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Tank slapping issue resolved

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Mr Grumpy View Drop Down
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    Posted: 30 Mar 2019 at 14:41
It will come a no surprise to some on here that I eventually solved the handling problem, wobbly handlebars, on my B750.

I bought the bike last year and found that it weaved in long corners slightly and 'tank slapped' when you took a hand, or both, off the bars. It had a pair of Avons on it which had plenty of life left in them - seemingly. Over the winter I checked the steering head bearings for play - none. Checked the wheel bearings and forks - all OK. Took all the pre-load off the rear shocks and played around with tyre pressures. Took the screen off even. All this this made no difference.

Then I stumbled across an article about tyre age and then another on long storage and its effect on tyres. The bike, I noticed in the folder of paperwork that came with it, looked as though it had been stored for about 3 or four years: so was it stored on those tyres? I checked the tyres again - front was manufactured in 2012 and the back in 2013. The recommendation seemed to be that tyres should be no more than 6 years old and also that fitted with the period of storage. If the bike had been stored and the tyres pressures not checked regularly, it can deform the tyre apparently.

To cut a long story short, I bought a new Pirelli Sport Demon for the front and had it fitted this morning - wobble gone!


Every time I have had a similar handling issue in the past it had always proved to be something to do with the tyres - I should have known.
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iansoady View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iansoady Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2019 at 10:44
Yes, on my first brief ride of the Spring last week on the V50 it was a bit squirmy. When I checked the tyre pressures when I got back I'm ashamed to say that they were in the low 20s......

Having said that, 6 years doesn't sound that old for tyres especially if they were stored in the dark - I believe UV is the big killer for tyre rubber.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnno Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2019 at 14:58
I remember a friend asking  me to ride his XS1100 yam as it was handling badly , so I took it for a ride I did not leave the drive way when I knew what was wrong . The front tyre was something like 12 psi found out he had never checked the tyre pressures since buying it new a year ago . 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote motomike1400 Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2019 at 17:00
My 2010 V7C has always had that hands off shimmy. Was on the awful Metz Lasertecs. Have been using Conti Go until yesterday. Had to fit a BT45 on back cos that's what was in stock. Still a Conti on front, nearly new. And the shimmy has gone! Might miss it.
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Mr Grumpy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr Grumpy Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2019 at 20:31
The mechanic who fitted the tyre recommended the conti's. Interestingly, they revs Royal Enfield dealer and the new interceptors are fitted with a Pirelli tyre remarkably similar to the old phantom. 
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Mr Grumpy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr Grumpy Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 2019 at 20:34
Originally posted by iansoady <div><br></div><div>Having said that, 6 years doesn't sound that old for tyres especially if they were stored in the dark - I believe UV is the big killer for tyre rubber.<br></div>[/QUOTE iansoady 

Having said that, 6 years doesn't sound that old for tyres especially if they were stored in the dark - I believe UV is the big killer for tyre rubber.
[/QUOTE wrote:



I don't know where the bike was stored - maybe under a cover.  The hardening of the compound can be a problem but lack of movement and correct air pressure can create a flat s

I don't know where the bike was stored - maybe under a cover.  The hardening of the compound can be a problem but lack of movement and correct air pressure can create a flat spot on the tyre. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nab301 Quote  Post ReplyReply Direct Link To This Post Posted: 03 Apr 2019 at 20:47
Originally posted by Mr Grumpy Mr Grumpy wrote:


I bought the bike last year and found that it weaved in long corners slightly and 'tank slapped' when you took a hand, or both, off the bars. It had a pair of Avons on it which had plenty of life left in them - seemingly. 
To cut a long story short, I bought a new Pirelli Sport Demon for the front and had it fitted this morning - wobble gone!


Every time I have had a similar handling issue in the past it had always proved to be something to do with the tyres - I should have known.

I had a similar problem  (and removed  hard luggage and screen) I documented on here  , the only difference being  my bike already had sport demons  fitted  and when I checked the head bearings they were in a woeful state  although replacing the bearings didn't cure the problem . I did replace the tyre with another pirelli and it cured the problem at the time  but reappeared soon after .... At least  I'm not the only one with the problem!  From using avons on other bikes I would have thought they would be more stable  than the Pirellis.  As suggested by someone at the time I'll  be looking at the rear end of the bike  when I get time , swing arm bearings  possibly.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr Grumpy Quote  Post ReplyReply Direct Link To This Post Posted: 03 Apr 2019 at 21:27
The mechanic did say that a worn back tyre can cause a weave as well. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iansoady Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2019 at 10:28
It's often when they get squared off by not going round enough bends.....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nab301 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jul 2019 at 00:15
My B750 needed more tyres recentlly ( only 4k miles on the rear and down to 1.5mm) the front badly feathered on the edges, bars flapping badly and tramlining  on any roadmarkings  or tar banding . I decided against Sport demons, briefly considered Avon roadriders but ended up fitting  "Metzeler Roadtec  01" tyres . 
The first couple of miles I thought I'd made a mistake  , the bike steered like an oil tanker ( compararatively)   . Within a short while though I had recalibrated my brain and every thing seemed fine , no more flappy bars , plenty of  predictable dry grip while changing direction easily and  looking at the forecast I guess I'll get to check wet  grip  this week...  
Nigel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr Grumpy Quote  Post ReplyReply Direct Link To This Post Posted: 02 Aug 2019 at 13:45
I've furnished re-fitting the back wheel after replacing the back tyre. Sport demon £105 fitted btw. I  haven't had a chance to take it out yet. Have a few hours free this afternoon but already raining. Unhappy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cylvabirch Quote  Post ReplyReply Direct Link To This Post Posted: 02 Aug 2019 at 16:17
I was very unhappy with the Metzler Lasertecs originally fitted to my V7Classic. Being a bit tight, I patiently waited for them to wear out before replacing them with Bridgestone BT45s. Worth the wait! Much better tyre.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 02 Aug 2019 at 16:34
Originally posted by Cylvabirch Cylvabirch wrote:

I was very unhappy with the Metzler Lasertecs originally fitted to my V7Classic. Being a bit tight, I patiently waited for them to wear out before replacing them with Bridgestone BT45s. Worth the wait! Much better tyre.


I'm curious to know what made you unhappy with the Lasertecs.I've recently had one fitted to the rear of the 850GT and can't decide whether I like it or not.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nab301 Quote  Post ReplyReply Direct Link To This Post Posted: 02 Aug 2019 at 21:14
Originally posted by Cylvabirch Cylvabirch wrote:

I was very unhappy with the Metzler Lasertecs originally fitted to my V7Classic. Being a bit tight, I patiently waited for them to wear out before replacing them with Bridgestone BT45s. Worth the wait! Much better tyre.

I have used lasertecs in the past on other bikes but  Roadtecs  which i fitted are a completely different tyre.
Nigel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cylvabirch Quote  Post ReplyReply Direct Link To This Post Posted: 03 Aug 2019 at 08:27
I had BT45s on my old T3 Cali and loved them. As soon as I bought the V7 I could feel that the tyres were just not as good. Hard to describe I know.
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