Author Topic: Surging, lurching, stumbling (Read 7623 times)

Yo Man · « **on:** October 04, 2015, 06:56:27 AM »

The title is a clue to my question. Between around 3000 rpm and 3800 rpm my '09 Stelvio does all of the above, making it a very unpleasant experience. This is most pronounced at steady and light throttle. Above 3800 or so, the bike is strong and pulls cleanly. It starts fine and idles smoothly at 1200.
Here's what I've done: loaded a map from Guzzidiag, changed to the recommended NGK plug caps, set the valves to 6 and 8 thou. Air filter is good. Here's what I haven't done; change the spark plugs (PRM8B are in it and look fine, but that's my next step), sync the throttle bodies. I don't have a "carb" balancer but I'll have to get one. I've never done that before but figure I can follow along the tutorial on this board.

The bike has 14,000 kms on it and has surged since I got it at 11,000 kms. Seemed to improve some after the new map but seems to be worse as time goes on. Any ideas out there?

redrider · « **Reply #1 on:** October 04, 2015, 07:25:26 AM »

Hi and my V11 Café Sport did exactly the same until I upped the idle fuel trim 30 points. I know, different motors , oranges and tangerines. I can detect a very slight glitch on very hot days but with Fall and cooler temps now, no worries. The vacuum gauges from Whitney are a necessity. Nothing will work out until the bodies are in sync.

Yo Man · « **Reply #2 on:** October 04, 2015, 07:54:38 AM »

Ok, thanks. I should have put that on my list of what I have not done. When I installed the new map I didn't adjust the CO trim, mainly because it was idling OK and I didn't know which way to go. I could try some new settings if that might make a difference.

lucian · « **Reply #3 on:** October 04, 2015, 08:09:14 AM »

Has the sacred screw been messed with? Is your map lamdas on or off? You will definitely want to check tb balance , And air bleed screws . Much has been written here on the proper tuning of the 8v. Also has the roller conversion been done? If not I would strongly suggest you have the cam followers inspected.

Yo Man · « **Reply #4 on:** October 04, 2015, 09:14:36 AM »

How do I know if the sacred screw has been messed with; paint? I also don't know about the map lamdas; would that be part of the new map I got from Mark? (sorry, I don't speak computer). I haven't had the roller conversion done. I plan to take the bike to Seacoast (500 miles) but thought I should put enough miles on the bike to actually start the premature valve train wear, in order to qualify for the required parts. Otherwise I'm paying for them to pull my bike apart, find insufficient wear, and reassemble at quite an expense to me. I'd rather make it a one time cost. The air bleed screws would be part of the tb balance, right? I'll have to get a balancer and tackle that.

Toystoretom · « **Reply #5 on:** October 04, 2015, 11:08:16 AM »

My .02 cents is that your throttle plates are not sync'd. The key here is that you say it does it during light throttle. Imagine that when you open the throttle just a bit that one of your throttle butterflies are open a little but the other side is still closed because they are out of sync from cylinder to cylinder. That means the side where the butterfly is still closed is strangling and is being drug along for the ride, making it pop and surge and buck and so on. If your throttle is open more than 1/4 everything is great. Your bike probably even pops excessively during deceleration because of this.

I would get your throttle bodies looked at before I did anything else.

Tom

Vasco DG · « **Reply #6 on:** October 04, 2015, 12:43:55 PM »

It's been said many times before but I'll reiterate it once again.

Remapping is not a magic bullet. The tune, all aspects of it, have to be correct for any map to perform correctly. If you have no idea about the state of your throttle bodies re-mapping will achieve nothing.

Make sure the tune is correct in all aspects then if there are problems they can start to be addressed. Is your bike stock otherwise? Or has it got an aftermarket pipe or some silly type of air filter? Any modifications from standard?

Pete

RANDM · « **Reply #7 on:** October 04, 2015, 04:16:30 PM »

Hi people. I'm new here, not promoting the sucking
of eggs but, just thought I'd mention what I use.

Manometer - 6m clear plastic tube of appropriate size,
1 x 2m length of wood, 500 ml two stroke oil <$10 +
some zip ties.
Two stroke is good as if, by chance a little gets sucked in,
it will burn off.
Hope this is helpfull to you.

Cheers Maurie.

Vasco DG · « **Reply #8 on:** October 04, 2015, 04:30:53 PM »

If you want to avoid the risk of sucking muck into your engine probably the simplest and most effective, (Also the most popular and reasonably priced.) tool available at the moment is the Morgan Carbtune.

Another interesting device recently invented and mentioned either here or on the Ghetto is a manometer box with a Bluetooth connection to your smartphone that allows you to use an app and your phone screen for balancing. Fantastic! Another wonderful 'New' thing that avoids you having to mess about with dirty, dangerous chemicals! For that reason alone it will probably be derided by some here.

Pete

Yo Man · « **Reply #9 on:** October 04, 2015, 07:00:30 PM »

Quote from: Toystoretom on October 04, 2015, 11:08:16 AM

My .02 cents is that your throttle plates are not sync'd. The key here is that you say it does it during light throttle. Imagine that when you open the throttle just a bit that one of your throttle butterflies are open a little but the other side is still closed because they are out of sync from cylinder to cylinder. That means the side where the butterfly is still closed is strangling and is being drug along for the ride, making it pop and surge and buck and so on. If your throttle is open more than 1/4 everything is great. Your bike probably even pops excessively during deceleration because of this.

I would get your throttle bodies looked at before I did anything else.

Tom

Toystoretom, I'm thinking you're right; that's a good description of what is probably happening.

I do realize that everything has to be "right" for the bike to work properly; I'm new to this bike, have limited mechanical skills and experience and also don't have access to all the tools a full fledged mechanic would have. So I'm slogging along, trying to figure things out as I go.

The bike is stock, stock muffler and air filter.

Randm, I may try your homemade manometer suggestion, thanks. I'll also look into your suggestions, Pete. Sounds like a good investment that I'm going to need to keep this thing running properly.

I really look forward to the day I get this thing running properly. It has surged badly from the day I got it and that largely ruins the fun of riding it, though in that part of the rpm range that it works right, I can really appreciate what it could be.

Vasco DG · « **Reply #10 on:** October 04, 2015, 07:06:07 PM »

Where are you? Perhaps there is someone nearby who can help you out?

Pete

Yo Man · « **Reply #11 on:** October 04, 2015, 07:20:29 PM »

I'm on the east coast of Canada. There is a Moto Guzzi dealer in town, new to the brand, and when I asked if they could sync the throttle bodies they gave me a strange look (like I had two heads) and said "we don't know how to work on the old ones"

So, I'm not looking for much help from them. I can figure it all out, once I get a manometer and sync the throttle bodies I think I'll be good to go. Thank goodness for this forum.

Vasco DG · « **Reply #12 on:** October 04, 2015, 07:40:17 PM »

Well they won't be much good with the new ones then will they because the balance procedure on all W5AM bikes has been the same since 2005. Clowns!

stick · « **Reply #13 on:** October 04, 2015, 09:00:00 PM »

Quote from: Yo Man on October 04, 2015, 07:20:29 PM

I'm on the east coast of Canada. There is a Moto Guzzi dealer in town, new to the brand, and when I asked if they could sync the throttle bodies they gave me a strange look (like I had two heads) ...

Well, remind them that you DO have two heads, 2 jugs, 2 throttle bodies, etc. !!! Just stating the facts...

RANDM · « **Reply #14 on:** October 04, 2015, 11:13:21 PM »

Quote from: Yo Man on October 04, 2015, 07:20:29 PM

I'm on the east coast of Canada. There is a Moto Guzzi dealer in town, new to the brand, and when I asked if they could sync the throttle bodies they gave me a strange look (like I had two heads) and said "we don't know how to work on the old ones"

So, I'm not looking for much help from them. I can figure it all out, once I get a manometer and sync the throttle bodies I think I'll be good to go. Thank goodness for this forum.

Pretty basic skill for a Pro Mechanic to have I would think? You might do betterer on your own. As long as you can purchase decent tools as you go, you'll only buy what you need for your
Goose - no waste = win. The home made Manometer works very well as long as you don't overfill it, you only need a meter/yard or so of oil in the loop, make sure there are no pinches and
your good to go, don't need a measurement scale as your only looking for an even oil level at idle and as you rev it up. When you rev the oil level will rise as the flexible pipe is sucked on
which is why you need 4 - 5 ft of pipe above the oil level in the loop so that there is no chance of any getting sucked over the top.

cheers Maurie.

tris · « **Reply #15 on:** October 05, 2015, 01:29:51 AM »

Quote from: Vasco DG on October 04, 2015, 04:30:53 PM

If you want to avoid the risk of sucking muck into your engine probably the simplest and most effective, (Also the most popular and reasonably priced.) tool available at the moment is the Morgan Carbtune.

Pete

:1: - I couldn't balance for toffee 'til I got one of these

Sasquatch Jim · « **Reply #16 on:** October 05, 2015, 04:23:24 AM »

Surging, lurching, stumbling, does this mean the bike has become a zombe?

Yo Man · « **Reply #17 on:** October 05, 2015, 09:19:12 AM »

Thanks for all the funny (and helpful) replies guys. Sounds like the Morgan Carbtune is a good choice. In the meantime there is an independent bike mechanic just a couple of miles up the road who works on all brands, mostly lower end, older stuff by what I see parked outside his garage. He's been self-employed and in business for several years and has a good reputation. Actually still owns a BMW R90S that he bought new, so he's the real deal in terms of being a bike person and mechanic, as opposed to the more new school "technician" type. I'm going to run up and see if he can help me out, which I expect he can. I'm going to read up on the process first, though, just so I know he won't be touching the "sacred screw", etc.

I'll report back, but if I go quiet for a while, it means he couldn't fit me in today and I'm going out of town for a couple of weeks.

smdl · « **Reply #18 on:** October 05, 2015, 09:11:44 PM »

Definitely make sure both you and the mechanic are aware of where the sacred screw is and that it should not be touched! The screw you do touch is different. I can send you a link to the procedure, if you don't have it already. Or you can take a short ride out to sunny Southern Ontario, and we can go through it together.

. I'm assuming that you loaded a single lambda map, or it probably wouldn't run...

Good luck. Keep us posted.

Cheers,
Shaun

stick · « **Reply #19 on:** February 04, 2016, 09:09:00 AM »

Yo Man, any update/progress/fix?

Kiwi_Roy · « **Reply #20 on:** February 04, 2016, 03:03:14 PM »

Does anything at all show up on the dash as it surges indicating a possible electrical malfunction

Ooopps, sorry I didn't notice how old the post was.

malik · « **Reply #21 on:** February 04, 2016, 03:16:02 PM »

And it may not be sufficient to merely replace the air filter. There may be accumulated dust in the air box &/or throttle bodies that has got past the filter that needs cleaning out.

Sasquatch Jim · « **Reply #22 on:** February 04, 2016, 03:58:05 PM »

Hell, I've been surging, lurching, and stumbling for years, even when I'm not on a bike.

jim_W · « **Reply #23 on:** February 04, 2016, 09:13:34 PM »

My CALVIN did this " surging, lurching, and stumbling" thing but would idle well and run wide open well. I rode it home from Nebraska to Phoenix doing a "wide open/coast combination. Not good for gas consumption.
A new throttle position sensor made it all better.

Yo Man · « **Reply #24 on:** February 04, 2016, 10:59:34 PM »

Quote from: stick on February 04, 2016, 09:09:00 AM

Yo Man, any update/progress/fix?

Winter in Canada has kind of put everything on hold. I did install a different map that got rid of the surging at the expense of fuel economy and I bought a Morgan carbtune at the end of the riding season but didn't have time to sync the throttle bodies before parking it for the winter.

I'm feeling pretty bummed about the flat tappet issue and feel like I'll need to deal with that in the spring. The uncertainty of whether or not MG will supply the new parts to replace the original, defective crap is playing on my mind. The previous owners bought the proper oil and filters from the dealer but kept no receipts or service records. The full cost in parts and labour may be more than the bike is worth to me.

Yo Man · « **Reply #25 on:** November 10, 2016, 08:51:31 PM »

I just stumbled, or maybe lurched, across this old post I started and thought maybe I should update my story. This past spring I had the bike rollerized and the throttle bodies synced, I'm running a different map (John's). The bike is running great and I enjoy it every time out. It's getting pretty chilly here now and I just changed the oil and tucked it in for the winter. While I can't ride for the next several months I'll look to this forum for my Guzzi fix and entertainment.

Tom H · « **Reply #26 on:** November 10, 2016, 09:04:31 PM »

Congrats!

Tom

News:

Author Topic: Surging, lurching, stumbling (Read 7623 times)

redrider

Vasco DG

Vasco DG

Vasco DG

Vasco DG