Education needed - Rings, bore, overhaul - Polaris ATV Forum
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post #1 of 24 (permalink) Old 01-04-2019, 03:15 PM Thread Starter
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Education needed - Rings, bore, overhaul

Ok, so noticed last summer that the Hawkeye was puffing blue smoke, so it's time to give it some TLC and do a top end rebuild, at least I think that's the issue without doing more digging. Obviously I'll be doing more research before any purchase are made.

Since I'd rather not drop the coin on finding a 400 to upgrade, and I'm going to be tearing down anyway, is there an advantage in getting an over bore kit? and what pitfalls should I lookout for in the process?

It's been 20+ Years since I've torn a motor down of any size so any help would be greatly appreciated.
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post #2 of 24 (permalink) Old 01-05-2019, 11:02 AM
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Do they offer a 'BIG BORE' for it?

The only thing offered from Polaris is a .025 mm (.010") and .050 mm (.020") oversize pistons. So if there's any cylinder damage, you will be boring to an oversize to freshen up the engine. There is no performance advantage to boring to the largest oversize other than a very small increase in low end torque, but it's unusual to find a used cylinder that can be accurately bored to .010" oversize. If there's any visible wear in the cylinder, it will have to be bored to .020" just to clean it up. In 40 years of rebuilding engines there is only one that I can remember boring .010" oversize. It was a little Honda with low miles, but the piston stuck in the cast iron bore from rust. The owner bought a .010 piston before the engine was torn down. There were some small imperfections in the cylinder after boring that would not have been there if bored to .020, but the imperfections would not affect the performance, so it went together and operated perfectly, but I knew in the back of my mind it was not perfect. The owner was perfectly happy.

What have you found in the way of big bore kits?
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post #3 of 24 (permalink) Old 01-05-2019, 12:25 PM
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What size is the Hawkeye? I have 300cc in my head for some reason. I don't think I have a book for that one so is it like the other engines with an overhead cam?

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
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Hers: 2007 Sportsman 500 EFI, Polaris Winch, 26" Bear Claw HTRs on Moose 427x Wheels. QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2001 Magnum 325 Warn winch and Moose 60" plow
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post #4 of 24 (permalink) Old 01-05-2019, 12:49 PM
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It is a 300 (299 cc to be exact) - either 4x4 or 2x4 - the engine was the same for both 2006-2011

Last edited by latebird; 01-05-2019 at 12:53 PM.
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post #5 of 24 (permalink) Old 01-05-2019, 02:11 PM
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Thanks! So my later generic Polaris ATV manual might have that in it. It covers just about everything from '98 through '07. Have to look at it tomorrow.

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2007 Sportsman 500 EFI, Polaris Winch, 26" Bear Claw HTRs on Moose 427x Wheels. QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2001 Magnum 325 Warn winch and Moose 60" plow
2017 Polaris Ranger 1000XP - Roof and front glass
SOLD 2004 Sportsman 600 Twin
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post #6 of 24 (permalink) Old 01-05-2019, 04:35 PM
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The Hawkeye is one I don't have a manual for. Yet
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post #7 of 24 (permalink) Old 01-07-2019, 06:59 AM
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My manual does not cover the 300cc engine. I am surprised since is has information on just about everything else. 250 and 400 2 strokes, 325 through 800 4 strokes. No specifics on any machine but it does cover the earlier engines pretty well.

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2007 Sportsman 500 EFI, Polaris Winch, 26" Bear Claw HTRs on Moose 427x Wheels. QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2001 Magnum 325 Warn winch and Moose 60" plow
2017 Polaris Ranger 1000XP - Roof and front glass
SOLD 2004 Sportsman 600 Twin
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post #8 of 24 (permalink) Old 01-07-2019, 08:42 AM Thread Starter
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I can find a .060 over and a .50 over kit... misprint on the .5 over?

https://www.ebay.com/i/382711112963?...3D382711112963 .060

https://www.ebay.com/i/312334161943?...3D312334161943' 0.50

But I can also find a Hawkeye 400 motor for $800 after shipping... Does anyone know if the 400 uses the same transmission as the 300?

"There are no problems. There are only Solutions. It's your job to find the right one.

2017 Sportsman 570 Touring EPS
3500 lbs Polaris winch with Synthetic Rope
Front Utility Rack
ODI Rogue Lockon Grips

2007 Hawkeye 300 17HP of gutless glory
25" STI Black Diamond ATRs
Pure Polaris Deluxe front Brush guard
Pure Polaris hand guards
ODI Rogue Lockon Grips
4" LED on the pod
8" LED light bar on the front bumper.
Badlands 2500 lbs. winch w/remote and Kong winch saver.
Full Aluminum Skid plate and A-arm guards(custom built)
Pure Polaris Front rack extension
Quadworks Stage 1 power kit
  • K&N Highflow reusable filter
  • Quadworks highflow prefilter
  • Dynojet kit
2" rear spring spacers
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post #9 of 24 (permalink) Old 01-07-2019, 09:27 AM
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So here's what I found out:

That was not a misprint on the pistons
Std. bore is 77.70 mm
The piston listed as .50 mm (.020 inch) is for a 78.20 mm bore
The piston listed as .060 inch (1.50 mm) is for a 79.20 mm bore

The 08 to 11 transmission for the 300 Hawkeye is part number 1332697
The transmission for the 11 400 Hawkeye is part number 1332928

The left and right transmission cases:
Part 3234448 and 3234449 for the 08-11 300
Part 3235265 and 3235264 for the 11 400

No - the transmissions are different for the 300 and 400, but the real question is will the 400 motor mount in the 300 frame

The 300 engine cases are 3089788 and the 400 is 3089240

Frames?
300 - 1016501
400 - 1017664

It would be a question a Polaris engineer would have to answer or someone who has physically made the conversion.

With a torch and a welder you can fit any engine in any frame, but getting things to line up and work together is the trick.
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post #10 of 24 (permalink) Old 01-07-2019, 10:52 AM
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Probably cheaper and easier to just rebuild what you have. I think the last top end I did was about $50 for the machine shop and $125 or less for the piston kit which included all the gaskets. I have gone .020 over on both my 325 machines and neither needed any jet changes to the carb. So it's fairly simple if you can take it apart and put it back together yourself.

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2007 Sportsman 500 EFI, Polaris Winch, 26" Bear Claw HTRs on Moose 427x Wheels. QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2001 Magnum 325 Warn winch and Moose 60" plow
2017 Polaris Ranger 1000XP - Roof and front glass
SOLD 2004 Sportsman 600 Twin
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