Topic: Tires, Tube or Tubeless: '78 cb750f comstar wheels

[bryanj]

Special tool Mate, cariable 30-50 ltr ish air tank with a nozzle that blasts the lot straight into the casing over the rim in a split second---tyre dont stand a chance!  Better than the Tractor pulling people who run there tyres tubless to save weight---they get them out by filling the casing with easy start and throwing a match!!!!

[Pillage]

Well alright, the SEARCH function actually worked out for a change!
Thanks for the info Terry, I need new tires on my 78F.  It clearly has tubes installed but the rims are clearly marked Tubeless.  Anyway that's what I'll try to do.  I've had great luck with Bridgestone BT54's, BT020 & BT021's over the years so the BT45's seem like the logical choice.  Thanks again,
Pillage
BTW, You've got a very sharp "F", nice pic.

Well I checked my F2 owners manual, my factory F2 workshop manual, and some old magazine articles and I can't find anything to say you can run tubeless tires on early Comstar rims. Tim (KGhost) is right, the F2 rims aren't marked "For tubeless application", but a later pair I have (19790CBX1000 front, 1982 CB900F2 rear) do.

Having said that, I'm running Bridgestone BT45's front and rear on my current 1977 CB750F2, tubeless. My other F2 ran tubeless tires as well, and I did thousands of miles on that bike, with no issues whatsoever.

Sadly this F2 has sat in the garage for three years now, and I had to re-inflate the tires when I recently re-sealed the engine cases and put it back together, but after three years, they were only down to around 20 psi (+/ -) each.

Running tubes in any tires is dangerous due to the possibility of a blowout causing a catastrophic tire failure at speed, but of course, can't be avoided on 1970's spoked wheels for obvious reasons, or earlier cast mags, due to porous castings.

This is has not been an issue with my Comstar wheels though, obviously for safety reasons I can't recommend using tubeless tires on them as I don't have any data to suggest that I can, but I do know that Comstars were designed for tubeless tires, and I can't see any physical difference in the rim design of either the "Tube" or "tubless" Comstar rim, so I'll continue to use them. Cheers, Terry.

[eldar]

I wonder if anyone has sealed their rims and run tubeless spokes? I know on the Tiger, I think it is a triumph, they sealed the rims and ran tubeless.

I would be we could seal our rims just fine but it is probably the rim lip that would not hold. I will have to check out a tubeless tire sometime to see. I would like to do tubeless but it is not a driving force.

[754]

BMW also uses sealed laced rims, claim they have to be factory resealed after replacing spokes, but I have a hard time believing that..

[KRONUS0100]

I run 78 comstars on my 76 750F without tubes......8700 miles there abouts, no problems.  the rims are not stamped either way.

[eldar]

Well you know bmw, they want to do all the work and rape you sideways.

[cafe750]

BMW also uses sealed laced rims, claim they have to be factory resealed after replacing spokes, but I have a hard time believing that..

The wheels on the newer larger BMW's don't need resealed as the spokes aren't laced into the center of the rim. They're laced into the edges of the rim, so that standard tubeless tires work on them. The older bikes, and the smaller F650's still use standard rims with tubes inside.

Um, Eldy, shop rates at my shop are the same as all the other local motorcycle dealers, and if a person wants to do their own work, we'll tell 'em how to do it, with common tools. The parts cost the same as the ones for my Hondas, so, I'm sorry you've had a bad experience with Beemer shops, but don't knock 'em all....

[eldar]

I do not have a beemer. They are the same as any dealer and charge a lot. Fail to see why you got so jumpy on that. If I went into university motors, I would get charged a #$%*load but then they just built a new shop.

Same goes with auto shops. Some are ok but 95% charge a lot.

[cafe750]

I do not have a beemer. They are the same as any dealer and charge a lot. Fail to see why you got so jumpy on that. If I went into university motors, I would get charged a #$%*load but then they just built a new shop.

Same goes with auto shops. Some are ok but 95% charge a lot.

Well, being that I'm a parts guy at a beemer shop, I get  a little touchy when someone says   "Well you know bmw, they want to do all the work and rape you sideways. " Thats all. 

[eldar]

Well I feel ALL autos and bikes are overpriced but that is just me.

[Terry in Australia]

Well alright, the SEARCH function actually worked out for a change!
Thanks for the info Terry, I need new tires on my 78F.  It clearly has tubes installed but the rims are clearly marked Tubeless.  Anyway that's what I'll try to do.  I've had great luck with Bridgestone BT54's, BT020 & BT021's over the years so the BT45's seem like the logical choice.  Thanks again,
Pillage
BTW, You've got a very sharp "F", nice pic.

[/quote]

Go for it mate, the BT45's are the best tire I've ever had, and I'll continue to put them on every bike I buy, until something better comes along.

And thanks for the compliment, I must clean that old bugger up and take it for a ride, it's covered in about an inch of dust at the moment, ha ha!

On second thoughts, my favorite riding country is still on fire, so I might have to wait a tad longer............ 

[fishhead]

Here's a link showing the difference between the tube type rims and tubeless rims (Kawasaki, Honda will be very simular). The ridge on the tubeless rim looks bigger than it actually is, but will be there on a tubeless rim to keep the bead from loosing it seal.

http://kzrider.com/index.php?option=com_fireboard&Itemid=107&func=view&id=208793&catid=5#208793

 I dont know if you have to sign up to see the link.

[eldar]

Seeing that difference, I have to wonder if it might be possible to weld a uniform bead to create that ridge on both sides.

I suppose everything has to be weighed against the safety factor and how much a person wants to risk.