engine trouble please help

raudogsmotors · Oct 19, 2014

I think i blew my head gasket but dont know

ok so i was riding my 2 stroke 66/80cc angel fire black horse when all of a sudden i herd a sneezing sound come from the engine and a blast of air come out on my left leg after that the bike wouldnt stay running id give it gas it die id peddle it n start it it would die i dont know what the problem i i asked a friend who works on ars said he thinks i blew my head gasket any advice or thoughts would be appreciated looking forward to riding again usflg

Kioshk · Oct 19, 2014

Re: I think i blew my head gasket but dont know

Sounds simple enough: have you verified that the head-bolts are torqued down properly?

maniac57 · Oct 20, 2014

Re: I think i blew my head gasket but dont know

Check that the acorn nuts are not bottoming out and that studs/nuts are not stripped.
Replacing the acorn nuts with connector nuts is a great upgrade. Connector nuts are like a double thick nut and grip the studs much better and are capable of higher clamping pressure.
Lapping your head and cylinder perfectly flat is another good way to be sure it doesn't happen again.
Use search box for tons of info on lapping

raudogsmotors · Jan 28, 2015

Re: I think i blew my head gasket but dont know

i dont know exactly what my head bolts are supposed to be torqued to in order to check that and it drove perfectly fine since i built it basically i heard a sneeze from the engine along with a blast of air on my left leg after wich the only way to keep the engine going is to keep the back tire moving via peddling with the drive chain engaged or riding it down hill and no matter if i give it gas or not it just bogs my dad thinks i either have a hole in my piston or i blew my head gasket if anyone could give me more in depth instructions id appreciate it
things i need to know:
1)exactly what the diagnosis is (in your opinion)
2)what the head torque bolts need to be tightened to
3)if it is my piston how would i be able to open it up and check without tearing the whole thing apart i.e.the easy way of checking

raudogsmotors · Jan 28, 2015

i have a 66/80cc angel fire black horse engine i was riding perfectly fine all of a sudden i hear a sneeze sound and a blast of air on my leg after that it will no longer start i peddle it and release the clutch and it sounds like its gunna fire but i go to give it a little throttle and it bogs itself right to death if i dont give it any gas it just coast for a little bit and winds down till it comes to a complete stop if i keep pettleing with the drive chain engaged it will sound a little like its fireing but just die i cant figure this out please help

cannonball2 · Jan 28, 2015

Check for the presence of spark, fuel, and a blown head gasket. Kinda sounds like the head gasket.

Trey · Jan 28, 2015

Re: I think i blew my head gasket but dont know

..........

raudogsmotors · Jan 28, 2015

I can't really see a good spark n had to strip the wires I have the green from the kill switch n green from the motor connected to the black of the magneto and the yellow black striped wire from the killswitch and blue from engine connected to the blue of the magneto idk if this is right I replaced the plug n plug cap with ngks but can't really be sure if there's a spark n I havnt been able to check the head gasket cuz I don't know the torque foot pounds for the headscrews but basically the only way the engine will run is if I'm peddling n even then its not actually running its trying to kick over

Davezilla · Jan 28, 2015

It's the head gasket.. Just check the torque... 8 to 10 lb/ft will do.
If you find these loose then re tightening will fix the problem, not uncommon for these to work their way loose on a new engine.

Davezilla · Jan 28, 2015

Re: I think i blew my head gasket but dont know

I answered you in your other post, I told you 8 to 10 ft/lb, but if you go up to 12 it won't hurt anything. The stock aluminum gasket does have a tendency to "smash to fit" so it's not uncommon for a new engine or fresh rebuild to blow the head gasket shortly after it's been running, just re torque and all should be good, run the engine like you normally would and after a few more hot/ cool cycles, check the torque again. Sometimes you may need to re torque a few times before it stays put on it's own, but it will most the time after the first or second re torque.

raudogsmotors · Jan 28, 2015

I read it was supposed to be 20-25 but I'm gunna listen to u guys I did tighten them to 20 but it never made a krinking sound so I'm sure I didnt crack the head but ill check the gasket how would I know if its blown n is my wiring correct keep in mind the wires have been striped to the wire n twisted together then heat wrapped there wired kill switch green tied to engine green tied to black magneto n killswitch yellow black striped tied to engine blue tied to magneto blue

Davezilla · Jan 28, 2015

The kill switch just shorts out the black and the blue mag wires when the button is held down so be sure that's where the kill switch wires go, it doesn't matter which wire goes where for the kill switch but the mag to cdi wires can't be reversed... Mag to CDI should be black to black and blue to blue, with one wire from the kill switch on each wire.

Also, if you have a white wire coming out of the mag from the engine, this wire is unused. It's supposed to be a 6 volt source but it can load up the mag enough that it'll lose spark power so it's best left unused. Some people have used it before to light up leds but trying to light up a headlight would most likely cause problems.

raudogsmotors · Jan 28, 2015

The white wire for the headlight is unused n electrical taped off blue is to blue n my black is actually green but it is to black if kill switch wires don't matter so long as ones connected to each then my wiring is golden

As for the gasket I havnt checked it yet n my acorn bolts are torqued to 20 but no krinking noise was made when they were tightened so I don't think I cracked the head even if I didnt hear a krinking sound is there a strong possibility I did crack the head or would I firstly know if I did (I.e) is there a specific sound that happens or thing that happens while I'm tightening that would let me know something horrible had just happened just need to check n replace the gasket if its bad n loosen up the acorn bolts asap and I should be back to riding correct?

I have never actually done any real work on the engine itself so when I put the new gasket on I'm assuming its like a car rub some oil on top n bottom of the gasket n place in it's proper place then torque the acorn bolts down to say 9 to 10 foot pounds to be on the safe side should I locktight the acorn bolts in place or would that be a bad thing laff

2door · Jan 28, 2015

Get rid of the acorn nuts. There's a chance they are bottoming out and not allowing the head to be torqued down properly or evenly. This is common. Replace them with shouldered (flanged) hex nuts.

If by "20" you mean 20 foot pounds. It's surprising that you didn't damage the threads. That's way too much torque. 120 to 140 INCH pounds is good.

There is no need to "oil coat" the gasket. It is aluminum, not a fiber gasket. Oil won't do anything. You should lap the cylinder head gasket surface to make sure it is flat before assembling things.

Tom

2door · Jan 28, 2015

I merged these two threads.

Tom

raudogsmotors · Jan 28, 2015

Define laping

2door · Jan 28, 2015

Lots to read on the subject of 'lapping'. You can usually find answers to questions by using our search feature. I typed in 'lapping' and got this for you. > http://www.google.com/cse?cx=partne....tab=0&gsc.q=lapping cylinder head&gsc.page=1

Tom

raudogsmotors · Jan 28, 2015

I'm a bit busy to browse Google right now so by lapping do u mean run my finger around the whole gasket make sure its smooth just need a short handed answer of what lapping is

fatdaddy · Jan 28, 2015

raudogsmotors said:
I'm a bit busy to browse Google right now so by lapping do u mean run my finger around the whole gasket make sure its smooth just need a short handed answer of what lapping is

Not to be mean spirited bro, But how could you be too busy to learn. If yer TOO busy to read? Then how ya gonna find time to actually fix it. BUT on the bright side, it is a simple fix. Yes grasshopper, I believe it is a head gasket. Lap it or dont, if the gasket aint burned sometimes you can simply re-tighten the head. I had the exact same problem on my 4th of july ride and no socket to tighten it properly, Finally made it to the shop. Tightened the head and its been fine since. SO, first just tighten the head and see what happens. Worse case, ya need a head gasket.
fatdaddy.

cannonball2 · Jan 28, 2015

Might be worse if he pulled the head down to 20ft/lbs(240in/lbs!). Might have pulled the threads. Hope not. Adding Helicoils is not a big deal though.

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