Vintage Dirt Bike Q & A

Anything and everything about Vintage Dirt Bikes! After you Register, email nathan@alp-sys.com and let me know so I can activate you.
It is currently Sun Jul 06, 2025 5:28 am

All times are UTC - 7 hours [ DST ]




Post new topic Reply to topic  [ 6 posts ] 
Author Message
PostPosted: Mon Oct 23, 2006 7:08 pm 
Offline
User avatar

Joined: Thu Jun 15, 2006 8:46 pm
Posts: 12
I rode the '79 CR125R for the first time ever today. I may post the story of the bike in a future topic, but right I am pretty pumped!

Anyhow, here is my issue. About a month ago, I had it running and was breaking in the newly installed LA Sleeve (from Wiseco) when I noticed a steady drip of black (coffee black) oil coming from the exhaust flange. After the bike cooled down, I tightened the flange nuts and stripped on of them out. After cussing a little bit, I overbored the hole and inserted a helicoil. Then was able to tighten down on the flange. I never really thought that tightening down on the flange would help, but I guess I was hoping.

Today, I noticed a return of the oil just much much less of it. Can anyone help me diagnose this? Is it that I am just running too rich - despite running at 40:1 per Clymer?

Thanks in advance to anyone who can help.

_________________
rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!


Top
 Profile  
 
 Post subject:
PostPosted: Mon Oct 23, 2006 7:48 pm 
Offline

Joined: Sun Nov 21, 2004 12:47 pm
Posts: 14
Exhaust flange leaks are really common, and your leak sounds excessive. I would suggest replacing the old gasket with a new one and using heat-resistant permatex on the gasket when you torque the flange back on. On my '74 CR125M, the brass gasket on the flange leaked excessive. I cut out a paper gasket from automotive gasket material and after I put it back together and raced it two motos, it did not leak at all. I don't recall if the 79 CR had a brass gasket. Despite sealing them well, use on the engine seems to result in eventual leakage at the exhaust flange and you have replace the gasket and/or use a sealant on a periodic basis.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Oct 23, 2006 8:45 pm 
Offline
User avatar

Joined: Thu Jun 15, 2006 8:46 pm
Posts: 12
Yes, the CR has a metal gasket at the exhaust flange.
I will cut out a paper one and use the high temp RTV you suggest. Do I need to make sure that it is compatible with fuel? Some of the RTV formuals say not use use when in contact with fuel.

I know, that's probably a dumb question but thought I'd ask.

_________________
rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 24, 2006 12:08 pm 
Offline

Joined: Tue Mar 15, 2005 10:35 am
Posts: 254
Just my op but you are probably running to rich. Not that I would do anything about the situation unless I was fouling plugs every 10 minutes or so.

The excess oil could be from something else like the transmission but I would look into carburetor for obvious flaws like floats/fuel level. If it is just the jets are a size to big and the bike makes good hp, play safe and to live with the drip rather then risk running lean.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 24, 2006 3:10 pm 
Offline
User avatar

Joined: Thu Jun 15, 2006 8:46 pm
Posts: 12
Hey guys, thanks for your help. This is a great source of information for me already, I wish I would have found it earlier in the job!

-tim


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 25, 2006 4:10 pm 
Offline

Joined: Fri Jun 02, 2006 9:06 pm
Posts: 109
Location: St. Louis, Mo
Like Ricortes said tranny fluid leaking in from cranks seals...I took the idea off the Suzuki forum and made a leak down tester(worked great) and not only found that the crank seals needed to be replaced on one engine but also found a base gasket leak on the other engine that was messing with my air mixture on my carb. Found out the 80 cr250's are notorious for base gasket failure and again guys on hear help me out....recommended dry fit as did the Honda shop that I talked to and that seems to be working. I plan on doing the whole smear.....new rod and bearings, seals, engine bearings,new cylinder and head nuts, gaskets and new paint, the other engine is good for now.
Food for thought. Good luck and good rebuilding!!

_________________
Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 7 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 44 guests


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 post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group