Tweet
Ive got this 90hp carb yamy 4 stroke and when i try to start the motor she backfires like crazy . When I first got the motor the plug leads and some were missing and the ign switch was faulty , hence new leads and ign switch . I dont have a manual but I set up the plug leads the same as a fuel inj engine , the motor only has 2 coils . Top coil lead 1 goes to # 1 , top coil lead 2 goes to # 4 , bottom coil lead 1 goes to # 2 , and the other to # 3 , does this sound right ? Any ideas of what to look for ?
-
-
Yes, its right! -
Did you rebuild the carbs or synch them?
Looks like you need to clean carburetors and re synchronize it.Comment
-
Would the carbs cause such a backfire ? There was a bit of old fuel in the carbs but nothing to serious . I will pull them off and go through them . ThanksComment
-
On my F80 didComment
-
Use fresh fuel and make sure the jets are cleaned.
If fuel is that old remove and clean the fuel filter and pump.
After rebuild the carbs you must sync the carbs.
Have a look:
Yamaha F60 - YouTube
Outboard Yamaha 50 HP carbs synchronization - YouTube
Equalizador de carburadores - YouTube
I hope this may help (worked with me)
Good luckComment
-
90 backfire
Thanks for the info , I cleaned the carbs and that part seems to work great . Found # 4 compression down to 80 and the others were up by 140 , sprayed storage seal in the cylinder and the compression did not come up . Will have to dig deeper into thisComment
-
Do a leakdown test to see what is not sealingComment
Comment