What is the right spark plug for the Mcchulloch mb290 leaf blower? It was given to me and it does not get spark through the plug but if you grab the plug wire end it is getting spark there. A Champion DJ7Y is what was in it but I don't know if it is the correct one.

any plug with a 10 or 12 mm reach will do the job
check the thread length in the head and that will be the thread length of the plug
most small 25 -35 cc engines all use the same plug

You can take a spark plug tester and plug one end into the spark plug wire and the place the other end on the spark plug and pull the starter rope and see if there is a spark present. Hope this helps.

I believe it is 2 to 1 ratio

Found this on another site ,might try this: i got the parts from bob's lawn mower in ny. phone 1-607-638-9297 and also found parts at another place but i only have a phone #1-800-645-2031 or mcculloch at 1-800-521-8559 or
1-800-269-6215 maybr this info will help others.

If it has not run for awhile, check the brushes. they might need to be replaced. The plug is usually moulded right on power cord. That might have to be replaced because if there is a problem with a broken or disconnected wire right at plug there is no way to see it. Hope this helps.

did you make sure the new spark plug was igniting if it is or if its weak you might have broke the flywheel key was it running fine when last used there can be alot of things it could be 2 cycle engines must have 120psi of compression ,the right fuel mixture,good plug right gap between flywheel & magnito (spark plug wire connect to to get spark) and not rust on flywheel & magnito hope this helps let me know thanks

Ok. Good job on doing what you could, right off! The simplest things are the most overlooked, and the most unforgiving.

So, you know your plug is wet, so you got some fuel flow.

Now let's figure out the plug no-fire problem. (This is under the assumption you haven't beat on this blower with a sledge-hammer at one point. The whole "key-way" is fried thing.)

1. Grab ahold of that plug THEN crank away. One time will tell you yes or no on spark. No, I am not joking, and yes, it is better than staring at the end of a plug and wondering if your eyes are bad.
In fact, better than a cup of coffee......in a bad way.

2. Check your kill switch. It is either: Grounding, or Open (open like it should be, UNTIL you push it, click it, or slide it, whatever you got). One CHEAP and fast way: Unhook the kill switch.
Then crank away. No spark? Not the kill switch then!

3. Check your spark plug GROUND. Let's say you got some shocking results from grabbing onto that bad boy. NOW check where the plug meets the cylinder head when she is screwed down in there. Believe it or not.....if it is funky, she won't ground right!
Hence, no worky.

4. You got no spark at all.....STILL. Let's look over your Spark Plug WIRE. Is she wore through? Is SHE grounding out? Has she heat failed? Then do #5.

5. STILL no spark. Let's check the last 2 things......
Rotor Magnets, and Magneto (ignition coil).
IF you have a volt/multi-meter, hook her up to the plug wire. No juice = Bad Magneto, or Bad Plug Wire. SOME juice = Good Magneto, but Bad Plug Wire (in some mowers/weedeaters, etc., remember that the Magneto is where the kill switch hooks too.
See if it is somehow grounding you out, by being loose but still touching the cylinder, etc.)

6. Failing Magneto. This can happen, and it does. You get SOME juice, just not ENOUGH juice. 2-Strokes make a lot of heat, even Magneto's give up the ghost after a while, sometimes. In this case, find a replacement!

http://lawnandgarden.owneriq.net/manuals/mfg/mcculloch_corporation/mb290.html
try the above site plus
heilbrothers.com
hope this helps

The User Manual States .025" (.635mm)

One suggestion, unscrew the spark plug and reconnect the high voltage wire. In a very dark area move the plug so that the plug thread touches some metal on the engine. Pull the starter cord. If you don't see a spark, remove the two screws on the handle and see if two wires are attached to the Stop Engine Switch. Remove one wire and bend it away from metal and try to see spark when pulling the start cord. If spark occurs, the Switch is shorted and needs replacing.