1988 WR430 Porting

First I'd like to say that this site is a fantastic resource. The restoration work you guys do is amazing.
I am restoring a 1988 WR430 for dual sport use (street legal) and have been trying to find some resources on porting work for this year engine. If anybody has any information (experience, magazine tech articles, etc.) they would like to share it would be much appreciated.

NYWR430,
Can't help w/ request but, welcome to the site. Post up some photos of your bike and what you might be working on. Always interesting to see what others are doing.

I don't port these things however half of the used ones have been tampered with in the area in front of the carburetor up high undermining the iron liner. From extensive email conversation with an individual in Sweeden my logic about these things being design limited by the fact there are long studs holding the top end together instead of the cylinder bolted to the case and the head bolted to the cylinder. Serious horsepower chacers make tubes connecting the reed cage to the transfer ports. This tactic is kind of done by rd 400 hop up shops but their studs are far enough out so they don't have to go external. I might remind you that the pin in those pistons is kind of short and has a habbit of hammering it's hole in the piston oblong. I don't like how the wiseco's skirts line up with the lands in the cylinder and woosner dealers have been awful evasive when I asked questions. I am not sure if their pistons are designed for the air or water cooled versions. Do what you want, I got a thick walled kx500 pipe and cut every weld and adapted it to the bike. Very happy, sounds like a modern bike now and that first 90 degree turn out of the engine has been made a lot less abrupt.

Fran

Interesting. The responses are much appreciated.

I found the steel piece which the exhaust pipe attaches to had a poor fit up with the passage in the cylinder. I ground quite a bit on the steel piece and am suprised I didn't girnd all the way through to match that up. Matching the cylinder to the cases without the gasket sticking in the flow of gasses is kind of challanging as well as there are no locating pins. The gasket in my instance got trimmed and sure could be put on in quite a flow reducing fashion. Just the coarsness of the aluminum casting and the uneven way the iron sleeve isn't blended in the way a modern (well I have seen the inside of a modern 125 husky) cylinder is. You might be happy with playing with these variables at least for a while.

Fran

Do any of you guys know if the center case is made from aluminum or magnesium (1988 WR430 water cooled)? I found a hairline crack by the kickstarter and need to weld it up. I know the TIG procedure for cast aluminum and cast mag are similar, but the filler rod will vary.

There is no doubt the two stroke standard shift sweedish ones have magnesium cast cases. The automatic ones had the cases come from a different supplier and are aluminum. I think the four stroke cases of that vintage are aluminum just because I ended up with a half case loose and it weighs more and seems to be aluminum however I havn't tried burning any filings.

I read you to mean there is a crack in the left case kind of in the carburetor area where the shaft the intermediate starter gear rides on is.

I could go on and on but might suggest you get new case or cases only one with a repaired crack in my bonepile re cracked and I can't really see how you could drill out an end of the crack hole and fill in all of the crack. Just welding on the clutch covers warps them. I have welded at the swingarm inserts but there is a large bolt holding that together and no oil. If the cracking is caused by kicking back during starting I would say you are doomed. If the cracking is caused by a foreign object getting between the gears perhaps low temp patch on the top?

Fran

Fran..k,
Thanks for the info on the magnesium cases.
The crack is located at the rear of the center case, just behind the kick starter shaft gear where the gear teeth come close to the rear of the case. The needle bearing under the kick starter gear had failed and jammed the gear into the rear of the case, creating a small stress crack. This had happened under the previous owner. I replaced the gear bearing when I purchased the bike and rode and started the bike many times afterwards without even knowing about the crack until now. Epoxy might be the route to take if warping from the TIG is a problem.

I have attached a photo of my '85 CR 500 barrel. You can see that the ports have been blended to the liner to aid gas flow.... This was done by the ProCircuit (UK Importer at the time) for Huskys. It did go rather well then....

Just an update on the magnesium case issue. I did the vinegar test on the center case and it started bubbling almost immediately. So, just as fran..k had stated, the center case is most definitely made of magnesium.

As to the porting, By now most used cylinders have been touched up as shown in the picture. I was thinking more of how the liner has kind of a hump in the area of the transfer at the sleeve. Just from memory and not actually holding one in hand and perhaps some filler could make that flow more like the new bikes come to start with. Also there is a design defect in that the frame backbone is quite close to the carb air inlet. This is a common problem when they went to monoshock but super exagurated with the frame design in this model. Getting a heat gun like a flooring tile guy would use and re forming the airbox to be as tight to the frame as possible and making that passage as good as possible is another trick without touching the ports. I havn't heard of VOR lately but they had the basic same frame and modified it in that area.

After you stated where the crack is you could probably tig it there without a problem. I have built a blob up near that area to add that extra bolt to the clutch cover the factory added somewhere around 1986 to ealier versions. I remember the clutch cover piece distorted a lot and got milled down a little to straighten things out.

Fran

I was hoping to get away with TIG'ing the case. I have a mill to shave the gasket surface down if there is any distortion. I was going to preheat and outgas as well as use backup argon on the opposite side of the crack for the first weld pass. What did you use for filler rod on your cases, frank..k? I was thinking AZ101 as this seems to be a good general purpose filler for unknown MAG castings. Bad part is that they want $150/lb. Any source of MAG filler by the individual filler rod? I don't need a full pound.
Thanks, for the great info guys.