Current status

Excaliburs, New Yorks

Current status

Postby swtuggle » 05 Mar 2012 16:28

I ordered and installed a new 39-tooth rear sprocket this past week. Had to cut 4 links off the chain so it would fit with proper play within the adjusters. Now it's towards the forward edge.
Took it out for a test ride. The appoximate 1" shorter wheelbase isn't evident, however the rear suspension seems a bit stiffer over bumps.
As for the gearing change, I was a little concerned at first about possibly having to feather the clutch from a standstill, but that proved to not be an issue whatsoever.
From what I've read, this puts my Ex on par with 3 1/2 and 500 overall gearing, and it feels MUCH better on the street, less stressed. I'm sure Morini geared the Excalibur so it could compete in the stoplight wars, but it's so much more pleasant with "normal" gearing.
With the additional load and broadened speed range per gear, the only problem I encountered on the 10-mile ride was regarding carburetion, and it was at one setting.
While in 6th around an indicated 60 mph & 4000 rpm and approx 1/4 throttle opening, there was a very mild surge with an audible hint of driveline snatch. My understanding is that it's still a bit lean at that opening, so I'll raise the X22 needles another groove, taking them to the fourth of five from the top.
It may be due to the temps I've been test riding in (high 30s to high 40s), but with a deflowered airbox and moderately baffled silencers, this engine seems to like its carburetion fairly rich compared to what I've seen others running on their Morinis. PHBH28, 40 slide, 50 starter, 47 pilot, 115 main, 264T atomizer, X22 (2.48/1.2/28.5). Overall plug coloring has been a light brown, so I guess I shouldn't worry about how mine differs from others, just get it to run as well as I can.
swtuggle
 
Posts: 47
Joined: 24 Oct 2011 02:36
Location: Steilacoom, Washington, USA

Re: Current status

Postby Morizzi » 15 Mar 2012 07:17

You can experience surging if the mixture is too rich too. If raising the needle doesn't help then try the other way.

Nothing there looks too far out except the main jet may be a touch small. You are running a 264 Atomiser with an X22 (not that different from an X1) Maybe that is your restriction. Even the older 500 motor ran a 125 which is about 19% more fuel availability.

Your 28's vs 26's means your jetting needs to be that little bit bigger just to allow for the slower air velocity through the venturi. Bernoullis (spelling?) principle.

Plug colour is encouraging. What plugs though? How are the earth straps? Where is the annealing line?
Morizzi
 
Posts: 39
Joined: 29 Oct 2010 22:53

Re: Current status

Postby swtuggle » 16 Jul 2012 02:57

During my 4-month hiatus from commenting on this thread, the weather has improved to allow more continual riding and testing. But of course, as the temps have risen, so has the tune of these carbs, which has been rather frustrating at times. I owned three dead-stock Guzzis, a V7 Sport with VBH30s, and two 850s, a T5 with ??30s and LeMans III with PHF36 pumpers. None of those were as finicky or temperature sensitive as this Morini with these PHBH28s. However, the Morini is considerably less restricted intake and exhaust-wise.

I've done a fair amount of swapping and adjusting jets, needles and slides (within the range of parts I have on hand). The plugs, NGK BP6ES, have been in and out, oh about a hundred or so times. Since the average temps are now another 30F (17C) higher than when I started dorking around with these things, I've had to constantly tweak things in order to appease my perfectionist-aspiring anal retention.

So, with an average outside ambient temp of approximately 70F (24C), my current settings are such: 50 starters (haven't touched), 47 pilots, 50 slides (40s started leaving the plugs a sooty black at around-town speeds, 1/8 throttle openings), X22 needles raised to the 5/5 notch, and 118 mains (largest I have on hand, and as Morizzi suggests, I believe they are a bit too small).

Now that it's warm out, the bike starts without choke, has very good throttle response, and runs out quite well when you put the coals to it. Even with the needles pulled all the way up, I still occasionally feel and hear a slight bit of stutter/driveline snatch when in top gear around 1/4 throttle, especially when I back off the throttle slightly between 50-70mph (80-113kph) and approximately 3500-5000 rpm. Any amount of throttle beyond that and it's fine (accelerating). It sometimes will exhibit a slight stutter in the lower gears during low load around 1/8 throttle and between 3500-4500 rpm.

I have a pair of 112 mains, and plan to drill them out to 1.25mm. That may require me to play around with the needle heights again, so we'll see.
swtuggle
 
Posts: 47
Joined: 24 Oct 2011 02:36
Location: Steilacoom, Washington, USA


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