Ignition Problem - Maybe ??

S N 3 A K Y · tinkerer Joined: 18 Jul 2003 Posts: 153

A mate of mine has just bought a granny-spec TF, It's stock as a rock and surprisingly gutless.
The previous owner told us that the head had been recoed approx 2000 kays ago.
Anywhoo, i decided to play with it a little to see if i could find where the power was hiding.
A compression test came back with reasonable results - all cylinders were just over 130psi. The air filter assembly had a tonne of oil in it, yet it doesn't blow shit-loads of smoke that i can see, so if it does it's only a little. Me thinks the reco on the head was bodgy.
I had a look at the timing, it was advanced to approx 18 deg BTDC. I backed it off to a stockish 7-9 deg, but it went even worse struggling to reach 80kph in second (auto), and the carb was beginning to miss when the throttle was stabbed. So i had a look at the air/fuel mixture screw, it was wound out approx 5 full turns, i wound it back in to make it 3 1/2 full turns. The miss got worse - almost enough to stall. Wound it back out to what it was, and it did stall.
Advanced the timing to approx 10deg BTDC, slightly better at revving but still gutless with a hint of a miss in the carb.
My question after all of this is, what would cause the engine to run better on so much advance ? It didn't ping that i could hear, so i'm wondering whether the problem is ignition or fuel related. Could the dizzy be stuffed, i know the cap is in need of replacing as the terminals are fairly pitted and worn, but would something so simple cause it to have these symptoms ? Could it be points ?
I'm really scratching my head, whats the easiest solution to get rid of a miss ? Advance the timing till it disappears ? Sounds nasty, but that's how the engine was before i started fiddling with it, i mean almost 20deg of advance is fairly brutal isn't it. Can the mark on the crank actually be out ?
Confused!

S N 3 A K Y

GROOV3 · petrol head Joined: 04 Oct 2001 Posts: 3682

hey dude
sounds dodgy
i got a similar problem oil in the air filter/carby wise and ive been told its probably the rings
i havnt lost power or anyhting though and mines running fine
if you find out the problem let me know as mine could be heading in the same direction

hypaTG · backyard mechanic Joined: 15 Oct 2002 Posts: 524

has the carb been converted to mechanical secondaries, because that will cause a bit of a flat spot.

HOTHOUSE GREEN GEMI · tinkerer Joined: 19 May 2003 Posts: 148

all i could say to that is maybe take ur rocker cover off and cheak ur rocker to valve gap It could be a valve that is not closeing i dunno cheak the leads etc

SBG81 · rice boy Joined: 05 Jun 2003 Posts: 44

check all your vacum lines around the place. make sure the points gap is i think around .45 and lines up with tdc on the shaft of the dizzy. also check the carby out or give it a complete haul up.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Sounds like the carb is up the shit. probably clogged up or something. check the bottom of the bowl for sludge, that is a sign.

Ben

Smokey · rice boy Joined: 24 Jun 2002 Posts: 38

there is a possibility that your timing chain sprocket has slipped a tooth. this would be your timing out by 10 degrees, which may explain why it was set on 18 degrees. take the rocker cover off and check if that sprocket is lined up as well, there should be a mark.

S N 3 A K Y · tinkerer Joined: 18 Jul 2003 Posts: 153

I thought about that today, i have a feeling that the head reco was done unprofessionally and it was installed with the timing chain 1 or 2 teeth out. I've reset the timing to approx 20 odd degrees BTDC, and the miss has disappeared. It's a little hard to determine exactly where the timing is as it's off the marks on the block.
But the thing is still gutless - surprisingly gutless after taking the compression test readings.
The lady my mate bought it off, was the kind of person that never let the speedo see the other side of 100kph. So i doubt she ever over revved the little 1600.
As far as the timing, i'll have a look at the cam gear markings and see if they're aligned properly. And as far as the carb goes, i think i'll instal a 32/36 or get the Niki recoed. I know there has to be a problem with it, as it's getting something like 250-300 kays per tank and as i said before, the engine is completely standard.
Many thanks to everyone for all their suggestions and helpful advice.

S N 3 A K Y