Spark partial failure at mid to high.. Ive tried it all!!

[McQuade]

Sorry all I can't seem to add a video. But cut to the chase here. 1985 200M high low chain driven. New parts: coil,cdi harness completely rebuilt, plug(also gapped) voltage regulator, carb,fuel line with inline filter, new tank petcock, head gasket, timed both valve and ignition, blah blah there's more sure. It starts right up, idles fine. You can rev it a little, any more then half and it s right out but the rpm does not seem to climb much. Pulse generator is gapped BUT I'm sure this is the problem.. To me it sounds like isn't advancing properly. It moves freely but the problem is how can you tell if the springs don't have the proper rate? I can't find a new setup, and my other spare engine was doing the same thing. This is absolutely insane the hours I've put into this with the hardly helpful manual, but everything ohms out. I've eliminated fuel. Brand new carb. Please toss some ideas at me veterans!

[danbur55]

Is the airbox connected to carb?? If so try lifting the lid up and see if that helps

[McQuade]

Is the airbox connected to carb?? If so try lifting the lid up and see if that helps

The aribox is connected. Without the lid, it's louder, and it pops back through. No air filter but it did run previously like that (not ridden)

[barnett468]

Is the spark pale blue or yellow? . . what is the plug gap? . . what is the valve gap? . . check can timing again you can see if it advances . . check float level . . post photo of spark plug . . try two sizes bigger and two sizes smaller on main jet . . check for air leaks with flammable carb cleaner.

[barnett468]

Correction.check. am timing again . . check ignition timing and see if it is correct and advances . . make sure mechanical advance unit operates smoothly and returns properly.

[McQuade]

Lines upTDC on the "F" line. Moves freely but to me sounds like it advances too much and/or too fast. Is their a test for its spring tension or something?

[danbur55]

correct me if i am wrong but shouldnt it be on "T" mark not F

[barnett468]

Lines upTDC on the "F" line. Moves freely but to me sounds like it advances too much and/or too fast. Is their a test for its spring tension or something?

You can mark your flywheel at different degrees then connect a tach and check the amount of advance of different rpms like 1000 . 2000 . 3000 and 4000 etc but I doubt this is your problem but who knows who has been in there berfore you and what they might have done. . . there is no tension adjustment on that particular advance . . if it has any free play the springs are loose which may cause probs.
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[barnett468]

correct me if i am wrong but shouldnt it be on "T" mark not F

The can should line up at tdv . . the timing F timing mark should line up at idle when using the lite . . I'm not sure what he was saying either.

[McQuade]

My apologies. The pulse generator is lined up with the pickup with the flywheel at the "f" mark. (Not running) cam time is where it is supposed to be.

[barnett468]

The F needs to line up in the timing I election hole at idle of around 1200 - 1400 rpm . . get a timing lit and check it.

[McQuade]

So I'll need a tach and a timing light? And out of curiosity, I've never seen any system that had to be set up from the start using a timing light. This must be why there is two lines on the flywheel right? Correct me if I'm wrong but the way I've done it, where the pulse generator is lined up and the "F" line, is wrong? I would have thought the entire purpose of the two lines was to set it oem advance, which from the distance between the two lines seems like a few degrees advanced. I guess I'm used to my camaro and the 11 degrees advanced. This system just makes the process annoying.

[barnett468]

If the springs are loose on your advance unit it will be advanced too far at idle so the lite will not lite up when the f is lined up

[danbur55]

From my limited knowledge as I understand these small motors the T stands for time and F is fire so if you line up TDC on F then when centrifugal advance kicks in you will be to far advanced. Unless your Camaro has been degreed in for performance cam you still line timing marks as spec maybe this will help clear things up

[barnett468]

Unless your Camaro has been degreed in for performance cam you still line timing marks as spec maybe this will help clear things up

DIdn't you mean to say Mustang?