1979 WR 250

don't forget these bikes usually fouled plugs on a regular basis due to high oil ratios and dubious jetting.

My 400 has two plugs - an ND W27 FS-GU (in the center) and an ND W24 ES-U off to the right side. The 24 has a considerably longer reach (sticks into the cylinder a bit, gets kinda close to the piston) and, judging by how much the center electrode extends out towards the ground electrode, appears to be a hotter plug than the 27. I've never used the spare plug and often wondered If it was just stuck in there to fill the hole after a compression release was removed (all courtesy of the PO). I have no clue what plug(s) I SHOULD be using, or if I even have them in the hole they came out of...
JT

unless you know you might foul a plug occasionally, I would find a bolt and replace that spare plug. sounds too much like a great spot for detonation to start.

the double plug is for racing where you get to the start, fire it up and it poohs itself, quick lead swap and your away...was common in the 70's before oils became "better". was common to see guys sitting beside the start line holding it wide open blubbering away trying to clear a cold engine before launching into a panic stricken plug change as the starter is walking the "walk"

I never (hardly) ever have plug problems. the plug in the husky is the same 1 it had when I bought it in 2011. probably should change it....

once your jetting is good, plugs should wear out not foul up.

I rode a pe 250 in the early 80's on the same plug until I decided to pull it out for a "look" it looked fine and back in it went only to come loose and fire out as I was roaring to work one day...had to walk back up the road to find it, open the gap (broken fingernail) and chuck it back in finger tight (hot hot hot!) so I could get to work and a spanner!

The 'two plug' thing makes a bit more sense than it did when I first convinced myself that wasn't a broken-off spark plug staring back at me (funny thing is that happened as I picked up the bike). I can't wait to get wrenching on this sucker (lack of time for the next couple of weeks).

it looks like a moron with a drillpress god i hate tweakin hackers i would make a plug cut some aluminim sheet and find a good welder and do my best to cover that shit up or get another head

your sure thats a WR it has the long rear brake stay is there a center tube under the engine ? think you should run some numbers

Frame # is MM, Engine # is 2066, There is a center tube under the engine. From what I can see, all of the 79's start with MM, but 2066 is WR.
In 37-ish years, I suppose it is possible someone has played Dr. Frankenstein.

I don't know your year, but all of my huskies take long plugs. Justintendo, correct me if I'm wrong, in my experience aluminum heads tend to pair with long plugs, since aluminum needs to be thicker than steel to achieve the needed strength. I'd be careful with that though, as you point out, plug getting close to piston can get problematic really quickly, and that 'custom' plug hole might not exactly fit the stock plug. I'm sure someone on here can name the spark plug you need without trying that hard.

not sure what an earlier husky takes..but theres always this chart

Wow, I've never understood spark plug designations better than I do when I am looking at that chart (not that I understand them that well when I'm looking at that chart).
As long as we're talking about fuel, etc. The 79 wants to run on 40:1 marina gas (no ethanol) and Castor oil like my LC bikes, right?

absolutely..even better if you cut that marina gas with some non-oxygenated race gas.

the chart will at least tell you what b8es means..

Fair enough, standard core, middle-of-the-road plug with long thread reach and a relatively large head if I read the chart right.
The race gas thing makes some sense. Would I really want to mix the castor, marine, and race gas, or just go to straight race and castor if I were to go that route?

marine fuel is just non-ethanol as far as i know. we are lucky enough in my area to have a few gas stations that have pure fuel, and its always 91 octane. i want more octane than that so i cut my fuel 50/50 with vp 110 leaded. we have a few pumps around that supply the vp too so i keep a few cans around of both. my chainsaw, leaf blower, line trimmer, and snow blower are all 2 strokes so they get their octane bumped up a lil bit too. i run ethanol in nothing but my autos.
how much race fuel you run would be up to you..and depend on what fuel you use. probably a question for another thread, but its been talked about here before. it alters your jetting making the bike run a bit richer, so you need to stick with it. i just dont like running the 91 octane, as husky called for higher and also some of the swedes were intended for leaded fuel.

I second justintendo by agreeing it a sparkplug that some moron broke the porcelin off from, I am of assuming you bought that way Eric

Seeing there is still wrench hex visible, just remove and replace with a stud plug unless you might find an old one way compression release. We used them for softer braking and also after the lining got wet and did not come back for a while.

Well Jim and Ruwfo, You're right, it is a broken off spark plug. Justintendo already called me on the $10 and a donut Pool table is still available if you're looking though

Assuming (broken spark plug left in aside) that the PO appeared to have at-least some idea what he was doing as a mechanic, I will probably need to do actual mechanical repair on this one. Which leads me to a couple of questions:

1) Which flywheel puller do I need? Husqvarna-parts has three, 26, 27, 33mm. I have a 26mm, though I couldn't find it last time I looked, so, might need to pick one up anyway. Based on the descriptions on Husqvarna-Parts, I probably need a 27 or 33mm for the '79, but which one? I do see a 26/27mm unit available on Amazon.com that indicates Motoplat compatibility, Anyone use that one?

2) Anywhere I can download the engine overhaul manual for this bike? Most of the manuals for newer bikes are available for download, but the '79 I can only find for purchase on Husqvarna-Parts. Not to say I won't pay Phil if that's my source, but a free for download is nice.

3) does this bike have a head gasket? I've been looking over gasket sets, don't see a head gasket, and parts manual doesn't include a head gasket. It makes some sense that a head gasket would be unnecessary since there are no pesky coolant or oil channels coming down from the top, but I've primarily worked on 4-cycle or L/C bikes in the past, so no head gasket feels a little 'edgy'.

4) Will the flywheel holder for my 85/86 work on the '79, or do I need to go find one of those too?

no head gasket on these, just lap the cyl head in everytime you take it off

is your flywheel holder for moto plats ? if it is your good

you have the giant motoplat on that old 79, im betting it takes the biggest motoplat puller. if you cant find your other one might as well buy them all, right? they are pretty cheap on ebay.
as suprize said, none of these air cooled swedes have head gaskets. they are lap fit. you have lapping/valve grind compound from installing flywheels, right?

Troy,
The 79 250/390WR's used the long style brake stay up until frame serial number MM5594 after that the WR's used the later style like the 1980 WR's have. This was due to the rear hub and brake plate was changed to the 1980 WR/OR rear brake plate and hub. This also required Husky to change the swing arm also.
There were many mid year changes on the 79 WR's. Probably more than any other model year. There was also frame changes and the forks were changed mid year. Also the Ohlins dampening specs were changed mid year.

Marty