Need to split crankcase to clean out broken piston parts! Very stiff, seems very tight around main bearing. Any tips?

BlAde belt torque IS TOO HIGH It's reducing the engines running speed TO IDLE ALMOST check the blade brakes are releasing fully and the blade bearing are not tight or seem to move stiffly if the blade moved by hand ige ENIGINE OFF SPK LEAD TAKEN OFF PLUGS FOR SAFTEY AND IGNITION OFF TO AVOID ACCIDENTAL HAND CRANK ROUND START HALFWAY ENGAGE THE BLADE SYSTEM SO THE BRAKE SHOES RELEASE FROM THE PULLEYS AND THE DRIVE BELT IS LOSE NOT ENGADEGED FULY TURN THE BLADE AROUND BY HAND IF THECBLADEXOR PULLEY IS HARD TO TURN UNLESS ITS CLOGGEDUP BY GRASS DEPOSITS BUILT UP IN THE DECK OR BEARING HOUSINGS TO FIX IT WILL NEED DISASSEMBLING AND CLEANING OUT OF DEBRIS THEN PUTING BACK TOGETHER IF THE PULLEYS ECT ARE NOT CLOGGED UP THEN THE BEARINGS may need either lubricating with a race bearing grease compound or or if the blade is almost impossible to turn then the blade BEARINGS are worn out And WILL need REPLACING by mechanic the deck ajustment may also be to much and its over TIGHENING The drive BELTS slowing down the engine HOPE THIS HELP WITH THE DIAGNOSIS OF FAULT CHECK THE DRIVE SYSTEM FOR THE BLADES FULY
INCLUDINGVANYVTENTIONING PULLEYS ETC UNDER THE MAIN BODY OF THE MOWER INVOLDED WITH THE BLADE SYSTEM IF ANY PULLEY ENGAEGERSXSEEM TO BE STIFF OR SEEMS TIGHT WHEN THE BELT IS LOSSEND THE PULLY BEARINGS NEED CHECKING OR LUBRICATING ETC THE BELT COULD ALSO HAVE SHRUNK TOO SMALL IF THE MOWERS BEEN STANING STILL A LONG TIME IF THE BELTS HAS DEGRADED AND SHRUNK IT WILL NEED TO BE REPLACED

does the selector drum rotate ok and is the gear selector shaft that the gear lever goes on straight and not tight in the crankcases.and have you checked the bearings on the input and output shaft are good.

First - Did you find ALL the pieces of the broken piston...if not...STOP and FIND them.. they are in the bottom of the crankcase...you engine WILL NOT live long if you have not gotten ALL the pieces--even the TINIEST ones out!! You mat have more damage than just a broken piston.. something caused it to break.. you may have cracked the crankcases...may have damaged the main bearing(YES) and/or damaged the crank bearing.. see if gas in leaking into the transmission oil.
There is an arrow on the piston that faces toward the EXHAUST port. If there are hole(s) in the piston, they go towards the INTAKE.
Do some more searching and repost the results for review!

Normaly you can remove the left crankcase on its own, however if it is proving difficult to split it is possibly tight in the crankshaft main bearing, you will need to remove the clutch at some point during this rebuild so do it now while you have the stability of the engine cases , undo the nut securing the crankshaft pinion on the r/ h side, the crankshaft is often easyer to remove from this bearing, also it is easyer to reasemble the engine and gearbox when previously dismantled correctly. Paul

Crankshaft and Main Bearings REMOVAL & INSTALLATION NOTE: When draining coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old. CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your and and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used. 2.3L Engine

1. Disconnect the negative battery cable.
2. Drain the cooling system and engine crankcase.
3. Remove the engine from the vehicle.
4. Remove the crankshaft front pulley, front cover, timing chain and sprockets, cylinder head, oil pan, oil pump and intermediate driveshaft.
5. Remove the rear oil seal cover bolts and remove the cover.
6. Remove the piston assemblies. NOTE: Mark the connecting rods and bearing caps so they can be installed in the proper cylinders.
   
7. Remove the main bearing caps and bearing.
8. Carefully lift the crankshaft out of the crankcase, so No. 3 thrust bearing surfaces are not damaged.
9. Remove the main bearing inserts from the engine block and bearing caps. NOTE: For cleaning purposes, the oil gallery and coolant drain plugs can be removed. To install:
   
10. Wash the cylinder block thoroughly to remove all foreign material and dry before assembling other components. Check to ensure all oil holes are fully open and clean. Check to ensure the bearing inserts and bearing bores are clean. Clean the mating surfaces of the crankcase and each main bearing cap.
11. Install the main bearings in the cylinder block. Note that the center front bearing is a thrust bearing and the front upper bearing has a small "V'' notch on the parting line face.
12. Lubricate the bearings with clean engine oil.
13. Carefully lower the crankshaft into place. Be careful not to damage the bearing surfaces.
14. Check the clearance of each main bearing as outlined in this section.
15. After the bearing has been fitted, apply a light coat of engine oil to the journal and bearings. Install the bearing cap in their original locations . (refer to numbers on caps). The caps must be installed with the arrows pointing to ward the front of the engine. Oil the bolts and tighten to specifications. Repeat the procedure for the remaining bearings. NOTE: Turn the crankshaft to check for turning torque. The turning torque should not exceed 4.5 ft. lbs. (6 Nm).
    
16. Install the pistons and connecting rod caps. Check clearance of each bearing, as out lined in this section.
17. After the connecting rod bearings have been fitted, apply a light coat of engine oil to the journal and bearings.
18. Turn the crankshaft throw to the bottom of its stroke. Pull the piston all the way down until the rod bearing seats on the crankshaft journal. NOTE: Guide the rod to prevent crankshaft journal and oil cooling jet damage.
    
19. Install the connecting rod cap. Align the marks on the rods with the marks on the cap, and tighten the nut.
20. After the piston and connecting rod assemblies have been installed, check the side clearance between the connecting rods on each connecting rod crankshaft journal.
21. Install the rear crankshaft seal and cover. Tighten the bolts to 5–7 ft. lbs. (7–10 Nm).
22. Installation of the remaining components is in the reverse order of removal.

hi,

ok now carefull tip the scooter onto one side, look at where the steering column attachs to the main frame, it's here you should find a bearing type collar, now you need to losen this and lubricate with a light gears, best to use a waterproof gease then tighting the collar up but
not too much otherwise your steering will again become tight.

Regards
GeWiz.

A service manual ( if you can find one ) is what you need. The second thing you need is repair parts. They are pretty hard to find. Babbitt's, a well known distributor, only has parts left in stock for the top end. Go to their website, www.babbittsonline.com/parts/viewbybrand/parts.aspx
and you can see what is left. There's also a diagram of the crankcase center halves. If you can't get the repair parts, spending hours doing an engine teardown is fruitless.

The teardown will require a flywheel puller, a case splitter, an impact driver, and a torque wrench (somewhat optional). Disassemble the top end then remove the left and right side case covers. Remove the flywheel and related electrics, the clutch, crankshaft drive gear, oil pump, kick starter, shift shaft assembly, shift drum end cap and index pins. Now remove the screws on the center case and you can then split the case. This gives you access to replace shift forks, gears, and bearings. Note that crank seals can be replaced without splitting the case.

I am not trying to be a smart *** here, but re-assembly is just the reverse of dis-assembly. This is why a manual would help. Another potential source for parts is to Google motorcycle salvage yamaha .
The normal things you would need to replace inside the center case would be bent shift forks (if shifting is the problem), busted gears, crank bearings and seals, and sprocket shaft bearing and seal. All else can be replaced by removing just the side covers.

If replacing the piston pin bearing no splitting is needed. If replacing the crank pin bearing splitting is needed. You knew that I am sure but I had to clarify. The flywheel is held in place with one washer and a nut on the end of the crank. Timing is accomplished with a woodruff key on the shaft. Using a flywheel puller tool is the proper method. It is a simple and low cost tool and it sounds like you have enough knowledge of engines to need one now and in the future. In a worst case scenario, use a mallet, striking the flywheel on four points around the perimeter of the wheel and in an "outward" direction. With some luck the flywheel will pop loose.

When you are purchasing the flywheel puller, buy a case splitter also. Also reasonably low cost, it makes the splitting clean and easy. I strongly suggest you install new crank bearings and seals. Whatever caused the crank pin bearing to go bad did not do the crank main bearings any good either. I would hate to see you have to split the case again eight weeks from now.

How are you planning to separate the crank halves, re-assembly and truing of the crank? The dealer should do this part. I can't find a free repair manual on the web but the next best is a parts diagram. Go to the site below where you can see a parts diagram for your specific bike. You will select the actual brand, year, model, etc., once you go to the site. Part numbers and prices are also shown. You can order parts from this site. In the event no price is shown on a particular part, the part is not in stock.
www.babbittsonline.com/pages/parts/viewbybrandand/parts.aspx

Top rating on this solution? Thanks!

I have a 2004 Polaris 500 with the same knock. Tear down shows tight lower rod bearing and wrist pin. The piston fits tight at .0015 clearance. The balancer seems OK also but did not split the crankcase.

Many craftsman compressor are built by champbell hausfeld using a dry type of cylinder and piston (no oil, no crankcase). If dry type, check for worn cylinder and piston ring. Pieces of the vinyl ring can jamb between the reed valves in the head causing air to escape from the intake. If your compressor has a crankcase and oil, check for broken reed valves in head. Spray soap solution on hoses, checkvalve, drainvalve, and fittings to check for leaks. Most likely problem is reed valves broken or open. Parts are available from sears or match parts to chpower.com. enjoy