Engine Bogging/Low Torque

[kdaddy1980]

Ok guys, here we go again. Yesterday i went to ride my bike and it was really hard to start..then all the sudden it kicked in and ran good, but when i give it a good throttling it cuts out and wants to die. The engine revs really good without the clutch engaged but as soon as i engage the clutch it slows to a crawl and dies...
heres what ive tried so far

1) check the spark plug and wire
2) replaced the boot on the spark plug
3) checked and adjusted the clutch
4)checked the fuel bowl on the carb and it was ok (full of gas) but not overflowing i adjusted the float pin slightly tighter because i thought maybe it was flooding the engine.
5) checked the choke adjustment and its ok
6) found the intake loose and tightened it up.
7) checked and cleaned the air filter, took air filter off still same problem
8) verified that fuel was coming out of the gas tank
9) checked to see if i had a screw loose in my head lol

i just cant figure this one out guys..last time it was the exhaust clogged from using too much oil.. im going to take the exhaust completely off again and see if maybe i missed a chunk of debris in it or something but it seems like theres no restriction.

let me know what you guys think or if you had the same problem Thanks

 

[crassius]

check head gasket & seals

 

[kdaddy1980]

ok i took the head off and looked inside and everything had carbon buildup on it, probably from running it with to much oil previously which clogged up the muffler. the head gasket looked a bit smashed and worn so i replaced it with a new one. i ran it without the exhaust on and it fired up but still same problem, i did notice a difference after changing the head gasket but its still doing the same thing, at wot it drops a turd lol, if i just goose it a little i can get it going but it falls flat on its ass if i gun it.

another thing i was wondering is when i cleaned the piston off i noticed that there was quite a bit of play in it, the piston twisted inside the cylinder about 1/4 back and forth if i moved it, should it be stationary? i havent gone through the bottom end of any of these motors yet but it seemed like a bit much.

 

[mapbike]

If the piston has any twist to it at all that would be measured more than a few .000" 's it's a BIG problem and you should stop running that engine NOW!

pull the jug/cylinder off and do a good inspection of wristpin bearing and wrist pin, also check that you dont have that big twist coming from lower rod bearing.

I was gonna say focus on something binding up on the bike instead of the engine until you mentioned having a 1/4" twist movement in piston and then now I'm back to serious engine troubles that may require some new parts to remedy.

map

 

[Jeckler]

I was going to suggest a clogged jet, but go with mapbike's suggestion first.

 

[kdaddy1980]

ok, i took the cylinder off and the piston is just flopping around in every which way and loose, and also the rods got about and 1/8 inch of play. looks like im going to have to tear into this thing and replace some parts...


as of now the odometer reads 1071 miles. i think i used too rich of a mixture for too long during break in period 16:1. so the bike i sold, i ran a 1/2 gallon of 20:1 then straight to 32:1. just before this happened i really reved the **** out of it going down the street, i was doing about 27-28 mph and all the sudden it just gave out..it started back up and ran suprisingly how loose everything is..

seems ive got my first taste of the mechanics at the heart of this this thing..might as well, ive got two more motors coming next week..i really rode the **** out of this bike lol off road ,in the grass...i even took it mudding one time, but that just clogged the gears up with mud haha do you guys think if i just baby the next one i can get more than 1100 miles out of it before any major work needs to be done?

 

[kdaddy1980]

so i started tearing this engine down, while pulling the case apart, i had to hammer the crank out because it was real tight in there i accidentally pushed the drive sprocket side bearing in about an 1/8 inch because i forgot to take the key out.duh! dammit lol then on top of that the magnet seemed to stick too so i hammered on it a little a messed up the threads on the magnet side of the crank. i had to use a punch and punch out crank from the magnet.anyways, i totally screwed up the threads and the nut wont even go on anymore, sooo..

im thinking about just ordering the crank with the rod and bearing on it already for 25 bucks and a wrist pin bearing for about 10 bucks..that should take care of it..

 

[mew905]

I hate to sound like an advertisement, but for an extra $35 + shipping you can get a dax balanced lower end. its a whole new case and such, with a custom poured, milled and drilled crank (I was talkin to dax a bit about this). They've got raving reviews already so I'd look into that if you can afford it, it uses high quality hardware as well.

According to the OP I was going to say maybe you're jetted too small? I used a 62 jet and it would have exactly the same symptoms, then I went up to a 70 (I dont have any in between) and it runs fine with a bit of four-stroking. However with the play in the piston I'd say you're probably losing a ton of compression through the piston rings. It's a good idea to stop running it like that as suggested, as if the piston twists and the ring gets snagged in the intake, its pretty much game over for the whole motor and potentially worse.

 

[maniac57]

ok, i took the cylinder off and the piston is just flopping around in every which way and loose, and also the rods got about and 1/8 inch of play. looks like im going to have to tear into this thing and replace some parts...


as of now the odometer reads 1071 miles. i think i used too rich of a mixture for too long during break in period 16:1. so the bike i sold, i ran a 1/2 gallon of 20:1 then straight to 32:1. just before this happened i really reved the **** out of it going down the street, i was doing about 27-28 mph and all the sudden it just gave out..it started back up and ran suprisingly how loose everything is..

seems ive got my first taste of the mechanics at the heart of this this thing..might as well, ive got two more motors coming next week..i really rode the **** out of this bike lol off road ,in the grass...i even took it mudding one time, but that just clogged the gears up with mud haha do you guys think if i just baby the next one i can get more than 1100 miles out of it before any major work needs to be done?

I've lost track of how many miles I have on my Pig, but it's a large number.This is due to my taking good care of it and not trying to get every last mph out of it all the time.You cannot ride these ht's like a dirtbike and expect them to last.
But I admit it IS tempting to gouge on them sometimes..
Just think, you can replace the entire kit for the cost of a top end rebuild on a motorcycle engine, so why not ride the snot out of it?

 

[sboricic123]

ok, i took the cylinder off and the piston is just flopping around in every which way and loose, and also the rods got about and 1/8 inch of play. looks like im going to have to tear into this thing and replace some parts...


as of now the odometer reads 1071 miles. i think i used too rich of a mixture for too long during break in period 16:1. so the bike i sold, i ran a 1/2 gallon of 20:1 then straight to 32:1. just before this happened i really reved the **** out of it going down the street, i was doing about 27-28 mph and all the sudden it just gave out..it started back up and ran suprisingly how loose everything is..

seems ive got my first taste of the mechanics at the heart of this this thing..might as well, ive got two more motors coming next week..i really rode the **** out of this bike lol off road ,in the grass...i even took it mudding one time, but that just clogged the gears up with mud haha do you guys think if i just baby the next one i can get more than 1100 miles out of it before any major work needs to be done?

Considering what you're paying in parts to repair it...I'd just be buying a new engine and keeping the old one around for parts. That's my opinion.
Mine has been doing the same thing but I noticed gas/oil was coming out of where the kill switch wires lead into the engine. I haven't thoroughly look at it yet though.

 

[kdaddy1980]

you mean the wires going into the magneto? if that's the case then you might have a crack in the case or something there shouldn't be any oil in the magneto, maybe the crankshaft seal is leaking.

the case isn't sealed at all besides being mated metal to metal i thought there was a gasket in between them but appearently it was just dirty oil seeping out of the case. i was surprised when i opened the engine up and there was no seal.

but yeah, when i get my new motor kits im just going to put the new engine on my bike and fix up the old one, put it on another bike and sell it for cheaper than i sell the bikes with new engines. i was thinking like $250 or so,ill explain that it is used and has 1000 miles on it.

 

[crassius]

unless the factory screwed up, there is a gasket between case halves - bad seals are often caused by the main bearings getting loose and allowing the end of the crank to go up & down

 

[mapbike]

Considering what you're paying in parts to repair it...I'd just be buying a new engine and keeping the old one around for parts. That's my opinion.
Mine has been doing the same thing but I noticed gas/oil was coming out of where the kill switch wires lead into the engine. I haven't thoroughly look at it yet though.

If you have oil/fuel coming out around those wires you have a failed crank seal, a $7.99 fix and I'd replace that seal asap or you will end up with a burned up engine if it get s to the point of causing to big of an air leak and creating a severe lean run condition.
A very simple fix once the magnet/flywheel is removed.

Vendors here list a crank seal but I think what I have seen on piston bike and Dax sites are the thicker seal for drive gear side of engine, here is a link to where you can get both seals for $7.99 shipped to your door.

http://www.ebay.com/itm/80cc-66cc-4...390?pt=LH_DefaultDomain_0&hash=item3382e56b4e


Happy Riding...
Map

 

[sboricic123]

you mean the wires going into the magneto? if that's the case then you might have a crack in the case or something there shouldn't be any oil in the magneto, maybe the crankshaft seal is leaking.

the case isn't sealed at all besides being mated metal to metal i thought there was a gasket in between them but appearently it was just dirty oil seeping out of the case. i was surprised when i opened the engine up and there was no seal.

but yeah, when i get my new motor kits im just going to put the new engine on my bike and fix up the old one, put it on another bike and sell it for cheaper than i sell the bikes with new engines. i was thinking like $250 or so,ill explain that it is used and has 1000 miles on it.

That's right...into the magneto. A buddy of mine has about 4 engines kicking around, so I just took my bike to him to figure out the problem. He's knows more about 2 strokes than I do. I believe it's just a seal though. I could feel air coming out but didn't try using soap and water in a spray bottle to check where.

 

[kdaddy1980]

unless the factory screwed up, there is a gasket between case halves - bad seals are often caused by the main bearings getting loose and allowing the end of the crank to go up & down

yeah your right when i looked at the engine a little closer, the gasket was just stuck on the one side, one side of the case has a lip on it and the other side has a recess for the lip to go in, i might use a thin layer of rtv silicone to seal it up when i put it back together

 

[kdaddy1980]

ok guys ,i finally got down to the root problem of my bogging. my new motors came in today so i put a new block on my bike with all the old accessories.
i was hoping it was the bearings bad on the old one that was causing it, but i fired up this new engine and crap! it was the same problem. i had a hunch that it was the carb so i was going to put a new carb on it and i didnt want to change the whole cable and throttle and everything so i took the cables out of the top of the carb and there it was, the tiny little e-clip that holds the needle was off and the pin had dropped down into the carb. so i put the clip back on the pin and wow im back on the road. this is a cns carb by the way, i love these carbs but that little clip can cause a world of problems, so if this happens to any of you and you have the cns carb check on that first. i heard the other models' jet screw falls out and causes the same symptoms..it just boggs out all the sudden when it falls out.

although the bearings being super loose wasnt my whole issue its a good thing that i tore this thing down. i think i caught it in time to just replace the bearings and slap it back together. it could have blew the whole motor. im gonna take it easy on this new engine.

 

[mapbike]

Thats great kdaddy1980 glad you got that sucker figured out and are back in business again.

map

 

[kdaddy1980]

thanks man, it feels good to be back on the road, i rode without a motor a couple times; a good 5 miles each way, about 20 miles within a couple days and man im sore now. i love having my motor just whippin up the hills like nothing, cuz some of those hills are a pain even just walking up.

 

[mapbike]

thanks man, it feels good to be back on the road, i rode without a motor a couple times; a good 5 miles each way, about 20 miles within a couple days and man im sore now. i love having my motor just whippin up the hills like nothing, cuz some of those hills are a pain even just walking up.

Heck yeah , just keep the rubber side down and enjoy.