1980 SR 250 - Won't Fire - Fuel supply issue?

[sbruton]

Hi all,

I am seeking suggestions on trouble shooting a problem I've got getting a 1980 SR 250 to fire up. I acquired this bike a couple of weeks ago with the hope of getting it running and then flip it to help fund my current project. My intention is to clean it up, fix the obvious problems, replace some parts with spares I have in my garage and then sell it to someone looking for a winter project. Seems simple enough right? Wrong. I've run into a jam with getting it started that I hope someone can help narrow my search:

In short, the problem is this... The bike rolls over well, has good spark yet will not fire and run. If I squirt a few mL of gas into the cylinder it will fire up idle and run well. In fact I had it running well enough on the weekend that I took it for a spin around the neighbourhood. However, after turning it off and letting it sit for a couple of days it will not fire up again without squirting fuel into the cylinder.

To date I have completed the following:

1.) removed the carb, removed all the jets and gave all the passages a thorough cleaning with carb cleaner
2.) confirmed spark at the plug with 2 different spark plugs
3.) confirmed that fuel is getting into the carb from the tank and that the petcock is not plugged
4.) replaced the intake manifold and gasket on the cylinder
5.) adjusted A/F mixture but not too sure what the stock setting is?? currently at 1.5 turns out.

I plan to pull the carb off and take it apart again tonight, but if there are any suggestions of particular items to check it would be really appreciated. Based on above I'm assuming I still have a blocked passage or a vacuum issue but I'm only guessing....

Any ideas or help would be greatly appreciated!

Thanks in advance!

 

[adventurco]

check the float height when you get back into the carb, if you haven't already.


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[sbruton]

I have not checked it and will definitely add that to the list... at least to remove another variable!

Funny thing here... as I walked through my garage this evening after work I hit the starter and it fired up but quit after a few seconds and then wouldn't fire again.

 

[DesmoBro]

Could be intermittent spark ? Is the plug wire in good shape? I usually cut 1/4" off each end and thread into new copper.....also are you using the choke?

 

[sbruton]

Could be intermittent spark ? Is the plug wire in good shape? I usually cut 1/4" off each end and thread into new copper

It seemed like I was getting good spark when I held the plug on the engine and it wasn't hesitating once I got it running. Regardless, that's a good call on trimming the plug wire just to ensure I'm getting a full strength spark in there....

.....also are you using the choke?

Yessir. I tried with the choke on, half on and off... no luck either way.

I didn't get a chance to work on it last night, but hope to look at it again tonight.

Thanks!

 

[sbruton]

The saga continues...

I put my good carb on and it fired up and ran well. I pulled both carbs apart and did a side-by-side comparison and didn't really notice anything terribly out of sorts. The needle valve is missing the wire that holds float tang to the needle valve and the spring loaded pin in the valve pin was locked up solid. I've since freed it up and sprayed more cleaner through all the passages and jets; reassembled and still no worky. All jets appear clear, the passages are allowing cleaner through.

Next steps I will take the parts from the good carb and try it again...