this post was submitted on 26 Jun 2026
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Hi all. Noob here back again. I got the screws out of the front master cylinder, but I have been having a different problem.

When under higher RPMs, the bike gives off a VERY strong fuel smell. It's still noticeable at lower RPMs, but not as bad. It didn't do this initially when I got it a few months ago, but I didn't ride it much initially.

Bike is a 2017 Honda Rebel 300. Fuel injected. No carb.

I noticed that the gasket to the gas cap was a bit cracked and distorted so I got a new gas cap. Didn't resolve the issue.

There are no visible leaks anywhere that I can tell.

The smell is very strong around the gas cap and engine, not so much the tailpipe. The bike seems to run great otherwise.

Unfortunately, googling seems to show this as a very nonspecific issue, so I'm a bit lost as to where to begin. I'm a huge noob when it comes to mechanical things.

Thanks!

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[โ€“] officermike@lemmy.world 4 points 1 day ago (1 children)

I'm not a mechanic and don't really have motorcycle experience. I don't know what would be the best approach, but I do have thoughts on where I'd start. If you don't readily see any obvious leaks, and you're convinced it's not coming from the tailpipe (which would indicate it's running rich and there's a sensor, ECU, injector, or tuning issue), I'd probably look into getting a fluorescent dye that can be used in fuel systems. With a bright UV flashlight, this will make any liquid leaks glow, so any leaks in fuel lines, tanks, inline filters, petcocks, or maybe even the engine block or cylinder head would show up. If the leak is on the vapor side of the fuel system, I don't expect the UV dye would help find it.

Alternatively you might be able to find it with a sniffer tool. I'm not endorsing the linked item below. I don't own it and I've never used one, but I'm including it as a reference. https://a.co/d/00jpwJua

[โ€“] dingus@lemmy.world 2 points 1 day ago

The UV dye is a very interesting idea! I really think that it's likely just vapor itself leaking which is why I haven't seen any drips anywhere, but it's something to keep in mind. I don't really feel that it is running rich because the smell seems to come from the engine or tank, but it is also worth investigating. The sniffer tool looks interesting. Never heard of that either. Lots of ideas to ponder!