Looking for confirmation... Honda CR85 supermoto

I'm just looking to see if someone can confirm if I will be able to run 17"s with a 120/70/17 rear slick or even a 125/70/17 rear rain on a 2004 CR85 small wheel? In my research I'm seeing some say it's very tight and can work others saying now way and have to switch to a big wheel swingarm... Basically I'm just wondering if I can run these and get away without switching out the swingarm.

Also aside from switching to heavier springs and fork oil any tips for suspension set up? I'm not really interested in lowering it as I still ride on dirt from time to time but I am open to hear people's thoughts. Any help is appreciated

 

Hello smokey11,

I have a 1993 CR80R (which, of course, had a 14" rear wheel) with a stock swingarm that has a 2.75 x 17 Sun rim on the rear. The old tire on it is a 115/50R-17 Dunlop KR108 slick, and there is about a half-inch of clearance at the front of the swingarm. Obviously a slightly narrower tire, and possibly a narrower rim than you are considering running, but it does fit well.

This '93 CR80 came to me with the standard adjustment for pavement racing of sliding the fork legs up in the triple clamps to lower the front end. Also, the time-honored trick of adding approximately 2" long PVC spacers to pre-load the fork springs was done. With a setup like this (the front made "stiffer" but the rear shock unchanged) rear wheel chatter in turns can become an issue. It was the case with this bike, and was a fairly common hurdle for those who modified motocross bikes (small or big) for road racing.

Heavier springs and fork oil may work for you, if you don't choose to make the typical-for-road-racing travel-limiting mods to the fork and rear shock, as you still want to take it off-road.

I did know a guy (an adult) who frequently won mini road races on a clapped-out KX80 that I doubt had any suspension mods at all. Of course, the front end would dive considerably under braking, but that didn't disturb him much.

Anyway, I hope this info is of some use to you.

Best of luck.

 

Hello Relic Room,

Thanks man for the feedback much appreciated. I will give the springs a go first and if need be ill lower and look into re-valving. As it stands now I'll give the 125/70/17 rain tire a go, it's going to be tight, worse comes to worse I'll have to grab a big wheel swingarm off of eBay. Again thanks for the reply, very helpful

 

The front tire on your full size sportbike is a 120 on a 3.5 inch rim, measure it or use it to see.

I have a 150r, with just BBR springs it was a seesaw, rideable and fun but it moved front to rear a bunch. I got it revalved and it was much better. I also ride mine in the dirt and did not lower the suspension but I did put the forks up in the clamps almost 2 inches. Had to raise the bars to do that. Had friends ride mine back to back with lowered ones most liked mine better.

Litz did my suspension and it is very good but, He never returned calls and he took about a month then just sent them back COD with out ever telling me they were coming, lucky my wife was home cause I was on a business trip. No notes or letter saying what he did. Just my suspension revalved and new stickers. I don't think I would use him again.

 

On my KTM 65 I had to make the axles slots longer about 1/2 inch and use longer bolts on the axle adjusters.

 

Yes that's what I was thinking as I have many front take off's from my track bike, my theory was wouldn't have to buy rears for the CR all season lol. I will give it a go and see how it works out,good call though.

More and more it's looking like springs and getting the forks and shock revavlved is my best option, appreciate the input about putting the forks through the clamps.

I should have mentioned earlier the rear is a 3.5"...

I'm in Canada so chances are I will send the suspension out to Steve Beattie at 26 Suspension, he is a flat track and MX suspension wizard so I'm pretty confident he can get me sorted.

Thanks for the feedback, much appreciated.