AP Custom and Precision LLC

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AP Custom and Precision LLC Powersports service from tuneups, machining, engine rebuilding and performance parts

Beginning with a hand-me-down snowmobile, the passion for motor-sports industry was born. Continuing through several self-owned performance build and years of excellent mentoring, life brought me to Wisconsin where AP Custom and Precision LLC was founded.

On the bench this week is more parts for a Krash 1200. Crankshaft is getting a full rebuild with all new ProX connecti...
09/01/2026

On the bench this week is more parts for a Krash 1200. Crankshaft is getting a full rebuild with all new ProX connecting rods, high quality bearings, and seals.

Ladies and gentlemen. This is another example of why you can’t have just anybody machine your parts. This Krash Reap...
08/25/2026

Ladies and gentlemen. This is another example of why you can’t have just anybody machine your parts. This Krash Reaper 1200 (dual port injection) was previously rebuilt in its previous life but very quickly suffered a second failure. We did a full investigation and found that the two pistons were .0005” different in actual size (we don’t machine to nominals). The piston-to-wall clearance was insufficient with as tight as .0031” and as large as .0052” when the spec calls for a whopping .0080”. Running insufficient clearance will result in high risk of seizure especially at the four corners.

With performance engines, the attention to detail is critical if you want the engine to survive!

Some freshly bored, chamfered and honed Seadoo 787/800 cylinders and pistons headed back to Nick at Jarman Powersports!
08/25/2026

Some freshly bored, chamfered and honed Seadoo 787/800 cylinders and pistons headed back to Nick at Jarman Powersports!

Fixing the abomination of a rebuild that someone else had done. Crankshafts are fun puzzles for a Saturday night! If y...
08/23/2026

Fixing the abomination of a rebuild that someone else had done. Crankshafts are fun puzzles for a Saturday night!

If you need cylinders done, we do those also! We primarily use WSM Platinum series pistons but can do other brand pistons upon request.

Sometimes people wonder “why does good work cost so much?” The real question should be “what corners are the cheaper o...
08/20/2026

Sometimes people wonder “why does good work cost so much?” The real question should be “what corners are the cheaper options cutting?”

Recently a customer contacted me with about a second opinion on a few red flags they observed before installing a “full rebuild” on his 787 done by another shop. Since the original builder refused to give support he decided to send it to us for a deeper look. Here is a list of things found (not everything is listed but this is the most notable concerns):

- Crankshaft was rebuilt with only new mains. Rods and lower rod pins were original and had rust pitting in them and clearly should have been replaced.
- Crank phasing was about 1.2 degrees out from 180*
- CB had new bearings but only one new seal. The other seal was bad and the gear should have been replaced due to excessive rust pitting/damage
- One cylinders had a sleeve replaced but it wasn’t installed straight so the ports weren’t lined up properly
- Cylinders had been oversized for Wossner pistons which call for a piston-to-cylinder clearance of .0048” but the builder only had .0028-0032” of clearance!

No doubt if the customer would have installed this engine it would have suffered a catastrophic engine failure very quickly!

If you need a your parts properly refurbished - contact us today!

Polaris 350 and Polaris 400L crankshafts in process. We stock them with various brands of rods depending if you want a...
08/17/2026

Polaris 350 and Polaris 400L crankshafts in process. We stock them with various brands of rods depending if you want a basic rebuild or something more for extreme performance!

Just catching up on work and getting some Seadoo 787 cranks rebuilt.
08/01/2026

Just catching up on work and getting some Seadoo 787 cranks rebuilt.

947/951 build time! First engine passed pressure test at 10lbs for 10+ minutes with no leakdown. Specs on completed bui...
07/16/2026

947/951 build time! First engine passed pressure test at 10lbs for 10+ minutes with no leakdown.

Specs on completed build:
Rebuilt crank, .25mm WSM pistons, 6 hole base gasket.

Specs for second engine (in process):
New WSM crankshaft. 0.5mm WSM platinum series pistons, 6 hole base gasket, and the head was milled to tighten squish (fix SBT massive squish due to them recutting the dome) and increase compression over stock. I need to check final squish and compression numbers after assembly is finished.

Seadoo 717 crank seal and main bearing failure. Customer self-installed a new top end and very quickly identified that...
07/03/2026

Seadoo 717 crank seal and main bearing failure. Customer self-installed a new top end and very quickly identified that the crank was making noise. We advised them to not run it. Thankfully no damage was done to the top end and we were able to properly rebuild the engine for them! This is yet another reason it’s good to pull the crank on a 30 year old ski even if you think “it just needs a top end”

07/03/2026

Seadoo 717 crankshaft main bearing failure. Crank was making noise and sucking air by the mag side seal. Installing a new top end did not fix this issue and thankfully the customer didn’t run it after they heard the noise.

Address

Long Road
Stockbridge, WI
54129

Telephone

+19204390938

Website

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