PHBH 28 Jet Sizes for 501XE Camel

[Ted]

I managed to order a set of PHBH 28 carbs that I'm going to rebuild in hopes of addressing the fueling hole that seems to exist at 4000 RPM. Since I have PHBH 30s that came with the American market bikes and as I understand others had 28s, hopefully this will improve things.

I'm trying to figure out which jets I want for it. Note my PHBH 30s are still on the bike (as I want to be able to still keep it running/riding) so I'm not sure which jets it has in it. But, the parts seem to be interchangeable overall. I bought three carbs which I believe came off of Moto Guzzi V50s, and so the jetting is likely incorrect.

I'm wondering if anyone knows what size main jets were used with this engine on the PHBH 28s, or alternately if anyone has a set of jets they've used that work well. I figure for the primer jet and the cold start jet I could pull the ones out of my PHBH 30s and probably have it be about right. On the main jets, I'm not so sure. In my manual I found the attached graph, but that manual doesn't seem to reference the 501XE specifically, nor I do find references to the PHBH 28s specifically (I see references to the 26s in there, actually), so I'd like to set myself up for the greatest chance of success. I suppose I'm probably best off buying a jet kit and just planning on swapping them out to play with some, but want to have a decent baseline.

Jets.jpg (119.96 KiB) Viewed 9280 times

[norbert]

Running the 501 with the original air filter and exhaust sytsem the original setting of the 28 PHBH Dellortos is almost the same with Camel 501, Excallibur and New York 501 as they all use the same air filter:
slide 40
needle X 18, 3rd notch
atomizer 264 BC
main jet 76
idle jet 42
choke jet 50
float/swimmer valve 250

When using other air filters like K+N or 350 airfilterboxes the main jet rises easily to 120-130 an even more

[3potjohn]

I never got my Coguaro to to run properly and hold a steady throttle at around 4 to 4500rpm without stuttering, cutting out and backfiring on the overrun, in spite of checking and swapping out some of my Kokusan ignition components, checking wiring, plugs etc and umpteen variations of carb settings until I recently returned my airfilter to near standard. This type has the cylindrical design with a “flowerpot”. I have stainless silencers with just the end cans, so less back pressure.Everyone seems to suggest binning the flowerpot,at least on Darts but it screwed my bike royally.
So currently PHBH28 43 pilots, 264BC atomisers, 118 main jet ( was 122 before) and because changing my needles is a right old faff they are on 3rd notch and were x18 but currently X1. Only thing now is a little hesitant pulling away from a standstill and a slight lag if I whack the throttle open at speed but compared to before I can take that.
I may return to X18 when I can work up to it as I have to undo my throttle twistgrip or the carb springs are so strong I cannot get them into the slides.
My grandaughter will likely laugh about such antiquated things one day.
John

[Ted]

Thanks for the suggestions. I've ordered the rebuild kits, and it sounds like I need to see what I have in there better. I know I have two 110 mains and one 100 main, but I don't know about the others within the 28s or what's on the 30s.

Truthfully I far prefer EFI. Then again, I used to program it for a living. Push a few buttons and it's doing what I want it to.

[3potjohn]

EFI on a Morini, now that would be a challenge.
John

[hendre]

check out this page for the carb values for the settings: https://www.motomoriniclub.nl/carb.html

[MickeyMoto]

Thanks for the suggestions. I've ordered the rebuild kits, and it sounds like I need to see what I have in there better. I know I have two 110 mains and one 100 main, but I don't know about the others within the 28s or what's on the 30s.

Truthfully I far prefer EFI. Then again, I used to program it for a living. Push a few buttons and it's doing what I want it to.

If you can design a simple, robust system, I'm sure there would be interest. The carbs are wearing out and the bodies are no longer available. A nice, new manifold would resolve a lot of the problems, too, with the rubber inlets...

[Ted]

check out this page for the carb values for the settings: https://www.motomoriniclub.nl/carb.html

Thanks. Looking at that, it looks like I may end up being best off taking the bits out of the PHBH30s on there now to put into the 28s, and that may get me the closest. These 28s I have that came off of a Moto Guzzi have 58 idle jets, 76 choke jets, and 110 mains. The needles are X10s. Then again, maybe that extra fuel would be liked by the carb. When my rebuild kits come I'll probably pull the carbs off the bike and then mix and match the parts to get the closest that I can. I also didn't check the jet numbers etc. when I rebuilt the 30s that the bike came with.

[Ted]

If you can design a simple, robust system, I'm sure there would be interest. The carbs are wearing out and the bodies are no longer available. A nice, new manifold would resolve a lot of the problems, too, with the rubber inlets...

It definitely could be done, the cost aspect is probably the biggest question. The key would be getting two throttle bodies off of some fuel injected motorcycles that are already set up for having fuel injectors mounted in them and a throttle position sensor (I was looking at the ones off of my BMW R1150GS and thinking about how they could potentially attach to the Morini, but I suspect those throttle bodies would be larger than ideal). You would also need an electric fuel pump and pressure regulator, and you'd need to find places to put them.

My first pick would tend to be a Megasquirt Microsquirt for the ECU. There is a cheaper setup that some have used with an Arduino Uno. I use an Arduino for an electric fan controller in my RV (motorhome) and carry a spare, but the unit itself is kept inside the RV where it is protected from the elements. I think on a motorcycle you'd be tempting fate to use it.

Supporting upgrades would involve doing a 12V conversion, and I then wonder whether the stock alternator would be up to the task of producing enough electrical power for running an ECU and 45 psi (3 bar) fuel pump. I tend to wonder about finding a location for a fuel pump. I haven't looked into what a lot of fuel injected motorcycles use. My R1150 has an in-tank pump that is similar to an automotive in-tank fuel pump, and is not particularly small. I'm sure other options are available, but I'm not sure how small any of them are that can support the required 45 psi for multi-port injection. Ideally, you'd want to add an O2 sensor to the exhaust although that could be done without.

I suspect that at the end of the day, you're probably looking at something in the range of $750-$1k USD for parts to do a conversion, doing it as an open source/community project (which is what I'd intend on doing if I went down that path).

[MickeyMoto]

Ok, thanks for that. Sounds interesting. Might be cheaper finding parts at a motorcycle wreckers. The Guzzi V7 appears to use a single injector. The problem on the Morini is space.

[Ted]

I think getting the throttle body assembles used/from a wrecker would be the way to go, and had figured that in the cost estimate. I used to own a Moto Guzzi V7 Racer but never got into it particularly deep to see what parts it had inside. Agreed that the Morini's issue is space. Maybe some of the newer fuel injected dirt bikes would have some smaller fuel pumps that would be sufficient still. However like you said, space is the real issue. Whenever you're adapting something that wasn't designed for an application, it usually doesn't fit quite as well.

[Ted]

I worked on getting the PHBH28s on the Morini in place of the 30s, and got the first one together. Unfortunately the two carbs use different atomizer types, so they weren't compatible.

I basically threw some parts from each carb together and I expect it will be too rich at the top end to start, but I'll see.

Slides: I used the 45 slide from the 28 (the 30s had 50 slides, which are leaner)
Needle: I used the X22 needle from the 30 (the 28s had X10 needles, which seem leaner)
Idle and starting jets: I took from the 30s, they were a bit smaller/leaner than what was in the 28s
Main jet: I used the 110 that was in the Guzzi carb. The 30s had 80 main jets, but with the different atomizer they use the smaller jets which don't fit in the 28s

When I get this together and running I'll see how it works. It seemed that before it was very lean at the top end and I think that in theory I've done a couple things that richen it up. However, because of the different atomizer types, I'm not sure how the main jet sizes will be impacted. I'll probably have to do some playing around. I don't expect it will work very well the first time.

[Steve Brown]

I've just put a Sei-V on the road with a spare 501 engine in it. I will eventually fit the 501 into my Camel after it's been tested and set up etc.
I had a surprise in that I had to reduce the main jet to 100 from 120 to stop it 8-stroking/hitting a brick wall at anything over 1/2 throttle. Part of the problem is I only have 26mm carbs to play, with so obviously the draw of the larger bore 507cc engine is even stronger through a smaller carb bore. I'd often puzzled over the small main jets specified for some 501's and as John suggests the flower pot isn't the only thing to think about here.
I'm using a standard road 500 airbox and standard front pipes with some stainless after market silencers that may also be contributing to the puzzle.
It does pull nicely though!
You also mentioned the different needle jets/pulverisers in the 30 mm carbs, well they were also a pumper type acceleration jet in those US spec bikes. They were worked by the throttle needle when it raised. Hence another needle type in the mix. I think you'll be much better off with the 28's.

[SupermotoDave]

My understanding was that us bikes had the larger carbs with accelerator pumps so they could be set up to run much leaner at a constant throttle for EPA reasons and let the accelerator pump deal with the need for changes in throttle openings. Best thing to do for usability is change to European spec with the smaller carbs.

[Ted]

You also mentioned the different needle jets/pulverisers in the 30 mm carbs, well they were also a pumper type acceleration jet in those US spec bikes. They were worked by the throttle needle when it raised. Hence another needle type in the mix. I think you'll be much better off with the 28's.

That makes sense, I hadn't realized that previously.

I got the other PHBH28 rebuilt yesterday and got the bike running. It starts up much better than it did before. I got the carbs sync'd and everything set up on it, did a few restarts and it started up much better than it ever did with the 30mm carbs (provided I didn't forget to turn the key on ).

The X22 needles were, not surprisingly, way too rich and it didn't take much throttle to get the bike smoking out of the exhaust and running poorly. Swapping the X10 needles back in helped tremendously. However at full throttle unless it's at very high RPM (and even then sometimes) it seems to hit a wall until I close the throttle enough that the taper of the needle seems to restrict fuel flow, similar to that "brick wall" Steve mentioned above.

I have the 110 main jets in there because those are the jets I have. So I think I need to get some smaller main jets and see what that does. The idle and start enrichment jets seem to be good, those are the ones that were originally in the 30mm carbs and I carried them over.

I rode it around the property some yesterday, and really enjoyed how it rode. The engine is much more responsive now, makes great power and torque throughout the rev range (so long as I don't get too much throttle in). I haven't ridden it on the road yet to see how it does above 2nd gear, but it seems like I'm heading in the right direction.