Planet Minis

toby hill · 02-25-2009, 10:52 AM

I have an 1981 honda z50, cant get it to start. I know, typical problem. I cleaned the carb, tons of spark, ok compression. The thing I noticed was it didn't even try to start. It sounded as though I had the exhaust off, but I didn't. In the manual it talks about a manifold leak. Could this be the noise i'm hearing and why it wont start? Does anyone know where the jet screws are suppose to be?

Wiley · 02-25-2009, 11:16 AM

Stupid question time - was the gas on? Or for that matter, was the gas getting to the carb?

LoudFastUgly · 02-25-2009, 04:34 PM

+1 Wiley's remarks. We've all heard of the gas cap vent causing issues with vacuum locking fuel flow. I've never seen it in my life, until 2 weeks ago on MY Z50AK3. Pop the cap off to temporarily cure this issue, you find air in the fuel line if you're experiencing this phenomena.

#1. Check that the throttle valve isn't installed backward, maybe you're hearing intake honk, not exhuast.

#2. Confirm valve timing. Check that the 'dot' on the cam gear lines up with the notch on the left side of the cam sprocket cover flange when the "T" is lined up with the notch on the engine case. You may find the dot to be slightly higher than the notch in the cam sprocket cover, this is a sign of timing chain stretch. If it's below, you're valve timing is off. Check valve clearance, should be .003mm on intake, .004 on exhaust.

#3. Confirm igntion timing. Check that the points are closed when "F" mark is lined up with the notch on the case. Check that they at least start to open when the "T" mark is at the notch.

#4. Confirm spark condition, nice bright blue. The NGK "R" plug tends to foul easily in comparison to the standard.

02-25-2009, 10:52 AM	#1 (permalink)
toby hill PM Newbie Join Date: Apr 2008 Posts: 8	Trying to start I have an 1981 honda z50, cant get it to start. I know, typical problem. I cleaned the carb, tons of spark, ok compression. The thing I noticed was it didn't even try to start. It sounded as though I had the exhaust off, but I didn't. In the manual it talks about a manifold leak. Could this be the noise i'm hearing and why it wont start? Does anyone know where the jet screws are suppose to be?

02-25-2009, 11:16 AM	#2 (permalink)
Wiley PM Newbie Join Date: Jan 2008 Location: Burlington, ON Posts: 48	Re: Trying to start Stupid question time - was the gas on? Or for that matter, was the gas getting to the carb?

02-25-2009, 04:34 PM	#3 (permalink)
LoudFastUgly 2nd Gear Member Join Date: Aug 2008 Location: GTA, Ontario, Canada Posts: 383	Re: Trying to start +1 Wiley's remarks. We've all heard of the gas cap vent causing issues with vacuum locking fuel flow. I've never seen it in my life, until 2 weeks ago on MY Z50AK3. Pop the cap off to temporarily cure this issue, you find air in the fuel line if you're experiencing this phenomena. #1. Check that the throttle valve isn't installed backward, maybe you're hearing intake honk, not exhuast. #2. Confirm valve timing. Check that the 'dot' on the cam gear lines up with the notch on the left side of the cam sprocket cover flange when the "T" is lined up with the notch on the engine case. You may find the dot to be slightly higher than the notch in the cam sprocket cover, this is a sign of timing chain stretch. If it's below, you're valve timing is off. Check valve clearance, should be .003mm on intake, .004 on exhaust. #3. Confirm igntion timing. Check that the points are closed when "F" mark is lined up with the notch on the case. Check that they at least start to open when the "T" mark is at the notch. #4. Confirm spark condition, nice bright blue. The NGK "R" plug tends to foul easily in comparison to the standard.

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