RZ/RD 350 & Misc. 2-Stroke Tech BBS

Hi all,

my RZ250R has some broken retaining tabs on the flaring/body work, i still have all the pieces just asking who has been successfull in either glueing or plastic welding these back together, and what product seems to work best

Thanks

Have a search on here, weve talked about this before and there is a lot of info on what to use.

Glue doesn't really work in my experience.

I used the plastic weld kits before and it worked well, but you must be careful to not melt through to your painted surface.

Acetone is the answer. For cracks you simply brush it into the crack and it will fuse the joint. For broken pieces you brush both end and join.

If you mix acetone with some ABS in a jar it forms a paste you can use to do repairs. Alter the ratio to get the mixture to a desired thickness. Apply to holes, etc. You can pour it into molds and form new pieces or make repairs. I repaired bodywork with pieces missing and used heavy foil to make a mold to replicate the missing pieces. Pour into the mold and when it sets the new part is chemically bonded to the other plastic. It's all I use here and I have repaired many, many fairings.

I use ABS welding rods and cut them into small pieces and mix with acetone to make paste. EBay has them in red, white, blue, black that match existing Yamaha colours so it makes repairs more seamless.

That's a great idea, totally forgot about that.

Have had good success with acetone as well.

I definitely take John's advice as being golden but personally I have had better results with the 2-part plastic weld products from JB and generics. Can be purchased at Cdn Tire.

My biggest complaint with the chemical and heat melting of plastic is it does not maintain flexibility. Excess rigidity in your repaired part will lead to further cracks. The plastic weld products maintain flexibility, bond extremely well and can fill holes if required. Use mesh if you want more strength. I typically grind back the thickness of the original part near the joint to increase surface area and can be completely hidden. I doubt there are many that repair as many fairings as I do. one-two a week on average. Have yet to break a bond that was properly repaired on both sides even with mounting strain on part.

Those tabs have considerable strain put on them when you are mounting or removing the part.

Brittle and cracking hasn't been my experience, but I do understand your concern. It is just more ABS plastic added to the original ABS. Once the acetone evaporates all that is left behind is the ABS.

I have used a 2 part plastic epoxy as well, but it does get quite brittle when cured. For non-ABS bodywork it is sometimes the only option.

I have replaced missing pieces up to about 70 sq/cm with the ABS/Acetone paste. That was using heavy foil to mold the missing fairing piece and pouring the ABS/Acetone mixture inside in a couple of layers. That piece was about 6 mm thick. You don't want to pour it in too thick or the acetone will not evaporate fast enough and you will get acetone coming through from the inside to the already cured/set outside and it makes the repair look bad. Pour it in as a couple of thinner layers. That lets the acetone evaporate from the first layer easily before the final layer is poured on top of the first. Both layers will completely fuse. The thicker it is, the more layers you use. Give it some time to fully set and get the acetone out if the repair is quite thick. Otherwise you risk acetone ruining your new paint. You'll know when it's OK.

I have poured some pretty large thick pieces while testing and using left over paste. There really is no limit as to the paste's uses.

I have repaired cracks without damaging paint but you need to be VERY careful. Put heavy foil tape on the painted side and get it as flat and smooth as possible over the crack. Then you use a small artist's brush to brush acetone into the crack from the inside of the piece. Take it easy and go slow. You don't need a lot of acetone to get the job done.

To repair a broken piece you can foil tape one side and brush acetone from the other side. When it sets you tape the other side and brush from the first side.

If you look into the makeup of Plastex and other kits you'll find they are just ground up plastic and solvent. You can make it yourself and apply the same way at a fraction of the cost. Take a coarse file to some ABS and make yourself some ABS powder. Add a few drops of acetone and you have a permanent repair. There is nothing magical about the power/solvent kits you can buy, it is just clever packaging of a simple concept.

ABS welding rods on eBay. Nice that the colours match Yamaha perfectly. I've used them all except yellow. https://www.ebay.ca/itm/Plastic-welding ... xyLm9S~8ff

Hi John,

I may take another crack at the Acetone method.

Are the Yamaha RZ fairings all ABS plastic?

Just to clarify, are you saying the colors of the rods in that auction match up well with the Yamaha OEM colors (with exception of yellow which you haven't tried)?

For whatever reason, it seems like re-melted plastic after a plastic weld repair (even professional ones) is far more brittle than the original and same deal with chemically melted plastic. I know it seems odd as injection molded plastics are originally just melted pellets but it is certainly the case in my experience. The 2-part repair material is far less rigid and brittle.

The 350 is all ABS. Some 500 parts, like the solo cowl are not, but I have used acetone to repair them.

Yes, my experience has been that the colors shown match very well to the RZ.

The welding rods can also be used to do more conventional repairs using a solder iron or another heat source. About the link I posted as an example...just be sure you are buying ABS rods as there are many other plastic rods available. That link has multiple types of plastic. I should have chosen a better link.

I've been pleasantly surprised with something I bought at the bike show a few years ago. It is essentially ABS dissolved with Acetone or MEK in a squeeze bottle. Just carve a groove & squeeze it on like toothpaste...

OldTZracer wrote: ↑Fri Jun 12, 2020 7:24 pm I've been pleasantly surprised with something I bought at the bike show a few years ago. It is essentially ABS dissolved with Acetone or MEK in a squeeze bottle. Just carve a groove & squeeze it on like toothpaste...

That comes back to what I said earlier. The kits are just ground up ABS and a solvent. Easy to make yourself and you get to pick your own colours.

great information

Playing around with Solvent now, with wait for it..... Filed down Lego blocks, and I plenty of colors to chose from.... see how it goes.