Carb help urgently needed

[T250tut]

I have a 1977 xs650D the will not tick over cleanly - it hangs on to revs making gear changes horrible. When stationary excessive blipping of the throttle will bring the revs down but after approx 1 min at 1000 rpm it goes run away and the revs just keep climbing. The hotter it gets the worse it is shunting back on the over run. Whats been done so far,
Electronic ignition of unknown age that came with the bike
New diaphragms
Carbs cleaned and cleaned again till cleaner that a nuns dreams
New seals on butterfly shaft
New brass floats set by vernier
New mains and pilot jets
Standard air cleaners with new filters
No air leaks - spray easy start around to check
Tried fuel screws from half turn out to three and a half and just when you think its getting better it will just cut out - stop dead - and refuse to start until the plugs are changed.
Electric start is useless but it starts from cold on kick start when screws are one and a half turns out with out choke.
Tia for all and any suggestions
Cheers

 

[bazz]

I have a 1977 xs650D the will not tick over cleanly - it hangs on to revs making gear changes horrible. When stationary excessive blipping of the throttle will bring the revs down but after approx 1 min at 1000 rpm it goes run away and the revs just keep climbing. The hotter it gets the worse it is shunting back on the over run. Whats been done so far,
Electronic ignition of unknown age that came with the bike
New diaphragms
Carbs cleaned and cleaned again till cleaner that a nuns dreams
New seals on butterfly shaft
New brass floats set by vernier
New mains and pilot jets
Standard air cleaners with new filters
No air leaks - spray easy start around to check
Tried fuel screws from half turn out to three and a half and just when you think its getting better it will just cut out - stop dead - and refuse to start until the plugs are changed.
Electric start is useless but it starts from cold on kick start when screws are one and a half turns out with out choke.
Tia for all and any suggestions
Cheers

Check your inlet rubbers again
Spraying easy start around the rubbers is not a 100% test
Mine wasn't doing the same as yours, mine was misfiring at idle
Did the test using carb cleaner and it made no difference to the revs
I fitted new inlet rubbers and it cured the problem

 

[Its been a long time]

Does the electronic ignition use the mechanical advance? If you're not sure, remove the chrome cover held on by two screw on the right side of the cylinder head. The mechanical advance lives in there. If it's in there, post pictures of it.

 

[650Skull]

Photos of all your ignition, mechanical or electronic advance, charging system, factory or pMA. Some aftermarket ignitions are prone to complications

When cold the choke/enricher needs to b used to start the bike. No choke the carbs aren't set up properly

 

[T250tut]

It's mechanical advance retard pivot pins on the arms lightly oiled and move freely. Battery was 13.4v engine off 14.2v at tick over and 19.1v at 3000 rpm. It has standard statorand charging system

 

[Its been a long time]

It's mechanical advance retard pivot pins on the arms lightly oiled and move freely. Battery was 13.4v engine off 14.2v at tick over and 19.1v at 3000 rpm. It has standard statorand charging system

Do the weights snap back fully when you use your fingers to fully advance the unit? If you haven't done so, the advance rod that runs right through the centre of the camshaft needs to be removed, cleaned and greased. There's labyrinths at the shaft bore that act to provide lubricant to the advance rod. There's plenty of information here how to do that.

It might help if we can see the ignition system pick ups on the left side and the igniter box if there is one.

19.1v is far too much for the charging system. I suspect your regulator might have an issue. The standard electromechanical regulator can be cleaned and adjusted. Procedures are here and in the shop manual. I changed to a modern rectifier and automotive regulator. Highly recommended.

 

[bazz]

It's mechanical advance retard pivot pins on the arms lightly oiled and move freely. Battery was 13.4v engine off 14.2v at tick over and 19.1v at 3000 rpm. It has standard statorand charging system

You don't want to be seeing any more than 14.2 v when the engine is revving
Be careful you don't boil your battery dry

 

[T250tut]

Any suggestions as to what reg rec to use?? Cheers

 

[Its been a long time]

Any suggestions as to what reg rec to use?? Cheers

Please do your due diligence but for a stock 77 XS650 charging system a UK member recently had success with this type.

https://ebay.us/m/UDJjkU

The Lucas UCB502 that I'm using seems no longer available.

I recommend you change the rectifier if its still the original one. I used one like this.

https://ebay.us/m/n4DNfJ

There's threads from me detailing what I did on my 77 650D. There's excellent guides in the technical section of this forum. Highly recommend you read them if you already haven't.

Check your alternator brushes are good too.

 

[bazz]

Any suggestions as to what reg rec to use?? Cheers

Do you have the standard alternator? Or permanent magnet type?

 

[gggGary]

carb sync done and or rechecked?

 

[650Skull]

Please do your due diligence but for a stock 77 XS650 charging system a UK member recently had success with this type.

https://ebay.us/m/UDJjkU

The Lucas UCB502 that I'm using seems no longer available.

I recommend you change the rectifier if its still the original one. I used one like this.

https://ebay.us/m/n4DNfJ

There's threads from me detailing what I did on my 77 650D. There's excellent guides in the technical section of this forum. Highly recommend you read them if you already haven't.

Check your alternator brushes are good too.

Fix the charging issue first

Link to an excellent tutorial on building an Auto Reg and Rectifier.

Yours is the B Type, as already mentioned
Source regulator as per IBALT's recomendations

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

 

[T250tut]

Sorry for the late reply - got busy. Have ordered a new reg rec from electrex- thinking the 18 or 19 volts going in to the aftermarket electronic ignition won't help. Will keep you updated

 

[Bruno_c]

While you wait for your new regulator to be delivered, you could disconnect the charging system and run the engine on the battery. This test will tell you if your tickover issues are related to the charging system or not.

 

[650Skull]

Sorry for the late reply - got busy. Have ordered a new reg rec from electrex- thinking the 18 or 19 volts going in to the aftermarket electronic ignition won't help. Will keep you updated

Photos were asked for. None given

Asking for pics isn't because we can't read.

It helps you help us to help you with diagnostics, helps up to identify the parts, bike and we see things we know that you are not aware of.

Buying willy nilly parts costs you money and time. Advice ignored costs you time and money.

Without pics and going off the information given, it seems your bike is in need of a major maintenance catch up requiring electrical, loom and switches ... a right good going through.

Go to post #7
Lots of links and general, and comprehensive, maintenance and information to identify and fix throughout this link.
https://www.xs650.com/threads/xs650...-other-information-including-xs750-850.30569/

 

[T250tut]

All comments and advice gratefully received but with a 19v output a new reg rec isn't willy nilly - i know it can be adjusted but as it's proved it can go that far out of range I can't be arsed testing every time I go out so fitting a new reliable solid state one is sensible imho. Advance springs n shaft pulled and greased. They fly our freely and the springs pull them fully home. Still no improvement

 

[Its been a long time]

Newtronic, the old Piranha as was. That wiring into the igniter isn't looking too clever? Suggest you take a look at that while waiting to get the charging sorted. The ignition system runs from the battery, I've no idea how charging at 19v will affect the Newtronics igniter, if at all. I'm not sure how too high charging voltage would have any effect since the Newtronics igniter is fixed timing, relying on the mechanical auto advance.

So, rpm still hangs even though you overhauled the advance unit?

 

[T250tut]

Yep only when hot but the hotter it gets the longer it hangs for . Duel screws 1.25 out seem to be the best setting and no leaks found spraying gas around seals

 

[gggGary]

carb sync done and or rechecked?

????

 

[Its been a long time]

????

^^^^^ this.

Ruling out everything else then including obvious stuff like throttle cable routing, carb balance etc....... If I was happy that absoutely everything was good then I'd be considering one size bigger on the pilot jets. Then see if anything changes for better or worse.