650 service

2day i serviced my 650 which was over dued points required nothing doing to them , timing fine.spark plug gap finevalves perfect no adjustment required.gearbox and final drive oil looked like new but changed anyway.engine oil changed with filter and sump taken off and oil screen cleaned but did not really need doing ,compressed air blown up oil holes.my bike may not look much but the engine as been well looked after in the pass.So happy with the little bikeRunning a touch rich so carbs to check 2morro

Good stuff, still think the older 650/750 bikes are under-rated.Recommissioned the NTX at the weekend after a few weeks standing. Not much to do but put back stuff I’d taken off and fix the new indicators.S’funny but my NTX runs really rich.Have a spare set of carbs to fit asap.All the bestSteve

my 750 tends to run rich also

My 650 NTX is also rich…thinking that the needle and needle jet were worn but if you guys have the same problem…

Rich is better than lean, many modern bikes tend to run lean for the dreaded omissions, I have found older Guzzis tend to seem rich especially if you are not doing more than 20 milea at a time.

Absolutely agree Bear but it does seem strange.

Not at all , older carb Guzis , tend to be awee bit rich especially at the low end, so that when you do whack it open you do not get the tendency to run very lean, or that is what I have been told. If they are within the mpg and other spec leave well alone unless you are real good at the old set up and sort out and can do things like plug chops and all that malarkey.

Johnno good to know the oil was ok and it is all good internally

Yes that makes sense, short runs, not long after choke, low throttle, depends what you’re going by as a guide. Usually plug colour, BUT, will be sooty because of the choke and not run long enough to get rid of it, so, the correct way to check it is, ride it >10 - 20 miles on fast open roads then look at the plugs, as GB says the problem is if say you tweak it to get it right for low throttle / short journeys it may tend to go lean for a good long run at higher speed. Then you find that actually you also need to change main jet size or something.

It goes something like:

Up to 1/4 throttle, idle jet adjustment + needle jet, 1/2 to 3/4 needle jet, 3/4 to full, main jet size.

But there is a large amount of overlap, so one affects another.

Appendix ~ accelerator pumps confuse the issue as well by making it momentarily rich, even the VHB’s have ‘atomizers’, not out & out pumps per se but same sort of function.

According to Guzziology THAT is the idea of the fuel pumps to whack fuel in on hard acceleration, mind the amount the Le Mans ones throw down it’s throat is measures in cc’s There is a lovely ammendum in one of the manuals, translated from the Italian that reads

"For fuel feeds this model is fitted with accelerator pumps and if the twist grip is not used correctly inn accordance with engine revolutions there migt e an excess of fuel ejected bby the carburettors (oh you don’t say!)

In these conditions the engine induces backfires and the risk of fire is quite considerable !"

sorted the 750 2day just like the 650 nothing really needed doing ,no time to check uj on 750 so that will be next job .Both bikes running brill and both now have a happy brown colour to plugs .I will be needing the rubbers between carbs and manifold soon on both bikes besides that i really need to strip paint work on 750 even i cant believe how bad it looks

I’m not disagreeing with you GB (and you quoted from my MG manual’s LM2 section verbatim ~ mucho respekto) I woz merely making the observation (inadequately, as usual, as I have an annoying habit of assuming everyone else knows what I’m on about ) that that isnt necessarily a helpful feature when trying to establish mixture strength by plug colour.

[QUOTE=johnno]

sorted the 750 2day just like the 650 nothing really needed doing ,no time to check uj on 750 so that will be next job .Both bikes running brill and both now have a happy brown colour to plugs .I will be needing the rubbers between carbs and manifold soon on both bikes besides that i really need to strip paint work on 750 even i cant believe how bad it looks[/QUOTE]
Did away with using the Guzzi inlet rubbers as the replacements didn’t last long.Got a 1 metre length of stell reinforced, fuel/oil proof hose from the local engingeers merchants for £10.A good seal and strong enough to hold the carb.Doesn’t look tatty either.All the bestSteve