NSR250.net Forums Logo: Honda NSR 250 Forums, Classifieds and Service Manual in English. Covering All Honda NSR 250 MC16, MC18, MC21 and MC28 models
NSR250.net Forums

#
 
#
 
Performance Engineering

  • NSR250 Forums Index ‹ NSR250R Discussion
  • Members Content
  • Members Garage
  • Subscription
  • Transactions
  • FAQ
  • Search
  • Register
  • Log in

Piston Marking


Reply to topic   printer-friendly view
Page 1 of 2  Goto page 1, 2  Next Download Topic





prelude2.2
Site Moderator
Site Moderator
 
Posts: 469
Joined: 20 Feb 2016

Location: Ireland
1996 Honda NSR250 MC28SP
    Send private message View user's profile
    Reply with quote  

Piston Marking

Wed May 27, 2020 9:20 pm » Post: #1 » Download Post

So I put new pistons in my bike after doing a re-nikasil job on one of the cylinders, because the exhaust bridge cracked. There is no more than 50 miles on these new pistons and one of them is showing huge signs of wear. is this common or is there something wrong? This is the smallest bore piston and it is of course oem. there is also a bit of wear under the piston ring, not sure if it shows in the photo. any ideas lads?
_________________
John 3:7
Back to top


Andy
Site Admin
 
Posts: 11949
Joined: 19 Jan 2004

Location: Devon, UK
1991 Honda NSR250 MC21
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 9:34 pm » Post: #2 » Download Post

Was the piston supplied with the barrel when it went for plating? Is the barrel relieved around the exhaust bridge?

You shouldn't see wear like that, and certainly not with only 50 miles on them.

You may be able to dress that piston back, but impossible to say just by photos. I would seriously err on the side of caution. I would be inclined to send the barrel back to the platers with a new piston, and have the clearance checked/rectified professionally.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.


Check us out on Facebook! Please "like" our page!
Back to top


Zeus

 
Posts: 210
Joined: 26 Jan 2020

Location: Malvern , UK.
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 9:48 pm » Post: #3 » Download Post

That doesn’t look right to me either.
Back to top


prelude2.2
Site Moderator
Site Moderator
 
Posts: 469
Joined: 20 Feb 2016

Location: Ireland
1996 Honda NSR250 MC28SP
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 9:53 pm » Post: #4 » Download Post

Andy wrote:Was the piston supplied with the barrel when it went for plating? Is the barrel relieved around the exhaust bridge?


Im not sure, i cant remember it was last year when it was done and it was the second time it was sent there. Hmm i might buy a new piston so, can sleeves be inserted into these nsr barrels because the nikasil coating seems to give trouble.
_________________
John 3:7
Back to top


Andy
Site Admin
 
Posts: 11949
Joined: 19 Jan 2004

Location: Devon, UK
1991 Honda NSR250 MC21
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 10:19 pm » Post: #5 » Download Post

Who did the plating? Frankly, sleeves are a terrible idea!
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.


Check us out on Facebook! Please "like" our page!
Back to top


prelude2.2
Site Moderator
Site Moderator
 
Posts: 469
Joined: 20 Feb 2016

Location: Ireland
1996 Honda NSR250 MC28SP
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 10:24 pm » Post: #6 » Download Post

sleeves are bad they are. hmm it thought they would be better. oh well.

I'll dig out who done the plating tomorrow
Back to top


Andy
Site Admin
 
Posts: 11949
Joined: 19 Jan 2004

Location: Devon, UK
1991 Honda NSR250 MC21
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 10:42 pm » Post: #7 » Download Post

Well, first you would need to have the barrels bored (buggers up the port timing). Then you'd need to fit the sleeves. Then cut out the ports, and blend them to the NSR spec. Then you need to consider the RC Valve pockets in the exhaust outlet. Once all that's done, you need pistons with the correct dimensions and thermal dynamics.

Alloy barrels were developed because the thermal expansion of the piston and barrel can be much more easily predicted and controlled. The Nikasil plating is far superior [when done right!] to steel liners, wearing far less, and the alloy/alloy combination allows a much closer piston to bore clearance. It's lighter too.

Oh, you'd need to find someone competent enough to carry out all that work too. Laughing
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.


Check us out on Facebook! Please "like" our page!


Last edited by Andy on Wed May 27, 2020 10:44 pm; edited 1 time in total
Back to top


prelude2.2
Site Moderator
Site Moderator
 
Posts: 469
Joined: 20 Feb 2016

Location: Ireland
1996 Honda NSR250 MC28SP
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 10:44 pm » Post: #8 » Download Post

Andy wrote:Well, first you would need to have the barrels bored (buggers up the port timing). Then you'd need to fit the sleeves. Then cut out the ports, and blend them to the NSR spec. Then you need to consider the RC Valve pockets in the exhaust outlet. Once all that's done, you need pistons with the correct dimensions and thermal dynamics.

Alloy barrels were developed because the thermal expansion of the piston and barrel can be much more easily predicted and controlled. The Nikasil plating is far superior [when done right!] to steel liners, wearing far less, and the alloy/alloy combination allows a much closer piston to bore clearance. It's lighter too.


Makes perfect sense.

So do you think the only option is sending off the barrel again with a new piston? any suggestions on where to send it?
_________________
John 3:7
Back to top


Andy
Site Admin
 
Posts: 11949
Joined: 19 Jan 2004

Location: Devon, UK
1991 Honda NSR250 MC21
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 10:46 pm » Post: #9 » Download Post

All ours go to Poeton Aptec.

https://poetonaptec.co.uk/
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.


Check us out on Facebook! Please "like" our page!
Back to top


prelude2.2
Site Moderator
Site Moderator
 
Posts: 469
Joined: 20 Feb 2016

Location: Ireland
1996 Honda NSR250 MC28SP
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 10:49 pm » Post: #10 » Download Post

whats the rough price they charge? I also have to send it from ireland Insured
Back to top


Zeus

 
Posts: 210
Joined: 26 Jan 2020

Location: Malvern , UK.
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 11:01 pm » Post: #11 » Download Post

Andy wrote:All ours go to Poeton Aptec.

https://poetonaptec.co.uk/

That’s handy to know, they are right near me!
Back to top


Andy
Site Admin
 
Posts: 11949
Joined: 19 Jan 2004

Location: Devon, UK
1991 Honda NSR250 MC21
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 11:05 pm » Post: #12 » Download Post

You'll need to contact them for the latest price. We had a trade price with GTPE, and I've not worked with them for 2 1/2 years now, so any reference I have will be out of date.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.


Check us out on Facebook! Please "like" our page!
Back to top


prelude2.2
Site Moderator
Site Moderator
 
Posts: 469
Joined: 20 Feb 2016

Location: Ireland
1996 Honda NSR250 MC28SP
    Send private message View user's profile
    Reply with quote  

Wed May 27, 2020 11:08 pm » Post: #13 » Download Post

I'll drop them an email so. The biggest killer with living in Ireland is the postage. UK companies swear we live on the other side of the World.
Back to top


Max
Supporter - Titanium
Supporter - Titanium
 
Posts: 367
Joined: 19 Dec 2019

Location: Northamptonshire, UK
    Send private message View user's profile
    Reply with quote  

Thu May 28, 2020 5:11 am » Post: #14 » Download Post

Andy wrote:You'll need to contact them for the latest price. We had a trade price with GTPE, and I've not worked with them for 2 1/2 years now, so any reference I have will be out of date.


Here is a quote I got from Derek @ Aptec in February this year (2020), admittedly to a UK address:

"the exhaust bridges are always relieved to allow for expansion, the bridge would otherwise expand into the cylinder and wear a flat on the piston rings.
That said it does look like this is worn to some extent.
The cost of the re-plate and hone is £137.92, return carriage £11.50 prices are plus Vat and turnaround is generally 10 working days."
Back to top


Max
Supporter - Titanium
Supporter - Titanium
 
Posts: 367
Joined: 19 Dec 2019

Location: Northamptonshire, UK
    Send private message View user's profile
    Reply with quote  

Thu May 28, 2020 5:15 am » Post: #15 » Download Post

Personally I would be tempted to ask Aptec if they could hone out your current plate, relieve that exhaust bridge back a tad and match to an OEM piston.

The extra postage to Ireland is worth it for those miles of green country roads and rivers of proper Guinness though eh?!?

Note: might be worth talking to them about the skimming of the head surface as well, most platers tend to do this as a matter of course, but if yours has just been done and it is square it would be a shame to loose metal (port timing and squish) for nothing.
Back to top


Reply to topic   printer-friendly view
Page 1 of 2  Goto page 1, 2  Next Download Topic

NSR250R Discussion

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

  • NSR250 Forums Index
  • All times are GMT
Powered by phpBB © 2001, 2005 phpBB Group


Hosted by NSR250dotNET © 2008 NSR250dotNET