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 High speed, low throttle stumble/power dip

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MotoMT
Carlotto
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Apr 07, 2017 11:45 am

Update: So I've pulled the gear off and wiggled everything around to line up properly at tdc, per Pete's instructions. Interesting finding, though: The bolt was stressed significantly, like almost to the point of breaking! I'll post a photo later, cause it's nuts how distorted it is!

It came out easy enough, but why the hell would it be over torqued so badly? Bad day at the factory? Or was someone in there previously for other work? Meh, who freaking knows?

Anyway, the bolt is on backorder a few weeks. It's a flange bolt M8 1.0 threads, grade 10.9, part 1A000425. Any issue with using a regular hex bolt and washer with the same specs? Other than not dropping the washer in no man's land, are there other worries with not using the flange bolt (that'll be like $12 shipped)?
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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Apr 07, 2017 1:54 pm

Not that I can think of but make sure you use a reasonably high tensile bolt and a dab of Loctite 243. Also make sure the locator peg is covered by the flinger disc not aligned with one of the holes!

Pete
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Carlotto
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Apr 07, 2017 9:07 pm

This is the bolt that came out of the right side. It holds the upper sprocket on the cam, or service shaft, or whatever the hell MG calls it.

It's stressed, looks about ready to snap about 1/3 down from the flange. And I'm assuming it's not supposed to be? This is the way it came out! I couldn't believe it when I saw it. The bolt is small: M8x1.0 and 25 mm or so. The torque is something like 22 ft-lbs, if I remember correctly. It just doesn't need much muscle to tighten, so WTF?

As far as I know, the bike never had any work done previously. A 2015 with ~3000 miles when I bought it. At this point, I don't care as long as I get it running like it should. Still interesting to see mysteries like this, though. scratch

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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Apr 09, 2017 12:46 pm

SUCCESS!

Got everything put back together last night. Just returned from a test ride. Power all the way to redline! 

Idle running and power under 5,000 rpm are better, too. Although without context previously, it seemed OK. It was anemic even though I thought it was running OK up until the power loss.

This was major surgery for me. But for fellow mechanically disinclined folks who don't have access to an MG shop, it's doable. Just make sure to go slow and learn from my mistakes (there were plenty). I tend to go down rabbit holes needlessly and had a few clueless wild goose chases (as mentioned in previous posts of this thread).

Here are things I learned (thanks for the knowledge around here):

1) The exhaust header gaskets get squished down once installed. It may appear there are no gaskets, but look closely, they are there. Surprised

2) The TPS sensor reading in Guzzi Diag can bounce around a bit when the bike is idling. This is normal, don't freak out.  Razz

3) Empty the gas tank before trying to remove it. Also, unplug the fuel pump connector and cycle the starter to release some pressure before unplugging the "quick" connector. Otherwise, you'll get angry. OR just leave fuel hoses connected and remove them with the tank. It's easy to disconnect at injectors and lift tank from there. Just don't kink the fuel lines.

4) If you use a ratchet to turn the crank, for setting valve clearance, etc. DO NOT be a dumbass and leave your ratchet on the nut when you start the engine. Don't ask me how I know this ...

5) Loctite 243 is oil resistant and is different than 242, hahaha!
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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Apr 09, 2017 3:01 pm

Looking at that bolt I'd say that it must of been apart at some point as the factory probably use pre-set torque ratchets for assembly and I've never seen a bolt that stretched.

You got the bike with very low miles. I'm betting that it had that head off for some reason, (Casting porosity maybe?) and was reassembled by one of our hairless ape bretheren, hence the stretched bolt and mis-timed cam.

Pete
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PostSubject: Re: High speed, low throttle stumble/power dip   Sat Sep 01, 2018 10:19 am

Figured I'd give an update to this thread. I just did the servicing on the Norge. Dummy me thought it was 10,000 miles. It's not, as you all likely know, its 10K kilometers and 6200 Miles..... I wouldnt have had the time before my N.S. tour anyway..

SWMBO is out of own, So I did the full service today, including swapping out for the larger windscreen and hand guards for winter riding.

As this thread shows, I had the bike apart a dozen times trying to run down the rev problem, and havent looked at the valves or plugs since it was fixed. I upgraded the NGK plug caps from stock and they seem to be holding well.  I diddnt replace them with the CR8EIX (iridium) but the plain old copper CR8E's. Has anyone tried the Iridium plugs? worth the squeeze?

When I checked the current gaps, they were .15IN and .20EX, whch checking my notes is what I set them as at about 3K miles. Was happy to see they havent opened. I reset them to .10 & .15, sync'd the TB's and reset the TPS. I've had similar experience with other vehicles, the first valve adjustment needs some, then never again, or maybe after 20K miles or more.

I'll use 10K miles as my new service point, so next is 16200. Of course the dumb mechanics wrench will pop up at 12400, but oh well. I did change the trans and diff fluids at 6300 before the trip, as they were likely original fills. Hope to be in sync from this point on.

Over time the tuning and improvement of the 8V motor has gone from feeling weak, anemic, and unimpressive to VERY nice, particularly after pulling the colostomy bag and the latest Beetle map. HOWEVER.......... During  my 3400 N.S. trip, I noticed something. At about 8500 miles the bike was transformed. The motor seems to have opened up, and the bike overall is MUCH more satisfying. I remember Dave R from MI telling me that a Guzzi isn't really broken in til 20K miles, and if thats the case, I cant wait to see the next 10K.... Loving the Norge now...... As many know, I was not thrilled with the motor and preferred my 4V GRiSO.... Well.... I cant say that anymore.... The Norge is one sweet bike.  I just need to straighten out my suspension, think the preload adjusters are out of wack, when I went to back off preload completely (counter clockwise) it diddnt reach an end, just kept spinning. I did tighten to full and found a stop, so I guess it re-threaded itself. I tightened to full stop and backed off 3 full turns. Will see how things are when I ride next. I really dont want to spend $$ on the suspension, its NOT bad, just not great.
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beetle
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PostSubject: Re: High speed, low throttle stumble/power dip   Sat Sep 01, 2018 4:06 pm

Despite claims to the contrary, the stock 8V Norge makes more power & torque than the 2V everywhere. I even posted Dyno charts on WG to shut Huzo up. Yet, he still tries to bait me.

A properly mapped 8V Norge makes a 2V look like a ditch pump.



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Grisonut
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PostSubject: Re: High speed, low throttle stumble/power dip   Sat Sep 01, 2018 5:06 pm

beetle wrote:


A properly mapped 8V Norge makes a 2V look like a ditch pump.




I feel the same way with the Grisos...
Some folks say that the 2V has more mid range punch. lol
Bullshit! lol
The stock 8V (forget sorted out) outperform the push rod mill on every rpm, torque or peak horsepower.
Doesn't matter though, I like 'em both...
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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Sep 02, 2018 5:17 am

Grisonut wrote:
beetle wrote:


A properly mapped 8V Norge makes a 2V look like a ditch pump.


I feel the same way with the Grisos...
Some folks say that the 2V has more mid range punch. lol
Bullshit! lol
The stock 8V (forget sorted out) outperform the push rod mill on every rpm, torque or peak horsepower.
Doesn't matter though, I like 'em both...

I think this issue for me wasn't just about power, by comparison, the 8V had no character or as a certain man of mystery would say....

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I felt that way about the Norge even after I got the rev problem fixed. The motor was boring except for the top 2K of rev range. Mid range and lower it felt sluggish, anemic, without character, where the 4V GRiSO was snappy, responsive, and crisp, and seemed to love to pull. Thankfully, the Norge now has the same feel and character.
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Grisonut
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Sep 03, 2018 9:35 am

Mkay...
I own both bikes and that's how they feel to me.
I rotate them weekly so they get "exercised" on a regular basis.
They both have character but the 8V has the Hooligan personality while the other is more civilized. lol
My 2017 only has 6500 miles and the 07 over 30K.
It took about 10.000 miles on my old 09 to completely broke in so your Norge will only get better from here.
Guzzis are that way I found out, weird.
In the grand scheme of things I don't know shit about Guzzis, just the GRiSO, cause that's all I rode.
I do like the 1400 Cali engine (got to test ride that bike a bunch) but I'm not a cruiser fan and the V7/V9 are mehhh to me..cute but not my thing.
Stelvio too tall for me so not interested...Norge and Brevas are not as 'Sporty" as the GRiSO so the latter won from day one.
But once your Norge is properly sorted and fully broken in you will find it does not lack personality, at least engine wise.


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