Tire inflation

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

SouthBayDon

Member
Joined
Jul 23, 2014
Messages
10
Reaction score
1
Location
CA - California
I'm new to the world of FJR. My last bike only required a little air in the tires every few months even though it was a daily rider (by choice, not required). Yesterday I checked the tires on my 06 FJR and the front only had 32 and the rear only 22. Yikes! Question is is this normal or should I be looking for a leak?

 
Seasonal change most likely. It's always a good idea to check for a leak, but top off the pressure and see if it is reasonably close tomorrow. Obviously if you're losing 5+ lbs overnight you have an issue.

 
Doesn't sound normal but it could be. Was gonna ask if your temperature changed a lot, but I see you are from CA. How long has it been since you last checked them? Did you last check them hot or cold? I would just pump them back up and keep a close eye on them over the week. I run 40F, 42R.

 
Tire valve stems leak if the core isn't fully screwed in. If the rim where the bead seats isn't clean will cause a real slow leak. Seasonal tire pressure change should only be a few pounds. The FJR tire/rims do not leak unless something is wrong. Tire pressure changes ~2% per 10º F of temperature change, which is roughly 1 psi when tires are set at 42 psi.

A little dish soap & water sprayed on the rim bead and on the exposed valve stem is a perfect leak detector.

 
Last edited by a moderator:
Yesterday I checked the tires on my 06 FJR and the front only had 32 and the rear only 22. Yikes!
After ionbeam's notes.....Depends if you had checked 6 hours earlier or 6 months earlier. If the former....yeah that's losing air too fast. Latter....meh. FJRs aren't necessarily faster or slower to lose air....it's usually how well they're set on the bead and how well the tire installer cleaned up.

 
Last edited by a moderator:
I recently bought a Motion Pro digital air pressure gauge. What a mind fucker this thing has turned out to be. I've seen a 4 psi. drop overnight when a weather front has come through. Leads me to think that barametric pressure has as much influence as temp.. I'm giving air pressure more attention these days. Can't count the times that I have gone out and felt that suspension was off. I'm sure psi was a part of it.

 
When money is of no object or care:

Take one of these:

cf-lg.jpg
add 2 of these
cf-lg.jpg
lf-lg.jpg


and you can monitor your tire pressure all the time for just a bit more than $1k.

And, for just a few dollar more, you could get a built-in TPMS which comes with its own motorcycle.

bmw-k1600-series-gets-luxury-corbin-seat-and-trunk-photo-gallery-53449-7.jpg


 
Tire pressure is the absolute pressure minus the ambient (barometric pressure). Even a MAJOR weather change does not change the ambient pressure enough to make a significant difference in the pressure you measure using a tire gauge. On the other hand, a big temperature swing can make a measureable difference as can a significant altitude change.

Regarding the FJR rims, I have had times when tires have lost pressure significantly over the space of a week or so. Other tire changes when I have essentially run the tire to the end of its life without having to add air. Usually depends on the condition of the Schrader valve and how carefully I prep the rims before I install.

 
Tony being a good sport and prepping my rim. Why is he smiling? The fumes from that little yellow can were awesome
stunned.gif


IMG_4361a.jpg


Never had to add air for the entire life of the tire after this rim prep.

 
When money is of no object or care:
Take one of these:

cf-lg.jpg
add 2 of these
cf-lg.jpg
lf-lg.jpg


and you can monitor your tire pressure all the time for just a bit more than $1k.

And, for just a few dollar more, you could get a built-in TPMS which comes with its own motorcycle.

bmw-k1600-series-gets-luxury-corbin-seat-and-trunk-photo-gallery-53449-7.jpg
I chose the later of Alan's suggestions, not b/c of TPM, but... that option just may have saved my life!. While in Wisconsin for NAFO; just starting into some big twisty roads, I got a red flashing dash (and an audio alarm) as I watched the digital LB's go down below 30 and quickly to 10. It was 0 upon my roadside stop, flat as a pancake. It was 42 at last normal glance and who knows when.

DSC00919_zps2e372fe5.jpg


DSC00920_zps7ece2bc4.jpg


DSC00921_zps3f3f5966.jpg


I have the TPM's F/R digital reading up all the time, but it really never varies much and I sometimes glance at it, but with that combination of the alarm/warning... it brought immediate notice. Still living and smiling
smile.png
and LOVING this option (along with about 50 more bells and whistles).

592961_zpsfa3dd3e7.jpg


 
Last edited by a moderator:
Wow, a $26,000 Tire Pressure Monitoring System!! Whadda bargain!!!
Ya, but it works real good ;) I nailed a K1600GT tire in CA this fall and it also showed me that I was in for a big let down if I didn't intervene. When you are in the middle of no where and have a flat it sucks, preventing it -- priceless ;) Well, almost priceless, just $26k.

 
My first and second car tire never leak air-ever. Even after being punted by a FJR.

Another reason to go to the Darkside
coolsmiley02.gif


 
Last edited by a moderator:
Man am I ever glad I got rid of that piece of shit FJR.

The failures keep mounting!

By the time gen 7 's arrive they will have killed off all mankind.

 
Last edited by a moderator:
Damn right. Mine lost 2 PSI in the rear tire in one week. Now I can't ride it without my bowels loosening.

 
There seems to be some paranoia regarding tire pressure fluctuation. I've ridden a few motorsickles over the past 50 years and have not yet come to a Jesus moment because a tire pressure fluctuated a couple pounds. Before I embark on a road trip I check the tire pressure. I carry a reliable tire gauge. I check my tires several times daily to ensure there are no nails, screws or other sharp items in the tires. If on a long trip I check the pressure after a week or so to ensure all is well. I also use Ride-On in my rear tire just in case shit happens. I'm knocking on wood, but after all these years and I do not know how many thousands of miles I have never had a flat while on the road. I have found nails and screws in the rear tires but no tire failures. Once I rode all the way from Austin, TX back to N. CA with a small nail in the rear tire. Checked the pressure daily and no loss of pressure. Disclaimer: I am not in any way affiliated with Ride-On!!

 
The ideal gas law says that PV=NRT. Doing a bit of calculation says that a change in temp from 25C (77F) to 30C (86F) with a starting pressure of 40psi gives a pressure rise of 0.6 psi. A pressure change of 4 or 5psi due to temperature is going to take a pretty drastic change in the weather. On the order of a 75 degree difference. Like from summer to winter. Not from a warm day to a cool day.

 
I had a leaky valve stem and rode the better part of 100 miles with not much more than 10psi in the rear tire. Much of those miles at 80 on the highway. Thought if felt a bit slippery in the back and when I stopped for gas the tire was damned near flat. Aired it up every 45 minutes until I got to my hotel and then put a new valve core in it. I did change the tire when I got to my midpoint destination where I was staying for a few days. I just didn't trust the tire carcass for dicing with the trucks on the ride home.

 
Top