Hi

Any ideas what might be causing these bubbles?

The bike has been in my shed which gets very hot (Qld summer westerly facing type hot ie very hot) for last 2 weeks whilst I await major service kits to come from England. And today I noticed these bubbles had appeared which presumably are along the weld lines of the tank.

They're not solid ie like rust but soft so my first thought was it must be the gas fumes expanding (only 5/6L in the tank atm) and the pressure vent must be blocked, but when I opened the petrol cap there didn't seem to be any pressure build up, well not that i could notice. I do intend on taking the tank off so I can check vent line when I deoxit electrical connections, but wondered if anyone has an ideas or seen this before?

I have left the petrol cap slightly ajar atm to see if they go down of their own accord. Not willing to pin prick them atm.
Thanks

They look to me like ozmosis bubbles like you get in the gel coat of a fibreglass boat. Has the tank been repainted recently, I am thinking of maybe some acid etching was done and hasn't been cleaned properly.
I had a similar problem when I was painting a steel boat in Brizvegas, it had the rust treated with phosphoric acid before undercoating and the water came from high humidity.

I only bought the bike a few weeks ago, but I suspect it has been repainted but not recently maybe 5 years ago.

The shed however does have very high humidity as water can come in at ground level during heavy downpours, and as you know we've had a lot of rain in last 2 weeks.

If that were the case, then if I move the bike to lower humidity location do you think the bubbles will go away naturally? (I understand they may come back under similar conditions).

Thanks for the reply

If it is ozmosis they won't go away. I would expect them to be doing some damage to the aluminium as they would be acidic. Releasing the fluid would be the best thing. I had to strip the paint and start over with the boat but if it is only in one place a good painter should be able to repair it.

Ok, thanks. I will go see a paint specialist and see what my options are, but it does sound like back to metal job.

Appreciate the input and advice.

ouch mic ....great look otherwise ...hope there is a solution

I guess it's better to know about it so it can be corrected, a stitch in time saves nine so to speak.

Given the issue seems to be paint (& prep) related, might be easier and cheaper to end up doing a k100rs se type tank top rather than have whole tank repainted.