2017+ Yamaha R6 Rear Master Cylinder Banjo Bolt

by Jason McDonnell

2019 Blog Post: 2017+ Yamaha R6 Rear Master Cylinder Banjo Bolt

KurveyGirl.com has some of the best customers in the motorcycle industry. Recently one of our customers reached out to us through social media. He shared a banjo bolt fitting issue for a 2017 Yamaha R6 rear master cylinder. It seems the traditional coarse threaded banjo bolt did not fit the 2017 Yamaha R6 rear master cylinder.

Executive Summary:

The KurveyGirl.com tech team was intrigued with this issue, as the banjo bolt that fit the rear master cylinder on a 2017 Yamaha R6, was the same banjo bolt Yamaha has used for the past 10+ Years (P/N: 90401-10172-00). The tech team researched the situation more closely; it seems that Yamaha in 2017 added a 90° adapter, called a Joint (P/N: BN6-25885-00-00) to the R6 rear master cylinder. A Yamaha Banjo Bolt with a new for 2017 part number (P/N: 90401-10049-00) had been introduced. KurveyGirl.com tech team ordered up a 2017-2019 Yamaha R6 rear master cylinder with the OEM banjo bolts and 90° adapter to investigate more deeply the fitting condition.

Once the team got their hands on the rear master cylinder assembly, they dived into what was different about the 90° adapter. First, the team confirmed that Yamaha had used an M10x1.0 fine thread for the banjo bolt. But in addition, both the banjo bolt and the 90° adapter had a shallower thread depth, when compared to the rear master cylinder. This shorter thread depth in the adapter was similar to the thread depth found on Brembo master cylinders.

The tech team confirmed that the shorter thread length on KurveyGirl.com’s banjo bolts worked with a variety of banjo fittings. From the thicker Yamaha OEM banjo fitting to the thinner Goodrich banjo fittings, the KurveyGirl.com titanium banjo bolts fit. Checking some other popular banjo bolts did not yield the same results, so carefully measure the length of your banjo bolts before installing to avoid any sealing issues to or damage to the 90° adapter.

Next, the tech team checked that the KurveyGirl.com flush mount banjo bolt is a great replacement for the Yamaha OEM low profile head, coarse threaded banjo bolt. No clearance issues exist when changing over from the OEM low profile head to a flush mount banjo bolt. This also simplifies the safety wire routing, by connecting the two banjo bolts together, without the need to drill a hole to anchor the safety wire.

After a detailed investigation, the Tech Team recommends the following setup for the 2017+ Yamaha R6 rear master cylinder.

Rear master cylinder to the 90° adapter:

Banjo Bolt: M10x1.25 single, coarse thread banjo bolt with low profile head.
[ Click here for a link to KurveyGirl.com single titanium banjo bolt, coarse thread, and flush mount head. ]

90° adapter to the rear brake Line:

Banjo Bolt: M10x1.0 single, fine thread banjo bolt.
[ Click here for a link to KurveyGirl.com single titanium banjo bolt, fine thread. ]

Team KurveyGirl.com

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