After a decade of wrenching FINALLY I GET TO RIDE...now...to tune it!

[Guest]

First of all, thank you to Everyone here for your help in getting me this far.
I appreciate all of the time and patience you have all had with my questions and frustrations in trying to slowly get my 550 running when time and budget would allow (and often when they wouldn't).

I took it for the initial ride tonight and it was a lot of fun! It's a pretty nimble bike. Not quite as quick as my old 92 Vulcan 1500 but it's certainly not 1/3 the fun....it's all of it and then some!

Ok now for the tuning bit.

I synced the carbs recently when I installed them after cleaning. I'm thinking it might not hurt to go back and double check the settings, but I do have an issue with bogging. Under acceleration the bike accelerates until about 3000 rpm. Once I hit there, until just slightly after 4000 the bike bogs and hesitates. A little more throttle and it'll pull through just fine, but that's sort of the meat and potatoes of the engine range so I know it can be improved. The best way to describe it would be as if I were accelerating using constant 3/4 throttle and then when I hit 3K if I were to roll back to maybe 1/3-1/2 throttle and then back to 3/4 after 4K. Of course in reality I'm keeping throttle constant, but that's the best way I can describe how the bike is behaving.

After about a 5 minute ride around the block a few times, cylinders 1 and 4 (brand new plugs btw) are colouring nicely and are a light brown. Cylinders 2 and 3 both had white electrodes. I know that means it's running lean so I give both cylinders a full turn of mix and then took it out again. It seemed like the bogging might've gotten a little better, but not significantly, so I gave both another half turn and took another ride and it was pretty much the same.

All the cylinders were set to somewhere around 2-2.5 turns out when I did the sync. I didn't want to go too too far on the screws without checking in first to see if maybe it's not purely a mixture issue. The one mix screw is very tight to turn, and of course it's the one that's hardest to get to so I don't want to adjust that a bunch and mess it up worse than it is already.

Also, I think one of the runs I switched to prime to see if it was vacuum related and it was not.

Thanks again for all the help!

(Rundown of the new bits: Cleaned and synced carbs, new coils, plugs, wires and caps, Dyna-S, all new boots and o-rings (airbox to carbs and carbs to engine), no vacuum leaks on the boots, new exhaust gaskets at the manifold, new Uni OEM filter, Stock airbox and exhaust, R1 Rectifier, SSPB)

[mmattockx]

A little more throttle and it'll pull through just fine, but that's sort of the meat and potatoes of the engine range so I know it can be improved.

Congrats on the first ride. I just want to correct your perception a bit. 3000-4000rpm is not at all the meat of the power on a 550. Aside from trickling through traffic, I seldom ride my 1100E below 4000rpm. Your 550 should be living well above 4000rpm where it can make power and run happily.


Mark

[cp___32]

Thanks for the info Mark,

I'm used to the Vulcan 1500 which is all low end. I'll check the performance in the higher range to make sure it's good.
I had set the timing but perhaps I'll check that again. I did the trick by rotating the rotor to mimic full advance but it was super tricky to do so maybe it needs to be fine tuned since I had to monkey with the ignition stuff last night.

How long do I need to run the bike at the affected RPM before I will see the results on a plug chop? Or should I just ride normally and read the plugs based on that?

[mmattockx]

I'm used to the Vulcan 1500 which is all low end. I'll check the performance in the higher range to make sure it's good.

Trust me, it will wake up in the top half of the tach.

How long do I need to run the bike at the affected RPM before I will see the results on a plug chop? Or should I just ride normally and read the plugs based on that?

Before checking the plugs try pulling the choke when you get to the problem area. If you are lean it will clean up and pull stronger, if you are about right it will bog slightly and if you are rich it will bog badly and fall on its face. That will give you an indication of which way you need to go. You don't say what throttle opening you are at, which really is what we need to know to diagnose which carb circuit is causing you trouble. My guess is you are lean coming onto the needles based on your description.

The way I check the jetting (on CV carbs, mind you, I am not familiar with the VM carbs) is:

1) Put a piece of tape on the throttle housing and mark the throttle opening in 1/8 increments from 0 to 100%.
2) Go out on a back road where there is no traffic to bother you and you can run highway speeds safely.
3) Get into 3rd or 4th gear and let it slow down to ~2500rpm or so.
4) Roll on the throttle to 1/8 and let it get pulling steady at that throttle position. Once it is pulling steady, pull the choke and see what happens.
5) Repeat this for 1/4, 3/8, 1/2 and full throttle. For full throttle you might want to let the revs get upwards of 5000-6000 before pulling the choke to be sure it is running hard enough to be an accurate reflection of full throttle operation.

On CV carbs (and likely similar on your VM carbs, hopefully someone will correct me if I'm wrong) the pilot circuits cover idle - ~1/8 throttle, the needle covers 1/8 - 3/8 and the main jet is 1/2 throttle and up. In between there is overlap of the circuits, but the above method will at least let you start to know which direction you need to go with each circuit.


Mark

[cp___32]

Thanks again Mark, that's a very comprehensive test.

I tried pulling the choke while it bogged had no effect on how the bike ran. It might've gotten a tad better but not by any noticeable measure. I'll need to wait till I can get somewhere that I can do the more comprehensive test you outlined. I do have Mikuni CV carbs so your test should work for me.

I double checked the timing and reset 1-4 using the full advance method. My 550 is one of those ones that didn't need adjustment with the original equipment so timing 2-3 is a bit of a challenge. I moved the pickup a little and it made a little improvement. Moved it more and it seemed to stay the same.

On my last test run I did give it the beans and it eventually slowed and stumbled at all RPM ranges and died when I pulled in the clutch. Choke didn't save it so I'm wondering if either the petcock is giving me troubles or if the floats are all a little low and I'm running dry. I'll have to order one of those float height kits to be sure. Any suggestions on a petcock rebuild kit? I am pretty sure I ordered some OEM replacement parts way back when I got the bike but I'm sure the parts aren't expensive to pick up to be sure.