Have only had the K100LT for a couple of weeks now, and have noticed the
new rear conti that had been fitted is losing 10psi pressure over a
three day period, There is still a white seal round the edges of the
rims.

Any tips on stopping the pressure loss.

Would it be the valve stem?

I had a similar issue with my front tyre. Took out the old valve, cleaned the internal thread and screwed in a new one.

Didn't work. Flat in a week.

The bike shop said the tyre was leaking at the rim and they stuck in a tube. I suspect that I may have put a dent in the rim and it can't seal properly.

Spin the back wheel to see if it's a tiny bit buckled...on both sides. If that doesn't work, pump up the tyre, take the wheel of the bike and stick it in the bath to see if you can spot any bubbles anywhere.

Good luck.

Bit of soapy water and a small paint brush, paint the soapy water on any area that could leak and you have to find it.
I have often found that the rim should be cleaned before a new tyre is fitted and I have yet to find a tyre joint that does it.
There are two places it can leak where the rim meets the tyre and at the valve.
Check the tread for a puncture if the soapy water fails to find a leak but 10psi in 3 days will show quickly.

Thanks for the replys, will try everthing suggested, I have noticed a new valve stem is fitted, no objects in the tyre, looks like possible bad seal between rim and tyre due to age of wheel (25 years)

Usually a quick wipe of saliva on a finger across the top of the valve minus the cap will immediately show if it is leaking there, if it bubbles up that is one leak there may be more. If that failsto show a leak then water with detergent in and a paint brush should show a leak but the best is to dunk it into a trough or if SWMBO is out, standing it in the bath is good because you can roll it forward till you find the leak. Once you know it is not the valve the wheel has to come off because the tyre needs to come off anyway.
Regards,
K-BIKE

Soapy water and Crazy frog, spot on.

The valve is leaking at the base of the stem.

Do they just screw out or would a good quality high temp clear silicon sealant do the job.

There is only one way to fix it and that is remove the tyre and replace the valve.

You will not have any success with silicone. I have a saying that only a silicune uses silicone.
It does have its good applications but that is not one of them.

Thanks for the advice

Banditrob wrote:Thanks for the advice

Check the valve cap. Once I had problems with cap on rear. When tightened it pushed the needle slightly, but just enough to let most of the air out in two - three weeks.

Used a small paint brush and soapy water, bubbles appearing at the bottom of the valve stem.

Valve stem replaced, Job done.