Another XR100 build thread

[redkow97]

This will be a mild "build," and all I have to show for my efforts thus far are the receipts for my new tires, and eBay XR80 front wheel, but it should serve as a good reference for me, and anyone else who is looking to get started in mini racing.

My costs so far:

1998 XR80 16" front rim: $29 + $16 shipping on eBay ($45)

Pirelli ML 75 (2.50-16) front moped tire: $27

Pirelli ML 75 (2.75-16) rear moped tire: $33

Kenda 2.25/2.50-16 tube: $9.99

Kenda 2.50/2.75-16 tube: $9.99

Current total: $125

I expect to find a bike for $700 or less. Really shooting for $600, and other than the parts I've already purchased, I don't really plan to do much to the bike except refresh fluids, and fix any leaking or smoking.

UPDATE as of 12/15/12 - Brought home a 2000 XR100 for $474.

New total: $599

Edited December 16, 2012 by redkow97

[i-Zapp]

here ya go. former OR member bike (x2) that's been freshened up.

http://cleveland.craigslist.org/rvs/3460631238.html

[redkow97]

I wanted to take a look at Jinu's old bike (with new parts) a few weekends ago, but finals and Browns tailgate got in the way. That was my loss, as it would have been a pretty good deal for an '01.

BUT, I found another bike about an hour closer, and only a year older. The owner had listed it for $1000 on 11/7 and then apparently wised up on how over-priced it was (or got desperate for cash) and re-listed it for $500 recently.

It's definitely been used, and the left-side case cover has been damaged, but it rides and runs pretty good. Needs a good carb clean, but otherwise in good shape, if a bit muddy.

$474 later (I had only brought $100's and $50's... had to borrow $24 from my buddy JB when the seller agreed on $475, but didn't have change!) it was on my trailer.

I had an "you idiot..." moment when I got home and couldn't get the bike to fire. Helps if I turn the petcock back to "on" before wasting energy with the kick starter. 2 kicks later, it was running great, just like it had for the test ride

[Hoblick]

Youll be fairly disappointed with those tires just an FYI

Rode my buddys xr with those tires and they have a really soft side wall, they sre noticeably thinner than the diablo performance scooter tires, and they roll over in corners.

Glad i went with the pirelli diablo performance scooter tires over the ml75

[Hoblick]

Oh and definately do a vslve check on it. Both mine were tight. One of mine would die and not start back up after a few races, ended up being valves out of spec.

Also check cam chain tension

I got a pdf manual if you need one

[redkow97]

What pressures were you running in the ML's?

I have heard people claim I'll run out of tire before full lean, but nothing about folding.

And I they suck, it was a $60 lesson. It's not like I've blown my wad on the prices so far :-)

[Hoblick]

we tried alot of pressures in them. from 18 - 30 psi.. trying to get them dialed in. i rode behind him and saw the tire rolling.

[redkow97]

Hmm. I'll have to hope it was too big of a tube or something.

[redkow97]

UPDATES & PICTURES (a couple of which aren't working. I'll correct when I figure out why...)

First pic of the bike, as it sat on my trailer 5 minutes after purchase. You can't tell so much, but it's filty...

When I got home, I wanted to show off my new toy for the wife. Spent 5 minutes cranking the kick-start and getting pissed off before I realized I had turned the petcock to "OFF" before I loaded it...

After a short test run up and down my street, and some baby wheelies in the driveway, I started trying to clean it up a bit.

This is why I picked it up for so cheap:

I would be concerned, but I checked the microfiche at the seller's house, and this part of the engine case isn't holding any oil. That corner was a bit of a concern, but by all accounts, the only thing that screw holds is the case cover itself, and trimming the cover for easier sprocket changes is a legal modification in teh stock XR100 class with OMRL. I will probably still replace the cover, and clean up the messy "repair" the previous owner did.

after getting started on cleanup, I let the bike sit a couple of days, but did manage to mount my ML75 front tire and new tube on the XR80 rim that had arrived a couple of days after the bike

The tires look less skinny on the rim, with the tube spreading it out a bit.

After a TON of mud removal, a tear-down of everything but the motor (the air box was filthy inside and out...), the bike sat like this around dinner time yesterday.

As of 10:20 last night, I had the carb and airbox cleaned, re-installed, and the bike was running.

Currently it doesn't want to run off choke, but some fiddling with the air screw should get me back into a better state of tune tonight. Wish me luck! I've never really messed with a carburetor before, and it's definitely a learning experience.

Edited December 20, 2012 by redkow97

[Hoblick]

Definately jet it. It makes a world of difference.

[redkow97]

Definately jet it. It makes a world of difference.

Does brand matter on the jet kits?

the "moose racing" carb repair kit is under $40, and gets really good reviews.

I know conventional wisdom on the main jet is 102-105. Not sure on the pilot jet. 38 maybe? I can look that up...

Also, should I remove the spark arrestor to get the most out of the jet kit?

[Hoblick]

Does brand matter on the jet kits?

the "moose racing" carb repair kit is under $40, and gets really good reviews.

I know conventional wisdom on the main jet is 102-105. Not sure on the pilot jet. 38 maybe? I can look that up...

Also, should I remove the spark arrestor to get the most out of the jet kit?

i just got jets from Pony. didnt buy a "KIT"

i bought one of the older style needles, and did a 102.5 main i think my pilot was a 38 or 40

yes, remove spark arrestor

[redkow97]

not a ton of progress to report at the moment, but will have a lot to say in about 10 days.

Jets are in my tool box (not point in replacing them and tuning the carb until it's 50 degrees or so), tires and rims are mounted, carb has been cleaned, new brake shoes are installed, but not adjusted, new chain is on my kitchen table, new air filter foam is in my garage, sprockets are on order, plugs should arrive wit the sprockets.

Most of my safety wiring is done.

Still have to figure out which catch can to purchase, and how to rig that up. A friend of mine has extra fuel line and carb overflow line tubing that I'll be using for that.

Anderson Door Co. Racing hoody, hat, long-sleeved T, and t-shirts are in my regular wardrobe circulation (seriously)

Just a matter of having enough free time to install everything, and probably pull open the motor to check valve clearances, cam chain condition, etc. then install the new jets and tune it all up.

I'm missing round 1 of the OMRL season due to the Mid-Atlantic tough mudder (PM me if you want to donate to the wounded warrior project! I'll post a link when it gets closer)

[redkow97]

well, everything except the new chain and sprockets is installed, and for the first time since I brought it home, it's all in one piece.

I'm getting a lot of valve or cam-chain noise. doing a shake down tomorrow, and then I'll tear it back open again to take care of the engine noises. I'm just excited to actually be able to ride the damn thing for more than 10 minutes.

[redkow97]

Bike ran effing great. I'm undecided on the tires. Hoblick got in my head! All I could picture while cornering was the sidewall of my tire buckling!

I crashed pretty hard about an hour into play time. Somehow my left thumb took the worst of it. It's pretty swollen, but I still have almost full range of motion, just with a bit of pain. Looking at my glove, I might not have a thumb to be icing right now if not for armored gloves.

I bounced my head off the ground lightly too. Another helmet bites the dust. Oh well. I had a (new) spare in the car and went right back to gooning it up before my thumb had a chance to start hurting too badly.

GPS confirms my bike hit 43mph with the stock 50 tooth rear sprocket. I have a 48 on the work bench that will go on with the new chain. Should be good for over 45!

I'm also happy to report that my bike (2000) was wheel to wheel with my buddy's 2007 CRF through all 5 gears. We drag raced with both of us starting in 2nd gear. Any slight advantage he had could be chalked up to him being lighter.

Fun day, even with the crash. Bike was totally damage free, just a scrape on the exhaust system I just painted. Figures.

[J_Copeland]

Good to hear your ok!

What size CRF were you keeping up with on an 100 ?

[redkow97]

Just another 100, but it's 7 years newer.

The main differences (only differences) between our bikes were that his tires are a lot bigger. He's running BT45's and I have much smaller ML75's.

Jb is also 20 lbs lighter though. We both had stock gearing.

[redkow97]

P.s. wear gloves. I crashed at 25 mph or less, and my glove looked terrible. I'd be seeing bone without it.

[RHill]

Figured I'd bump this up.  A few friends and I are thinking of making mini sumo xr100's.  Any pro tips?  Those tires end up working for you?