Topic: F3 750 Comstars = tubeless?

[Patrick]

Can I run tubeless tires on the Comstar wheels on an F3 750?

Thanks.

Patrick

[Porscheguy912]

I'm fairly sure that thats the whole idea of the mag rims.
Someone correct me if i'm wrong.... But i remember someone telling me that thats why honda went to mags; so they could go tubeless.

[UnCrash]

Some of the comstars can be run tubeless.  These are stamped "Tubless" somewhere on the rim.

Mine alas are not,so I run a modern tire with a tube inside.  Just fine as I don't plan on going over 120 mph anyway...

[Patrick]

All I can find stamped on my rims is the size of the wheel and the name of the manufacturer (DID), so I didn't know if they defaulted to tube or tubeless. The mags on my other bikes run tubeless, but they are somewhat later models. The PO ran a tube, I can see, but there is no telling what is the correct thing to do based solely on what this particular PO did. I've just heard that tubeless is safer and that's the way I would prefer to go, if possible.

BTW, this bike will never see 120 with me on her....

Patrick

[UnCrash]

I believe that no "tubless" stamp means that they are not the tubless Comstar.

Andy750 can comment a bit about flat tires.  I believe he runs tubes///

The Comstars from my 78 CB750F3 are not stamped "tubeless".  I tried to have my local bike shop mount my tires without a tube, but the tube-less valve stem would not seal correctly on either rim so he gave up...

Cheers~

[jtb]

I run tube in my '77 comstars

[754]

I think if you get the right valve stem it will work, they will not be porous like some cast wheels could be.(if tyou want to do over 175 at Bonneville they MUST be steel.. )

You may however need and inflatable cord thing to seat the tires and dont go nuts on pressure.. (seating pressures ,may be 1 reason some mags claim to need tubes)

Years ago I got a deal on Gooodyear AT's with RWL, a buddy bought 6   16",s off me. Then he ran them tube-type tires tubeless on his Morris Mags forever.. bet he still has 2 left.. lol..

[markjenn]

My 79 CBX Comstar wheels say "Tubeless Tire Applicable" on the rim and I've been running tubeless without problem.  If the early Comstars wouldn't run tubeless, I suspect that the valve stem hole not being designed for a standard tubeless valve stem would be a giveaway.

- Mark

[Patrick]

The only way this bike will ever see 175, 754, is if I shipped it to Bonneville on a jet. Even if you dropped it from that jet it wouldn't make it to 175...

I figure the stem hole is different from an automotive stem hole. Is it different from stem holes in other bike wheels? Like something more modern?

[Bodi]

The rim profile is different and running tubeless on a tube rim is not a good idea. There's only that little bit of rubber keeping your butt off the pavement grinder...

[upperlake04]

 The Honda owners' manual for the 78 750F3, the 4" x 6" booklet, has 3 pages devoted to tire servicing which include a section on changing and repairing inner tubes. The word 'tubeless' does not appear.

[754]

I may have given bad advice above, the rim profile may NOT be correct for tubleless tires.

I do believe we had a conversation way back with a tire supplier..RE running tube-type rubber on a tubeless rim. The gist of it was the tube-type may not seal as well, and slowly leak.. the guy running the AT,s on the Morris Mags did say they would lose a bit of air after about a month..

[CHRISF2]

here's a link to a similar discussion earlier this year:
http://forums.sohc4.net/index.php?topic=34498.0

also, years ago there was a thread on the old mailing list
about this subject. Someone at that time reported that
there is a certain size automotive pull-through stem that
fits in the comstar rims, but the specifics are lost to me now.................

[markjenn]

Someone at that time reported that
there is a certain size automotive pull-through stem that
fits in the comstar rims, but the specifics are lost to me now.................

On my 79 CBX, I used standard automotive pull-through stems as the PO had installed tubes and I wanted to go back to tubeless.  (Again, I'm sure this is Okay with this particular bike because the rims say so.)  As I recall, there are two sizes of auto stems and one of them fits perfectly.  I believe it is the same size that is used on tubeless rims on modern bikes as well, at least in US spec.

I'm getting normal leakdown rates (on the order of one psi a month with Bridgestone BT45s).

- Mark