1990 Johnson 200 full throttle issues

[mjfrederick]

I have a 1990 Johnson 200 VJ200TXESM that is giving me issues when running above 3200-3500 RPM. It'll go up to 4500 RPM roughly at WOT, and run good for 30-40 seconds, then it will lag down to about 2500 RPM, then begin surging between 2500 RPM and WOT. If I run it around 3500-4000 it'll run longer, but eventually the relit is the same. A few points: the oil intake is not being used, I'm pre-mixing 50:1, I have replaced the spark plugs, plug wires, redid the fuel line/filter setup, verified the carbs are not dirty(they look brand new), decarbed the heads, and the thermostats are not installed. I get no alarm at all when this happens, and the temp gauge on the dash isn't showing anything significant. I know the high temp alarm works as it went off recently when I got bogged down in some mud. Telltale is showing good flow.

 

[fishman204]

Re: 1990 Johnson 200 full throttle issues

put t-stats in and 4500 wot is tooo low.May need a lync-sync the throttle and timing

 

[mjfrederick]

Re: 1990 Johnson 200 full throttle issues

Thanks for the advice. Had a feeling the first response would be to put the t stats back in. That being said I never thought of a potential timing issue, so I went and looked at those linkages and it appears that I'm missing some pieces to the timing adjustment. I'm not at home now, but I'll post a picture when I get home.

 

[mjfrederick]

Re: 1990 Johnson 200 full throttle issues

OK. I've finally had a chance to check my shop manual, and I'm certain I'm missing some parts for the Max Spark Advance adjustment (See attached pic). I've tried checking most of the parts sources I can find on the web, and the parts don't appear to be available. Have they been replaced by something else, or am I just screwed?

Edit: Having issues attaching photos from my work computer.

 

[mjfrederick]

Re: 1990 Johnson 200 full throttle issues

Oh, and we found the reason WOT was only getting to 4500... there was a wire blocking the throttle from advancing to full.