Author Topic: New Project: YFZ/Banshee Hybrid (Read 44060 times)

2ndmoto · « **Reply #90 on:** December 02, 2016, 02:17:26 AM »

Banshees come with 26mm carbs stock. 2 into 1 commonly run 35 or 36mm, which is fine, because as mentioned it is essentially a 175cc motor. That is all that is sucking at any time, unless something has gone terribly wrong.

I would steer clear of running a 2 into 1 carb. I just don't see how they can be effective at feeding both cylinders at high rpm. The fuel charge has to change direction back and forth so fast, how is it going to pull equally through each cylinder? Seems like the fuel (and lube) would hug the inside walls.

jcs003 · « **Reply #91 on:** December 02, 2016, 05:02:49 AM »

I have a set of 28 mm pwk carbs if I fail. I am still fairly confident I can get everything to work harmoniously. Keep in mind, my goal is for this engine to make its power in the lower rpms

jcs003 · « **Reply #92 on:** December 09, 2016, 09:32:25 AM »

I believe I discovered my issue. I believe I am getting coolant in the combustion chamber

Skeans1 · « **Reply #93 on:** December 09, 2016, 06:31:24 PM »

Quote from: jcs003;71084

I believe I discovered my issue. I believe I am getting coolant in the combustion chamber

John what makes you say this?

Jerry Hall · « **Reply #94 on:** December 09, 2016, 11:53:16 PM »

Quote from: jcs003;69698

looks like a backfire caused this damage:

I believe this was caused from the use of a cheap $13 coil to troubleshoot wiring. any other thoughts?

John

A misfire from a bad ignition component will not usually trigger a crankcase explosion but anything that causes the ignition timing to be a mile off can cause a crankcase explosion.

Most of the reeds that I have seen like yours were damaged when the engine was kicked over and a hydraulic lock occurred because the crankcase was full of liquid. The crankcase is often filled with fuel when the petcock is left on overnight and the float valve is bad. Sometimes coolant fills the crankcase when the transfer ports have been ground into the coolant passageway or the rubber plug under the exhaust port is missing or bad.

When the bottom end has been hydrauliced, something has to give. The crank seals will be pushed out of the cases or it caves in the reed petals or breaks the dividers in the reed cage that supports the reed petals.

jcs003 · « **Reply #95 on:** December 12, 2016, 12:38:43 PM »

Jerry, this makes sense because at one point the crankcase filled with fuel and I needed to flip it on its end and drain it. I hope I didn't blow out anything except the gas and reed valve. I guess if the plugs are damaged, I would have coolant in the transmission oil.

Jerry Hall · « **Reply #96 on:** December 12, 2016, 04:23:17 PM »

If the rubber plugs are blown out, it will usually leak coolant from under the base gasket in the front of the cylinder. When it leaks in this area, coolant either leaks down the front of the engine on the outside of the cases or leaks coolant directly into the crankcase where the crankshaft resides.

jcs003 · « **Reply #97 on:** December 13, 2016, 11:07:23 AM »

Time for a leakdown test I presume

Jerry Hall · « **Reply #98 on:** December 14, 2016, 09:46:34 AM »

A crankcase leak down test will not always show a leaking head or base gasket because of the low pressure used. A low pressure leak down test (0 to 10 psi) will show a leak when the gasket has a piece missing or is pushed to the side of the sealing surface. A leaking head gasket will sometimes not show unless the engine is running at wide open throttle where the pressure can be over 1000 psi.

jcs003 · « **Reply #99 on:** December 14, 2016, 11:32:43 AM »

I got new o-rings, so I should probably just change them.

jcs003 · « **Reply #100 on:** December 28, 2016, 06:02:45 AM »

After resealing the head I discovered I likely have a bad crank seal. Probably related to the filling of the crankcase with fuel as Jerry stated.

Looks like a rebuild is in order.

jcs003 · « **Reply #101 on:** January 07, 2017, 12:41:08 PM »

Found out the crank is also shot. Rebuilding the engine now. New hot rods crank is sent out for true and weld.

jcs003 · « **Reply #102 on:** January 23, 2017, 06:06:15 AM »

new seat cover.

jcs003 · « **Reply #103 on:** February 13, 2017, 05:13:58 AM »

well, got this thing back together and it has no power. I am thinking the exhaust and/or fueling is the problem. it will start and drive, but has no power. basically refuses to rev. any thoughts?

Jerry Hall · « **Reply #104 on:** February 13, 2017, 09:58:59 AM »

Quote from: jcs003;71802

well, got this thing back together and it has no power. I am thinking the exhaust and/or fueling is the problem. it will start and drive, but has no power. basically refuses to rev. any thoughts?

Is the no power problem new problem since the rebuild or was the rebuild suppose to fix the no power problem?