Jump to content

Sign in to follow this  
fxstbi

240 Pro sounds lean but it’s not

Recommended Posts

As I remember the 1982 models ran fine,but the later ones knocked just like yours does when hot.Sorry I can't remember why or what the cure was.Was the compression higher on the later ones perhaps?

Share this post


Link to post
Share on other sites
 

Huski, thanks for the reply, that's interesting to know.
Up to this point: I have re-jetted to the where the bike wants to blubber and not clean out and still the same. I've tried some 104 race gas, same thing. I did try using brake cleaner sprayed on the flywheel and intake tract as it ran and it's all good. I put in a NGK B6HS and that seemed to reduce the knock some, I think. I'm going to pull the pipe and make sure everything is ok there. I have a new NGK iridium plug that I'll try after the pipe is checked/cleaned. I'll clean the exhaust port while I'm there. 
If anyone else has a suggestion please chime in. 
My old TY 175 is looking pretty good right now! 🤨

Share this post


Link to post
Share on other sites
 
On 12/13/2019 at 12:14 PM, fxstbi said:

Thanks everyone for the replies. After extensive checking and testing I haven’t found anything wrong so I went back to the carb and increased main jet size to 118 and put in a new NGK B6HS plug. It actually runs better! It still has a little lean sounding knock or ping at almost full throttle. I’m going to go up to a 120 main and give it a try. 

I would have never guessed that I would increase jet size so much. Like Alberto indicated above, my bike came with a 105 installed. I was surprised when I was told 112 is the correct size. Thank you all for the help. 

What atmospheric pressure do you have at your location. If you have lots of sun and are quite high up altitude wise then that could have a bearing on your issue. Inspect that carb and ensure both pilot and passageways are clear. Two strokes do react to the air temperature and altitude. Higher you go the thinner ( less dense) the air.....hence detonation.  

Share this post


Link to post
Share on other sites
 

Good suggestion. I'm in Texas so about 400' MSL and the temperatures are in the 60(f)-70's here in  winter. My carb is a new OKO and I run a fuel filter. 
 

Share this post


Link to post
Share on other sites
 
 
 

My "lean but it's not" issue is about 90% gone. I'm not sure what I did to help it but I did do the following:

Pulled the pipe and cleaned the carbon out of the header. I scraped and used steelwool in the exhaust port so it's very clean. 
I went back to a 115 main jet and left the 52 pilot. Needle clip is in middle position. 
I put in an NGK Iridum plug.

I put a new cylinder and air box intake boot in too.

Its much better than it was, unfortunately I don't know what "fix" fixed it. 
 

Thanks all for the replies!

  • Like 1

Share this post


Link to post
Share on other sites
 
 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...