I currently have 3 different dirt bikes in the garage, all three are from the honda family, 2 are Honda XR’s and the other is an XLR, and I was interested to see if the caps where interchangable. Well were they ?
No, dirt bike gas caps are not universal. They vary in size and style with some being lockable and some threaded. The size of the thread varies, although some dirt bike tanks will have the same size thread making the caps interchangable.
Straight away with mine I realised that the XLR had a lockable gas cap which is a totally different beast to the threaded variety. I believe this is to do with the gas tank being metal because I am unsure as to weather you can even get lockable gas caps for plastic tanks?
The plastic caps I have are both from XR’s and are interchangable between the 2. Both tanks look to be the same size and the caps look identical.
You also get a centralised breather tube on the threaded plastic tanks whilst on the metal tank cap there is no breather hose.
Gas Cap Sizes For Dirt Bikes
You may get lucky and have a cap at home either from another bike or from another machine, like an ATV for example that will fit the bike you need it for.
If you are looking to buy a new gas cap then to be sure you are getting one that fits you should look to buy an OEM version. OEM stands for Original Equipment Manufacturer, so you know if you order an OEM Honda cap it should fit your honda bike.
OEM are going to be a little more expensive but it’s got to be worth it so you know it will fit and likely better quailty, especially the rubber seal. You will be able to pick on up for under $20. Non OEM caps will cost under $10 so the saving isn’t huge.
If you are looking at buying a non-branded cap then you are going to need to know the size of the thread when ordering, otherwise you could end getting the wrong one.
From what I have seen you get smaller threaded caps at 41mm diameter and bigger ones at 49mm diameter. Sometimes you also get the option of a small or large grip on the cap which simply refers to the amount of plastic you have to grip when you twist open and closed.
In my pics throughout this post the plastic caps shown are in a large grip style.
The smaller threads usually fit the smaller sized bikes, 50cc and some 80cc and then everything above usually the bigger thread. That is not gospel though so do your own research before buying.