Quick Carb question '77 550E

[SeanGSUK]

Hi, opened up my carbs to give them a clean. I have pods and a 4-into-1 exhaust.
The main jet is a 97.5, is this ok with the pods and exhaust or do I need to go up?
I think stock is 80 on the VM22SS carbs? Plugs are slightly brown on the tops like a chicken OXO stock cube, no oily blackness. Bike is hard to start from cold but runs like a beast once started though.

[tom203]

So once the beast has warmed up, it behaves well - idles well, takes off and runs happy ?

[hampshirehog]

Hard to start when cold is often either a valve clearance issue (have you checked them) or a blocked enrichment circuit (= choke system) usually the pick up tubes or the passage in the float bowls or a tap problem - turn it on prime for 30 seconds before trying to start.

I would have thought your main jets were on the high side but if your plug chops (proper chop, not 'an average) are telling you otherwise and she runs well then it is fine.

[chuck hahn]

Plug color sounds about right...not lean but not overly rich either..a tad rich is always better than too lean any day. I too would go after valves, intake boot Orings, and new intake boots if found to be cracking or seperating from the metal flanges.

[SeanGSUK]

Quick Carb Question '77 550E

Cleaned out the choke passages, one was slightly blocked, hopefully when I put them back on it should start a bit better. There was some varnish on the choke plunges too.
I haven't checked the valve clearances, something I could do with doing, I'll see how she runs once the carbs are back on.
I think, as the plugs colour confirmed mix as being right, or as near as, I will stick with the 97.5, I can always adjust the pilot screws if it is a bit rich. Removed who knows how many years of crud, varnish, paint and the odd insect!
They look great, just hope they run great!
Set the float height to 24mm, they were all pretty close to that tbh. I'll check the intake boots before i put the carbs back on too.
I'll post an update once she's back in one piece, could be helpful to others?

[tkent02]

I haven't checked the valve clearances, something I could do with doing, I'll see how she runs once the carbs are back on.

Adjust the valves before you burn them up.

[hampshirehog]

Make sure you check the passages in the float bowls where the 'choke tubes' slide in. Give them a squirt of of something to make sure they're clear.

And check your valves otherwise you could be chasing your tail.

[SeanGSUK]

Quick Carb question '77 550E

Carbs back in, took a little coaxing to get going 'til the float bowls filled but she runs well.
The reasons I took them off to clean were that she was a pain to start from cold and also, every 20 miles or so she would lose power and die. I'd leave her 5 minutes and then she'd fire up straight away and we'd be on our way again.
Now the cold starting is sorted as I left her a few hours and she turned over quick and started fine.
I thought the power loss was due to a float bowl sticking and not allowing fuel through, but they have all been checked, levels are right, channels are clear.
The only think I can think of is that the pilot screw on no.2 is out of adjustment. I can't turn it though as it is stuck in there and the PO had striped the head off it. Any other ideas?

[Nessism]

So you didn't even take the pilot screws out? How do you plan to clean the carbs if you are not even taking the carbs apart?

Oh, and adjust your valves before you damage the engine...assuming it's not damaged already.

[SeanGSUK]

Pilot screw

Can't clean something I can't remove? I didn't want to damage it further by trying to dig it out somehow. Choose your battles. All the others came out along with, jets, chokes, sliders, new o-rings, gaskets etc, all blown through with carb cleaner, etc. Just that one pilot screw I didn't remove. Everything adjusted as per the guide on this site and she runs well...for 20 miles! I don't think the valves are causing the splutter/stop part of the journey.

[tkent02]

Try popping the gas cap open when it quits at twenty miles.

See if it doesn't magically decide to keep running.

[SeanGSUK]

Try popping the gas cap open when it quits at twenty miles.

See if it doesn't magically decide to keep running.

Good call, will do! I think I need to clean out the pet cock too, it sounds like there is a load of gravel in the bottom of the tank!

[Charlie G]

Good call, will do! I think I need to clean out the pet cock too, it sounds like there is a load of gravel in the bottom of the tank!

The symptoms you have match what my 450 was doing when the petcock took a dump. There is a backing plate in the petcock for the diaphram and it had broke into 3 pieces. It would strand me 50 miles from home. I'd swear and have a smoke and give it one last try and fire up she would. Took me about two months to figure it out. Might be your problem, maybe not.

cg

[SeanGSUK]

Thanks! Just stripped down the bike ready for for draining the tank and removing the petcock, Hopefully it will be an easy fix.

[SeanGSUK]

Tank and petcock cleaned through, diaphram in one piece, I think the breather hole may have been slightly clogged. Bike starts better from cold now.
I have a different problem now though. I let the bike warm up but it sounds a little erratic on idle. I noticed that exhaust pipes 2 and 4 are running cooler than 1 and 3 (assuming 1 is the same side as the petcock?).
Any ideas? I have brand new spark plugs in and pilot is 2 turns out on each. Coils maybe, plug gap?