rm85 2005 not staring after rebuild

Bring it to TDC and check the timing marks. Make sure tight seal on reeds, and do a compression test just to make sure. It should start anything over 125psi but 160 is where it should be. Swap carbs if you have access to another one.

Make sure the plug is wet. If it isn't and you are kicking away without starting, I would look at the carb again. I always put old carbs in the ultra sonic to break of the debris that is in the passages that arent easily accessed. They aren't that expensive if you buy one on Ebay or over the net.

What does OK spark mean?

That much gas..... Sounds like a stuck or extremely rich float height to me.

Was at a race one night when I noticed the pan on the stand was full of fuel. Kid tried to kick it to go to the gate for next race, kick starter about locked up. Me and a buddy pushed it and got him going "after getting sprayed with race fuel". Once he got it going I realized he needed fuel . Got him back and topped off a tiny piece of dirt on the needle seat was all I could think.

But yes filling the pipe with fuel will cause it to not start.

Is the arrow or dot on top of the piston pointing to the front?

Make sure the reeds are not chipped or worn and that they flex open/snap shut when you push on them from inside (gently.)

Try a new spark plug. Even though you are getting spark, little engines really like having a big, blue spark. Often times, that's all they need.

If the piston hit the crankcase you have bigger problems than it not starting.

You put a fucking DRILL on the flywheel to make it start?!?! Wow. Here's some very valuable advice. Take that bike to a professional mechanic because, respectfully, you have NO CLUE! Do it before you wreck anything else

Hey Scooter never been to a kart race huh?

You have a strange problem here. You said parts were missing from the exhaust governor, and the bike was a non runner. I've rebuilt several RM85's when my son was younger, and I would put some valve paste on the crank where the flywheel goes and twist it a little, then clean it off and put it back on without the key way, so we could change the timing easy when we needed to. Check to make sure the keyway is in there, if it's not, you may think the timing is on but it may not be. Also check the plug wire end. They just screw onto the plug wire. I have had them go bad and cause these types of problems. RM stators can go bad, but don't usually prevent starting. The bike dies when it gets hot. Suzuki actually gave me a new one free when it happened on one of our 85's. It's obvious you have gas and compression, the spark you said was pretty good. I think that's where your problem is. Once the plug gets wet, it won't fire. The spark may be weak or timed incorrectly. I concentrate in that area. I've been a mechanic for over 30 years, and I'm betting it something simple. There's not that much to it. Just to add this. Once I had a drz110 that wouldn't start. had spark, but was weak. The fix was the module. Swapped it out, and bang, it started right up.

Huge ^^^. Overlooked.
If your piston is touching the crank for any reason, you don't want it to start. Cause' if it does, you're just going to start the whole rebuild process aver again.

And it apears that it is still being overlooked or ignored. I predict the OPs next thread is titled: "Success!!..... but then it grenaded 3 seconds later."

Let's review. You rebuild a motor, but it won't start. You're a qualified mechanic but instead of chasing the root cause of your freshly rebuilt engines failure to start, you throw a drill on the crank. Because you've done it before. Apparently at cart races, this is standard. Fair enough. Could that be because carts don't have KICK STARTERS on them? I'm betting your 85 does, and if it won't start on it, there's a reason. WHILE you were spinning it with the drill it backfires and you realise you were spinning it the wrong way. Would that because you failed to perform a simple basic task first, like perhaps checking the direction of rotation first? If you're qualified, what standard are we using as a benchmark here? If you rebuilt an engine in a car and it wouldn't start, would you just drag it on a chain to get it to fire? Because theres no way to get a DRILL on the crank. "Blimey mate, I forgot to set the lash on those valves! None of the bloody things are opening! Hope the boss doesn't find out about THIS one! That's the third fuckup this week. I'll get the sack over this if he finds out!". Then we find out that the piston is hitting the crank, and you, as a qualified mechanic, are asking if this is a problem. Seriously. If you bought all the right components and everything is assembled properly, it should run. Period. So over your storied career of 10 motocross and 1 superbike engines, this is how you've reasoned out your fix for the current problem. Fascinating.
Allow me to pass on some sage wisdom given to me years ago by a wise old German fellow. If something won't function as its designed, there's always a reason. Find it. Don't just go get a bigger sledgehammer, and beat it into submission. That won't fix it. That comment preceded a whack across the back of the head, since my father was entitled to do such things. I'm almost 50, and in the 35 years I've been fixing things(not always the right way) I've never proved him wrong. Or forgotten his words. It's fair to say I've fixed a lot more than 11 bike engines. But there's always a chance to learn something new. Like starting a cart engine with a drill. Nonetheless, if it's an engine or mechanical, the same basic rules apply.
Here's my next piece of advice. Find out why that piston is hitting the crank. Maybe your parts guy sold you the wrong one. Possibly in the right box. It happens. I've been bitten by that too. Even better, get that 2 stoke mechanic to look at that motor. You're missing something. There's no shame in admitting defeat and getting help. (Ask Winston Churchill. It's the reason you don't speak German now). There IS shame in proceeding blindly and breaking more shit, while your ego prevents you from making rational decisions.

Lol. Scoot said pretty much what I did.....just a lot more of it.

And I have to say, he is 100% correct. It's a small bore two stroke. Very VERY simple. If it has fuel, spark, and compression, it will run. Pistons hitting other parts are not part of the equation. Tear it down, measure all the parts and replace the obviously wrong, incorrectly installed, or worn out parts.

Awesome post Scooter!!!

A little off topic here but looking through youtube for crazy one off builds of rc cars, boats or planes. It shows the true craftsman in the world are still over in Europe. Cost effective yet some of the most unique craftsmanship I've ever seen.