'08 RMZ450 Sumo Details

As we head into winter, I want to get lined up for parts to be able to set up my MX bike for the occasional pavement track day as a sumo. I am planning on buying a set of Warp 9 wheels with rotors and using the stock front caliper with the adapter bracket they supply. I also plan to use a separate chainset for sumo to accomodate the gearing differences. I ride at the fast end of the intermediate group / slow end of the fast group on a typical sportbike track day if that matters. I will likely be into the fast group all the time in another couple of track outings. My questions are:

1) Will the 4.25" rear rim width be an issue for me? What size tire on that rim, 150 or 160?

2) Will the stock caliper be enough for pavement use on a big kart track?

3) What is a good choice for track only rubber at my level and the bike's speed potential? I do not expect to be backing it in much, if at all.

Any other things I need to address for this?

Thanks,

Mark

I've got an 07 with a 4.25 rim & its no prob at all, i'm pretty sure some guys are running up to 5".

I've run 150 & 160 tyres with no issues, different brands sometimes seem to be a bit different in width for the supposedly same size but the worst that has happened is a little bit of rubbing on the muffler.

I don't know how tyre prices are over there but here its pretty much the same price to buy slicks or good street tyres here so slicks are the go, but i've used good street tyres & they've been sweet as.

Don't know bout your standard calliper, something you'll have to try, depends on how hard the track is on your brakes.

Thanks for the reply. I wasn't worried about the 4.25" rim being too wide, more too narrow for tire selection. If it will handle a 160 with no problems that is fine.

Does a light bike like a sumo get big slicks up to temp OK? I am fine with slicks and they are pretty affordable compared to premium street rubber. I will check with our local track supplier and see what he thinks about rubber selection for a sumo.

I am not really that hard on the brakes compared to some people, but we will see. I have not run a track day on the kart track yet and it may tax brakes much harder than our other local track. I will have to try it and see. I will make sure I bring a bottle of fresh fluid just in case I need to bleed them after a session or two.

Mark

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