Nissan NS8B only running on 1 cylinder

[MILLSMAN]

I have a NS8B that only runs on the top cylinder. Bought it to fix it up and resell, but now probably just for parts because of many "issues". Bought and sold 20 of these small HP motors in the last 10 years but this one has me puzzled. The motor starts up in 2 or 3 pulls but runs rough and the smell of gas is obvious. Pulled the lower plug wire and no change in running. Pull the upper plug wire and it dies. Checked the spark - good on both cylinders. Checked the compression and 65 on both cylinders. Switched spark plugs (new) and still only runs on upper cylinder only. I am stumped!

 

[pvanv]

Fix the carb.

 

[Sea Rider]

Ain't 65 PSI of compression way low, should be difficult to start or even die soon after the OB was started.. Lower cylinder must be real shot as not to ingite lower plug if a strong spark is being produced.

Happy Boating

 

[hicr_nut]

Check the reed valves.

 

[Sea Rider]

Reed valves seldom go bad, unless carb has sucked metal parts at speed and screwed reed valves.

Happy Boating

 

[Lund_bC]

my ns8b has a week lower cylinder and almost stalls. i have no clue why but it runs good at speed and has for 6 years

 

[pvanv]

You have a different issue on a different motor; Better to start your own thread. However, what is a "weak cylinder"?

 

[Lund_bC]

i mean if i take one spark plug wire off while running it almost stalls or does, the other it just keeps running perfectly.

 

[jbcurt00]

i mean if i take one spark plug wire off while running it almost stalls or does, the other it just keeps running perfectly.

As suggested, start a topic about your NS8, asking about yours here is considered a hijack .