Chinese Scooter Club

Klaas · Mon Jul 21, 2008 7:14 pm Ticking noise.

Hello guys,

My Znen 50cc has about 450 kms on it now, I just changed the engine and
transmission oil and adjusted the valves. Inlet 0.05mm and outlet 0.10mm.
To get the valve cover off I unscrewed the you shaped pipe that seems to be
part of an EGR device, according to some pics and comment on this site.
Now the bike has developed a rather hard ticking noise after getting warm.
I suppose that cannot be the valves, as they would rather tick wen cold,
and quiet down wen getting warm. Everything is reassembled after the
maintenance, everything works OK, just the ticking. It is loudest near the
exhaust and bottom part of the engine. When left idling for a while it will
get louder, I suppose it has something to do with the engine getting hot.
Started from cold it is not there, only after warming up some.
I felt around the exhaust for leaks but cannot find any. I torqued all the
exhaust bolts and also the head bolts before valve adjusting.
I am running out of ideas here, should I not have disturbed the emissions
device (if that was it)?
Does it sound familiar to one of you? I just ask because the engine did not
do this before. Oil is OK and everything is working OK.
Perhaps some of you have a suggestion.
Greetings,

Klaas.

threedogs61 · Tue Jul 22, 2008 12:58 am

I imagine the ticking sound has to do with your valve adjustments. You may have to try again.

Try as I may I never could get them right. Better to leave them "ticking" than over adjust in the wrong direction. My scooter ticks like hell...but runs great.

thruss91 · Tue Jul 22, 2008 10:27 am

tighten your exhuast tappet slightly to around 0.08

J€Di · Tue Jul 22, 2008 12:13 pm

Both tappets should be set to 0.05mm, it's a dead easy job.

Take off the fan cover and fan, and take the rocker cover off the top of the engine. Depending on your scoot, you may have to take off a few panels to get good access.

Align the timing mark on the flywheel (the T mark) with the lug on the crankcase, check that the camshaft sprocket has two holes lined up with the top of the head and a third hole visible, if not give the flywheel another full rotate round to the T mark.

Now your engine is at top dead centre, adjust the tappets by slackening off the locknut and slackening off the tappet, inserting the correct feeler gauge between tappet and valve stem, and tightening the tappet so you get some grip on the feeler strip. Not too much - you want to be able to slide the feeler gauge out with some resistance.

Now hold the tappet so it can't rotate and tighten up the locknut - check it again and tweak it if you have to.

Then do the same for the other tappet.

Job done - replace all the covers and away you go.

Edit - just read your post properly, and I spotted straight away what the problem is. Your exhaust tappet is WAY too loose, both should be 0.05mm. It's gonna sound like someone hammering away like mad in there with it set that large.

Fox · Tue Jul 22, 2008 12:20 pm

Yep! The exhaust valve gap is way too big. I set both my valves to .005 inches or .127mm

larry8 · Tue Jul 22, 2008 12:53 pm

1.0mm = .040"
0.1mm = .004"
0.05mm = .002"

I think any setting between .002" and .005" would be OK

Might not have set them at exactly top dead center.

Klaas · Tue Jul 22, 2008 1:05 pm Tappets.

Hi guys,

Thanks for the suggestions. I will reset the tappets. I was talking
millimetres though, and some instructions I read specified these
settings. I will keep you posted.
Greetings,

Klaas.

Fox · Tue Jul 22, 2008 1:12 pm

Make sure you do it with a cold engine.

Klaas · Tue Jul 22, 2008 5:51 pm Tappets.

Hi,

The settings you all suggested worked fine, both are 0.05mm now,
noise is gone. I suppose my info for the exhaust one was incorrect.
Many thanks all! This is some forum, I post a question and get some
five replys within a day, great!
Greetings,

Klaas.