Johnson QD-15 Question

[Kawaiikeno]

Does anyone know if a QD-15 is a bushing or a bearing motor ?
Thanks Mike

 

[racerone]

The QD models all had needle bearings on the rod journals.----Needle bearings on upper and lower journal.----Bushing on the wristpin.----That wrist pin bushing was the issue.-----Unless someone installed pistons and rods from a 61 / 62 or 63 model.----Those used the same wristpin bearing used up to the 125 HP V-4.----Takes a small atomic bomb to damage that bearing.

 

[F_R]

Racer beat me to it. He's correct--as always

 

[Kawaiikeno]

Perfect! thanks a lot. I have yet to restore a 10 or a 15hp 1950's motor and it's time to change that

 

[kbait]

The QD models all had needle bearings on the rod journals.----Needle bearings on upper and lower journal.----Bushing on the wristpin.----That wrist pin bushing was the issue.-----Unless someone installed pistons and rods from a 61 / 62 or 63 model.----Those used the same wristpin bearing used up to the 125 HP V-4.----Takes a small atomic bomb to damage that bearing.

Thanks Racer! So, ‘61+ is fine @ 50/1. what about 3, 5,5, and 18hp’s?

 

[Crosbyman]

Duckworks Magazine

 

[racerone]

The 3 always had bronze bushings in that era,-----The 5.5 / 6 HP had plain bearings on crank mains up to 1979.----The 5.5 HP got needles on big end rod journal beginning in 61 year.----The 18 HP always had needles on the upper and lower crank journals , and big end and wrist pins.----Bearings and 2 stroke lubrication is still a big mystery to some !-----The well designed / sized bronze crankshaft mains on the 5.5 / 6 HP will last forever on 50:1 on my opinion.

 

[kbait]

The 3 always had bronze bushings in that era,-----The 5.5 / 6 HP had plain bearings on crank mains up to 1979.----The 5.5 HP got needles on big end rod journal beginning in 61 year.----The 18 HP always had needles on the upper and lower crank journals , and big end and wrist pins.----Bearings and 2 stroke lubrication is still a big mystery to some !-----The well designed / sized bronze crankshaft mains on the 5.5 / 6 HP will last forever on 50:1 on my opinion.

Thanks!

 

[Kawaiikeno]

I have a hard time taking anything anyone says seriously after they say it is ok to run any motor with any bushings at 50:1 as I can show anyone first hand what the crank and rod and block look like afterwards

 

[racerone]

??--The main bearings on the 6 HP are bronze.----Never an issue at 50:1 on them !!