How To Change The Fork Oil On A Triumph Bonneville

Changing the fork oil on your motorcycle can help keep the internal parts in good condition and improve rebound and dampening. In this video I'll show you how to drain and refill Triumph Bonneville fork tubes, which are similar to many other bikes. It's important to get the level right when refilling, and I'll demonstrate a very useful tool for that purpose.
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amzn.to/3OMdE9x (fork tube level tool)
amzn.to/3qjIZXK (fork tube level tool)
amzn.to/3qmbWlW (PJ1 fork oil, 10 WT)
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[@plkujaw]

Where did you take the 120mm distance from? Is it somewhere in service manual? Why is this method better than just filling by the required volume?

[@tinderboxarts]

That could use some more explaining. So, on this particular bike, there are aftermarket progressive springs and that is the recommended measurement. For stock springs, there may be a measurement from the top too, but it may be measured with the spring removed. There could also be a specification to fill by volume, although that can be tricky when there may be some existing oil left behind during a change. Ultimately it doesn't matter how you get to the correct amount of oil as long as there isn't too much or too little in the tube. And, there is wiggle room. If you are off a couple of millimeters it won't be the end of the world. Since there are differences among models and model years, you should attempt to look up the recommended spec either in a Triumph manual, in a Hayes or other third party manual, or in the documentation with your third party suspension. If you can't find the spec, you can measure the existing oil level before you drain it and that should get you close unless you've had a significant leak.

[@FREE_PUREBLOOD333]

That's unusual...fork oil air gap is usually measured from a fully compressed fork tube with no spring inside.

[@tinderboxarts]

You bring up an important point. In a sense it doesn't matter which way you do it, you're just trying to get the oil level in the correct range. So the measurement can be done with or without the spring installed as long as you have the right measurement for the choice you made. To complicate matters more, the spring may or may not be the stock one, and the correct range may be a matter of debate. On this particular bike there are aftermarket springs installed and the measurement was based on the original factory level of oil with these springs. But, the measurement will be different with factory springs or if measured without springs. And, the range of oil level can vary somewhat without negative consequence. A millimeter difference isn't going to be noticeable.

[@fabiopunk1661]

interesting, I think I will just use a ruler and syringe to suck out oil, going slowly. However, I am stumped: I see no damper rods?!?!?

[@tinderboxarts]

You can see the fully assembly in an older video of mine here: kzbin.info/www/bejne/e5SXo3RvaLtmic0si=b8YAzJhk-v5Q4-m6

[@fabiopunk1661]

@@tinderboxarts thanks a lot!

[@michaeljameszaruba2243]

You're a world of information. There's nothing you can't do

[@paulsire]

Great upload, very informative. Sold my T100 last year for a GS1250, but enjoy your bonneville how-to's. Hope to get another one in the future

[@tinderboxarts]

That's a big change! I use my Bonneville for local fun and shenanigans but when I go on a long trip or ride in the winter I use my R1200RT for the extra wind and weather protection. You should keep an eye out for older Bonnies in your area. They are great bikes and every rider should own at least two bikes!

[@jackjohnson65]

Always enjoy watching your videos, the motorcycle one especially.

[@tinderboxarts]

Glad to hear it, thanks!