Yamaha yz 250 1991

sandman768 wrote:

Looking good👍 the radiator grilles are very hard to find! 

TooOld4WFO wrote:

I rebuilt my rear shock for my WR250 1991. The Yamaha manual does not show disassembly or reassembly of that rear shock. The manual suggests it...

I rebuilt my rear shock for my WR250 1991. The Yamaha manual does not show disassembly or reassembly of that rear shock. The manual suggests it is not rebuildable.

I found this rear head seal on eBay and used it.

https://www.ebay.com/itm/314753602243?epid=4038191638&hash=item4948c6d2c3:g:7cEAAOSwsIRkzc-b&amdata=enc%3AAQAIAAABICYZRjjBPJLlCBxFefNg91LboiKYefhWMnAB%2B8WzGUBhNqgAs9ZNsWCVOZ2f5uwrP5W6Z7E2UFbC2OjabimfB2L5AzI9YaMd3rMxDQJWbCstI43NSofH0bWO4ioybL1F1E5T%2F7QbHTUOhA4%2BykUTdUUt%2FlshRE4BetTTVZfJE6CNWtvzBdlrbv4GDu84ngBK4CdAcdw4Lu5B95rbrFkS0P3tuG6t93h0oAw96mOKOTeWdAnitiF1cBt0zBJlTq22HdE99GORIRbKgMNzmsekHf4%2FzVYivgYe2t%2FxdaTqF0rnvrlUxi5TFuHxFm6e%2Bhge4QI6un0ZzdbUolXzGjQ7FE3CG%2FUqapaRc2VMjpHkZQBJVyMbN6KGiDmwDqDe34OTXQ%3D%3D%7Ctkp%3ABk9SR4zT55y8Yg

I purchased Yamaha branded suspension oil. I rebuilt it exactly as I would any piggybacked rear shock. Topping off through the compression adjuster and than sealing it up there.

 

 

I should have topped off to that screw at the top vs the adjuster. That’s how I would do it again.

TooOld4WFO wrote:

This is what I wrote on one of my restores. This is how I Cerakote. How I use Cerakote. [url=https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.cerakote.com&data=02%7C01%7C%7C5e47344000ad4079411208d696cb5c34%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636862197496115338&sdata=t5S1hsmUazGVeI3baHZwfEWSGX%2FK8abrQZohzbGrW2I%3D&reserved=0]Cerakote main Site-Press Me[/url] Cerakote is a...

This is what I wrote on one of my restores. This is how I Cerakote.

How I use Cerakote.

Cerakote main Site-Press Me
Cerakote is a fantastic product to use. It comes in the color so desired along with a small bottle of hardener in the oven cure series. The oven cure or heat cure tend to have the most amount of desirable attributes vs an air dry. The air dry product line do not use a separate hardener. You just pour the contents in and spray.
Although Duracoat was cheaper as I remember, it also featured a catalyzing agent. Cerakote in my opinion is quite a bit more user friendly and more durable. Many respected firearm manufactures use the Cerakote refinishing line. This is quite an endorsement of the quality of the paint. The series I normally purchase.
Cerakote Heat Cure Series- Press Me
Prep of parts has been a variety of means. The most consistent one I use is bead blasting. A small compressor would be just about useless with a cabinet this size. I have a stand up air compressor that has a huge tank on it and it will run the whole time I am media blasting. Anything smaller like a 10 gallon or so compressor you will have to wait in between spraying for pressure to build back up.
Harbor Frieght Blast It Cabinet- Press Me
But I can’t say this is a must. I haven’t noticed poor adhesion of the paint not doing much other then wiping or cleaning the part before spraying. I have used carb cleaner, lacquer thinner and soap and water. Rarely will I sand before painting. Not suggesting you shouldn’t do more then what I have.
I use simple bailing wire or such to hang parts.
Wire for hangin parts when painting- Press Me

I stretch a long piece as to attach my smaller painting parts to. The thin wire makes it easy to even attach bolts to it and it’s a cinch to then bend a short loop on the end to either hang on the strung line or in my oven.
The oven I created is (2) smokers from Home Depot I grafted together.
Home Depot Smokers Electric- Press Me

This worked great for gun stuff since I could refinish barreled actions and they would fit inside. Moto stuff is obviously more limiting. Pipes will fit but no rims, frames, subframes or even non elevating bike stands. For heat I usually am around 250 degrees for steel and lower around 150 for plastics and other thin metal parts. Yes you can safely heat plastic and rubber enough to cure. I go at least 2 hours at 250 although they say an hour at that temp. What I have found is you should wait at least 2 weeks before seating bearings or subjecting those painted parts to heavy use. I can absolutely tell a difference.
Without applying heat it can take days for parts to harden enough to touch. Without heat you do not get the same adhesion and strength. I did my rims and waited weeks to dry. They wouldn’t fit in my oven. I had air dried before and felt it would work if you waited long enough. Nope. Paint easily came off the rim.
Typically I use an 18-1 for mixing. So 18 parts paint to 1 part hardener. Since I normally spray not more then 1-2 ounces at a time I convert ounces to CCs and use a large hypodermic body to measure hardener. About 1.5 cc or so per ounce. That’s a tiny amount of hardener. Having that syringe body helps immensely in getting the ratio right.
Syringe Body to properly measure out hardener- Press Me
I used to just guesstimate the hardener to paint. But if a more gloss finish is desired you should pay attention to your ratio.
I don’t reduce it at all. It’s designed to be sprayed from the bottle. Fortunately it flows extremely well from either a touch up gun or airbrush. I used to only airbrush it when I was refinishing firearm parts. And for small parts that method is preferred. It covers unbelievably well with light coats. This is the main reason for most of the spraying I did I rarely mixed more then a couple ounces. It goes a super long way.
Most any air compressor can power a detail gun. But the small 1-2 gallon tank sized compressors will not easily keep up with even a detail gun. It will run most of the time to keep filling the tank which is not the best. Heat will build and you will have to watch out for water being fed into your air line. I use a water separator that plugs in first to the tank then the airline.
Water Seperator for Air -Press Me
You do not need an expensive detail gun. I have had great success with an EBay cheap one costing under $20.
Cheap Detail Gun Ebay- Press Me
But if you’re not well versed in how to clean one and care for it you will see an even shorter life span then what I saw. I finally had to stop using it since due to its inexpensive quality it started leaking past the needle.
I bought a $50 gravity fed detail gun at Tractor Supply. The quality of it is several times better.
Better Quality Detail Gun but still Inexpensive- Press Me
Just get a gravity feed one and not a siphon feed. It’s just easier. I use lacquer thinner to clean up and I wear latex gloves while working with the paint.
A light tack coat at around 20-30 pounds psi through most detail guns is enough to start.
I have my fan adjustment at about midway between narrow and full. I turn down my material always. I want to see just a light cloud of material coming from the nozzle.
After a few minutes wait I will apply more paint. The tack coat dries quickly and should provide a great base for heavier coat to adhere to. I don’t think I have ever ran Cerakote as it is designed to cover fast and lay thin. I would not paint any high wear item with it due to how thin it sprays. For frames and other parts that may see rider contact rubbing on those parts there are better products.
Remember Cerakote was designed primarily for the firearm industry. Due to tight tolerances you simply can not have heavy build up of paint.
I spray enough to cover the part. Normally a couple coats after a tack is enough to cover. You can certainly spray more but do not expect it to cover irregularities, deep scratches, or other issues you are hopeful the paint will fill.
It’s best use is spraying just enough to cover the part in color. Even with a light coating the hardness of the properly dried part is impressive.
I can’t remember if you should or should not put immediately into your oven. I’m hit and miss on this anyways. Just follow their guidelines if any.
I marked the dial on my heating element after I figured out what heat setting for a constant 150 and 250. The nifty gauge on the doors gives me a quick reference to check.
I never pull items out after being heated for whatever time I needed to. I unplug the machine and just let it cool down on its own. Normally overnight.

I wouldn’t even think of rattle canning painting anything on my bike. For a little more time and expense I can have a professional quality job along with durability. My concerns over any painted item not catalyzed (hardener added) is oil, gas, washing and other behaviors related to cleaning taking it off or dulling it.
I don’t get squat from them for this promotion other then satisfaction from using it. Anyone can do it. But there is upfront cost. You can see my references for some cost ideas. Start with some testers which still are like $30. Just remember it doesn’t take much to cover. I have kept hardener in a refrigerator to help it last longer. For last 3-4 years I have been spraying I have never had to buy more hardener. Cerakote is very generous with giving you extra.