does anyone have a work around or suitable replacement?
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trev45



Joined: 15 Jun 2011
Posts: 449
Location: Sydney Australia

PostPosted: Tue Sep 08, 2015 6:31 am    Post subject: Reply with quote

Who many do you need ?

Trev
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Tue Sep 08, 2015 7:41 am    Post subject: Reply with quote

Hi Trev? Ralph here. Need two for Greg's YB6 which is sold. Hope I'm talking to the right bloke... Embarassed
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trev45



Joined: 15 Jun 2011
Posts: 449
Location: Sydney Australia

PostPosted: Tue Sep 08, 2015 1:06 pm    Post subject: Reply with quote

Its me sweet pea
I will have a look tomorrow for you

Cheers Trev
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Wed Sep 09, 2015 1:58 am    Post subject: Reply with quote

Cool. I'll get Greg to drop you a line. Thanks.
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who



Joined: 10 Nov 2010
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Location: Melbourne Australia

PostPosted: Wed Sep 09, 2015 5:39 am    Post subject: Reply with quote

Thanks for looking Trev.

What we are doing is using a 1-58 (41mm) black silicone radiator joiner hose. I'll cut 2 x 25 mm pieces, and use a spacer under the threaded alloy frame bump stops to compensate for the reduced wall thickness of the rad hose.
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trev45



Joined: 15 Jun 2011
Posts: 449
Location: Sydney Australia

PostPosted: Wed Sep 09, 2015 7:00 am    Post subject: Reply with quote

Yes that's what I worked out with Greg too

See you at the Island ?

Trev
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Thu Sep 10, 2015 2:30 am    Post subject: Reply with quote

Dunno, I'll have to see how things pan out. It would be good to catch up again. Thanks for looking at this problem with me. Regards,
Ralph

PS: I'll post a photo of how it ends up for anyone who is interested.
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Sun Sep 13, 2015 11:49 am    Post subject: Reply with quote

I know a lot of this stuff is obvious, but here is how I have countered a few of the usual problems with the YB6.

Bump stops, unfortunately the silicone 1 5/8" (41mm) hose was lost somewhere, so I found a rubber radiator hose that was about 40mm ID. I used a brand new blade and used a hose clamp as a cutting guide, rotating the clamp once you come up to the worm part. Quite a good cut, and final clean up on the side of a grinding wheel. You can see I have placed some washers under the thread in frame bump stops to compensate for the 2.6 mm difference.







Triples were seized and wouldn't release. Copper mallet on the head-stem, and hit the copper mallet with a larger sledge hammer.

The bearings always corrode on the side that loads when it is on the stand, put the cups into a lathe, or do it by hand, clean up best you can, clean the white stuff that was once called grease off (tooth brush and petrol), I used a wire brush on a grinder to clean up the bearings once the gunk was off.

Remember these bearings don't spin, they rotate through 90 degrees. Rotate the top cup 180 degrees, and turn the bad parts of any of the rollers to the inside of the bearing (180 degrees) Once re-packed and assembled there was no notchiness, and all was as good as you could expect.

No grease seal on this one? It must have been like this from factory, the bike has only 5K on it.





Cleaned as above, new bearings would have been the ideal fix, but this has worked well:



You can see the repair to the choke cable? They generally break at the point that they transition from the triples, to the engine. The cable outer was kinked and broken, but the inner was good with out broken strands, lots of penetrant to wash out the inner, then double wall heat shrink starting small and working outwards in consecutive layers. The cable is strengthened as a result.. The double wall stuff I used has a heat sensitive adhesive on the inside, so it sticks and provides some rigidness.

Finally, this is how you balance the carbs on the YB6. Use a FZR1000. lol.



Not sure if any of this is useful, I'm sure most of you who own these things would have worked it out. Cheers, and thanks Trev for your help.

Also, the dust scrapers on the forks, Ducati part number 000048396. It was a punt, but they are the same.

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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Mon Sep 14, 2015 10:54 am    Post subject: Reply with quote

A couple more thoughts... I could engage in some self deprecation here... Very Happy

The Yamaha airbox clamps are not up to the job, the engine heat deforms the bimota plastic airbox, pulling it off the carbs. CV carbs need a stable environment to operate in. What I have done here is use standard sort of hose clamps in place of the oem ones. You will probably need a mate pushing down on the airbox while you lever down the front of the clamps while you do them up. It's a bit of a pain, but once you have them done up, and the airbox is as it should be... sweet running.



Also, last of nanna's tips, I've replaced the tank pull down rubbers (didn't come with any) with orings. They probably work better than oem.



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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Mon Sep 14, 2015 1:07 pm    Post subject: Reply with quote

Always good to see piccies of a Bim being resurrected....and you certainly seem to have been through the mill in just wanting rubber bump stops initially with ceased parts...gunked up bearings etc etc....punt on Ducati fork dust shields worth it....as they used the same Marzocchi M1R 41.7mm forks on their 750paso bikes and a few others......I've heard before about there being no oil seal under the headstock......a few models had them but there was a tendency for tight steering as when all clamped up it drew down on the rubber seal making it tight as it was oversized in diameter...so the fix was trim it back or remove it...I suspect Bimota though most bikes would be often stripped, never used in the wet....or just parked up as display pieces....
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Tue Sep 15, 2015 6:31 am    Post subject: Reply with quote

Thanks for the heads up on the Paso forks, the Bimota ones are almost impossible to find. Not surprised regarding the seal, the bimotas seem a bit random when it comes to build (I only really know the YB6-8's)

I sent out some inquiries and could have some made to oem spec, but I would need a a few orders to make it worth while. Though using rad hose and spacers does an acceptable job. Cheers,
Ralph
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bimotabob



Joined: 06 Jul 2013
Posts: 110
Location: New Zealand

PostPosted: Thu Oct 15, 2015 5:47 am    Post subject: Reply with quote

did that lower steering head bearing not have a metal cover and internal o-ring? Looks like you can see the bearing rollers, no way that would last like that a long time.
The frames get so hot I find the oil comes out of the grease due to the heat and weeps out the top.

When i brought mine the aluminium cover and oring fitted bwtween the lower triple clamp and frame to stop the shit getting in was broken, had a crack down one side. Interesting to hear it happened on other bikes. As a result my races rusted out and cost me plenty for new ones.
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who



Joined: 10 Nov 2010
Posts: 402
Location: Melbourne Australia

PostPosted: Fri Oct 23, 2015 7:42 am    Post subject: Reply with quote

Sorry Bob, I missed your reply, I don't get notifications for some reason?

No metal cover and oring on this one. Other triples I have here have them. I doubt this one ever had them fitted due to the low Km's. Rather than risking pressing off the lower bearing (and perhaps destroying it) I just did as mentioned above, and it should be good for another 20 years! I wasn't doing a restoration, I just wanted it to be functional and safe.

Yes those radial bearings are a pain in the pocket, I'm sure you could probably find tapered roller bearings if you didn't intend to alter the rake from standard setup. the YB11 doesn't have adjustable rake and runs normal tapered roller bearings. I'll measure them and see if they fit in the same hole. Cheers,
Ralph
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bimotabob



Joined: 06 Jul 2013
Posts: 110
Location: New Zealand

PostPosted: Sun Oct 25, 2015 9:10 am    Post subject: Reply with quote

a guy from round here brought a set for his YB11 but he got the YB8 type. Another club member snatched them for his YB10 as they are like mine also.
I think around $300 a set which is the dearest steering head bearings in the world!
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