850 le mans 111 ... Won't run above idle

[Huzo]

Can’t you just put the timing light on there and find out ?

[John A]

“Maybe the flywheel was changed and the marks aren't correct“

The timing marks on my 81-CX were wrong from the factory.

I’ve not seen a Guzzi with accurate timing marks from the factory.  With the marks on the engine flywheel corresponding to marks on the transmission there is a lot of room for error. Side to side is usually good. The fix is to accurately find top dead center on the left cylinder and fabricate a pointer, usually bolted to the inside of the bell housing that has a flat to sight along, reducing the parallax. I doubt that is the problem and I’m starting to wonder if the cam timing is off. What is the history of the engine?

[Stevex]

Is it possible someone's had the flywheel off and fitted it in the wrong position?

[Pastaboy55]

I guess it is possible that someone's had flywheel off and not put it back in the right position Bikes only done 63,000 km's was NZ new


I know nothing of the history of this engine ... Only owned the bike for 20 months restored it cosmetically ... Looks really good but won't run
Made the mistake of buying at distance sight unseen ... Seller lied through his teeth said it was running mint sent a video of it running but video I worked out was 4 years old.
paid way to much for it and now spent way too much money trying to resolve it.

 


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[Muzz]

A person well versed in Guzzi stuff who used to be on this site says to pass on that your slides are too lean "before you do something stupid".

Yeah, he did have a way with words.

[Pastaboy55]

Thanks Muzz   ... Were his initials PR or VB

Will look into the slides thanks ... They are standard slides though and the right lean burn carbs for the bike that has only travelled 3000km's from new ...
Do we know what number a pair of richer slides would be I think mine are 50/3

Cheers Marc

[lucian]

I would agree it's a lean condition. When the throttle is opened there is too much air and not enough gas. I would start by re checking float levels.

[Chuck in Indiana]

Grasping at straws.. float bowl vent clogged?

[chuck peterson]

Grasping at straws.. float bowl vent clogged?

I had a kinked vent hose on a phf..cal3

[Muzz]

Thanks Muzz   ... Were his initials PR or VB

Will look into the slides thanks ... They are standard slides though and the right lean burn carbs for the bike that has only travelled 3000km's from new ...
Do we know what number a pair of richer slides would be I think mine are 50/3

Cheers Marc

Right first time   Question has been asked.

[Tony F]

The slide cut-away only has an impact in the 1/8 to 1/4 throttle range. Above that the needle and needle jet come into play. The lean burn carbs are problematic, do they still have the original lean burn needle and needle jets in?

50/3 is the US spec slide, euro bikes had 60/3, the former is the richer slide. Have you got (or got access to) a copy of Guzziology? It has some discussion on these carbs.

[Stevex]

If it was a slide problem, surely all Mk 3s would have the same symptoms and it would be a well known problem.
You need to find someone in NZ with some carbs you could fit and try, at least you'd have a definitive answer carb wise.

[Muzz]

From the man himself.

Quoted  "I reckon he'll find they are 60's or maybe modified 50's with an increased cutaway. I think it's bogging off idle because the slide is making the mixture incombustible. Guzzis generally use slides that are too lean and PHF's and PHM's compensate by setting up the accelerator pumps to puke in tons of fuel. Stupid and wasteful.

Mark at Guzzi Classics was having problems with some shitbox loopy he'd put a G5 engine in one day when I was there. It wouldn't take throttle. I said to put in richer slides, he did, it immediately ran beautifully!"

[Pastaboy55]

Thank Muzz

I strongly suspect we could be getting close ....I've had two sets of carbs on this bike now ... Being an early 82 le mans 111 mine had carbs identical to MARK 1 and 2's (Pre lean burn style)
But I suspect that the slides were worn as I could see a lot of scuffing on the walls of them ... So I hunted for , found and purchased a set of PHF 36 lean burn carbs these came off a japanese import
Mark 111 with only 3000kms on it slides looked perfect I ultrasonically cleaned these carbs and caarefully checked the float levels 18mm. got new cables and adjusted all but 2mm of lash out of them.
Checked both slides were opening and shutting together.  On Thursday i recieved from my parts supplier new choke plungers new float valves and seats and all new standard jets to try.
So will fit these tomorrow and check which slides are in the new carbs and get back to you.

Thanks so much for the advice really appreciat it Muzz ... regards  Marc

Tony F I don't have a copy of or access to Guzzyology sorry ...