Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 14, 2012 20:10:18 GMT -6
did you check the needle and seat? maybe the seat is causing the float needle to jam. so you have confirmed that fuel flows from the petcock to the carb? hey alley wasnt there an in depth video on here about rebuilding your carb that showed close ups of how to install the seat, needle, and float? maybe taking it all apart and re building all over again might solve?
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 13, 2012 14:25:23 GMT -6
well the idea is to hook the crank case vent hose to a catch can and then put a filter at the top of the can so that way it gets better pressure relief and also the oil that builds up in the can will drain back into the crank case via gravity like you said. now as far as your idea goes with the fitting going into the oil fill, that would be an excellent idea when i get around to building a DIY oil cooling system. after the oil passes through a small radiator, i could loop the system back to the oil fill hole to complete the cycle. i just need to find an electric pump capable of pumping oil at a strong enough pressure that wont erode from pumping hot engine oil.
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 11, 2012 22:45:26 GMT -6
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.
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 11, 2012 20:54:56 GMT -6
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
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 11, 2012 20:02:02 GMT -6
1. sea foam: what sea foam was designed to do is break down the molecular structure of any moisture/water in fuel and the alcohol like additive mixes with the broken down water/foam mix thus turning the water into a combustible solution. i have also seen people put sea foam in their oil before an oil change so they can run it through the motor to get water/moisture build up mixed in with the bad oil, then they drain the oil thus clearing up their oil passageways from water. 2. im not sure about your scoot but on my roketa 150cc, at the end of my carbs drain hose, there is a shut off valve for use in draining fuel when planing on storing bike for long periods of time. the baja 50cc ive been working on has one as well. im not sure if its something only a few of manufactures put on scoots but so far i havent seen a carb drain hose without one. ive inspected about 6 scoots in my area, and even the two 250cc scoots i checked out had them. maybe if your float is good, and the scoot does not run like crap, maybe just put a plug or install a shut off valve to it and be on your way. keep it nice and simple
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 11, 2012 2:17:33 GMT -6
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.
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 9, 2012 21:15:03 GMT -6
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.
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 9, 2012 5:28:10 GMT -6
im pretty good with finding other ways to achieve things when it comes to these scoots. if you could just tell us what brand/model 250cc that your having this issue with, we could help you get your seat fixed asap. let us know cash
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 8, 2012 23:43:41 GMT -6
inside the carbon fiber muffler i owned, it also had the very cheap fiberglass packing. it worked great for a few days but after most the packing blew out, it would get hot and the resin coating would form dark spots and flake off, finally one day it caught fire at a stop light had to pull over and put sand on it. believe or not the muffler was still in great shape besides the fact the packing was gone. i drilled out all the rivets but could never get the ends to pull off. i think they tack welded it together. i tried all my tools, my table vice, a person on each end, tied to a tree and pulled with a car on one side and rope on other. couldnt get it to separate. so finally after 2 days, a few attempts each day, i gave up and ordered a stainless. i also was thinking about putting a dirt bike muffler on mine because they were cheap but i sure bet that it would have been super loud and may not have the proper back pressure thus causing the rings on piston to break.
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 8, 2012 20:13:29 GMT -6
i purchased mine from amazon and it works great. they had a few of the 80$ ones that are identical to the ones on ebay but i went with the 120$ one. just a little advice, AVOID!!!! any after market mufflers that have rivets!!!! the carbon fiber one that i had on my scoot had rivets and was also poorly packed. all that held the packing in was sheet metal with a bunch of holes in it. after a few backfires it blew the packing apart into smaller pieces and then started blowing out of the muffler. the muffler i got from amazon was a little more expensive then the 80$ ones but mine is all WELD no rivets and it is glass sealed on the inside, so none of that sheet metal that has a million holes. heres a link if you want to see it. www.amazon.com/Scooter-Moped-Performance-Steel-Exhaust/dp/B005H98RGI/ref=sr_1_2?ie=UTF8&qid=1333937540&sr=8-2 and yes alley does have a very nice muffler that is in fact tunable.
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 8, 2012 20:02:56 GMT -6
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
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 7, 2012 21:24:37 GMT -6
i went to visit my father he lives in tampa. the day i was supposed to ride home the weather took a turn for worst, had to wait out the storm and the next day my father just drove me home, scoot in the back of his pickup.
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Scooter Doc
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Post by bcgreatness on Apr 7, 2012 4:01:35 GMT -6
if people drive their scoots into water deep enough to make the clutch slip need to think about sealing off the engine really good and running the air filter up the side of the bike, maybe to the top of the handle bars, that way with the snorkel intake they can use their scooter as a jet ski, besides, who would get a scooter just to ride on the road? sheesh...
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 7, 2012 3:20:33 GMT -6
i would upjet for sure, also check your diaphram needle in your carb to see if its adjustable, you might be able to notch it once or twice, that should help allot with adding more fuel. you also never mentioned if you upgraded your airbox. if you have not i would recommend doing so because with your new cam shaft upgrade and your free flow exhaust upgrade, you wont notice much different in overall power until you increase the amount of air flowing into the motor. happy scooting!
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Scooter Doc
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2008 Roketa MC-74-150cc & 82' Honda CM 250 Custom
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Post by bcgreatness on Apr 7, 2012 3:13:57 GMT -6
you can move your tach wire to run from your cdi, just follow the wire that goes from the cdi harness that runs to the positive on the coil, ive done so already and its pretty spot on.
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