Rough Idle and poor transition to power???

[ChevyReb]

Nissan 1988 70 HP idles fine out of water but seems like its missing a cylinder when in the water idling...shakes a lot. Also it wants to shut off when you go from neutral into gear and try to accelerate slowly. If you gun it it will go and once its going it seems to run great.

At first I thought the low speed jet was clogged in one of the carbs, but since it runs good on the dog ears and hose pipe out of the water now I'm not sure what to do.

All help appreciated!

Thanks.

 

[ChevyReb]

Re: Rough Idle and poor transition to power???

Did a compression check. Lower cylinder is at 121 and upper is at 135.

 

[pvanv]

Re: Rough Idle and poor transition to power???

I'd suggest going through the carbs.

 

[ChevyReb]

Re: Rough Idle and poor transition to power???

I'd suggest going through the carbs.

Just did those a couple of months ago...I guess maybe some trash is in the low speed jet??? Will check that again and repost results.

Thanks for the assistance!!!

 

[henrye718]

Re: Rough Idle and poor transition to power???

Get one of those light up in-line spark testers. You can actually see if there are missing sparks or it starts to fire very weak @ a certain RPM then brighten up again once past the dead area. Its like a $6 tool.

see it in action here on u-tube.

http://www.youtube.com/watch?v=0td1w20Shao&feature=related

 

[rogerwa]

Re: Rough Idle and poor transition to power???

I have an '89 90hp and I have had a bot of trouble getting it right. Follow the adjustment instructions in the manual to the letter and you should be fine. My motor has a higher than normal, at least in my book, idle speed at around 1000-1100 RPM.

For me the trick was getting the idle butterflies (or whatever they are called) adjusted and syched correctly. Then I set the mixture screws and the final idle speed. My mixture screws like to be in the 1 3/4 turn - 2 turns out. The spec is less than that but spec doesn't work well for me in the idle mixture settings.

The net is to go back and make sure all settings are correct.