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Chrome bore replacement. V7 850 GT

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ReggieV View Drop Down
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    Posted: 16 Aug 2016 at 18:57
A friend of mine is considering buying an V7 850 GT which it is believed to have chromed bores.
Am I correct in assuming that if required, these can be changed to "standard 850" 83mm nikasil coated bores as used by the T3, T4 and 850T?
 
If not, what's the solution?
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2016 at 19:05
They can be replaced with nikasil plated cylinders. I recently did so on my 850 GT. Gilardoni piston and cylinder kits are in stock at Stein Dinse at the moment,for how long who knows.
I'd suggest to your friend if he goes ahead with the purchase and removes the barrels that he also removes and inspects the cam followers.I did and found that they needed to be replaced.Good luck to him.

Edited by Dave P. - 16 Aug 2016 at 19:33

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1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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ranton_rambler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ranton_rambler Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2016 at 20:40
Or 88mm barrels and pistons, although I think there's a little more work involved to do that.
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ReggieV View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ReggieV Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2016 at 20:48
OK thanks for that, I just wanted to make sure this was the case so that he can consider this when / if he purchases.
 
I doubt that he'll want to go to 88mm but that's up to him.
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NeilD View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NeilD Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 05:36

isnt there a slight issue with pushrod clearence whenusing the later barrels ? Nigel at NBS did mine, I think he swapped valve gear from a later engine onto my 850GT as an alternative to reshaping the area..

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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 07:39
There are no issues with the Gilardoni kits,they go straight on.That has been my experience anyway with both the 750 and the 850.The big bore kits raise some issues I believe.

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1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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italianmotor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote italianmotor Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 09:03
I think if he'd used later valve/rocker gear with earlier barrels he would have had to file the pushrod tunnels to make it fit as the later valve gear sits at a different angle to the earlier valve gear.

I had to do this on my S3 when I replaced the barrels as the only ones available were V7 Sport type. The S3 uses later T3 type valve gear, so I filed the pushrod tunnels on the new Gilardonis to accomodate the different angle of the pushrods. Worked out fine.

 
Originally posted by NeilD NeilD wrote:

isnt there a slight issue with pushrod clearence whenusing the later barrels ? Nigel at NBS did mine, I think he swapped valve gear from a later engine onto my 850GT as an alternative to reshaping the area..

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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 09:32
Just to clarify.If your friend buys a standard 850GT and the Gilardoni kit specified for that model,it all goes straight on.Complications arise when fitting parts intended for a different model which are almost right but not quite.As per Adams experience above.

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1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ReggieV Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 09:55
Again thanks for the help.
We went to look at the bike yesterday and he's not going ahead with the purchase. I just wanted to be sure that we knew where we stood regarding this issue if he had purchased and didn't want to run the (believed still fitted) chrome barrels.
 
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 10:00
I see.May one ask where this bike is/was advertised? I 'd like butcher's myself.

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1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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italianmotor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote italianmotor Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 10:22
Yes, absolutely right. Gilardoni kits are great things.

Originally posted by Dave P. Dave P. wrote:

Just to clarify.If your friend buys a standard 850GT and the Gilardoni kit specified for that model,it all goes straight on.Complications arise when fitting parts intended for a different model which are almost right but not quite.As per Adams experience above.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dukedesmo Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 11:38
You could always get Langcourt to remove the chrome and then Nikasil plate the original cylinders?  http://www.langcourt.com/page16.html
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 12:10
Originally posted by Dukedesmo Dukedesmo wrote:


You could always get Langcourt to remove the chrome and then Nikasil plate the original cylinders?  http://www.langcourt.com/page16.html


True.I've considered that option.You would need different piston rings though to run against Nikasil.The Gilardoni option just seems easier though it is probably more expensive.Have you any experience of using re-plated cylinders? It is an interesting alternative.

TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Amboman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Amboman Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 14:40
Rings for chrome bores will work with Nikasil as well. I've had several sets of cylinders replated by Millennium Technologies when Gilardonis were out of stock. Pistons must be carefully measured to make sure they're still usable - the ring grooves in particular are critical. Millennium replated cylinders have worked just as well as new Gilardonis. 
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2016 at 16:42
Ah! I got that wrong then
I'm sure I read somewhere that the rings weren't compatible.It may all have been a dream.

TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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