MCB Performance FAQ

Proper break in of a 2-Stroke Engine. This a VERY common question and can be summed up with one sentence: Increased Load over Decreasing Time. What that implies is the engine needs LOAD for proper marrying & seating of components and the load should be increased over a reduced schedule.

How this would normally work:

1 - ALWAYS start with 100% NEW fuel and a PROPERLY LEAK TESTED engine per factory guidelines. Carb(s) / Injectors MUST be clean, filters replaced and hopefully if there was a failure you have isolated and corrected the root cause before simply replacing parts. 

2 - Heat cycle #1 - Start the engine and bring it to just UNDER operating temp and then let it cool COMPLETELY (i.e. overnight) Ensure it is oiling! Revving the engine BRIEFLY and not over 1/3 throttle once or twice is fine.

3 - Heat cycle #2 - Check for leaks. Pull spark plugs and verify relatively dry cylinders. Start engine and bring to full operating temp and note cooling system burping and top off as needed. Let engine cool COMPLETELY again.

4 - First ride should be SHORT (15-20 min). This is where you will be putting the first load to the engine by applying short / brief bursts of throttle up to 1/2 throttle and slowly rolling into and off the throttle varying the LOAD. Again let cool completely and check bores/plugs , cooling system, and ensure oiling. After this you may ride as much as you wish but NO LONG WOT for the first tank and varying throttle and loads for the next tank full.   

Snowmobile specific info: 

1 - With most later Ski Doo Etec's you MUST have the ECU put in break-in mode (anyone with a professional BUDS interface can do this). DO NOT add premix to any Direct Injection (ETEC) engine.

2 - Carbureted engines CAN use premix during break-in however no more than 100-1 and the oil MUST be premix-compatible. 

3 - Any cable actuated oil pump (Earlier Cat, Polaris, Skidoo, etc) you may find it beneficial to shorten that cable adjustment to allow more initial oiling just remember that it does NOTHING additional at WOT. On the Polaris 800's this adjustment can be left for the life of the engine as Polaris ran these engine VERY oil-lean. 

4 - Its ALWAYS a good idea to measure/monitor and CALCULATE YOUR OIL RATIO being used! Fill both tanks then after usage measure the top off amount of each (gallons to ounces) and calculate. This will give you piece of mind that all components are operating properly   

If for any reason you are not happy with your purchase after receiving your item, you may return the item(s) within 7 days of receiving your order or a refund of your costs as long as the merchandise is in fully resalable condition (no damage, no stains, no wear and tear)

All returns must have its original packaging with freight prepaid and insured. All returns will be assessed the industry standard 15 % restocking fee. Returns must be made within 15 days of "Return Authorization" date.

Any returns must be noted with a full description on the front of the manifest or bill of lading in order to be recognized as valid. Prior to any returns, customer must contact MCB Performance at 810-395-7162.

"In-Stock" items usually process in 24-48 hrs and shipping times vary based on your choice of service and location.

Occasionally, items shown to be in stock or available get pre-sold, in this case, you will be sent a email notification that your item is on backorder. You have the option to continue to wait for that item, cancel your order for a full refund, or select a different item to order.

If you are ordering an Item that has a core required BEFORE shipping the order you may be notified of this need first.

 

To the extent permitted by law, neither MCB Performance nor any of its employees, related partners or their respective officers will be liable in any way for any loss, damage, cost or expense suffered or incurred by you or claims made by you because of your use of this site, unavailability of this site or in connection with any products, services or information advertised, offered or supplied through this site. MCB Performance maintains the exclusive right to cancel or refuse any order without limitation. Including price omission, incorrect price, typographical errors, suspicion of fraud, and delivery area restrictions

 

DUE TO THE INHERENT USE OF HIGH-PERFORMANCE PRODUCTS, MCB PRODUCTS AND EACH PART THEREOF, ARE SOLD “AS IS” AND WITH ALL FAULTS, TO THE FULLEST EXTENT ALLOWED BY LAW, MCB MAKES NO WRITTEN, ORAL, EXPRESSED, OR IMPLIED STATEMENT OF WARRANTY OR GUARANTEE ON ANY PRODUCT OR PART SOLD. MCB WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, OR SPECIAL DAMAGES, INCLUDING, BUT NOT LIMITED TO DAMAGE, INJURY, LOSS OF LIFE, LOSS OF PROPERTY OR EQUIPMENT, LOSS OF PROFITS OR REVENUE, OR CLAIMS FROM ANY INDIVIDUAL OR ENTITY ARISING FROM THE USE OF ANY MCB PRODUCT.

Q- What is MCB Warranty on your parts and Kits? MCB Performance goes to great lengths to ensure the quality of all the components we sell. We even choose to NOT sell many other manufacturers parts simply because they don't meet our QC standards. Our reputation is worth more than a few extra sales. That being said because of the nature of Powersports and the performance/severe usage of these parts, MCB offers NO warranty on the life of the components we sell. MCB DOES guarantee the quality and application (assuming we have been given correct specifications) on all of our GENUINE MCB Components and kits. As it has always been, it is the TECHNICIANS RESPONSIBILITY to verify all critical specifications as shown in the factory service manual and or our custom specifications if needed. Should an exception arise during this pre-build dimensioning, contact us immediately and we will gladly offer assistance. None of the Powersports industry offers any warranty and never has because there is simply no way to control the end user variables that have a direct and immediate effect on the effectiveness of our components. If you DO see a warranty offered you should seriously question why.....

The following procedure is mandatory when rebuilding most any modern 2-stroke with a Torodial combustion chamber (i.e. Rotax, BRP, Skidoo, Suzuki, etc). This outline is designed for the do it yourselfer with limited tools although it does require a simple dial indicator (in .001 maximum) as well as a deck bridge.

Look closely at the photos and you will see that these simple measurements are easy and VERY important to the proper operation and longevity of your build. 

This also the SAME procedure if you prefer wish to also gauge the OEM piston projection dimension.

1 - The parts needed shown below:

 2 - Dry install any base gasket in the kit and NOTE THE THICKNESS. You can try the original thickness you removed but VERY often it will need to be changed for many reasons.

3 - Install the pistons WITHOUT RINGS, in the proper orientation WITH pin bearings (clips are not necessary at this point)

4 - Lightly lube the piston skirts and install the (CLEAN) cylinders and lightly tighten the cylinder bolts (not shown in pic).

Zero your indicator to the top of the cylinder casting 

Showing the zeroed gauge again...

 Bring the piston to its highest possible level and note the reading, do this a few times to verify you have established top dead center. Note: this is also how OEM piston projection dimension is gauged.

Once the gauge is zeroed to the cylinder, position it now right next to the edge of the bore IN LINE with the piston pin and reverify its zeroed.

With the piston at TOP DEAD CENTER walk the gauge off the edge and let it rest on the very outmost edge of the piston but not dragging on the cylinder wall. This dimension is then recorded. (note this gauge is reading .011 down the hole)

Repeat this measurement on the other side of the piston again IN LINE with the piston pin. (note the gauge also reading the same .011 as the other side)

If the numbers vary, simply average the two numbers

Now we can do the same for the cylinder HEAD. We want to determine the depth of the quench band cut in to the head. Some engine do NOT have a noticeable cut however the quench/squish band may taper rapidly away from the bore edge.

As shown, once again zero your gauge to the sealing surface of the head

 

The blue dot below showing where we want to measure the step in the head

Again walk the gauge off the edge of the head right at the bore wall interface. Read and record this dimension. (Note the gauge here is reading .025)

 

 

Now we simply add the piston clearance dimension the head step dimension and you have an exact measurement of quench/squish. In this example we have the piston down the hole .011 plus the head step at .025 for a total of .036.

Now with this total measurement (.036), compare it to the required clearance guidelines outlined in our MCB Top-End instructions or the factory service manual.

To adjust this dimension you can simply increase or decrease quech by using a thicker or thinner base gasket. This is why MCB includes several of the critical gasket sizes in our complete kits. 

Some key additional points:

- The material used in the base gasket can have an effect on how much it yields once it is fully torqued. For instance a composite gasket will often show a tighter quench once fully torqued vs lightly tightening the cylinder bolts for just checking.  

- In general if the engine is tuned and running properly and has FRESH good quality fuel you are always safer to go TIGHTER rather than thinking that you can reduce detonation with a looser quench dimension. When quench is too loose the MSV (velocity of gasses pushed in to the combustion chamber) becomes highly detonation PRONE as fuel can puddle and these is less heat transfer.

 

Note the gasket below is a "6 hole" gasket which should measure .060

 

showing the actual measuring of the gasket and you should do the same to help compare your choices once you know what you need to install 

 

a paper style "7 hole" gasket measurement, note the variance and this is why its a good idea to validate the gasket!