kz440 valve stem and/or tubes?

I bought a 1981 KZ-440 ltd belt of a guy a month or two ago for $300 and have been fixing it up after it sat in a garage not moving for 5+ years. I have the engine in a good place now and have moved on to replacing the badly dry rotted tires.

I pulled the wheels today and took them to a shop for them to throw on the new tires I bought since I don't have the tool to break the bead. To my surprise the guy came back saying the tires were running tubes and he didn't have a valve stem small enough to fit the hole. The tires he was running were marked tubeless.

*note I don't have a decent motorcycle shop in town. I have to drive to the next town if I want one so online solutions are preferred

First question: Can I run these wheels with the tubeless tires I bought? The front tire has markinges F-1027, AsaHI 3, and J19x1.85 DOT. The rear is marked R-1037 and J 16xMT2.50 DOT. Both wheels appear to be cast magnesium. If I can run them tubeless does anyone have a suggestion for valve stems that would fit? The holes are just over 300 thou in diameter.

Second question: If I can run them tubeless would drilling out the holes to a more standard 430 thou be reasonable?

I am happy to go take pictures of the wheels if needed.

This topic is controversial. Some will say that unless the wheel is imprinted with "tubeless tire applicable" (or something to this effect) then you should run tubes. Your bike originally came with tubes so that would be the obvious choice. You can run tires labeled as "tubeless" with a tube inside without issue. On the other hand there are thousands of folks that convert wheels like came on our KZ's to run tubeless with good success. You may have to ream the valve stem hole if you can't find a small diameter valve stem. Regarding the safety of running tubeless without the safety bumps on the rim profile know that some of the early KZ wheels were labeled tubeless but they didn't have these safety bumps so that should tell you something there. While they are a nice feature Kawasaki apparently didn't consider them mandatory.

You can run tubeless tires - that is no problem at all. However, you need to use tubes in them or you will have problems that could very easily hurt you. Buy tubes. Using them is no big deal at all. Ed

Not saying I would run them tubeless yet, but I like to be informed. Should they be run tubeless what are the potential problems? I appreciate your input.

Here are 2 reasons; I’m sure there are others.

1. The tires may not hold air for long (if at all).

2. Because the tube type rim does not have the raised inner ridges (see image below), the tire may suddenly go flat if you hit a pothole of other irregularity in the road. This may cause a wreck.



Tubes are not very expensive. So why would you even consider taking the risk? Ed

Thanks Ed. I already ordered two tubes, and was just curious of the downsides.

For comparison: KZ550-Ltd tubeless cast alloy wheel >> note the smaller ridges than the wheel in the pic above. "Tubeless" is cast into the wheels & the diagrams don't show tubes.

1980 KZ550-C1 Ltd wheel.

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It shouldn't be an issue with the 440. A V rated tire with a tube inside is lowered to a H rated due to heat. That means instead of running at a max of 150+ MPH, it can only run at 130 sustained speeds safely due to heat generated.
Steve

Along those lines & if the rim profile is the same as the 550-Ltd pic above, since it isn't a powerful motorcycle,
I was thinking a 440 w tubeless tires would be fine going tubeless if the wheels are marked thusly.
To be on the safe side I wouldn't ride 2 up.


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650ed wrote: Here are 2 reasons; I’m sure there are others.

1. The tires may not hold air for long (if at all).

2. Because the tube type rim does not have the raised inner ridges (see image below), the tire may suddenly go flat if you hit a pothole of other irregularity in the road. This may cause a wreck.

Tubes are not very expensive. So why would you even consider taking the risk? Ed

Two comments:

1) My KZ750 front wheel was labeled "tubeless" but there were NO raised inner ridges. Are you suggesting my wheel is unsafe? And if so, why do you think Kawasaki sold the bike that way?

2) There are MANY people on GS Resources which have converted their tube type wheels to run tubeless and I've never one time heard of anyone having any issues. And again, I had a GS bike with a front wheel labeled "tubeless" but there weren't any raised inner ridges on those wheels either.

And BTW, I think the raised inner ridges are good safety features, but the tire will never become unseated when hitting a bump.

I don't know the reason behind some tubeless type rims having the ridge and some wheels not having them. It may be that the angle of the rim differs between the two styles; I know that various rims have different profiles. Regarding the tire losing air if a bump or pothole is hit at an angle; I suspect that it might do so if the air pressure was somewhat low rather than up to the correct pressure, but I don't have any hard evidence to support that belief. Ed