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Discussion Starter · #1 ·
First off, I'm completely new to the site and to working on Honda twins, so please bear w/ me. Anyway, I just picked up a 1979 CM400T and want to do a Tracker style build w/ some type of dual sport tire; however, I am having trouble finding many options for stock (18f, 16r) dual sport tire sizes and have yet to find a front/rear set that would work for this bike. I live on a mountain and am on/off gravel daily during my commute which is why I am interested in a more aggressive tire.

So given the lack of options in the stock tire sizes, I was thinking I could upsize my rims to 19f, 18r Comstars from a CB model bike (or maybe a CM400A as I've seen a few) since there are way more dual sport options in those rim sizes. Hoping to stay w/ the Comstar style rim as I am personally fond of how they look, but I know not everyone is a fan. My questions:

- do you know of any dual sport or aggressive tread tires that would work well on the stock rims? From what I've seen, there are so many more options in the larger rim sizes, hence this post.

- otherwise, would you recommend this approach? if so, what to watch for?

- if so, which CB or other model(s) would be most compatible w/ this bike? do I need to stick w/ the Reverse Comstar design of the stock rims or would the regular style used on certain bikes also work?

- I suspect I might run into axle/bearing size issues, depending on what model the larger rims came from, would it be possible to swap the hubs from the stock rims or would it be better to get a new axle and bore out the mount if needed?

- will the rear drum from another bike be compatible here? if not, can I swap the stock parts over?

- how about the front disc, would the rotor be compatible?

- if no to all above, would you then recommend I mix and match front and rear? what should I consider before doing this?

- OR, is a Tracker style build too unrealistic given the stock tire size options and/or bike model?


Not sure if I'm asking all the right questions, so any and all info is greatly appreciated, thanks!
 

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Oh boy, you've stepped into a deep subject here. To switch to a 19" comstar front it will be simpler to find another Honda that has the front tire size you desire, and swap the front end entirely (from steering bearings to triples, forks, wheel, brakes and all) Find conversion steering bearings and a list of compatible donor bikes here: https://www.allballsracing.com/forkconversion.

For the rear I suggest finding an 18" comstar from a CB400T or A model, it'll bolt right on give or take but it may be narrower than you can find a tire for. Some of the bigger bore Hondas of the period came with wider wheels, but adapting one of them to your bike may take some work, I've never actually looked at what's involved there.


And give this a read too: https://www.hondatwins.net/forums/23-member-introductions/121120-critical-read-before-posting.html
 

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Discussion Starter · #3 ·

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Discussion Starter · #4 ·
Thank you Alan, you've stopped me cold in my tracks. I will have to take a closer look at those Becks I just posted and stick w/ the stock wheels. Or maybe only replace the rear if it's not too much of a task. Thanks for the instructional post, I've been checking out the site and will post an intro before i sign off for the afternoon. Thanks again!
 

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I totally didn't mean to put you off wanting 19f/18r comstars, you can certainly do it for relatively cheap and fairly easily too. Spoked wheels are certainly easier when the dark magic of wheel lacing and spoke length calculating has been revealed. We can offer tech support through your conversion. In my opinion (which should not affect yours, it's your bike) those tires are not worth the time or money for a bike you want to actually ride hard.
 

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On the other hand. I'm running a 19/16 wheel combo on the '79 CM400T. Front end is from a 1981 CB900F which gives me 39mm forks instead of 33's and dual disc brakes. It does raise the front end since the forks are longer so to cure the suspension geometry the rear shocks are CB750 units from Progressive. All Balls bearings took care of the swap for the steering head, had to make steering stops.
You could easily swap wheels from the CB400T2, CB400 or CB450T, it's a direct swap with same axles, spacers, etc. That would give you the 19/18 combo and the mount Heidenau K60 tires using the 100/90/19 and 110/90/18. https://www.heidenautires.com/product/k-60/
Here's the road bike
2014.jpg
 

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Discussion Starter · #7 ·
Thx guys, I had no idea this would cause me so many headaches. After searching for new wheels along the lines suggested by LDR, I realized it was going to be an expensive endeavor as shipping costs for the wheels was expensive and I would likely have had to find 2 separate sources adding to those costs. So, I did an even deeper dive into tire options and have settled on using a mixed pair w/ a Vee Rubber VRM-163 120/90-16 on the rear and a Shinko 705 4.10-18 on the front. I found a very thorough review by a guy running this set-up and he was very pleased w/ the Vee and highly recommended pairing it w/ the Shinko 244 or 705; I went w/ the 705 b/c I do more street riding (commuting to-from work) than I do dirt, w/ other travel mostly on logging roads (so not really 'off-road'). He preferred the Vee over the Duro HF904, so I went w/ it. Anyway, this will have to do for now as it gets me on the road sooner and cheaper. I figure I can always change later giving me time to test this set-up and while I continue searching for more affordable, different wheels. Thanks for all the info!

BTW, really like the "road bike", LDR!!!
 
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