84 250r top end rebuild not running correctly

[joel93]

hey guys i picked up a 84 250r and this is my first top end rebuild on a 2 stroke basically it was a bunch of parts in a box and the guy cooked the piston the bottom end was fine nothing in case and no rod play so i had the cylinder bored to lowest amount over i could then put a weisco piston in it lubed everything by rubbing every moving part i could think of with the 2 stroke oil that i will be running in it maybe to much ? made sure piston was in correctly torqued all to spec all new gaskets made sure the marking on the rings were facing up cleaned the carb on it got it all assembled i made my oil ratio a little heavy 32:1 mixture i used 5oz instead of 4 so i kicked it over a few slow times first then kicked it hard and it started the second kick let it idle for 2 minutes then shut it down i had to have my thumb on the gas lightly to keep it alive i was figuring idle just needs messed with let it cool for an hr then started it again was idling it and then died out then i kicked it over and it started again and did that about 3 more times the carb looked very soaked then i pulled the plug and it was soaked i cleaned it and heated it put it back in and it continued to do the sAme thing over and over again could it be my oil mixture ? or something messed up with the carb or the top end dead already ? i have not checked the cylinder pressure yet any info to help point me in a direction would be a ton of help

[350for350]

You need to try to supply a little more info. What the carb soaked with and where? What was the plug soaked with? Was it really oily? How's your electrical system? Did you check everything to make sure it's all within specs? How's the jetting the carb? What kind of intake and exhaust are you running? When you say that the last piston was "cooked", was it scored like it just had a lot of wear or did it look like it actually got hot enough to start pulling aluminum off of it? I'm not trying to sound like an arsehole, but these are all questions that you need to answer in order for us to help you figure out what might have happened.

[joel93]

Hey no offense taken just didn't think to ask myself any of that when posting i cleaned the carb with gum out carb and choke cleaner there was some crud on the intake side I pulled the jets made sure they were cleaned out I didn't separate the needle valve to see where the last person had set it probably should have. I cleaned out the choke made sure it was moving freely as well the wetness on the plug seemed to be thin Not to crazy thick and oily electrical system I did not take any ohm readings off the stator or pick up coil I just checked spark on a head bolt before I tried starting it and it was strong stock carb to my knowledge and stock pipe it has a answer silencer on it which it came with when I got it the bad piston the guy gave me with it had a bunch of scoring the sides like it was ridden hard before warming up properly and the metal was moved down covering the top ring I'm out of town right now for work so I can't take any of the ohm readings and stuff like that

[350for350]

Be sure to check all of that when you can.

[John Tice]

Start with the basics; whether a cast or forged piston, oil holes need to be drilled in the piston in the exhaust rib area. Wiesco has instructions on their info sheet; basically, the exhaust rib needs to be scribed on the piston for marking the hole locations. 2 to 3, 1/16” holes need to be accurately drilled. If the shop who bored your cylinder neglected to tell you this, I’d be suspect of their qualifications in boring 2 stroke cylinders. As far as break in goes; when properly bored & honed, an easy ride on a couple of tanks of fuel is all that’s needed. It’s always good to spray soapy water on the outside gasket surfaces looking for air leak bubbles.
JT

[joel93]

Hey john I did remember reading bout that drilling the holes on the exhaust port side but I thought that was only for if there was a exhaust bridge ? I don't remember seeing a split down the exhaust port side but I can't remember off the top of my head but I'll defiantly Check when I get home and I'll defiantly try that soap idea

[John Tice]

If it’s a 250R Honda, there’s a rib in the exhaust. You might take a couple of pictures of the cylinder top & bottom for your reference. 2 strokes are a wonderful simple powerful engine; the do-gooders have killed the engine.

[atc300r]

Wrong ,The 81-84 250r cylinder does not have an exhaust bridge.The 300r Hondaline cylinder is bridged.The 85-89 liquid R cylinder is bridged exhaust.The 87-89 liquid r has bridged intake.
If it’s a 250R Honda, there’s a rib in the exhaust. You might take a couple of pictures of the cylinder top & bottom for your reference. 2 strokes are a wonderful simple powerful engine; the do-gooders have killed the engine.

[joel93]

Hey guys so I got to tinker today for a bit so I went through the carb again set my air screw 1 1/2 turns out set my needle valve on the second ring down from the top made sure the choke was working correctly so then I took a compression test had the choke open had it wot and kicked it a bunch of times I got it up to 200 psi ! Which is obviously way over spec I pulled the head back off and found the piston had a ton of I burnt fuel sitting on the top I took a bunch of pictures but I don't know how to upload pictures on here yet put it all back together checked all the electrical all was fine except for the secondary coil on the ignition coil it was out of spec by a bit I had 4K ohms and spec was 8k-15k ohms I checked the spark off the cylinder looks fine but I'm guessing it's weak enough to be getting smothered by the fuel possibly?

[350for350]

Sounds like you're on the right track. I'm not sure it's very common, but I've heard of spark looking good when the plug's out and grounded on the engine and when it's in the engine, the spark is weak under compression. Since your coil is out of spec, I'd see what it does with a new one. I hope you tried to clean some of the built up crap off of the top of your piston.

[joel93]

Hey guys so I got the new coil in and tried it same issues ! So I tried leaning the fuel mixture a bit still the same so I noticed my exhaust pipe is a little loose on the exhaust port so I started it and pulled the pipe real snug into the socket and it would die instantly when I did that so I pulled the pipe and silencer all apart and wouldnt you know a freakin rats nest ! It plugged the pipe right by the silencer got it all out and it idles and runs great now !! So figured I'd just let you guys know what the issue was thanks for all the support

[Rob Canadian]

Welp. Glad you got it sorted out. Darn rodents...

Must admit. Good story. :)

[350for350]

Good deal!