500W carb questions

Maestro, SEI-V
Canuck750
Posts: 111
Joined: 29 Jan 2018 22:14
Location: Edmonton, Alberta, C

Re: 500W carb questions

Post by Canuck750 »

An update on my progress jetting the Mikuni VM carbs on my 500W - I ended up with 25 pilot jets and 125 main jets, needle on 2nd clip from bottom.
Changing the main jet from 130 to 125 really improved wide open throttle, the bike will now pass 90 mph whereas it struggled to get to 80 before.
I have the Elektronik Sasche ignition module on position 3, I found this to be better than positions 1 and 2 and as I went with a higher number the bike just ran worse until I got to poisiton 8 or higher it hardly ran at all.

Trying to get the tachometer to work properly with the electronic ignition, Elektonic Sasche instructions says to flip the second dip switch on the module up or down to get a steady and correct reading. My tach just flops around on accelleration but it will setle down to 4200 +/- rpm while cruising. Could be the old Veglia gauge is starting to die, most of the Veglia electronic tachs I had on my Moto Guzzi 850 Eldorado eventually failed completley and upon opening them up the plastic components that encase the magnets swell up and crack and the unit can not be repaired.

Has anyone found a new replacment electronic tachometer that will fit the original rubber mount and bezel?
Seagreen
Posts: 86
Joined: 18 Jan 2018 21:18
Location: Cheltenham UK
Location: Cheltenham, Glos

Re: 500W carb questions

Post by Seagreen »

Hi Canuck, I hope that you do not mind my piggybacking onto your carb thread but I am hoping that someone may be able to help with my 500 carb/ignition.
Currently my 500 seems to run OK but I feel that it is a bit slugginsh - struggles to reach 95mph and seems to me to me a bit slow off the mark, especially from a standstill when the engine seems to bog down a bit at small carb opening. Since I bought the bike a couple of years ago now, I have renewed all the jets and needles and float valves so that they are as per the manual (PHBH 26). I have also replaced the air filters with the standard filters, purchased from either NLM or Mdina, can't remember which. This has made the bike run a bit better but I am not impressed with the speed. I took it out again for a ride last w/end and on my return I removed the spark plugs (NGK BP7ES) - see photo (LH plug is rear cylinder) - and to me it looks as if the mixture is a bit on the lean side - the centre electrode is a light brown, almost beige, but the ground electrode seems to be OKish but a bit pale, in my view. If it is runnimg a bit lean, has anoyone got a suggestion as to where would be the best aspect to start changing, needle height for example?
I believe that the valve timing is OK but when I renewed the cam belt I felt that the timing marks did not truly line up as per the manual, there was approx 1/3rd tooth out from the manual's stated positions. Could this be the cause of the sluggish performance? The timing marks were aligned in the same positions as when I removed the old cam belt. I do not want to understate the performance but I would have expected a bit more form a 500cc bike of that age (1981).
I have checked the ignition timing and that seems OK - it was somewhat retarded when I bought the bike - and it uses the red spot coils. I have a Sachse ignition to fit but before I do that I would like to see if I can coax a better performance out of it before changing as that will just add another variable into the equation.
Any help would be much appreciated.
Thanks,
Charles
Attachments
NGK plugs
NGK plugs
IMG_3496.JPG (402.24 KiB) Viewed 4567 times
mbmm350s
Posts: 666
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: 500W carb questions

Post by mbmm350s »

Hi Charles,

Back in the day the road tests of 5 speed maestros reported top speeds of 105,103 and 101 mph (bike, which bike and superbike)
- presumably prone as one sitting recorded 96mph. Standard gearing.

Mark
morini_tom
Posts: 920
Joined: 05 May 2006 13:47
Location: Northampton

Re: 500W carb questions

Post by morini_tom »

Hi Charles,

Its hard to say from the photos but I would say those plug colours look pretty reasonable actually.

You mention the timing marks being about 1/3 tooth out- The bottom pulley has multiple keyways in it so you can pull it off the crank and rotate it until you find a position that gives you the correct cam and crank timings.
Seagreen
Posts: 86
Joined: 18 Jan 2018 21:18
Location: Cheltenham UK
Location: Cheltenham, Glos

Re: 500W carb questions

Post by Seagreen »

Thanks for your comments Tom, I did not know that the bottom pulley had multiple keyways - I will check to see if I can get it closer.
Mark, thanks also for your comments, it would seem that perhaps I am expecting too much form this bike by way of performance? If I remember correctly the Triumph 500 Daytona from the early 70's had a top speed of c.105 mph so I was expecting better from the Morini. I had the single carb Triumph T100ss back then and it certainly seemed to go with a bit more zing!! Maybe my memory has decieved me...........
It is not that I intend to ride at these sorts of speeds but I feel that it is symptomatic of something being not quite right.
Thanks again for your comments.
Charles
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: 500W carb questions

Post by MickeyMoto »

Hi Charles,

I hope all is well.

Could it be modern fuel is the culprit? Not sure if the mix we use has the same bang as 4 star!

The 500s were not renowned for more speed compared to a 31/2 Sport. More torque and a more relaxed motorway cruise. My 501 Excalibur engine in a 31/2 frame ran out of steam at 95. That did have a J cam and not a hot one.

My present 31/2 Sport does not feel as quick as my memory leads me to believe from the 80s. Mind you, that had a Ricky Racer 2:1, so maybe it sounded quick.

Also bear in mind the co-efficient of drag has probably increased over the years, if you get my drift... :)

M
Vitesse
Posts: 218
Joined: 05 Jan 2019 13:42
Location: Barnacle
Location: Crowcombe

Re: 500W carb questions

Post by Vitesse »

MickeyMoto wrote: 13 Oct 2021 21:19
My present 31/2 Sport does not feel as quick as my memory leads me to believe from the 80s. Mind you, that had a Ricky Racer 2:1, so maybe it sounded quick.

M
Piggy backing a piggy backed post . . .

What reg was your 350 from the 80s? Curious as mine has a Ricky Racer and you never know . . .
'It must be a .....'
Posts: 365
Joined: 12 Sep 2010 12:25

Re: 500W carb questions

Post by 'It must be a .....' »

Hi, I agree there are perhaps too many variables,
The standard 500 5 speed has quite tall gearing which can show up any carburation issues especially when the bike is loaded up

It might help if you could give the carb settings and the gearing your using

I used to run a 1973 Triunph 500 up until the 1990s; the standard gearing on these can be on the low side (I changed the gearbox sprocket)
A friend had one of the last Daytona 500s up until 2002 yet the 5 speed Morini 500 is quicker (standard gearing)

My 5 speed 500 had a hesitation around 4500 revs yet went really well at higher revs/speeds
Pilot 45
Main 125
Starter 48
Needle X1 3rd
Slide 40
Atomiser 264T
I always meant to change the Atomisers to 264CE which the Camels use to see if I could cure the hesitation

Sometimes 42/43 pilots help to improve things eapecially low rev glitches; I've fitted these to my 500 and 501 engines
Later 500 Camels have X8 needles (4th), early Camels use X1 needles like the road 500

Good luck with the quest, take care Ian
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: 500W carb questions

Post by MickeyMoto »

Vitesse wrote: 13 Oct 2021 21:40
MickeyMoto wrote: 13 Oct 2021 21:19
My present 31/2 Sport does not feel as quick as my memory leads me to believe from the 80s. Mind you, that had a Ricky Racer 2:1, so maybe it sounded quick.

M
Piggy backing a piggy backed post . . .

What reg was your 350 from the 80s? Curious as mine has a Ricky Racer and you never know . . .
:)

I bought it back a few years ago and it had an NLM 2:1 so not yours! :)
huub
Posts: 194
Joined: 24 Jul 2006 15:11

Re: 500W carb questions

Post by huub »

check the gearing , the 500 has a tall gearing , the 5 speed box is pretty similar as the 350 six speeder , with the 500 first gear pretty much the same as the 350 second gear.
if you dont run on highways all the time , a couple of teeth extra on the rear sprocket actually improves the top speed of a stock 500.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 500W carb questions

Post by norbert »

To me the sparks look pretty well and I wonder wether and where you do want exceed 95 m/h with an almost 40 year old italian clasic bike.
If it´s for competition entering circuits it would be much better to try a 501R from a Camel 501 but for the road with a 478 5-gear you should not complain struggeling wit 95 m/h. Mounting a half fairing you can gain a lots of m/h :wink:

cheers from the Sierra de Carzorla/Spain :P
norbert
Seagreen
Posts: 86
Joined: 18 Jan 2018 21:18
Location: Cheltenham UK
Location: Cheltenham, Glos

Re: 500W carb questions

Post by Seagreen »

Sorry to be slow in responding but I obviously failed to post my thanks the other day when I wrote a reply so, very many thanks to all who responded to my query, I will take a look at jetting etc to see if I can get rid of the initial hesitancy when starting off from a stationary position. Good to learn that plug colour looks ok although it is always difficult to interpret these things through a simple photo - colours are not always what they seem.
Regarding MickeyMoto's comments about drag resisance, I have no idea what you mean or are implying :shock: :lol: !!?
Norbert, I do not intend to ride at 95mph for any length of time, it is just that having never ridden a Morini, I was curious to know whether the bike was running well/properly so a full throttle blast would give a good indication that all was well or not - crude but reasonably practical, I would have thought?
As for the belt timing, I will take a further look this winter when I will also upgrade the ignition system to a Sasche version. Additionally, I will check out the sprocket sizing.
Once I have checked all the jets etc I will report back,
Thanks again for all your suggestions and repsonses.
Adios,
Charles
Post Reply