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Mercury 20hp 200 Thunderbolt Ignition

K

Kraftsman

New member
Hi guys, I'm new to the forum and new to boat ownership. I just bought an older, but decent shape, flatbottom that came with a 20hp Mercury 200 with Thunderbolt Ignition. First of all, I know virtually nothing about the motor. First of all, I can not even tell you if it's a 2 or 4 stroke motor. There is a serial number on the bracket that mounts the motor to the boat. It reads 4105056. Can any of you experienced folks here please tell me what it means? Also, if it is a 2-stroke, what is the fuel mix ratio?

Thank you much for any input!:eek:
 
Wow! That was quick.

I was told by a friend that it was a 1970's motor, but that was all they could tell me. I currently do not have any pictures but will try and get some if that will help. I will tell you this though, the Mercury insignia passes through a blue stripped band that goes around the circumference of the motor. The motor itself is black.

Thanks for the response.
 
Also, if the motor really is a 2-stroke, what type of oil is specified to be used in it? Is there such a thing as marine 2-stroke oil? Please pardon my ignorance, I just don't want to burn the thing up. Thanks.
 
TCW-3 mixed directly into the gas? I use TCW-3 in my injected Polaris snowmobile, but I have never mixed it directly into the fuel. So, the waterpump impellers are notorious for going bad?
 
You make a statement that you do not want " to burn the thing up " -------------then you question advice on installing a new impeller ????-------Sad really !
 
There is no auto mix or injection on your merc 200,so you need to premix,as racerone says at 50:1 with TCW-3. An impeller should be changed every two years as the rubber dries out and perishes.When an engine is new to you it's a good idea to change the impeller anyway if you don't know the history of it.Even if the seller says he replaced it last week. Welcome to a very expensive hobby and enjoy:D
 
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