need help with 84 xr200r rfvc

Hey all, new to the forms and just reposting my issue in this forum due to engine type. To start with, i am not an expert, dont claim to be but i do know my way around an engine. I picked up two 1984 xr200r bikes with the rfvc enginesicon1.png. one of the engines had a valve let go and went through the top of the piston but the bike is in amazing shape and all origional. the other bike is a little rough but the guy who owned it was in the process of rebuilding it and already bought all the parts...new cam, timing chain, guides, valves but was only partially assembled. I pulled the engines on both and put the engine in the origional bike. After getting it all back together with alot of help from forums and reaseach I was unable to get the bike to start by kicking it over. I was able to start it by jumpstarting it and on the first start up it was pouring blue smoke and throwing oil out the exhaust. I figured the rings were bad so i tore it down and the rings were good, cylinder and all was in great shape. I changed the rings anyway but i discovered a bad head gasket as well as a leak on one of the head bolts that was the incorrect bolt. after getting it back together i am encountering the same issue, will not start by kick start. it will start by a jump start and this eliminated the blue smoke. Now i am getting a white smoke but bike will not idle and boggy at low rpm. not sure if the timing is exactly perfect, went by info i found, lobes on cam down, line across the cam sprocket and the T is lined up as close as possible, as well i am unsure of any adjustments that can be made on the twin carbs. any help would be greatly appriciated. also, on a side note, i took the carbs off again and when i kick it over with no carbs the engine pushes air out the port where the carbs bolt on. this is why i decided to ask for help. I was under the impression it should be a suction when kicked over.

 

just an update, i took the carbs off again, and when i place my hand over the intake port where each carb mounts on i only get suction out of one of the intakes. the same intake also blows back compression into that carb. the other port doesnt seem to have any suction or compression when bike is kicked over.

 

The two-valve XR200 is the preferred bike.   Also there is an XR80-200 thread but you may get some help here.

The OP posted in the 80-200 site but that sites is pretty focused on the two valve motors.  Since his motor is basically just a smaller bore 84 XR250R RFVC motor I thought the best technical help would be on this forum. 

i dont mind posting where ever i am asked or told i may get any advice besides swap the engine. i would like to get it going.

Air pushing out the intake could be an intake valve adjusted too tight and not sealing.  Also, when you replace rings you always hone the cylinder so the new rings will seat in.  The rings not seating could explain the white smoke.

agreewith BajaR,, inlet valve tight or stuck. Smoke could also be just whats left in the exhaust from previous smoke too.

Sorry took so long getting back with an update. So, i removed the valve cover and noticed that the intake valve was out of adjustment. As were the rest of the valves. So after adjusting the valves and putting it back together again. The bike started first kick...yay. or so i thought. The bike was still smoking alot. I figured that it could still be all the residue oil in the exhaust, so i took off the exhaust and cleaned it out as best as possible and then figured the rest would burn off after a few rides. Well after numerous trips out in the trails with the bike it is still smoking and it is also loosing oil. I have to top it up after each ride. You can also put your hand at the muffler and it will spray a fine mist of oil onto your hand when the bike is running. Now, i am at another impass. There is alot of compression, if i slack off or take off the decompressor then i cannot kick it over due to the amount of compression so I dont think it is the piston and rings. Bike also starts within 2 or 3 kicks cold, first kick when its hot. Also has lots of power, now i am not really familiar with the bike as far as how much power its supposed to have but it slings dirt pretty good pulling away. So, the only thing i can think of is the valve seals could be bad to explain the oil loss. Didnt really want to get into changing the valves and valve guides if i didnt have to.

I'll say you are on the money with the valve seals.  I guess you wont know if the valves, guides etc need replacing until you pull it down.  Everyone will tell you to do the job properly but who knows maybe just replacing the seals may get you by for awhile??

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