In fact even among racers, 550 modifieds with lots of bottom end power, and just reasonable top end, are always more desirable. No recreational rider can afford that. New customers can use coupon code USED10 at checkout for 10% off your first order of Used, New Old Stock, or OEM parts from Watercraft Werks! This aftermarket reed cylinder uses JS440 JS550 piston port spacing. The opening on the stock flame arrestor also matches perfectly to the throat opening of the new 42 Kiehin carb. may experience better results with a 16.0 pitch on the Hammer 105 only. Air leaks, not engine modifications, are by far the number one cause of 550 piston seizures. Not completely sure of how the system works from end to end, but ( and different skis could be plumbed completely differently ) , if the . By accepting all cookies, you agree to our use of cookies to deliver and maintain our services and site, improve the quality of Reddit, personalize Reddit content and advertising, and measure the effectiveness of advertising. JavaScript is disabled. The porting mods used in all our 550 kits is the result of many months of performance and wear evaluation testing. Peak waterspeed (sea level, flat water)82-85 43.8 mph; 86-90 45.1 mph, HAMMER 92 (octane) Intended for the serious recreational rider, this 550 kit shares many of the Sleeper kit mods along with a cost conscious selection of aftermarket bolt on parts. There are many aftermarket companies that build high rpm and high compression 550 race boats for their sponsored team riders. 89 550PP, 44MM SBN carb, Westcoast exhaust, Mariner head, OceanPro rideplate, Quadra-Fin rideplate, Solas 14x19 prop, Tuned Pipe, 147 RV, Mariner intake manifold , 44MM SBN Carb, K&N performance arrestor, 91 XP hood, X4 Hull- R&D rideplate, NuJet prop, RAM cup holder, Commercial Tiny Tach, http://www.pwctoday.com/f149/2-inline-silencers-40-each-274305.html, If this is your first visit, be sure to
This system permits much closer working tolerances between the impeller and the pump housing without risk of collision. Dual 38 carbs are commonly used on modified race boats because they offer better overall throttle response than a heavily modified 44 Mikuni carb. may experience better results with a 16.5 pitch) The use of a lightweight driveshaft can improve acceleration ability on racing 550s, however its often a relatively small performance increase, that comes for a high price. I also have a coffman's inline silencer/resonator that I'll use so it shouldn't be too loud cool I'll ask around, is that factory pipe? THE GOALS OF MODIFICATION The goals of every GROUP K modification is to offer the maximum possible overall power increase while making the minimum possible loss of reliability and power band range. Welcome to Watercraft Werks! But later in the day it started bogging down but would eventually pull and get up to speed. The biggest performance problem of the standard JS 550 is the lack of low speed acceleration. With many rear exit systems we experienced terrific deep water re-start problems due to the amount of water that backed up in the exit tube. 1988 Js550 seemed to be running alright at first. During testing, we found that more radical porting specs could sometimes improve peak waterspeeds, however the strong low end and smooth power delivery were seriously hurt. All rights reserved. The use of a lightweight driveshaft can noticeably improve acceleration ability on racing 550s, however its often a relatively small performance increase that comes for a very high price. DESIGN WEAKNESSES The 550 engine has several inherent design weaknesses. check out the. I have a Westcoast exhaust, manifold, and waterbox. Unfortunately, many 550s will still have the original crankshaft in the engine. Both Hammer kits yielded the best low end and mid-range power using the Coffman Climax pipe (fits on 86-93 manifolds only). This page was generated at 08:04 AM. The new 42 Keihin carb offers better overall fuel mixing and throttle response than any large throat carb we have tested. For a later model 93 machine thats not a problem, however there are many 550s with one or two hard seasons on the stock crank. FULL Bilge and flush kit. As a result we recommend dual carbs to no one, and we do not use them on any of our 550 kits. Even if this shimming is perfectly executed, the impeller will regularly crash the rear hull mounted pump case due to hull flexing and engine torquing that takes place during cornering . COOLING SYSTEM All of these 550 kits can operate reliably with the single input cooling system along with our cooling system upgrade. (set-up clearance is .003-.0035 ; wear limit is .008) On any racing or high output recreational packages we recommend set-up clearances of no more than .004. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Our 550 reed engine modification kits are as follows : STD KAWASAKI JS 550 Peak waterspeed (sea level, flat water) 91-93 37.8 mph, SLEEPER Intended for the average recreational rider, this engine kit consists of modification to existing pieces only. The porting mods used in all our 550 kits is the result of many months of performance and wear evaluation testing. Cars UK [rating:3.0] This closer fit offers much better thrust at low engine speeds and results in more controllable acceleration off the corners. Peak waterspeed - 49.8 mph 1990 Yamaha Super Jet - 701 Motor, ride plate, Stainless impeller. Its our position that the carburetor that can provide the best fuel mixing, at all throttle positions, is the carb that will provide the best overall acceleration and throttle response. If your machine will be operated on only smooth water, blueprinting offers little improvement for the money spent. The price of these aluminum charging flywheels would easily be worth the performance for a racer with a Hammer 105. Starts up good, no choke needed. DESIGN WEAKNESSES The 550 reed engine has a few inherent design weaknesses. Kawasaki 300 Sleeper Engine and Pump Mods, Kawasaki JS 550 Engine Modification Kits, Kawasaki SXR 800 & SXI 750 849cc Big Bore Mods, Kawasaki SXR 800 849cc IJSBA Stock Class Upgrade, Kawasaki 900-1100 Sleeper Kits for Triples, Kawasaki STX 1100 Di High Performance Mods, Kawasaki STXR 1200 & Ultra 1350 Single Pipe Engine Kits, Sea Doo 951 GTX Di High Performance Mods, Yamaha 633-701 Recreational Engine Mods, Yamaha Super Jet 845cc Big Bore Hammer Mods, Yamaha 1100-1200 Sleeper Kits for Triples, Yamaha 1200 GPR-XL-XLL Recreational Mods, Competition High Performance PWCs for 1998. Modifying your 550 with a keen awareness of these weaknesses is what permits the construction of an effective yet reliable modification package. Many other aftermarket companies simply sell their 440 combos for the piston port 550s they usually work poorly. I generally ship within one business day with tracking. We strongly recommend that you read this entire pamphlet before deciding which modifications are right for you and the kind of riding you intend to do. CRANKSHAFT The stock 550 crankshaft is actually a reasonably well built unit. Personal Watercraft Impellers & Components. Does not work on 91-95 reed cases. Charlie. Something went wrong. The Hammer 105 is not for the meek or the weak. If okay, it would be a cheap fix. These high rpms are needed to generate the 50+ speeds on some pro mod racers. PACK YOUR PARTS CAREFULLY !! When recreational riders purchase the same parts and modifications used by these racers, the unfortunate result is the same unreliable all top end engine that the racer has. Kawasaki JS550 js550SX JS 550 JS440 Kawasaki 650sx ignition restorations 650 X2 JetSki Solutions uses only the highest grade materials for each application in our remanufacturing processes. If you intend to use a 440 style manifold/pipe combo, we recommend only the Coffman Classic pipe and manifold. Sealing on an area that narrow is easy on the low compression/low operating temperature stock engine. 06-02-2010, 02:13 PM. EXHAUST SYSTEMS While the Sleeper kit utilizes the complete stock exhaust system, the 550 Hammer kits are intended to be used with aftermarket exhaust components. Why would you want it quite?? Since a new gasket kit was laying in the hull I set on taking the engine apart. 1996 2023 Group K. All Rights Reserved. A Skat Trak impeller, along with nozzle boring, are mandatory modifications for all Group K 550 kits. If the porting is performed by someone with very little 550 experience, that may be true. Both Hammer kits yielded the best low end and mid-range power using the Coffman Climax pipe (fits on 86-93 550 manifolds). The reliability of the total loss ignitions weve tested has been so poor that we do not recommend them. Making good increases in the acceleration and peak speed of a 550, without hurting reliability, is not difficult. Hope to see you all on the water! The engine compartment of your finished Sleeper will look 100% cosmetically stock. If that is the case, then restart should not be a problem, But if there is a lot of water in the box, maybe it could create enough back pressure to make starting difficult. Surprisingly, they offered only slight increases in overall performance (about 1 mph). GROUP K offers a simple to use pressure test kit that allows you to quickly test for any air leaks that your engine may have. Strangely enough, the 3011 crank is dimensionally identical to the 550 crank, but made from much better materials. In fact even among racers, 550 modifieds with lots of bottom end power, and just reasonable top end, are always more desirable. Westy's in until I get the issue . All the duals we tested proved to be very difficult to tune and keep synchronized. Seeking is the point at which the handlebars no longer control the true direction that the boat is traveling in. Dyno-matting will give much better results than turf as it is made to deaden sound. TJ that 550 OEM H20 box is going to rob a ton of power from that 650 motor. Under the loads of stock power output, that four year old crank might last another two years. We believe the tiny increase in peak water speed was not worth the loss of overall reliability. HEAD GASKET SEALING The amount of head gasket sealing area between the cylinder bores and the thru stud holes in the 550 piston port cylinder is very narrow (much narrower than the 440). #6. Cylinders and heads are typically prepared as matched pairs only to assure that you have the proper squish clearance and compression ratio for the quality of gasoline that you intend to use. This air leak can make the fuel mixture lean enough at high rpms to cause a piston seizure. 88 JS550. I'm getting close to finished on my 550sx pp project. #1 JS550-B1 waterbox delete? No piston port 550 on earth can pull a 16.5 or steeper prop. I have a js550 with an sbn44. In any case, all ported cylinders are honed before return shipment. Hyundai i20 - Euro styled Getz replacement The reliability of the total loss ignitions weve tested has been so poor that we do not recommend them to anyone for applications. the raspy mettalic sound of a aluminum waterbox tends to piss people off. The Sleeper kit will give best results with the 15.5 pitch while both Hammers will work best with a 16.0. COOLING SYSTEM All of these 550 kits can operate reliably with the single input cooling system and our cooling system upgrade. (set-up clearance is .0045-.005 ; wear limit is .009) On any racing or high output recreational packages we recommend set-up clearances of no more than .006. The Hammer 105 can not and should not operated at high rpms on pump gasolines. Our 550 engine modification kits are as follows: STD KAWASAKI JS 550 Peak waterspeed (sea level, flat water) 82-85 35.2 mph ; 86-90 36.5 mph, SLEEPER Intended for the average recreational rider, this engine kit consists of modification to existing pieces only. Piston clearance inspection is available on request, and cylinder boring (using pistons furnished by you or us) is available in oversizes of .020and .040. These mufflers permit the engine to pull easily into the higher rpm ranges while maintaining tolerable increases in sound level. Contrary to rumor, the stock waterbox yields very good overall power levels in all pump gas applications. These 91 dual ring pistons run consistently .004 larger than the single ring piston port type pistons. Just the same, this is the fastest pump gas compatible 550 reed kit available anywhere. Designated trademarks and brands are the property of their respective owners. Speeding up throttle response in this way has diminished the need for lightweight flywheel total loss ignitions. reading more and you also run the risk of serious overheat from uncooled exhaust so you are correct in not wanting to remove the water box. However when they became even a little wet, they offered very restricted air intake ability until they were removed and allowed to dry out. Peak speed - 47.4 mph HAMMER 105 (octane) - Intended for the serious modified class racer, this kit offers national class power output along with the best in race level reliability. Kawasaki 300 Sleeper Engine and Pump Mods, Kawasaki JS 550 Engine Modification Kits, Kawasaki SXR 800 & SXI 750 849cc Big Bore Mods, Kawasaki SXR 800 849cc IJSBA Stock Class Upgrade, Kawasaki 900-1100 Sleeper Kits for Triples, Kawasaki STX 1100 Di High Performance Mods, Kawasaki STXR 1200 & Ultra 1350 Single Pipe Engine Kits, Sea Doo 951 GTX Di High Performance Mods, Yamaha 633-701 Recreational Engine Mods, Yamaha Super Jet 845cc Big Bore Hammer Mods, Yamaha 1100-1200 Sleeper Kits for Triples, Yamaha 1200 GPR-XL-XLL Recreational Mods, Competition High Performance PWCs for 1998. For a later model 90 machine thats not a problem, however there are many 550s with four or more seasons on the stock crank. We recommend that a stock waterbox silencer be used on the Sleeper and Hammer 92. Good luck with a solution. Engines intended for moderate recreational use can easily live with .006-.007 set-up. All early style 550 pumpcases were manufactured with no stainless steel impeller housing liner. UPS weight limit makes engine shipping practical and affordable. 1983 Kawasaki JS550 - Mariner head, Mariner Rideplate, SBN44 w/ K&N Filter, BCW Intake Manifold, Factory Pipe water box, LS Exhaust Manifold, Cauffman full exhaust. I'm sorry did you say something.. All Material Copyright 2009 Watercraft Superstore. The Sleeper will start and idle like a stocker, have the sound level of a stocker, and run on 92 octane pump gas. Jun 2, 2010. Come join the discussion about performance, modifications, troubleshooting, maintenance, for all SeaDoos, Waverunners, and Jet Skis. 2040Parts.com © 2012-2023. (SEND head, cylinder, exhaust manifold, carb, and pump exit nozzle), CARB BORING AND INTERNAL CIRCUIT MODIFICATION, COMPLETE PUMP BLUEPRINTING & SCOOP GRATE MATCHING, SCOOP GRATE TOP LOADER TYPE (ROUGH WATER USE ONLY), *prices subject to change based on manufactures pricing. HANDLING For all 550 models, a slightly longer aftermarket ride plate is a big handling asset. How did you determine it was the water box ? Peak speed (sea level, flat water) 38 carb 45.6 mph ; 44 carb 47.2 mph, HAMMER 105 (octane) Intended for the serious modified class racer, this kit offers national class competitive power output along with the best in race level reliability. INTAKE SYSTEMS The standard 44 Mikuni carb is an excellent carburetion choice for all modification levels of the 550. All Rights Reserved. Check Out Our Pro-Series Steering Systems, Now In Stock! This is not what any recreational rider wants. muffler/rear exit tube gave our 550 test boats the best overall performance and best sound levels when resonator mufflers where used in the nose of the boat. check out the. THANK YOU pwctoday community for all of your friendly knowledge. AIR LEAKS The lower end of your 550 should be totally air tight up to 8 psi. Under the loads of stock power output, a two year old crank might last another year. For the best experience on our site, be sure to turn on Javascript in your browser. So each April they gather a fine collection of both at the airport at Half Moon Bay, Calif., and open the gates. It has long been our opinion that the reed cages in the after market 550 cylinders are much larger than they need to be. Surprisingly they offered only slight increases in overall performance (about 1 mph). These cylinder and head specifications play the key role in determining the amount of overall power that the engine can make as well as the quality of fuel that you must use. 95 sc yami 760. 09-02-2019, 09:21 PM. In fact, the free floating bulkhead bearing system in the 1990 model 550 sx is so flexible, it virtually eliminates the need for shimming the engine and pump altogether. Our enhanced specifications and processes are designed to eliminate all known failure modes in each specific part or sub-assembly. item 1 MARINER Waterbox Kawasaki Jetski JS440 JS550 550SX MARINER Waterbox Kawasaki Jetski JS440 JS550 550SX. For riders who run their 550 very aggressively in rough water conditions we recommend the top loader type scoop grates. The unusually heavy flywheel of the stock 550 slows throttle response and acceleration. The organizers of Pacific Coast Dream Machines have known this for the last 20 years. Whatever spray it may be exposed to will not clog the all stainless steel screen element in any way. The intake mesh of the stock arrestor is so well guarded in the engine compartment that it is exposed to very little water spray. I have a 1987 js550 full mod.. bigger sbt pistons, full westcoast pipe, west coast exhaust manifold, marnier waterbox, light weight flywheel, pjs dual cooling head, ocean pro nosel, solas impeller, bn44. All other orders will be billed to a visa/master card or sent freight collect cod cash. That, along with the high price tags, made them a very poor value. Safe steering, beyond this speed, is done with a combination of body english and proper weight transfer. Reddit, Inc. 2023. If you intend to use a 440 style manifold/pipe combo, we recommend only the Coffman Classic pipe and manifold. For the best experience on our site, be sure to turn on Javascript in your browser. The longer plate reduces porpoising (the nose of the jetski bouncing uncontrollably) and improves high speed stability. If the cylinder is bored to an oversize, that critical area becomes narrower yet. Westy went back in until I couldn't stand it anymore, took the one out of the 300. The engine compartment of your finished Sleeper will look 100% cosmetically stock. Not completely sure of how the system works from end to end, but ( and different skis could be plumbed completely differently ) , if the water in the box is coming from pump pressure, then when restarting in the water should be with little or no water in the box. VGC, OEM Kawasaki 440 550 JS SX Fuel Tank & Water Box Rubber Pads Dampers Set of 4, - Kawasaki Jet Ski 1982-1995 JS300 JS440 JS550 / 550SX Water Box Part# 49070-3702, Complete Rebuild Gasket Seal Kit Kawasaki Jet Ski Js550 Sx550 JS SX 550 91-95, 1986 KAWASAKI JS550 EXHAUST MANIFOLD / MUFFLER PIPE, - 1986 KAWASAKI JS550 EXHAUST MANIFOLD / MUFFLER PIPE, KAWASAKI JS HOT SEAT PERFORMANCE WATER BOX / EXHAUST MUFFLER, KAWASAKI JS 440 550 SX SUPERTRAPP PERFORMANCE WATERBOX, Kawasaki 440 550 js sx Kerker aftermarket exhaust pipe head chamber NEED WORK, KAWASAKI JS550 JS 550 550sx 440 Mariner KERKER Exhaust Pipe Expansion Chamber, Kawasaki Jet Ski JS440 /JS550 /550 SX Choke Cable NEW Vintage, Kawasaki 11009-3779 JS440/550-550sx Jet Ski Exhaust Manifold Gasket Aftermarket, Kawasaki Exhaust Gasket 550 JS js550 Coffman Factory pipe half pipe set kit, 1987 KAWASAKI JS550 EXHAUST MUFFLER-COMP WTR BOX, - 1987 KAWASAKI JS550 EXHAUST MUFFLER-COMP WTR BOX, Kawasaki 550 Jet Ski JS SX 550 Js550 Complete Gasket Seal Kit 1982-1990, Kawasaki JS-440-550 440 550 Jet-Ski Jetski Splined Prop Impeller Holding Tool, Kawasaki JS 300 300sx sx waterbox water exhaust lock muffler box housing, - Kawasaki JS 300 300sx sx waterbox water exhaust lock muffler box housing, USED - No Name 440 550 Aluminum Waterbox - Needs Weld, Kawasaki 300 440 550 JS Exhaust Pipe Cover 49107-3701, Kawasaki 440 550 JS SX Kerker Hi Performance Exhaust Pipe Stainless Steel Nice, Kawasaki Jet Ski Js 440 550 Sx Exhaust Manifold Gasket, - Kawasaki Jet Ski Js 440 550 Sx Exhaust Manifold Gasket, M-G 320514t Exhaust Manifold Gasket for Kawasaki Jet Ski JS440 JS550 440SX Jetsk, KAWASAKI JS440 JS 440 550 OEM QUALITY Exhaust Manifold Gasket Seal 11009-3023, OEM - Exhaust Tube Kawasaki JS550 82-85 - 92059-3041, NOS Kawasaki JS550 Jet Ski Muffler Bolts - Part # 92150-3776 - Obsolete - JS 550, M-G 330513t Exhaust Head Pipe Gasket for Kawasaki Js/Sx 550 Js440 400 Jetski, NOS Genuine Kawasaki Exhaust Pipe Gasket JS550 JS 550 1991 1992 1993 1994 1995, 4 Pack Kawasaki Motor Mount Js440 Js550 Sx550 Xir750, - 4 Pack Kawasaki Motor Mount Js440 Js550 Sx550 Xir750, Kawasaki 550 Jet Ski Js550 Js 550 Top End Rebuild Head Gasket Kit 1982-1990, - Kawasaki 550 Jet Ski Js550 Js 550 Top End Rebuild Head Gasket Kit 1982-1990, New Kawasaki JS JS550 JS440 JS300 Drive Shaft Oil Seal AC1799EX NOS 92050-501, Piston Gasket Top End Rebuild Kit Kawasaki SX JS 550 1982-1990 .25 mm Over, - Piston Gasket Top End Rebuild Kit Kawasaki SX JS 550 1982-1990 .25 mm Over, NOS Genuine Kawasaki Muffler Exhaust Pipe Gasket JS550 JS 550 91 92 93 94 95, Kawasaki 440 550 JS SX High Performance After Market Exhaust Manifold, Kawasaki JS 440 550 JS Side Exhaust Output Hull Fitting Tail Pipe 59156-506, New WSM Exhaust Gasket 1976-1995 Kawasaki Jet Ski 400 500 JS SX 550, KAWASAKI JS550 JS 550 SX EXHAUST PIPE GASKET GENUINE OEM, 1986 KAWASAKI JS300 EXHAUST MUFFLER / WATER BOX, NEW KAWASAKI NOS 11009-3779 EXHAUST MANIFOLD GASKET JS550 JS440 JS400, Kawasaki 300SX/JS300/JS440/JS550/550SX Performance Steering Nozzle, OEM - Exhaust Hose Waterbox Kawasaki 440 550 - 92059-3722, KAWASAKI JS550 JS 550 Exhaust Head Pipe Gasket Seal 11060-3730 GOOD QUALITY, Kawasaki 440 550 JS SX Exhaust Manifold in good condition, Kawasaki 440SX 550SX JS Rear Exhaust Hose Tube Hanger Hook Stainless Steel, OEM 86-95 Kawasaki X2 650SX JS650 SX650 Exhaust Waterbox Water Box, 1985 KAWASAKI JET SKI 550 JS550 MUFFLER EXHAUST PIPE SILENCER 18001-3008, OEM - Exhaust Hose Upper Exit Kawasaki JS 400 440 550 - 92059-528, Kawasaki OEM Muffler Damper 1984-1985 JS550 Jet Ski # 92075-3701 NOS- NEW, KAWASAKI JS440 JS 440 550 OEM QUALITY Exhaust Head Pipe Gasket Seal 18067-502, 1989 KAWASAKI JET SKI 550 SX JS550 EXHAUST HEAD PIPE MUFFLER HEADER 49062-2053-Y, NOS Kawasaki Jet Ski Band, Muffler # 92072-511 JS550 JS440 JS300 + More PP907, Kawasaki Jet Ski 550 JS Coffmans Half Pipe Climax Exhaust Gasket Set NEW, Breather Head; Elbow-Water Hose; Kawasaki JS440 JS550 NOS : 52014-3002, KAWASAKI OEM EXHAUST GASKET JS550 1986-1990 11009-2461. Granted, these smaller tracts may not be able to pass enough mixture for 52+ mph peak water speeds, but thats not the performance objective of our kits. Just beginning to look for a new/used water box (87 js550) - . This page was generated at 08:04 AM. Review my outstanding feedback and purchase with confidence! All rights reserved. This air leak can make the fuel mixture lean enough at high rpms to cause a piston seizure. There are many after market companies that build high rpm and high compression 550 race boats for their sponsored team riders. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. GROUP K offers a simple to use pressure test kit that allows you to quickly test for any air leaks that your engine may have. Reliability of the 550 engine is seriously affected only when the engine is forced to turn excessive rpms or when compression ratios are set too high. A 15.0 or 15.5 Skat Trak impeller and, along with nozzle boring, are mandatory modifications for all Group K 550 kits. Welcome to our new store! AIR LEAKS The lower end of your 550 should be totally air tight up to 8 psi. I know it will be kinda loud and I want to reduce that. It was in the ski originally but it was too loud so I bought a stock one and took it out.. blew that one. For any further questions you may have regarding your Sleeper or Hammer kit, you are welcome to contact us directly for assistance. TOP END MODIFICATION All Group K 550 kits include cylinder porting. Most orders have a 1-3 day handling time. A finned ride plate can give added stability at high speeds. It bears noting that no aftermarket cylinder head can resolve the sealing problem. Aftermarket grates are recommended for all kits, however brand is not crucial. The 550 pump delivers the force of thrust to the hull through the pump case mounting points, not the driveshaft ( like a 440 style pump). Use of this Web site constitutes acceptance of the 2040Parts User Agreement and Privacy Policy. IGNITION The stock 550 ignition has no built in rev limiter, however it does have an unusually heavy flywheel that slows throttle response and acceleration. Along with that, all Hammer kits and over bored Sleeper kits are recommended to be assembled with the durable and reusable .040 solid copper head gasket. Our full catalog of parts can be accessed from the above menu. The Coffman systems have been designed specifically for the 550. For customers who prefer to prepare their machines with a dual or oversized input systems, we can also prepare the special exit plumbing needed to make those systems work. IGNITION The stock 91 550 ignition has a built-in rev limiter that comes in at about 6,500 rpm. By simply disconnecting one wire in the electrical box, the limiter can be eliminated. Privacy Policy. As a result, no bulkhead bearing support is needed (like on all 440s). For any further questions you may have regarding your Sleeper or Hammer kit, your are welcome to contact us directly for assistance. I love the sound of my skis. Besides, the high rpm 550 engines used by the sponsored pro racers will typically get a new crankshaft every 25-30 operating hours.