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

MC21 reed valve cage query


Reply to topic   printer-friendly view
Page 1 of 1   Download Topic





sami1

 
Posts: 88
Joined: 15 Dec 2014

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

MC21 reed valve cage query

Sat Nov 28, 2020 2:55 pm » Post: #1 » Download Post

Hi all,

Having completed a bottom and top end rebuild, I found my bike was smoking considerably more upon start up than it did before the rebuild. Much less smoke once warmed up.

I’ve adjusted the oil pump ( thanks Andy) so that at WOT, the line on the middle of the pulley meets the marker on the pump body. No marks on my carburettor slides for 50% throttle.

Upon removing my carburettor twice, I found about a small teaspoon of oil in the bottom of both reed cages.

Is this amount of oil normal?

My air filter is OEM and seems somewhat oily?

Any info appreciated.
Back to top


Andy
Site Admin
 
Posts: 11948
Joined: 19 Jan 2004

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

Sat Nov 28, 2020 8:45 pm » Post: #2 » Download Post

It's a tricky one to comment too much on, and I will never comment, or allow comment on anything other than standard setup for reasons I've gone over a number of times. It's something you really need to make your own informed decision on, or entrust to a 2-stroke specialist if you're uncomfortable with fiddling. However, in my personal opinion, there's a large [safe] margin for error in the standard setup to cover a wide range of [Japanese domestic] fuels and operating conditions.

Manufacturer's standard settings are always going to be rich. That means for a 2-stroke the standard oil pump is going to over-oil to some degree, and the jetting/needle is going to be rich... it would be financial suicide to release a 2-stroke with edgy/lean settings.

It's common for the filter to be quite wet and oily, as there's always a lot of "stand off" from the carbs. It's also common to see a little oily residue in around the reeds, but there shouldn't really be much more than just a misting.

Sorry to be so vague, but make of that what you will. Remember though, any deviation from the OEM settings is on your own head! 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!
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  

Sun Nov 29, 2020 2:24 pm » Post: #3 » Download Post

Also worth mentioning that during reuild you probably used 2T oil to assemble? This may take a little time to clear.
Have you had the engine up to full temp yet?
Back to top


sami1

 
Posts: 88
Joined: 15 Dec 2014

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

Sun Nov 29, 2020 3:37 pm » Post: #4 » Download Post

Hi Max,

Yes the engine has reached full temp several times and I carried out the various heat cycles as per the full engine rebuild section.

I have come down two sizes on the mains and still quite a bit of smoke upon start up. Using rock oil synthesis fully synthetic injector oil.

I guess I’ll just have to do some more mileage and see how things go.
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  

Mon Nov 30, 2020 7:43 am » Post: #5 » Download Post

In that case have you tried a plug chop under load to assess the fueling? It is a bit of a faff to do but it is the best way to see how the engine is burning.

Might be worth posting a video of the exhausts running as well? before and after warm.
Your idea of smokiness could differ from mine for example...in the end I would always point you back towards performing a plug chop though, it is the only safe way to know you are running the bike rich enough.

Good luck
Back to top


Reply to topic   printer-friendly view
Page 1 of 1   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