[rick1970]

While playing with the zook (std 1.3) i have noticed that i can run 15deg + inital timing and have no pinging issues. Now since this jigger has had more than a few questionable repairs before i got it i'm wondering if the cam timing is a bit out. Pretty sure the guy i got it off said it had had a new belt fitted some time ago, by him.

Symtoms -

Low down power is ok, better at 10' advance than at 15'

Top end is sluggish, better at 15' than 10'. Struggles to reach 6000rpm, even in lower gears.

Fuel consumption is nothing to write home about.

Ignition system is good, mech and vac advance is working, compresion is ok, valve clearances are ok. Has 4k carb (altho problem was still there with rebuilt std carb) with manual choke. No cough and splutter at high revs, just runs outta steam at 3500rpm

Ideas?

[SuziBlu]

[rick1970]

Ok, should add that i run it on 95. Have run up to 20' inital with no high speed pinging, dose ping a bit at low speed when u floor it tho. Low end gets worse.

[want33s]

Rip the timing cover off and have a look.. Only way to be sure.....

Also check the vacuum advance is working.

[FullyZooked]

Wonder if this is another exhaust related issue? I'd set timing at standard and drop the exhaust from manifold back. See if that let's it breath a little better.

[Scrawny]

Is the 4K carb jetted to suit the 1.3? As Want33's suggested get the cover off and make sure it's right

[lump_a_charcoal]

I think the 4k jets are different, but on WOT are the same quantity (if that makes sense).
Sierras are eg. 25 and 25, whereas the 4k is 20 and 30.

[SuziBlu]

[steak_knife]

want33s wrote:

Rip the timing cover off and have a look.. Only way to be sure.....

Also check the vacuum advance is working.

my thought's on this matter....

[SuziBlu]

steak_knife wrote:

want33s wrote:

Rip the timing cover off and have a look.. Only way to be sure.....

Also check the vacuum advance is working.

my thought's on this matter....

Yea, same here, but in the original post he states its working fine. Bit sus but.

[rick1970]

Yes, checked vac advance and its working fine. No overheating issues.

Can i check the cam timing without taking the front cover off? Or can anybody give me the valve open/close degree specs so i can check it with a degree wheel?

4K carb has the primary jetted down a bit, was running way rich with std jets. Can't remember the exact drill size, but was about half way between Suzuki primary jet size and std 4k jet size.

[Scrawny]

Waaaaaaay easier to just take the front cover off to check ya timing

[steak_knife]

SuziBlu wrote:

steak_knife wrote:

want33s wrote:

Rip the timing cover off and have a look.. Only way to be sure.....

Also check the vacuum advance is working.

my thought's on this matter....

Yea, same here, but in the original post he states its working fine. Bit sus but.

he said mechanical.....
Sound's a lot like the diagram in the Vacuum Advance...

[Rockhopper]

Mate, problem could be a partially blocked catalytic converter, especially if it's had carby problems in the past. Converters don't like it when the engine runs rich, and if you have a standard exhaust, it's possible you are running a 20 something year old converter.

[rick1970]

No catalytic convertor, 2" exhaust from origional cast manifold with one muffler.

But i did find something......

While putting a new alternator on, in my rush i left the adaptor that houses the flap for the stove pipe off, so drawing air straight into the air filter box. On the drive to work, preformance was noticably improved.

Pulled the air inlet pipe that runs up the RH guard and, of all things, there was a fookin great wasp nest in the end . Pipe was around half blocked off

Guess you should sometimes check the simple things first

[SuziBlu]

rick1970 wrote:

Ignition system is good, mech and vac advance is working,
Ideas?

Stekky, Maaaate, as I read that, sounds like he is saying vac checks out.

[Scrawny]

rick1970 wrote:

No catalytic convertor, 2" exhaust from origional cast manifold with one muffler.

But i did find something......

While putting a new alternator on, in my rush i left the adaptor that houses the flap for the stove pipe off, so drawing air straight into the air filter box. On the drive to work, preformance was noticably improved.

Pulled the air inlet pipe that runs up the RH guard and, of all things, there was a fookin great wasp nest in the end . Pipe was around half blocked off

Guess you should sometimes check the simple things first

That'll do it

[steak_knife]

SuziBlu wrote:

rick1970 wrote:

Ignition system is good, mech and vac advance is working,
Ideas?

Stekky, Maaaate, as I read that, sounds like he is saying vac checks out.

You edited that....

[SuziBlu]

[rick1970]

Bit of an update.

While i said the mechanical advance was working, it apears not to be working that well.

With timing set at 20' @ 800rpm, i only get 32' total @ 5000rpm (vac advance disconnected). So only gettin 12' advance from the dissy, which quite obviously isn't enough.

Anyone know what the total figure should be?

Have to pull the dissy on the weekend and find whats going on.

[royce]

I hate it when I get to a thread too late

incorrect cam timing wont account for running that much ignition timing, would make it even more gutless though

sounds like youve found your problem though, I dont know the total figure though sorry

[rick1970]

ok.................pulled the dissy, checking the mechanical advance for something wrong. Couldn't really fault anything. Cleaned, lubed, reassembled and refitted. Started and ran as before.

Pulled the cam belt cover. No1 at TDC, rotor pointing to No1 plug lead post, buttom belt pulley keyway pointing straight up (aligned with mark on block), hole and mark on cam pulley pointing straight down (180' out from notch on cover). Cam 180" out??????

Thoughts?

[steak_knife]

Wind the crank till the mark on the cam pully line's up, then double check....

[rick1970]

steak_knife wrote:

Wind the crank till the mark on the cam pully line's up, then double check....

Marks align. Rotor now pointing to No4.

[royce]

correct,g series time on number 4

[rick1970]

Cheers

[rick1970]

Think i still have a mechanical advance issue tho

[steak_knife]

rick1970 wrote:

Think i still have a mechanical advance issue tho

Mechanical only work's just off idle, if you can twist the rotor a lil bit & it spring's back, it's working.

i stick to my comment, i think it's the vacuum advance.
whether the diagram has a hole in it of vac supply problem.