300/440/550 1987 300sx question

[skihed17]

New to the forum: My nephew just picked up a 1987 300sx that was torn down and a parts machine to go with. Up unitl now, reassembly has gone smooth.
The machine starts, idles for a short time, stalls and will not restart. I have checked the basics: Machine has good compression, spark, reeds look good. Kill switch tests positive for continuity. New fuel and fuel lines were installed. Carb rebuilt with new kit. Also installed a blockoff plate and am running premix 50:1. I bypassed the fuel selector switch, running the carb directly off the reserve feed from the tank.
The one thing I'm not sure of is which line on the carb is the feed and which is the return. (Any info would be great.) Funny thing is, it responds the same way regardless .
Being that this machine is so old, it seems that the local dealers are giving me conflicting numbers or have no info at all. Searching on this forum, I have found these numbers to be a good starting point ( Low 1 1/4 High 1 9/16). If rebuilding the carb (again) yeilds the same results, I'm thinking the problem may be electric. If anyone can shoot me some numbers and testing procedures, that would be helpful.

Thanks in advance.

BTW, once this machine gets up and running, the spare machine will be parted. If anyone is looking for anything, let me know and I'll see what I have left........if and when it runs. lol

 

[WFO Speedracer]

Check the height on the lever that opens the fuel needle if it is too low it will cause these symptoms as the needle does not open far enough to allow an adequate flow of fuel and it actually runs out of gas.You are usually better off reusing the old lever but people have a tendency to use the new part even if it is not adjusted properly.

 

[skihed17]

Thanks for the response.

Made adjustments, got everything up and running. Now the one-way bearing is engaging one in every four times so now the engine's back out and I'm working on that.

Can anyone tell me what kind of oil you use in the starter case?

If anyone has the torque specs on the mag bolt, that would be great.

Just got back to the project, been busy. I'll keep you guys posted.
Thanks for any and all responses.

 

[Pro-pulsion]

The one way bearing? Do you mean the starter bendix? If so, just let it sit in some ATF for a few minutes and throw it back in. I can't remember with my old 300 but if it's anything like the 650's, that plug in the front cover is just an inspection hole for the timing marks. There isn't supposed to be any oil in there. But, just for good measure to prevent that starter bendix from further dry seizing, add an ounce or two of AFT in that hole and all should be well.

 

[WFO Speedracer]

Nope PRO the 300SX has a unique starter clutch similar to those used on street bikes,if I recall correctly pretty much any weight automotive engine oil will be fine in there,usually you can pull the clutch apart and replace just the springs,spring caps and the rollers and it will work fine,if the face of the gear where the clutch rides on is not all beat up,if it is you have to replace that also,you should be able to tell by doing a visual inspection.

 

[Pro-pulsion]

Awesome bit of info WFO, I was wondering what he meant. I remember rebuilding my old 300 but it was a JS300 and I didn't recall seeing anything like that. But then again, I didn't have to dive into the front cover either :nana: This is why I love this site, great people with great knowledge.

 

[WFO Speedracer]

Actually the starter clutch is under the rear cover and it has a dipstick to check the oil level with.