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V7II Cush Drive

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jefrs View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2018 at 19:05
Originally posted by Mike H Mike H wrote:

+1, I've had to do this. 

Try roundabouts on a maxi scooter with automatic clutch and CVT and too much throttle play ShockedShocked

Know all about throttle snatch then




Yes, been there. test rode a Burgman 400 to find out if automatic clutch was any good. Lost all drive on min roundabout and reapplying throttle produces too much. Quite embarrassing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2018 at 19:11
Originally posted by Brian UK Brian UK wrote:

I know this might sound odd, but how much slack do you have in the throttle cable? Many, including myself, have found that reducing this slack to the absolute minimum does reduce that snachiness you describe. You just need to be sure that turning the steering from lock to lock has no effect on the tickover speed.


Yeah, I've got minimum slack, maybe 2mm. It's not that.
It's not the throttle pick-up, that's surprisingly smooth; the power comes back on with silent clunk, I feel the engine come up and then nothing for half a mo and then there's this nudge

It's still on used bike warranty. The dealer is going to have a look at it.
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motopete View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote motopete Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2018 at 20:06
Jefs, don't worry about the backlash you describe at the wheel - it's perfectly normal, there's loads of backlash in the transmission as a whole but mainly in the gearbox.

Regarding snatchy pick-up from closed throttle, that's down to an over-lean mixture (emissions regs) and a fairly basic FI system that appears to have a delay between cracking the throttle open from idle and actually squirting a bit more fuel in...

What I find works quite well is to crack the throttle just off idle, wait a second, then apply the throttle you actually want - it seems to give the ECU time to "catch up" if you know what I mean.
Cable adjustment is critical - it's essential you have the bare minimum of slack in the "opening" cable so you can feel what's going on with the butterfly at the other end.


PS. The clatter that Chris mentioned is also due to backlash in the gearbox, as Brian says the clattering is triggered by uneven pulsations at the flywheel, exaggerated by the slightly lean mixture that means the engine doesn't idle as smoothly as it might.

Pete.
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2018 at 21:29
Originally posted by jefrs jefrs wrote:

Yeah, I've got minimum slack, maybe 2mm. It's not that.

Sorry to disagree but 2mm is not minimum. You need to get as close to zero as possible.

Ask around other guzzi forums and you will get the same answer from those who know. I didn't invent the idea.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2018 at 22:06
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nab301 Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2018 at 22:40
Originally posted by jefrs jefrs wrote:


Is the cush drive in the wheel hub?
How easy is it to replace the rubbers?


The cush drive rubbers part number seem to be common to  a lot of the small blocks . This is the set up on my Breva 750, same part number as the V7 II     Gu32632510.  
They fall out on removal and it took my pea sized brain a little while to figure out how to refit them  , so i guess maybe someone else could have refitted them incorrectly on your bike ? Assuming it uses the same set up. They can be refitted incorrectly with difficulty ( and a drop of superglue) as per the second photo Embarrassed








Edited by nab301 - 03 Oct 2018 at 21:24
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jefrs View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 05:29
Originally posted by Brian UK Brian UK wrote:

Originally posted by jefrs jefrs wrote:

Yeah, I've got minimum slack, maybe 2mm. It's not that.

Sorry to disagree but 2mm is not minimum. You need to get as close to zero as possible.

Ask around other guzzi forums and you will get the same answer from those who know. I didn't invent the idea.


It pulls tight when the steering is turned. Can't very well have the throttle lifting taking a tight corner. 2mm is a guestimate and it is the maximum.  Start engine, turn steering, if the throttle lifts loosen the cable. It lifts turning right which is to be expected, about half a turn of the adjuster free there. Return cable set first to shut the throttle (that needs a hair of slack too on turning) because the throttle return spring isn't that clever.  
Just been over it again today, the twist grip is very sensitive.
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jefrs View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 05:43
The bike is still under a used bike warranty so it's going to be checked out later this month. They were the last people to have the wheel out changing the tyre. 

The throttle is pretty smooth response, it doesn't have the usual FI flat spot. I can feel the engine pick up and then feel the little delay as it takes up slack at the rear, and then the thump as it engages drive.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote V7Chris Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 07:29
On my V7ii, I have experienced this part throttle low speed drivetrain lash (jerkiness) since new, so did the same model that I road tested before I ordered mine, and so to it seems do many others. It does seem to improve over time (although who knows, this could be just sub-conscious rider compensation or familiarity), and  general smoothness and response to the throttle input definitely improved when I disconnected the lambdas.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 11:28
Originally posted by V7Chris V7Chris wrote:

On my V7ii, I have experienced this part throttle low speed drivetrain lash (jerkiness) since new, so did the same model that I road tested before I ordered mine, and so to it seems do many others. It does seem to improve over time (although who knows, this could be just sub-conscious rider compensation or familiarity), and  general smoothness and response to the throttle input definitely improved when I disconnected the lambdas.


Having just fixed the same problem on the Enfield (I think they invented this cush drive, in 1912) I noticed the effect very quickly. It is really only a problem taking very tight turns slowly. It is possible to drive smoothly to reduce the effect. And the rubbers on the RE were also only 3yo.  On that bike the new rubbers are a tight fit and the problem has gone. 

I did not notice it on the 2018 V7iii demo bike nor this 2015 V7ii on test ride. I was perhaps more concerned with the heavy traffic then.

I had disconnected the Lambdas but put them back on after 'clearing the tables', which worked. I have an 'oily' problem with the breather box and the breather pipe is running into a K&N as a temporary until I can get the air box out to clean it when I get a tuit. That lets the engine breathe properly and run more smoothly too. It still needs a warm up but not for as long now; then pick up from idle is smooth without the FI flat spot.
This 'thump' is not engine management, it feels mechanical. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 16:38
Have you taken the back wheel off and looked?

There is always a possibility that the cush drive on your bike has been assembled incorrectly at some time, the only way to know is to look.
Normally those cush drive rubbers last as long as the bike.
Brian.

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jefrs View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 23:10
Originally posted by Brian UK Brian UK wrote:

Have you taken the back wheel off and looked?

There is always a possibility that the cush drive on your bike has been assembled incorrectly at some time, the only way to know is to look.
Normally those cush drive rubbers last as long as the bike.


Being under some warranty I gave the dealership a bell and they want to have a look. I'll let them have first dibs. The had the wheel out to change the tyre after I bought it but before I took delivery

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 03 Oct 2018 at 23:28
Maybe they left the rubbers out.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jefrs Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2018 at 12:05
Originally posted by Brian UK Brian UK wrote:

Maybe they left the rubbers out.


They didn't strike me as complete idiots but I'll give them the chance to fix it. They have to get their "Moto Guzzi specialist" to check it out (he's not in every day). I wonder if it wasn't he that changed the tyre.  

Any bike mechanic should know what to do with a cush drive, they have after all been around since 1912, they're pretty simple.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote motopete Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2018 at 12:56
IIRC Jefs, I found it moderately fiddly to keep all the rubbers in place whilst manipulating the wheel back into position.
Pete.
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