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Constant low pressure on rear tyre

pakyrs

2019
CB650R ABS
Jan 28, 2024
Oxfordshire
Riding Since
2007
Hi all,

I haven't found a common pattern in the search, and the query that I am sharing might sound incredibly dumb, but this is my first bike with 180 at the rear and the first time I use such bike in a relatively cold country (South of England).

I pumped my tyres a month ago as per manual 36/41 psi. Then monitored with my gauge over the month to observe changes, measures where always taken with the tyre rested and not after a ride (as it will obviously be higher) For context the bike stays in a single brick garage, granted temperature can vary a lot, during the last month we had highs of 24c and lows of 11c perhaps lower at night as well.

Based on the below table, have I got a micropuncture at the rear? And if so could I use slime and sort it? The tyres are not even 1 year old so it bugs the hell out of me to have to change the rear tyre already.

Screenshot_20240921_120702_Obsidian.jpg

Cheers

P
 

Redrocket

CBR650R
Mar 17, 2023
Riding Since
1968
I'd say that the rear tyte loses more pressure than mine (based 40 miles N of London). The pressures on both my bikes (tubeless tyres) drop slightly over time but equally can rise if we get a spell of hot weather. Pressures always taken "cold" and with the same gauge.
If you can't find anything in the tyre such as a thorn it could be that the valve is leaking slightly. I assume you always have a valve cap fitted?
 

miweber929

2014
CBR650F
650 Alumnus
Staff
Feb 13, 2015
Woodbury, MN
Riding Since
1975
I would hesitate to use slime unless absolutely necessary, shops HATE HATE HATE the cleanup afterwards when installing a new tire and instead make sure your valve core and stem are tight and sealed and look the entire tire over for a puncture. 10psi over a month is a small hole.
 

JRinKtown

2018
CB650F
Jun 30, 2019
Apart from any issue with the tire, It could be a loose valve core. Check the tightness with a core tool. If tight it still can be the core. Sometimes the seal in the core becomes brittle and loses pressure. In that case a squirt of silicone lube into the stem can freshen it up and cause it to seal again. Worth a shot :)
 

pakyrs

2019
CB650R ABS
Jan 28, 2024
Oxfordshire
Riding Since
2007
Thanks all, I'll inspection the tyre closely, but I couldn't see anything in particular.

Is this the core tool you mean?

And silicon grease if necessary:

I would rather avoid slime on tubeless, I use it on my bikes with an inner tube and can all be chucked away.

Thanks

P
 

pakyrs

2019
CB650R ABS
Jan 28, 2024
Oxfordshire
Riding Since
2007
Inspected the tyre and found a little hole.

Is there any way to repair this, it's a bummer to have to replace the tyre being new.

Cheers

P
 

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JDude

2020
CB650R ABS
May 20, 2020
Ottawa
Riding Since
1979
That is about the best case puncture that I’ve seen, definitely repairable. When I had one in a similar spot on the rear it was a half inch tear.
 

Redrocket

CBR650R
Mar 17, 2023
Riding Since
1968
Yes, you can't get a more straightforward puncture than that. It's perfectly legal and safe to plug it.
 

enshiu

2016
CB650F ABS
Mar 30, 2023
Riding Since
2021
Its not on the verge of the tyre so in the middle just plug it. I have a rubber flap on the rear swing arm to prevent the nail issue
 

Traffic

CBR650R ABS
Oct 14, 2024
Riding Since
1924
How do you know that little hole is leaking air?

Go to service station, over pressurise tyre to 50psi then put a dab of spit onto hole, if no air bubble forms then no leak.

I'd be at least doing that before plugging it, plugging tyres is a emergency procedure only and highly dangerous on a motorcycle tyre.

Don't forget to depressurisation the tyre before leaving service station either.

0Failing all that, the only real way to find leak is to remove wheel and submerge it into a tub of water.
 
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