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Post by wideopen on Feb 28, 2014 21:34:50 GMT -5
GY6 170cc its been blowing seals and gaskets ever since I installed the BBK.. so recently bought an NCY crankcase decompression kit for my gy6 kit is basically a threaded fitting that replaces the oil dipstick and about 2 foot of clear 1/4" hose pipe. Question is were do I put the end of the hose hang it high away from debris? or run it into my breather?
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Post by JerryScript on Mar 1, 2014 0:36:40 GMT -5
Put a fuel filter in the end of the tube and zip tie it up the frame. You want to get as much of the oil as possible to drain back down. Test it out, and after it's warmed up, give it some good revs. If you have any oil make it's way out, or you see the fuel filter fill up even partially, you'll need a catch can. Get a small metal bottle, put a hole in it's lid to tightly fit the tube, then mount it on your frame with plumbers tape and/or duct-tape. Run the tube up the frame with zip ties, then curve it up and over into the hole in the metal bottle's lid. You will need to check the catch can often at first until you determine how often you need to empty it, based on how fast it fills up.
BTW- A second base gasket would probably prevent the need for all this.
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Post by wilds on Mar 1, 2014 1:06:06 GMT -5
Blowing seals and gaskets... You shouldn't get that much pressure in the engine case!
To me it sounds like you have bad piston rings.
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Post by alleyoop on Mar 1, 2014 1:11:54 GMT -5
I have a question, is the Valve cover Vent hose blocked or kinked that would cause the crankcase not to vent.
I have a 182cc bbk and I have no such blowing of gasket problems.
Alleyoop
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Post by millsc on Mar 1, 2014 6:41:15 GMT -5
I have a 177ccs I have put a few hundred miles on it no such problems either I agree with wilds you have some other issue.
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Post by UniqueSP on Mar 1, 2014 7:42:52 GMT -5
Mine did that. Even with the hose i was holding it all the way straight up and the oil would blow right up and out of the house. my valve cover vent was fine. Turned out it was the piston rings.
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Post by carasdad on Mar 1, 2014 8:42:49 GMT -5
Agree with all of the above.. EVEN if it is a new BBK..they only time I have seen oil come from the vent tube is when the engine has blow by. Those vent kits they sell are just a Band-Aid for an underlying problem....that being piston ring blow by. For 12 bux you can buy a 'special' check valve for the blow by..it allows air out instead of in. BUT the problem is not air being sucked into the vent..it is from pressure in the crank case. That 'special' Scooter check valve is nothing more than a $2.99 Chrysler PCV Valve btw..that you can get at any auto parts store. Oil blow by indicates piston ring blow by and is common on the GY6 150 engine when the ring seat is bad. When it is to the point it blows engine seals..you REALLy have an issue that needs to be fixed..vice covered with a PCV Valve Band-Aid....  Glenn |
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Post by justbuggin2 on Mar 1, 2014 9:55:44 GMT -5
I agree with the guys above you have way to much blow by but did you just build this motor if so then you my just have the rings not stagger or clock correctly
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Post by dakotafig on Mar 1, 2014 18:11:04 GMT -5
Compression test would answer everything.
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Post by wideopen on Mar 1, 2014 19:36:32 GMT -5
when I installed the rings I clocked them "from the top to bottom" 12-6-9-3. there is no oil blowing out the pcv vent hose. I crank the engine pretty hard at wot 8-9k for a period of time I think that was my problem it can't take the pressure. The vent hose I bought is a cheap NCY kit it does not have the oil canister just a hose barb and 2 foot of braded hose. oil will rise up top of the tube and blow out when cold I run 10-40 SAE oil. I got a new canister style oil catch can vent that also connects to the pcv along with new 61mm HOCA piston/rings gasket kit on order from scrappydawgs, and partsforscooters.
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Post by dakotafig on Mar 1, 2014 21:04:00 GMT -5
So your saying you don't get anything out if the valve cover vent, yet your crankcase is building pressure? Sorry maybe I didn't understand what you were meaning. Wide open throttle or not that air flow is coming from somewhere and if it is enough to be more than what the valve cover can vent that's probably bad. I put an actual breather filter on the end of my valve cover vent. I brought the hose up to the side of the frame under the seat and zip tied it making sure there were no dips in the hose. The filter looks like a mini uni filter.
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Post by wideopen on Mar 1, 2014 21:41:00 GMT -5
My oil is still clean after 2k not black. There is nothing wrong with the pcv and vent it pulses air while the engine is running no oil blow by. I'm just going to go back over everything new piston, oil catch can, and use permatex copper spray a gasket on every gasket. Only thing I can figure I crank it down on flat roads 1k over redline too much pressure build up in the case and that's where all the oil stays. race cars have belt driven vac pumps that line to the lifter valley high rpm builds tremendous pressure. might also balance the crank this time while its out if possible.
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Post by skuttadawg on Mar 1, 2014 23:13:03 GMT -5
My Echarm came with a decompression tube that has a removable plug in the end of the tube . I have seen some with a catch can in after market parts . At first it never had any come out since I rode it in the midrange until it was broken in . My Echarm does have a rev limiter in the ECU ( it has EFI and no CDI box ) . If I would hit the rev limit and hold it at WOT sometimes a tiny sip of bubbled oil would be in the tube . I emptied it every other month as it would only be a sip and I would put in a sip of fresh oil to top it off . I think decompression is a great idea since it helps prevent blowing out seals and gaskets . My Echarm has enough HP to where I do not have to max it out to cruise 60+MPH even with a passenger . I have hit 75 MPH and got a warning ticket for going 72 on an interstate .
Has anyone tried installing a kit with a catch can ?
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Post by wilds on Mar 2, 2014 2:07:03 GMT -5
Has anyone tried installing a kit with a catch can ? I have tried a catch can.  It worked, but some oil still squirted out of the can! After I changed to new piston rings I had no problems with oil being pushed out of the breather tube. |
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Post by carasdad on Mar 2, 2014 7:41:22 GMT -5
Cheapest fix..AND works the best.. Cost is 2 bux! This what I did until I fixed the blow by issue. Take a $2.00 8 oz.Hamster water bottle from wal mart..bore a hole in the bottle bottom to allow gases to vent.. Fill bottle with steel wool..but DO NOT pack it in tight or the air will not flow. Pop out the check ball in the tube at the bottom or saw the tip off to remove it. Use NO CHECK VALVE or it will prevent oil back flow into engine. The steel wool acts to catch the oil..cool it and hold it in the bottle..so at idle..low speeds or when shut off..the pressure being lower..the oil will drain back into engine. The vent hole on the bottles bottom allows built up gases to pass through. Run just a hose from the valve cover vent to the nipple on the bottle and attach it up on the frame above engine level..about seat height.with Zip Ties. Now your blow gas escapes the hole in the bottle and the oil is trapped in the bottle then recycled.. Looks too easy huh? Well on the old scootdawg site I posted this...many many tried it..it worked and they ridded themselves of the problem without some expensive oil catch can and check valve.. Here is a pick below. Ok can't post a pic without an offline photo account and link..this gets annoying..I can post on other sites..  Ok..let me try this..here is a link to my same post on another forum WITH a nice pic.. Glenn 49ccscoot.proboards.com/thread/8198/easy-cheap-effective-oil-catch |
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..BAD TO THE BONE..
