Counterblance delete in 1993 350L 4x4 - Polaris ATV Forum
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post #1 of 5 (permalink) Old 08-30-2019, 07:34 PM Thread Starter
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Counterblance delete in 1993 350L 4x4

Hi All,
Have a 1993 350L 4x4 (2-cycle) with a bad counterbalance and water pump. Besides a little more vibration, any reason to not just delete the counter balance all together and use an electric pump to move the coolant?

I've heard that removing the counter balance is/was a common practice when racing 2-cycle motorcycles. As this is an old and super cheap 4x4 ($300) that won't get heavy use I feel like there is not much to lose to try it out.

Anyone else every try this? Looking forward to hearing your thoughts.
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post #2 of 5 (permalink) Old 08-31-2019, 07:34 AM
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When you remove the counter balance and water pump, you should remove the oil pump at the same time - block off the oil pump opening, remove the oil tank and premix your fuel. You will need to the leave the counter balance drive gear in place as it sets the distance for retaining the crankshaft in the bearings or you could have the drive gear machined into a spacer to reduce inertia and allow the engine to accelerate faster. You need a puller to get the counter balance out and you will want to remove the bearing in the RH engine case that supports the oil pump drive end of the assembly to assure the bearing does not vibrate out and cause unexpected noise or damage.

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post #3 of 5 (permalink) Old 08-31-2019, 08:10 AM Thread Starter
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Hi Latebird,
I truly appreciate your response. Couple comments/questions.

Good to know to leave the drive gear in place. Didn't realize it was important for bearing retention. Top end speed or speed off the line is not important so there is no need machine it into a spacer.

If the counterbalance is removed I presume the bearing in the case half needs to come out so it doesn't accidentally fall out on its own. Is this accurate?

Love the premix idea and pulling the oil pump but I am not aware of a bearing that supports the oil pump. Could you please show me in a drawing or will it be evident when I pull the oil pump?

Thanks!
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post #4 of 5 (permalink) Old 08-31-2019, 09:42 AM
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Explanation

Quote:
Originally Posted by pigseye View Post
Hi Latebird,
I truly appreciate your response. Couple comments/questions.

Good to know to leave the drive gear in place. Didn't realize it was important for bearing retention. Top end speed or speed off the line is not important so there is no need machine it into a spacer.

If the counterbalance is removed I presume the bearing in the case half needs to come out so it doesn't accidentally fall out on its own. Is this accurate?

Love the premix idea and pulling the oil pump but I am not aware of a bearing that supports the oil pump. Could you please show me in a drawing or will it be evident when I pull the oil pump?

Thanks!
You kinda missed what I was explaining;

The bearing I was referring to is the bearing in the case on the other end of the counter balance (I presume the bearing in the case half needs to come out so it doesn't accidentally fall out) - you have that right

Pulling the oil pump is not mandatory, but with the counter balance removed, there is nothing to drive the oil pump - removing the pump and tank eliminates the possibility of someone thinking it is oil injected and putting oil in the tank and driving it without oil mixed with the fuel.

I hope I explained this so you understand what I'm trying to convey.

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post #5 of 5 (permalink) Old 08-31-2019, 01:09 PM Thread Starter
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Hi Latebird,
my apologies for misunderstanding but it makes sense now. I did not realize that the oil pump was driven by the counterbalance. Pulling all remnants of the oil injection system really makes sense.
Thx again!
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