XR racing

Ok, I know lots of you have XR100s and such, So I thought I would start an XR100 setup and performance thread. What are you doing to your XR to make it racey? I am currently exploring the option of running an xr80 in the stock xr100 class here in Alberta. and here is why.


We cannot run XR80 front wheels on the 100. It is a run it as it was build class. So my thought is the XR80 should get through the turns better then the 100. Also the 80 has a closer ratio transmission then the 100. It is the same frame and fork, only a different swingarm. The HP difference is less then 1hp in stock trim. It is lighter (although my fat ass will negate any advantage there). With smaller wheels it should accelerate slightly better thus negating the lower hp.

I should let you all know that we only race on kart tracks up here. There are not alot of places to really stretch a bike out on any of the tracks.

So what sayth the beeb? How do you think an XR80 could stand up to an XR100?

Also what have you done to make your 100 raceable?

 

It's only a 1 HP difference but it is significant when you're talking 5HP stock on a CRF100. Every 1/4hp counts with mini's, particularly if you're a larger adult.

I ran my 100 with the stock front end and 19" wheel for a while. It wasn't bad, but wasn't great either. A fork brace made a good difference.

Currently my 100 is setup as follows

BBR120 kit w/cam and valve springs
Kitaco Hi-Flow oil pump
24mm Keihin carb
BBR frame brace
BBR shock Spring on stock shock (utter crap but cheap)
1986 CR80 forks (direct bolt on later year 80/85 require stem change)
2007 CRF150R front brakes (bolts on to any cr80/cr85 fork)
Excel 17"x2.5" rims with Buchanan HD spokes on stock hubs
Dunlop GP125 120 rear tire on front and rear

 

I like the transmission in the 80 also, but never had a chance to really ride it in anger. I'd say the real question is can you get good sticky rubber in the right sizes and profiles? If so, rock that stuff!

 

On the tires, I tried a couple different tires in the stock sizes and found the Bridgestone BT45's to grip better than any of them. YMMV.

 

Why in the world would you run 125Gp rears on the front??? Talk about some heavy handling.

 

Tried the 95 up front and 120 in the rear first. I was running onto the edge of the front and had 1/4" wide unused strips on the rear. Swapped to the 120 on the front and tire usage became uniform and it "feels" better all the way around.

I know it sounds crazy but it just seems to work...

 

Try the proper rims sizes that the tires are designed for. I have done several with no issues. JMO

 

Can't fit a 3.5" on the rear with the 100 stock swingarm, at least it doesn't appear that i can.

Also, isn't the reccomended 95 width 2.5"?

 

Your right but a 2.75-3" will fit if the wheel is all the way back.

 

On another note, XR/CFR100 are hard to find up here for a reasonable price. Lots of 80s around though. That is another reason I am looking at the 80. Also I like to be a bit different then everyone else. The hard part about the 80 is the 14" rear wheel. Tires are not as easy to find for the 14".

 

Pirelli makes a 14, SL26? It's huge and heavy with an ugly profile but it works. Wears fast though.

 

This is cool we got this section. I have a 96 xr100 i picked to run the stock class. Just grab a xr80 frame,froks,front wheel, tank,handle bars, and seat all for 65 bucks. So now all i need is to find the best place to buy bt45's and i should be good to go.

 

This is an XR100 motor in an RS125 chassis, with a Kitaco 145 kit. Built this last year to race along with our RS150 and give us more classes to compete in.

 

did you get that motor from TN, I shipped one to a Anderson in CA last year, If so glad to see the young man put it to good use

 

You can lace a stock 16" rim on that rear hub with some Buchannon spokes, thats what I did to my 80. As a matter of fact I have an extra brand new in the wrapper OEM 16" rim i'd probably sell.

 

You're killing me Earacing!!!!!

I gotta find a steal of a deal on a RS roller...

 

The class doesn't allow it. Have to run the stock hoops and hubs.

 

its seems mini racing in canada is more about 'spec' classes for their thunder(xr,ttr, klx 100's) and supersport(nsr,ysr) classes, all in the interest of rider ability over tuning. you can run a tuned xr80/100 in the formula thunder class, but the spec classes is where all the best battles and races take place!

 

Yeah, there are plenty of mod classes if you want to run those. But the spec classes are much bigger and have the closest racing.

 

Actually this one came out of a donor bike, and I bought yours as a spare. Your motor is going back into the donor bike (an NSR chassis) soon so I can sell it. Too many bikes!!