Vintage Dirt Bike Q & A

Hello all,

New to the two stroke world, and came upon a 73cr250 for the right price and couldn't pass it up. (free)

I am an avid rider, and have 3 streetbikes. 2 New and 1 vintage 4 stroke.

The problems as they currently exist on my 'new' cr are as follows...

Preface: I was able to fire it up today and it ran WFO for as long as it took me to hit the kill button. (1.5 sec.) So I know it will run.

Problem: After fixing the throttle issue, and beginning to start to kick the bike over, the kick start now seems to be stripped. I am so bummed, since it only ran briefly. How bad of a dilemma am I in? Can someone point me in the direction I need to head to repair this?

Problem 2:(perceived) without the engine running.. if I put it into first gear and then pull the clutch, the bike won't move. It doesn't disengage the clutch. The actuator on the case moves, but the bike is still in gear. What am I looking at to fix this??

Thanks for help, and I can't wait to ride this thing!

If you all have some questions, I may be able to clarify the situation.

anyone? bueller? bueller? bueller?

The kick starter is a common problem and you may be taking that side cover off anyway. They just wear out and have to be replaced. OK place to look is eBay. I've heard ones from an MT will work but haven't actually done that swap myself.

The clutch plates are just sticking. Probably got a little bit of moisture in there. What I prefer to do is put the bike in 2nd gear, pull in the clutch, and rock the bike back and forth VIOLENTLY.

I've had ones that were so bad I needed to bump start the bike and haul my lard butt up and down a steep hill with the clutch pulled in before they broke loose. Not recommended of course.

When you take the side cover off to work on the kick starter, you may be able to pull in the clutch and CAREFULLY insert a screw driver to pry the plates apart. The clutch basket is made out of an aluminum alloy that is just a little more brittle then a cap gun. Bend any part of it and you need to replace it. I am of the belief that once friction plates start going bad you are SOL since they will stick every time you leave the bike sit for a week. It is only about $20 to replace them with a set from Dennis Kirk.

Thanks for the heads up.

I took the right side case off this afternoon. Nothing looks worn in there. I managed to remove the shaft, and re-seat everything. I put it back together and it 'seems' to catch now. I haven't, however put a good kick into it as I have no oil in it now. Which, leads me to my next question...

What type of oil goes in the crankcase? Is it just 30w gear oil? I apologize for my ignorance. I know nothing about dirtbikes, nevermind a 2 stroke.

I am going to crack the other side open and see if the plates are sticking. I will move about very gingerly.

Thanks again for the info.

chad

Transmission is 1 quart of 30 wt detergent motor oil. Not to start an oil flame war, but I would recommend you stay away from the stuff that advertizes itself as ~high milage. Shell is one of the outfits that makes this and I have had trouble with a worn clutch becoming unusable after trying this stuff out. Probably fine with a new clucth but on something that is borderline can cause problems. Castrol is the brand Haynes recommends.

I use Castrol 10-40 in all my bikes and it works great. I'm sure there are other brands that work, but if it ain't broke.....

CHUD,

I don't think this bike is good for you. Really!! Nothing free ever is ya know. I foresee all sorts of bad mojo befalling you if you continue with this project. Who knows. You may just wind up herding sheep on a mountain in Wyoming or something. Just look what happened to Jay Blevins. He got an Elsinore and a week later bought an inflatable Liberace doll. Not good my friend. Not good.

I can spare you the agony and anguish of such a fate though. Package that puppy up and ship it off to me. I mean, it didn't cost you anything... YET! Look at what I can save you from. I know I know... I'm a heck of a friend and you haven't even met me yet. Just ask Jay.

_________________
Those who can make you believe absurdities can make you commit atrocities.

Loren Davis
51y

Excellent post. I knew I'd get this from someone.

btw, here are a couple of shots as it was when I got it...I'll post some more as it cleans up.



I got everything sorted out on the bike. Thanks for all the tips. I was able to ride it down the street this afternoon... WHAT A BLAST!!

Here's a recap from another forum I belong to. Cheers, guys

"UPDATE:

SHE LIVES!!!!

Went through the carb again this afternoon and installed a new o-ring, and adjusted the float so it'd stop overflowing gas.

There was an issue with the bike that it kept wanting to run WFO when I got it kicked over. I'd taken the carb off, inspected the throttle linkage, 3hrice. Well, somehow, getting it put back together, the throttle would spin just a tit's hair and not seat fully. Thus, making it run like a mofo wide open.

Got that sorted, and sealed a few pinholes in some of the rubbber bits, and she purs like a kitten. A really LOUD, fooogin kitten.

The clutch had also been sticking and wouldn't disengage when the lever was pulled, but I was able to break it loose by letting the bike idle, and then pushing it and popping it into gear. Once it warmed up a bit, the plates let loose and she shifts like a charm. I rode it up and down the street a few times, but it was dark and really quiet in the neighborhood. I decided I'd better wait til everyone is at work to ride the wheelie down the street.

So, she's almost as good as new. I need to order an air filter online, and replace the seals on the front forks and she'll be good to go.

HOT DAMN!!"


update to the update... I got the filter, and seals for less than 30 bucks delivered. woohooo

Is there a way to remove dents in the tank from the inside? or perhaps another trick you all have managed to figure out? I have heard from a street vintage forum some crazy things, none of which I care to try.

thx folks

Is it my eyesight or did someone use that expansion chamber as a skid plate?

_________________
Those who can make you believe absurdities can make you commit atrocities.

Loren Davis
51y

one thing i heard was filling it with water (not FULL full, just enough to cover the dents) and then freezing it. ice expands, pushes out the dents. i know it works on mufflers, but has anyone tried it on an aluminum tank?

Yeah, that pipe is pretty dented up. The bottom is even worse. My neighbor said the guy used to race this bike, so I know it's been ridden hard.

Does the water thing REALLY work?? I'd be afraid to break a seam or something, even though they say welds are stronger than the material it's joining...

I might be better off cutting the exhaust pipe in half, beating it out and welding a seam back together.. lol.


EDIT:

Here are some pics of the pipe.. such good shape.

Hi CHUD,

I don't know about freezing water in the gas tank thing. Might work. Might also bust a welded seam. I think it may depend on how bad the dents are. If they are from just pressing ones knees together in a flying death grip, like on my Elsie, they should come out pretty easy. If they have jinks and ridges then using compressed air or expanding water will probably find a weaker spot first. Post some pictures of the tank.

As to the pipe. If you have a torch or electric welder or a good buddy with one I'd cut the pipe, smooth out the dents, and reweld. Or, you can get a new pipe from one of the vintage dealers. About $150.00 or so I think. (Avoid Red Racer as the new owner seems to have screwed several people.)

HTH,

Loren

_________________
Those who can make you believe absurdities can make you commit atrocities.

Loren Davis
51y

Thx for the info. The tank isn't bad. It's probably a 'pucker moment' in the tank. I'll try compressed air first. If that doesn't work. I can probably get a paintless dent repair guy to fix it.

For the pipe, I am going to take a plasma torch and cut the bad sections out. I will then form a new piece of metalfor the repair and weld it back in. It may not look pretty, but it will work until I can afford another 'lung'.

Thanks for all your posts, guys. I do appreciate it.

Let me say I have never tried the compressed air with an Al tank.

I have tried it with a steel tank and the results were unsatisfactory. You know how tanks are kind of saddle sharped? Now imagine the part that snuggles up to the top tube of the frame turning inside out and the tank becoming a balloon. Well not quite a perfect balloon as the original dent was still there. Those dents are structually sound, like trying to crush an egg in the palms of your hands.

What I stick<sic> with now is hot melt glue and a home made dent puller. I've also heard those 'Pops A Dent' pullers from auto supply stores are essentially the same hot melt glue but straddle the dent with and pull it out with a threaded rod. Once again, guy who did it did it on a steel tank but reported it worked amazingly well for a <$20 piece of junk.