Difficult to start Z650

[dads58]

I have a 1977 z650 and it runs great, once I have managed to start it that is. Choke does nothing, no spark at all.
Turning the starter a few times will result in an occasional spark. Eventually the occasional spark will develop into a weak tickover. I then have to coax the throttle very gently for about 5 mins before I can start reving. Choke at any point results in instant cut out. There are K & N`s on the carbs. the carbs are fully serviced and balanced, and I have fitted "Split Spark" plugs which give a very healthy spark. Timing is spot on. I have noticed that the spinning speed on the starter dips significantly when I do give it choke, if that helps at all.
Any ideas Engine Guru`s? This is driving me nuts!!!

[Robby]

Does that one have points ignition?

The first thing I'd do would be make sure the points are opening up, if they are then make sure the battery is healthy - you're looking for 12 - 13 volts across the terminals.

Has it been standing for any amount of time? Could be some shit in the carbs, or even some water at this time of year. If the points are ok and battery is healthy, drain the carbs and see if theres any water in the fuel you drain out.

[dads58]

there is a new points plate on it complete with new points, and condensers. The points are openingup o.k.
There was an overflow leak from the float needles so I have replaced them and air blasted all the jets. I then went on to put new fuel in the tank.
The battery was fitted new last summer and has been on the optimate ever since. Its showing a good 12.6 v on the multi-meter.

[Scotsman37]

When was the last time you WD40'd your electrical connector blocks between the starter switch and the battery plus the connections into the fuse box? There may also be a further connector block situated underneath the fuel tank as to connect the front set of wiring to the rear as Kawasaki's have that type of wiring setup and so maybe yours has that too.

Connector blocks could be clogged with crap from the road and causing freqent intermitent grounding of the current as that happened with my friend's bike.

[Big Pete]

when the K&Ns were fitted, were the idle jets uprated?, some carbs need both doing, most only need the main jet uprating, I cant remember what sort are on the 650. Also, if there are starting problems its worth doing a compression check. If the rings are worn low compression makes it hard to start, once the engine fires a few times the rings are pushed out by gas pressure and will then seal, so it runs all right once its going.
____________________
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[bish777]

before you start it, drip some oil into each cylinder through the plug holes, and see if it will start better, if so your compression is a little low.

I changed to pods on my GSXR 1100 and it was a bugger to start till i rejetted it. Try turning the pilot screws out a bit richer (try half a turn at a time but try not doing it too much) to see if it improves, at least enough to start on the choke, as too rich will foul plugs.

[dads58]

I got home a bit late tonight so I will work through the tips later this week and let you know of the results. The bike is in pretty good nick, and has only done 24,000 mls. Pic attached

Cheers guys for the info.

[dads58]

hi guys,
Tried the wd40 on all terminals, split all the bullets, sanded and re-connected them. done a compression test which is showing 8 bars per pot. Comp ratio on this model is 9.5:1 so I guess I am a bit low.

I have tried the shot of oil in the plug holes, even tried the plugs in the oven trick. It just doesnt want to know. I think that still leaves the jetting to look into. Maybe it is a combination of a few things. If there is still no joy when I have checked the idle jets I am going to have to get the head off and fit new rings to get compression back up to scratch. (lucky I picked up a gasket set and rings on ebay last year)

Cheers for the help, I will keep you posted.

[slowarse]

thats a really sweet looking bike that!

[bish777]

check the leads and coils arent a bit tired.

Possibly the alternator is just really tired and needs a good service??

[dads58]

Tah for the compliments on the bike, it handles great with the Metmach swing arm and Marzocki shox.

The leads are bonded within the sealed coils, so unless I join them it would mean complete replacement. I have a couple of new coils but they arent the right ohms, I need a balast resistor to convert them.

As for the altenator, I did find a bit of rust on the stator ( down to condensation) when I recently did a polish . I wd40`d it but maybe I should have given it a proper clean. I will try that before I take the head off this weekend.

Cheers

[ZRX61]

Those 650's were notoriously cold blooded (I've had about 10 of em, still have 2 of em in pieces in the garage), usual mod was to throw a set of carbs & manifolds from a Z1/Z900/Z1000 on em. makes em idel when cold, ya don't have to wait 5 minutes for it to respond to throttle input........... & has the added benefit of making it haul ass in spiffy fashion





.. If ya need cheap parts.. one of my '78 Z650 C2's is at the bottom of Regents Canal...

[dads58]

I spent all day doing the rings yesterday. The compression is back up to a healthy 130lbs per pot. I tried the starter on choke and.....nothing. same old coaxing without choke to start it. It did start a bit easier though, and was sooner in its stride.

It will probably be o.k. in the summer but for now I am going to concentrate on the carburation. Maybe get hold of a set of Z1 units and see how it goes from there. It seems that a may have been a combination of several things but with your help I am improving everything step by step.

Ironically I have another z650 , a standard , minter. Its only done 11,000 mls from new i dont have any problems with that but it doesnt see rain or cold. I keep it in a heated shed specially built for it. pic supplied.

By the way zrx61, where is this canal for the C2 parts?

[ZRX61]

It's in London, the bike has been in the canal since '80....

Quick fix: go up one size on the pilot jets. (about $2 or $3 each over here).
Take one out, read what size it is.. or if ya know they are standard just look in the manual to find out the size & order the next size up.
According to a parts book I have for C models in front of me they used a #15 pilot as standard.

[dads58]

cheers zrx61,

Big Pete mentioned that last week so I ordered some from Z-power. Its only just down the road so I am picking them up tomorrow.