gas in oil help! By bcgreatness (Read 12,319 times)

[bcgreatness]

hey fellow docs, got a good one for ya. i have seen a few on here and online, but prior to a few days ago, ive never come across a 4 stroke 50cc in person. Well luck has it that somebody i know had just purchased one about a week ago, knowing that it needed a little tlc, and rode it over to my house for me to work on since im the best mechanic they know. after a very quick inspection, i noticed a couple of things that needed immediate attention. 1) handle bars loose. i could turn and the tire would stay in same position. 2) the carb was leaking fuel at a dangerous rate. i put a 1/4 gallon of gas in it, next day it was all gone lol. 3) had a few wire issues, broken switches, a bad ground, battery shot, brake light only lights when you use front brake leaver. over all, my bud got it for very cheap, sure it needed a little work but besides all that i listed, it ran pretty darn good up and down the block. so heres where the fun happens. upon inspection of the front forks and steering column, ive noticed that the bike had been in a wreck at some point in its journey. the very most bottom seal/bearing was cracked and missing pieces which i put a new one on, and the top i had to put a few extra washers to get the handle bar mount to stay still because it had been stretched out. next i took the bucket and seat off so i could gain access to the carb. i marked all of my connections even though i could hook it up blind folded, and i rebuilt the carb. after i get it all back together and let it sit for 5 hours to make sure the new silicon i used was dry, i kicked my heart out on the kick starter until it finally fired, fwew its rough getting the petcock to pump the fuel back into the carb. after it fired up i noticed that the throttle cable needed adjusting so i took the seat and bucket back off and finished the adjustments. idle was perfect. so while i was standing back admiring my excellent work, i heard a familiar sound coming from the engine. this sound i could not have forgotten as it was still fresh in my mind from the 120 mile ride to tampa that i did on my 150cc. the sound i can only describe as a somewhat hollow sound and you could almost swear that you could hear all the internal moving parts in action. i heard that sound on my 150cc because by the time i made it to tampa, i had blown most of my oil out from the vent due to crank case pressure. back to the 50cc, so when i heard that familiar sound, i was like ah ok well it might not have any oil in the bike at all. so i reach down and take off the oil dip stick to check and make sure it needs oil. well, as soon as i took the dip stick out, oil came pouring out of it like i had just blown the hoover dam up with scud missile. i let it drain for a few mins, then i tilted the bike over and let more pour out to where it gave an accurate reading on dip stick. i start the scoot once more, and i still hear the sound so i immediately shut it off after about 5 seconds. i remove the oil dip stick and it pours out like it did the first time. ?! so as i let it drain out, i realized that the consistency of the oil is rather loose, it was not thick like oil should be. i dipped my finger in it and sure as snit, i smell gas! what i dont understand is how the hell that much fuel and oil mix and the bike still runs?! it runs like a champ, no stutters or jerking, on the stand, it will still hold WOT. i would take it for a run down the road but im not taking any chances on that test. so i have a few ideas of where its coming from but im going to remove drain plug and let it all out and see exactly how fast its filling up. what could cause this issue but still allow it to run good? im stumped for now. if it were my scoot i would have had it apart already but since my bud wont know until tomorrow when i break the news, and he pays me to fix it, i wont know for sure until then lol. any ideas or suggestions? thanks crew yall the best! happy easter by the way

[Bashan]

If you have a vacuum fuel valve the diaphragm could be leaking. This lets gas run down through the vacuum tube directly into the intake manifold. Rich

[redrider]

MY Honda done the same thing ,and my vacuum fuel valve was bad just as Rich said .Pull the vacuum line from the valve and fuel will run out the port if its bad

[jct842]

Here we go again, charging a buddy to fix something that we don't know how to fix!

[bcgreatness]

sorry for the late reply, was a busy day. anyways, it is not the petcock. if it were then the scoot wouldnt run so darn good, would bog out and die lol. just for kicks i did remove the hose and its not free flowing the fuel, i took a few puffs on the ol vacuum hose and every puff it would pump fuel perfect. im almost positive on my next idea of why it could be mixing oil and fuel. last night i drained the fuel oil mixture and let it sit overnight to assure that gas wouldnt build up and lock the piston. today i put it back together and added the proper amount of castrol 10-50 synthetic motorcycle oil, i rode that scoot around for 2 hours today wot the whole way trying to beat the hell out of it, she didnt stall or give me any problems, not even a sign of a fluid leaking anywhere. shut er off and checked the oil dipstick and its about an inch higher then what i put in, the fresh new oil i put in was mixed with fuel and had the consistency of water. ohh well, it rides hard no loss of power, starts on first kick. i will put about 50 miles on it before i give it back so that way i can change the oil a few times to assure all fuel is absent, but first i must take apart the motor.

[Bashan]

How many ways can raw fuel get into the oil? Since you ruled out the vacuum line I'm thinking crankcase breather. I'm not sure how that scooter is laid out but on my CF Moto Pegasus it would be possible for gas to get to the case via the air intake system. There would have to be fuel leaking into the system somehow though. Can you smell any gas after you ride it and if so where? Rich

[sprocket]

Check the valve cover vent and it if is attached to anything on the other end, disconnect it and put a fuel filter on it and zip tie it up high on the frame...

It is the only way I know to get raw fuel into the sump...from the valve cover and down the cam chain.

[Alleyoop]

1. I am wondering if this scoot has a canister to catch fumes and it is drawing gas through the vacuum line from the intake. When it draws vacuum it is on the downstroke so it would be sucking and if the canister is getting gas and not working it would draw gas through the vacuum line on the down stroke.

2. The Fuel Ratio screw could have fallen off or is missing or you forgot to put it back in. My crankcase got lots of gas in it because once the Fuel Ratio screw vibrated Loose and fell out. It would idle and run good and you can hear the difference in the tone of the muffler RUNNING RICH AS crap and a lot of the gas is going down into the crankcase.

Just a Thought
Alleyoop

[bcgreatness]

its all good. i gave the motor a good once over and everything checks out. today i rode this thing around for a few hours and even went two up for a while just to get it running nice and warm. between that time i did a few tests. first i took off vent hose and rode around for a long time just to see what would come out, it came out squeeky clean. second, i started up scoot and pulled the vacuum line from the back of petcock and it shut off every time, so i know thats working, it dont leak either. every so often i would stop and do a complete oil change on it and after doing that all day the oil keeps a more natural constancy. i believe that it was flooding because the carb was leaking very bad for who knows how long before i got my hands on it. after i rebuilt the carb is when it quit leaking gas into the motor overnight. all the gas in the oil just needed to be flushed out. im just worried because i dont know how long the oil had gas in it so it seems to run excellent right now but the damage to the bearings is unknown. on this the vent hose is run from the valve cover to the side of the air filter box and is sucked back into the carb. a catch can would be nice. been meaning to put one on mine for a while, need to get around to that. sending this very slow but good running 50cc home tomorrow.

[bcgreatness]

update. upon inspection of the scoot today, none of the fuel has leaked into the motor overnight. 1 small victory. i checked the oil level and it was slightly higher then what i put in to it, slightly odd. ran the scoot for a few hours to let it warm up so i could check the oil again and see if it was where i filled it to. when i went to check the oil, it was still good looking, but i could smell the gas a little more then yesterday. not a super heavy smell like before but still a noticeable difference. for the hell of it, i borrowed my neighbors northern tools compression test kit and the motor was throwing out 80-90 psi almost good but a little too low for ignoring although it does run and i rode by a police speedometer showing a solid 41mph! .from my years of experience wrenching on cars and semi trucks, and all of my tests i performed, all the signs pointed to one thing. it was time to get down and dirty, oh joy... first order of business, check the piston rings. how does one do this? if you dont know, heres a tip. some people run compression tests with oil dry or oil full. you want to run an oil full test so you get accurate pressure. so first order of business, get a meat injector ( VERY handy tool for mechanics! ) fill it up about a quarter of the way with fresh oil, set aside. run compression test normally, note PSI. next, remove pressure gauge fitting from spark plug hole, then grab your injector. inject a very small amount of oil into spark plug hole a LITTLE! but enough to cover top of piston. tap the starter enough for the piston to make a full revolution. repeat the process 1 more time. next you hook the gauge back up and run your compression test again. if your rings are good, you will get a 5-15 psi gain on next test. that = good rings. so i know the rings are good. on to the next test today. next thing that comes to mind when having a some what low psi is the valve seats. time to pull the valve cover off. upon checking the valve adjustments, i noticed that the intake valve was set perfect but the exhaust was a little loose, but not enough to cause it to stick. while i was thinking about sticking valved it reminded me that if a valve does not seat properly then that would cause a lowered compression test and a possible fuel oil mixture but the adjustment was not that far off. the seats looked in excellent health upon outer inspection. so as i was saying about the signs pointing to one thing, i was certain of it now. it took only 30 mins to take the scooter apart enough to get to work on the head of the motor. after about 2 hours of removing parts and marking parts and jumping on computer to watch videos on here to double check i was not going to bomb this job, i finally got the head of the motor off and discovered that a very small piece of the head gasket had blown out from the piston side going to the exhaust port side. the side of gasket on piston side was blown out to about the side of a horizontal grain of rice, and the size of the gap on the exhaust side was about the side of a pin needle head. scraped off gasket, lightly sanded gasket seat area with 1000 grit sand paper. got a sheet if cork gasket maker and traced out the gasket shape, cut it out, and sealed it off with the red super high 700degree temp silicon gasket maker. it took me from 7am to 10pm today to finish putting it all back together. ive done a few head gasket jobs on cars and trucks, but i do have to say doing one on these small motors is a real PITA!!!!!! the most difficult part was juggling the valves, springs, and rocker arms while trying to align everything up! and i thought that the hard part was going to be getting it put back to proper TDC. its actually very simple assuming that you MARK ANYTHING AND EVERYTHING THAT MOVES WITH A REAL TIRE CRAYON! other then that it was all pretty simple once i took it apart to see how it all goes back together. so i finished the gasket job around 3 or 4 pm, and while i let the head gasket dry up, i started work on the CVT, taking the cover off, cleaning it out, checking the bearings. once that was finished and put back together, i took a short dinner break. i went out, lit a smoke, walked over to the scoot and kicked it once, no start, twice? nope, 3rd times a charm! nahh, 4th kick, fired right up! i let it idle while i finished my smoke and then took it for a ride. i tell you what that thing was pretty quick for a 50cc before but its almost as if it took a good 12 hour nap and woke up with the energy of a 5yr old. it runs about the same speed but gets there slightly faster. i dont even have to do a compression test to know it will be right but i will do one tomorrow for the hell of it after i change the oil a few more times, flush gear oil and refill that and maybe a new spark plug. now i know yall are wondering where the pics are, well sorry, im not sure if i posted it when it happened but i threw my phone at a wall. it still works but the screen is broke. too bad that would have made this a good post... well im beat, this little 50cc has put my body and mind through a 1000 mile marathon. happy scooting all

[jct842]

;D Cork to replace a metal head gasket?

[bcgreatness]

yeah i know, i wasnt going to use a gasket at all but the guy wanted a gasket. i grew up on dirtbikes, my father showing me everything he knows ( still teaching me to this day lol ) on 3 of our bike builds, we removed the gaskets completely as to slightly reduce the size of combustion chamber via piston ride height. napa says that the cork gasket maker sheet is treated cork that can handle gas and oil. never heard that before lol. the less he spends in parts, the more money i make.