Hard start and won't idle

[David Keith]

-Has an intermittent electrical problem & leaks air between cylinders where the two inward bearing lube holes are. The labrynth seal was not sealed...

2001 Blue Banshee 350cc with:

-FMF gold series pipes -K&N Filters -New Boyesen reeds

-New pistions and rings with 125 psi compression

-DynoJet kit metering needle #4 position, (four of six positions) this got rid of bog

-#340 main jets; plug chop looks good

-#27.5 low speed jets

-Will not idle, but runs great if you keep it revved...

-There is intermittent spark on the right side. Timing light does not flash all the time.

 

-The leak is in between the cylinders! Apparently that middle labrynth main seal is bad.

The cross-over tube is removed & plugs inserted. The exhaust ports are plugged to. Then I applied 6 psi into one cylinder, it blows out the intake of the other. I stretched a balloon over one intake, the put air into the other & it blew up the balloon!!! BIG PROBLEM DISCOVERED. This was a fast leak, not slow.

-Now its apart, not the first time. Looks like the middle seal was not sealing accross the small width between the lube holes for inner bearings, these holes are about 0.260 dia. & the laybrynth seal seal width is about the same... Shouldn't it be wider??? Ths engine has had the cases split before. There was lots of Yamabond in some areas & hardly any in the crankshaft middle area... We need more good mechanics.

 

-Anyone have a good used engine for sale???

 

::

 

David

Edited October 29, 2006 by David Keith

[sheefreak]

Make sure the pilot jet is clean and you can see daylight through it. If you haven't, run air through it. Fatty's like a bigger pilot pilot jet also. depending on your airbox setup, I would run 27.5's w/ your airscrews closed down a little, or a 30 and open um up. If you find your pilot ckt is clean and still won't start, might want to look at compression. A motor will run like shit on the bottom end, and give you all kinds of trouble starting if you have sticky rings, worn rings, etc.

[Dinner]

Do you use the choke the start it when it is cold? Next time you start it, have the choke out and leave it out for a bit while keeping the revs up and see if it will run off both cylinders. My shee used to act up like that on my older carbs and i had to pull the choke in and out a few times to pull enough fuel into the cylinder that wasnt firing. Once i did that, it ran fine.

 

And if you think its electrical, switch plug wires and see if that changes the problem to the other cylinder

Edited August 4, 2006 by Dinner

[Hilarious]

TORS means throttle override system. They are supposed to

a failsafe against your carb slides sticking open.

The TORS will keep your engine from building up any rpms.

Unplug the wires going to them.

As far as your pilot jets go...if you have your air screws almost

fully seated on the stock 25's, you need to put larger ones in there

and set your air screws to about 1.5 turns out. Put the 27.5's in

there and do that and seee how it runs.

Sounds more to me like a jetting problem. Mine used to be hard

to start untill i got the jetting right.

Its a trial and error process, man.

[kb7kuh]

Just another thing to check would be the reeds. Mine was a bear to start when I had V-force 2 reeds. I checked them and they looked fine, a little rounded off on the corners, but still hard to start. I put the stock reeds back in and started on the first kick.

 

Oh yea, dump the TORS

Edited August 15, 2006 by kb7kuh

[Justintoxicated]

does it idle better or worse with the choke out?

[David Keith]

With the choke out it floods with gas & stalls. I have even removed the spark plug after doing that & it verified that the plug is wet after it stalls.

 

It definitely has an electrical problem. The timing light only flashes about half the time when connected to the right side spark plug wire!!!

 

I took the coil & blackbox to a local Yamaha dealer. They said the coils checks good & there is no way to test the blackbox. They said it is probably the blackbox ($351) or ignition stator ($371).

 

Where can I get a blackbox to swap & try?

[dajogejr]

I vote coil. Normally, when you swap leads and it follows the leads, it's the coil.

 

For a cheap, quick fix....replace the end caps on the spark plug leads. They're known to go.

 

I have two used stock coils I'd be happy to part with one of them if you'd like.

 

There is no way to test the CDI that I know of.... Ricky Stator has a brand new CDI for 125...stay away from the stealership on those.

 

PM me if you'd like...I can get one out to via Fed Ex tomorrow!

[Axcalibar]

please cut 2 wires goimg to the thumb throttle or unplug it

[David Keith]

please cut 2 wires goimg to the thumb throttle or unplug it

 

That is done.