4 stroking and backfiring from under head

[Malvaerin]

So I just replaced my head gaskets and moved e-clip to second notch because of lurching, backfiring, and small sprays of gas/oil from under header when giving more than half throttle, problem still happens so now I'm 24 hour curing some gasket maker on header because old/new/and gasket paper roll gaskets all seem to have the same issue. Only thing I can think is the nut on one side is wrong size/bad threading and it's allowing pressure to push through help please

 

[Chaz]

Check the weld on the flange/header to be sure that it is not preventing the nut from seating flush. See if your flange is nice and flat. Better to order or make an all metal gasket. There are also metal covered gaskets available. I don't think any kind of paper gasket would work for long at that location.

How many miles are on the engine, roughly?

 

[Malvaerin]

Roughly 250 miles

 

[Venice Motor Bikes]

It sounds like the head is warped from over torquing the head bolts.... Take the head off & sand it flat again using some sand paper on a piece of glass.

Only torque the head bolts to 12 ft/lbs.

 

[Malvaerin]

It sounds like the head is warped from over torquing the head bolts.... Take the head off & sand it flat again using some sand paper on a piece of glass.

Only torque the head bolts to 12 ft/lbs.

Thanks man I don't have a torque wrench so I'm doing it til i have a fair amount of trouble turning them, guess that's too much though I'll try flattening it back out and see if that helps

 

[Malvaerin]

Well after replacing the gasket and flattening the head I now have a leak in both front AND back of my block/cylinder. Overnight curing gasket maker again only this time with no aluminum gasket on, hope this fixes it but if not at least restores SOME compression because after flattening I had 0 power. Literally would not move even though I was wot and 5 mph before attempting to start er up

 

[Greg58]

How did you sand the head? As Norm suggested tape sand paper to a flat piece of glass to get it true. A good way to check the flatness is to lightly spray the gasket area of the head with paint before sanding, low spots will still have paint.

 

[Venice Motor Bikes]

It sounds like you did it wrong...

 

[Malvaerin]

How did you sand the head? As Norm suggested tape sand paper to a flat piece of glass to get it true. A good way to check the flatness is to lightly spray the gasket area of the head with paint before sanding, low spots will still have paint.

I did it with a piece of glass and sand paper but ended up bending my head gasket as it was too tight going onto the header bolts, after replacing it with nothing but gasket maker engine seems to be doing fine though I haven't tried it with wot because the gasket maker was curing. Thanks for the help, any idea why my clutch won't stay tight? I only use it to start up, and when going down big hills so I don't kill the engine from it coasting with no throttle. As it is I won't even stop at most signs because the difficulty of getting going again. Kind of a bad thing but could it be from me revving throttle with the clutch engaged?

 

[Malvaerin]

Ok so earlier it was running smoothly but because my gasket maker was still curing I didn't take it above 1/4-1/2 throttle, now after it finished the 24hour curing cycle it's back to sputtering/not starting (fixed it by doing the following; pedaled and tried to start it, got no power several times, moved petcock to all positions uncapped and recapped spark plug cdi boot, fiddled with kill switch in case it got stuck with no luck while moving/attempting to get power from throttle, more pedaling downhill still no power. Finally came to life while pedaling and twisting throttle which I was doing throughout) still spitting from under head (wasn't sure if it was front or back because nighttime low light conditions) still lurching when throttle is turned even a little bit

 

[Malvaerin]

Any help would be greatly appreciated as I even flattened the head down to where even the lip/step-down was nearly even with lower edge, and also sanded cylinder flat using glass/marker/sand paper as instructed ^ up there. Before sealing it up with gasket maker goop. Won't get any power at all at wot (wide open throttle) actually sputters and spits and lurches so much that I lose momentum. Please help me as this is my only means of transportation

 

[Malvaerin]

Update, a lot of the four stroking and timing misfires/misses have stopped since I fixed a connection issue from cdi-block-throttle&killswitch. Still having slight backfires coming from under hea while wot but at least I CAN wot it now. Only problem that remains is that after a couple 1-2 mile rides my clutch is so loose it stops disengagement of the drive, not sure why it keeps doing this if anyone knows how to fix it please let me know. The first time I tried to remove the clover/flower nut I had trouble spinning it so I had to whack it a lot with hammer and screwdriver I think that caused my locknut to not sit right to keep clovernut locked in place might be the cause but not sure because locknut still sits in clover groove but with a quarters thickness worth of gap between the two.

 

[Greg58]

The clutch problem sounds like the clutch cable is stretching or breaking, I had one do the same thing once. To remove the flower if you lock the clutch lever in its a lot easier, just count the turns the flower nut makes and it easy to get it set back.

 

[Tyler6357]

Why not just get another cheap stock head? Only $7
https://www.ebay.com/itm/80cc-cylin...0&_nkw=motorized+bicycle+head&_from=R40&rt=nc

 

[crassius]

reaching thru frame and pulling clutch arm toward you allows flower nut to turn freely

 

[Malvaerin]

I did it with a piece of glass and sand paper but ended up bending my head gasket as it was too tight going onto the header bolts, after replacing it with nothing but gasket maker engine seems to be doing fine though I haven't tried it with wot because the gasket maker was curing. Thanks for the help, any idea why my clutch won't stay tight? I only use it to start up, and when going down big hills so I don't kill the engine from it coasting with no throttle. As it is I won't even stop at most signs because the difficulty of getting going again. Kind of a bad thing but could it be from me revving throttle with the clutch engaged?

 

[Malvaerin]

Update, once I turned my attentions to cdi connectors and got some performance back and less misfires, I clipped/stripped the wires from block, cdi, and throttle and put new wire clips on them, wouldn't start so for some unknown reason I decided to check where the block wires connect to the magneto in case I had pulled them loose or something. Turns out that my "compression" issues were only loose cdi connectors and a magneto whose grounding wires (that come off the coil) had broken loose from the solder that held it into the block. I didn't have a soldering gun so I tried to heat up the solder with my bic with no success. Ended up cutting off a piece of my Walgreens reward card that I hardly use and wedging it under the coil which pressed the grounding wires back up against the solder tightly. No misfire or sputtering occurs any more even at WOT (yay!) I know it's a temporary fix till I can get a soldering iron but it works! Fingers crossed that that small piece of plastic doesn't break loose and ruin my magneto.

 

[Malvaerin]

Thanks for all the help guys!

 

[dr.Z&X]

Update, once I turned my attentions to cdi connectors and got some performance back and less misfires, I clipped/stripped the wires from block, cdi, and throttle and put new wire clips on them, wouldn't start so for some unknown reason I decided to check where the block wires connect to the magneto in case I had pulled them loose or something. Turns out that my "compression" issues were only loose cdi connectors and a magneto whose grounding wires (that come off the coil) had broken loose from the solder that held it into the block. I didn't have a soldering gun so I tried to heat up the solder with my bic with no success. Ended up cutting off a piece of my Walgreens reward card that I hardly use and wedging it under the coil which pressed the grounding wires back up against the solder tightly. No misfire or sputtering occurs any more even at WOT (yay!) I know it's a temporary fix till I can get a soldering iron but it works! Fingers crossed that that small piece of plastic doesn't break loose and ruin my magneto.

use a cheap pen torch to solder the blue and green wires or anything else but white. attach the wires to each side each side of the mag n they will act as you're hot n nutral wire too your CDI.
the ohns accross the wires u just attached should be no more than .327-.345 anything more than that will mean it is going bad. so from there you should seal up the mag hole where the wires go through to prevent water from ruining the mag permenantly. let me know what CDI you have and what carb i can give you the low down on what to do next. or engine kit...

 

[dr.Z&X]

don't listen to thwae fools took me alot of time to find out exactly how to test this **** its obviously super difficult if it isn't right in front of me