Vintage Dirt Bike Q & A

Just joined, thanks Nathan for the help with that, I have recently acquired a 1980 CR250R off of craigslist for $400 and it is going to be my winter break project, I got 3 weeks to burn Its in pretty good shape I think, the engine runs great, after sitting for a month I rolled it out of the shed opened the valve pulled the choke and it fired up in 1 kick, it has the expected worn out bits like the rear sprocket, fork seals, break shoes and chain rollers. I also had to get a new set of bars for it as the old ones are bent up. Here is a photo from when I brought it home, yes I got rid of the pro circuit muffler the first day, he had a super trap on it before but decided it was too loud and used bailing wire to put that thing on, I repacked the super trap and stuck it back on, sounds much better.


I have all of the replacement mechanical parts I just need to order a new seat cover, decals and a new rear fender as it currently has a poorly fitted and hacked aftermarket one on it. Has anyone dealt with DC Plastics before, they seem to have every thing else I need and then some for the best prices, I might need a new set of rear shocks it I can't fix the stock ones, the left side one shakes pretty good so I think the shaft bushing is worn out.

Another question, on the expansion chamber where it slides over the exhaust flange? on the engine is all stretched out it looks and leaks quite a bit, is there a way of sealing it back up or getting it to fit better so it works properly?

Anyway sorry for the usual long winded first, I'm a new guy post, thanks in advance
Nathan

HI nathan . try VMX racing for the plastics ,they are much closer to the original and are shinny unlike DC plastics.vmx also has the best seat cover . as for the shocks progressive has 17.5 inch shocks which are reasonable , however if you want the best go for ohlins also available from vmx ,but be warned they are not cheap,$750-800.
good luck
Jim Richardson #84

Cool thanks for the info, I saw the Ohlins and they do look nice but since I think I well mostly be doing trail riding the progressives would work if I can't get the original ones fixed, or if I'm lucky and I might find a set of Fox Airshox on ebay for a reasonable price. I'm think I am just looking to do a good riding restoration on it, just something to have fun on and I like to wrench on things

Does anyone know if there is a Krylon fusion red paint color that is close to stock, I still have to sand down the previous owners spray bombing on the tank and front fender and repaint it.

depending on what you mean by "stretched out", you might be able to remove the pipe
then remove the pipe manifold from the cylinder. Use the pipe manifold as a mandrel to
hammer the pipe flange back into shape. If it is too screwed up, you can cut the pipe
flange off, fabricate a replacement and weld it in place. It is important that you
completely seal the pipe to the cylinder. As for a silencer, there is a gentleman selling
rebuildable repros of the original on Ebay. Mounts to the stock brackets and tucks in
much better than most of the aftermarket stuff.

I also noticed you need some side panels. Those are available from VMX as well and will
go a long way in preventing burns to your left leg when riding.

If you want to paint your plastic tank, you will need to do some king of seal and prep to
prevent the paint from bubbling and peeling as the gas fumes seep through the plastic.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Cool, I did find a set of side covers on ebay but noticed too late that they are for a 78/79 and not an 80, so if anyone wants to trade, let me know. For now I am going to run it without side covers and use the supertrap muffler not pictured and pick up a different set of side covers and muffler later, trying to spread the cost out a little bit.

I thing the pipe from age and vibration has just literally been stretched out around the pipe manifold. I was thinking I could take the pipe manifold off and put it over a bar or something and use a body hammer to stretch it out a bit and maybe make a couple of lengthwise slices in the pipe, pull it together with a large hose clamp and weld and grind it back together to reduce its diameter a little.

Is there a way to sand the plastic down and polish it or something instead of painting it, unfortunately the previous owner did a spray bomb job on it and I well need to do something but if there is something better then just paint I can do that.

That might work, but since the manifold is a casting, you run the risk of cracking it.
IMO, the easiest fix would be to cut the bent flange off the pipe and weld up a new one.
The flange can be fabricted by simply cutting a length of thin wall tubing of the correct
diameter and TIG/MIG weld it to the pipe. You get a perfect fit and can switch to after-
market pipes in the future because your manifold won't be deformed.


There was a guy on Ebay that was advertising plastic fuel tank renovation without paint.
He posted some pics of restored tanks and they looked brand new. I think he was listed
under AHRMA or vintage MX or something like that. If your tank hadn't been painted, you
might have been able to polish it up.

VMX sells a complete plastic kit for your bike (except tank) for $250. They also have
aftermarket pipes and silence that look pretty good.

Dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Good point on the header pipe, I didn't know it was cast, I well definitely just weld a new bit on the end of the pipe instead. For now I am just going to go and get all the worn out mechanical bits, and rear fender, replaced and ride it, I well replace other things like the exhaust and rear shocks as money allows, the shocks well be first. I don't mind it looking well worn for a while, sleepers are fun

Good idea. That bike is a rocket and was THE bike to have in it's
day. Should still be a blast to ride. Let me know if you run into
any problems when you decide to start renovating, I did a frame
up restoration on a '79 a while back and picked up some useful
info along the way.

Don

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Yeah that's the cool thing about this bike, aside from the worn out bits which are to be expected on a bike of this vintage, its in real good shape. The bike lived in Arizona up until about 3 years ago so there is no rust on the thing and its mainly just dirty so it doesn't need much restoration, a good clean, new seat and decals and do something to freshen up the tank and it should look pretty good on its own.

Anyway the first project well be to make a stand to work on it with, welding is fun and I figure I can whip one up for about $15 or less.

Cool bike, in reference to your seat cover talk. I put a VMX cover on my 80 and it fit well, but i recently picked up a complete 1980 seat with a Hi-Flite Foam kit and cover that has an additional nose peice that rides up the tank to allow for better riding posisiton and better safety for the you know whats. I dont know if they still offer this setup but it might be worth checking out.

Well, I started digging into the bike, I got the rear sprocket and brake pads changed out and one of the chain rollers that I got worked in the upper front position but in the upper lower it was running into the brake stay/arm so I well have to find something else for that. I also found that my clutch lever is broken, not the actual lever but the mount, so I well have to order a new one of them.

Here's the kicker though, as I was threading the chain back on I noticed the drive sprocket is not bolted in, nothing, so I well have to figure out what size bolt to get and a washer for that now as well. Oh well I just have to remember its a 30 year old dirt bike.

How did your bike turn out?
I have a friend who resurrected a 1980 basket case to mint condition.
I couldn't believe the condition of this bike before he started. He told me the cases had been full of water, etc...