New HS motor very rough idle

[Deleted member 8310]

skyl4rk!

Now THAT is new and unexpected.

Have a super busy day tommorrow (so much for labor day holiday) but will
test this out at the first opportunity.

Thanks, I'll let you know.

 

[Deleted member 8310]

not yet

Ok checked out the idle jet o-ring and all is well there.

Test run afterward shows the problem still there. Darn thing missfires as if
it's not getting spark or fuel and yet it is. Most obvious at highest speeds.

It's missing so badly I don't want to ride it anywhere.

 

[RdKryton]

Another thing I would check is the fuel flow from the tank. The shut off valve has a strainer that screws into it and these tanks are notorious for having dirt and carp in them from the factory. The fact that is getting worse could be the fuel flow is not enough the make the float needle seat. If the fuel level is too low in the carb both the idle and the high speed will be affected. It easy to check. Just pull the fuel line off the carb then open the valve. It should flow with a good stream. If it just drips or flows real slow, you found your problem. good luck.

Jim

 

[Deleted member 8310]

what if

Fuel flowing freely. Carb is clean jets are clear.

Found evidence of backfire on carb intake port.

What if the factory set the timing off by one tooth? The thing idles like it
has a cam in it and more than one cylinder. The problem is consistant at
every speed.

Without busting the case open how would I determine if timing is off. (Really
wouldn't know if I opended the case either.) Definately in over my head.

 

[Deleted member 8310]

surprising answer

Busted the case open to find the arrow on the timing gear lines up with the
dot on the crank's drive gear.

BUT

Turning the motor through it's cycles revealed the timing was advanced
causing the exhaust value to close when the piston was only half up to
expel burned gas. This left gases in the cylinder which had to escape
through the intake valve.

No wonder there's black exhaust burned into the carburetor intake!

Talk about a motor working againest itself.

Retarding (according to the marks) the cam gear put valves and piston
in perfect sync through all cycles.

The arrow on the cam gear is cast in place but the dot may not be can't
tell. Looking at the exploded drawing of the motor/crank it appears that
gear is part of the crank which can only mean the dot was incorrectly
placed.

Have to work on the bike frame before reassemble so it'll be a day or so
before running the engine to see how it goes.

Didn't know squat about small engines when I started this project but
learning a ton now.

 

[skyl4rk]

Good luck, I hope you figure out the problem.

 

[Deleted member 8310]

that was it

Bike isn't ready and couldn't wait so bench ran the motor and it now runs
perfectly. Can't wait to get it into the bike and go for a ride.

Another indication of lower quality than Honda, what an ordeal.

In case you'd like to see what the inside looks like posting a pic of the timing
gears.

 

[MotoMagz]

Bike isn't ready and couldn't wait so bench ran the motor and it now runs
perfectly. Can't wait to get it into the bike and go for a ride.

Another indication of lower quality than Honda, what an ordeal.

In case you'd like to see what the inside looks like posting a pic of the timing
gears.

Glad to see you found the problem.I know you worked on that gearbox for a while and now the engine.I sure hope you can enjoy some time on the bike.And thanx for the picture, hope I never have to see the inside of mine! MotoMagz

 

[jason ivanoff]

mine did that and it was my fuel line. it looked tight,but it was not sealed good

 

[locutus_1]

i have the same gear box the hoot chain drive but mine barely engages the bell at full throttole i wont even move... ive changed the srpings still nothing.. i think i got a larger bell than i need and the shoes are maxed out..

what do you guys think?