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 High speed, low throttle stumble/power dip

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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Dec 04, 2016 6:09 pm

Interesting...... Thanks Pete.

When I saw it was just rollerized, thats what I thought it would be. Was hoping it was a connection or TB leak, etc.  Was the drop off sudden like a switch? Would it rev to redline in lower gears with light throttle?

I can get the motor to spin to redline in the lower gears with light throttle but anyload over 600-6500 rpm and it bogs down.

I think it is unlikely the cam gear is my particular problem. I got it with the problem at 1500 miles. What are the chances it came from the factory 1 tooth off? The bike was a 2014 sold in October of 2015, then the PO traded it for a Harley Sportster 883 in March. It got sold to a wholesaler (who I bought it from).

As for the blocked/restricted exhaust, not sure how to address/check that. I seem to remember someone suggesting a clogged cat as well, and that sounds like it may be a possibility. There is a cat eliminator pipe available from AF1, MG parts and Guzzitech. Any recommendations on which is best?

For $h!t$ & giggles what should I be looking for compression wise? Its still under warranty, will probably just drop it off at MI and let them figure it out.
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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Dec 04, 2016 6:14 pm

If it was a flat tappet bike that's been rollerised it may well of happened then. Even if you ensure that the top sprocket doesn't jump a tooth it's possible the bottom one will and the crank will move.

If it is a tooth out the compression on one side will be much higher than the other. Oddly the 8V isn't a collision motor if it's one tooth out. Amazing given the cam timing.

Pete
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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Dec 04, 2016 6:52 pm

Pete Roper wrote:
If it was a flat tappet bike that's been rollerised it may well of happened then. Even if you ensure that the top sprocket doesn't jump a tooth it's possible the bottom one will and the crank will move.

If it is a tooth out the compression on one side will be much higher than the other. Oddly the 8V isn't a collision motor if it's one tooth out. Amazing given the cam timing.

Pete

I doubt that it is, it is a 2014 model. I'll see if my compression gauge fits.
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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Dec 04, 2016 7:05 pm

Nothing is ever impossible. The motors are assembled at Noale by people who aren't paid a lot and therefore don't give a shit.

Pete
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beetle
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 12:36 am

Oz1200Guzzi wrote:
since I haven't ridden an 8V with Beetle map magic



I've offered you a ride on mine numerous times. Just do it, next time.




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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 1:04 am

And if you want the 'Milder' *Little-old-person* version you can ride mine Very Happy
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Oz1200Guzzi
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 12:59 pm

Thanks Mark and Pete - I don't really like to ride other peoples bikes, though have ridden yours some years back Pete. I will do this the next time we are together, and mine is available for a comparison should you so desire. I am also wary of the difference between my riding ambitions and capabilities - doesn't matter so much on my old hack, it puts me out, and not someone else.

Next time we should do this comparison before we hit the piss - all bets are off once imbibment begins...
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MotoMT
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 9:46 pm

Thanks for the updates everyone! Taking a break for a bit over the winter. Maybe after Christmas this will give me something to check.

My plan for the spring is to get the bike into more capable hands, since I'm just shy of useless on my best day. Will definitely show this thread when discussing the bike's history with the tech.

In the meantime, I'll keep on lurking (and maybe post a time or two).

Any chance somebody on the board knows a Guzzi expert in Montana, preferably around Helena?  ; )
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Charlie J
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 10:26 pm



Next time we should do this comparison before we hit the piss - all bets are off once imbibment begins...[/quote] . A comparison you say. Always good to compare your bike to others. We need more comparisons. Closely followed by beer.
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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 11:33 pm

You guys are making me want to make Australia my next post deployment vacation....
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Charlie J
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PostSubject: Re: High speed, low throttle stumble/power dip   Mon Dec 05, 2016 11:48 pm

Its a mighty good place for GRiSO's.
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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Thu Feb 09, 2017 11:44 pm

PROBLEM SOLVED!

As inexplicable as it may sound, the right side cam was one tooth out. No known reason why. The Tech's at MI said that they checked both sides and that it was clear that the right side had been taken apart and reassembled. I got the bike at 1500 miles, and it had been serviced at a dealer in CA at 600 miles with NO warranty claims, so it is a mystery WHY someone would have done this. They also said that there was some silicone on the right side as well indicating some work. The rest of the bike checks out good, all is in spec and running well Cant wait to get it back, and see if I like the 8V motor more than the 4V 1100 in the GRiSO.

THANKS for all the help and advice.
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beetle
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Feb 10, 2017 12:18 am

cheers




.
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MotoMT
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Feb 10, 2017 2:55 pm

Thanks for the update, Bulldog. Much appreciated!

Sorry for newb question, but is this an "engine out" fix? (Assuming this is my issue as well).

Also, how feasible is it that this is an issue from the factory?

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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Feb 10, 2017 3:53 pm

I haven't seen one timed wrong from the factory but anything's possible.

Checking the cam timing is definitely NOT an engine out job Very Happy All that is required is the flinger plates on the ends of the camshafts be removed after the cylinder in question has been set up to TDC compresh. If the timing is out you have to unload the camchain tensioners before removing the sprocket and moving the chain which will require the tank to come off on the RH side but it's still only an hour's work max if you know what you're doing!

Pete
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MotoMT
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PostSubject: Re: High speed, low throttle stumble/power dip   Fri Feb 10, 2017 4:02 pm

Thank you, Pete. Good info.

I'll update whenever I figure out my issue. Hoping it's the same as Bulldog9's and ends up being relatively easy.

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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Feb 12, 2017 9:36 am

No idea how long this situation existed, but I'd rode it for about 4K miles this way. Should I be concerned about any long term issues?
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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Sun Feb 12, 2017 10:50 am

Doubt it. If it didn't bend a valve and it's running fine now you should be golden.

Pete
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Bulldog9
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PostSubject: Re: High speed, low throttle stumble/power dip   Sat Feb 18, 2017 2:15 pm

*UPDATE - Picked up the bike today and glory be, it runs great!  Could tell the difference immediately in how it started and idled, sounded healthy. Prior to this it sounded 'off' and generally weak.  Now Revs straight to redline with a little coughing in the upper revs, but understandable, its never 'been up there before'.

Of course it was pouring rain and MI is a 1.5 hour ride anyway, so not much ability to play. My general impression of the motor though is it just doesn't seem as lively in the low to mid range as the 4V in the GRiSO.

One thing I did notice was that the throttle is now snatchy, and it is obvious the stock map is too lean. After I warm up, am going to go put the Beetle map back in it and hope I get to have a bit of fun before it gets packed away.

MI did a great job, highly recommend them. Dave of course is one of those rare gems of a human being, and all his employees are much the same. Honesty, respect, comraderie are the hallmarks of MI.


Last edited by Bulldog9 on Thu Feb 23, 2017 7:50 pm; edited 1 time in total
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PostSubject: Re: High speed, low throttle stumble/power dip   Wed Feb 22, 2017 12:27 am

100 miles on the healthy 8v Norge with Beetle Map...... WOW what a difference...I'm liking the 8v much more now. The cam alignment made things much better and the new map much more betterer. Thanks again all!


Last edited by Bulldog9 on Wed Feb 22, 2017 7:15 pm; edited 1 time in total
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beetle
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PostSubject: Re: High speed, low throttle stumble/power dip   Wed Feb 22, 2017 12:58 am

cheers
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MotoMT
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PostSubject: Re: High speed, low throttle stumble/power dip   Wed Mar 29, 2017 11:03 pm

Pete Roper wrote:
I haven't seen one timed wrong from the factory but anything's possible.

Checking the cam timing is definitely NOT an engine out job Very Happy All that is required is the flinger plates on the ends of the camshafts be removed after the cylinder in question has been set up to TDC compresh. If the timing is out you have to unload the camchain tensioners before removing the sprocket and moving the chain which will require the tank to come off on the RH side but it's still only an hour's work max if you know what you're doing!

Pete

Going off of Bulldog's successful repair at Moto International (9 hours away from me, but still the closest Guzzi shop  Sad ) I decided to check in the hopes my issue is the same.

Image is of the right side at TDC on compression stroke. This appears off, but it's late and I don't trust myself to go further at this point without checking with some smarter folks.

I'm not finding much online specific to this, and my Google-Fu is failing me. From what I've read, the pin and R need to be aligned to six o'clock, in-line with the bolt hole. Am I understanding that correctly?



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Pete Roper
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PostSubject: Re: High speed, low throttle stumble/power dip   Wed Mar 29, 2017 11:33 pm

Yes you are.

That looks like it's two teeth out! Fuck me running! Are you saying this engine is ex factory?

If it is two teeth then I'm even more amazed it hasn't bent a valve!

Pete

(Edit) Nah, on closer inspection it's only one. Simple fix. Take the cap off the tensioner on the RH barrel, drop the sprocket off and manipulate the chain round a tooth until it's at the 6 O'clock position. Then turn the crank until the sprocket slips back on, hold it there and wind it back to TDC to check that it's still in the right position.

Then put the bolt and flinger ring back on with a bit of Loctite 243 and make sure that when you tighten it one of the useless holes in the flinger doesn't align with the locator peg.

Then put the tensioner plug back on and turn it by hand to make sure nothing biffs. Put it all back together and see if it pulls clean to 'Blurp-Blurp-Blurp'!
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MotoMT
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PostSubject: Re: High speed, low throttle stumble/power dip   Thu Mar 30, 2017 8:14 am

Excellent. As always, the help here is invaluable! I'll post an update and hope it's a good one...
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PostSubject: Re: High speed, low throttle stumble/power dip   Thu Mar 30, 2017 1:22 pm

Good find , and good luck with the fix Thumbs Up
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