Can head bolts be changed one at a time with out removing head on crf 450x

Question edited for clarity.
Question moved to model category.

Torque Specifications - Honda CRF250X Owner's Manual ...

ManualsLib https://www.manualslib.com > manual > Honda-Crf250x

Honda CRF250X Manual Online: Torque Specifications. ENGINE Torque Item N•m kgf•m 1 Cylinder head cover bolts 10 1.0 2 Exhaust pipe joint nuts 21 2.1 3 10 ...

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HONDA CRF250X

Honda http://owners.honda.com > 2005 > 2005_crf250x
side cover bolt (8). 6. Install the collar (7) and seat bolt (9) tighten the bolt to the specified torque: 20 lbf·ft (26 N·m, 2.7 kgf·m). Servicing Your Honda.
180 pages ..

Air cooled 50cc motors usually have 4 long bolts holding the head on, they go up through the 'jug' and through the head to bolts under a decorative cover or just out inthe open. remove nuts or entire bolts and then use a mallet to whack the 'jug' (cylinder) to break it free of the lower gasket, pull jug up and off piston, remove old piston by circlips or other retention and install new one. pinch rings and work jug back over piston, lower onto case gasket (if you didnt rip it removing it) and button back up. Check cylinder before replacing piston to make sure a new one will work. If the walls are scored, you will have to get it bored and use a +.25mm piston.

CHECK BELOW..


Tightening torques
Bolted connections Tightening torque
Bolts, nuts M 6 10 Nm
M 8 20 Nm
M 10 45 Nm
M 12 60 Nm
Deviating from above
Exhaust pipe to manifold 40 Nm
Installation
Note
t Only remove the new cylinder head gasket from its packing immediately before installing.
t Handle the new gasket with extreme care. Damaging will lead to leaks.
- Place a clean cloth in cylinders so that no dirt or emery cloth particles can get in between cylinder wall and piston.
- Also prevent dirt and emery cloth particles from getting into the coolant.
- Carefully clean cylinder head and cylinder block sealing surfaces. Thereby ensuring that no scoring or scratches are formed (when using abrasive paper the grade must not be less than 100).
- Carefully remove metal particles, emery remains and cloths.
- Set No. 1 cylinder piston to TDC and then turn crankshaft back slightly.
- To centralize, screw guide pins from 3450/1 into front outer holes for cylinder head bolts-flechas-.
- Place the new cylinder head gasket in the centralizing pins -A-. Lettering (Part No.) must be readable.
- Fit cylinder head, screw in 8 remaining cylinder head bolts and tighten by hand.
- Remove the guide pins with tool 3450 by the bolt holes. To do this, turn the tool left until the pins are removed.
- Fit remaining cylinder head bolts and tighten hand-tight.
- Tighten cylinder head in tightening sequence as follows:
- Tighten all bolts to 30 Nm.
- Then tighten all bolts a 1//4 turn (90 °) further using a rigid wrench.
- Then tighten all bolts again a 1/4 turn (90 °) further.
Note
There is no requirement to retighten the cylinder head bolts after repairs.
The rest of the assembly is basically a reverse of the dismantling sequence.
Note
When the camshaft is turned, the crankshaft must not be at TDC. Danger of damage to valves or piston crowns.
Installing toothed belt and adjusting valve timing > Chapter.
Filling with new coolant > Chapter.
- Interrogate fault memory > Chapter.

clean the carb and check settings , also timing and valve clearences !

let me see if i can get some info 4 you.

edit
REMOVAL

1. Drain the coolant and disconnect the upper radiator hose.
2. Remove the breather hose (between the air cleaner and the head cover).
3. Remove the air-intake hose.
4. Remove the vacuum hose, fuel hose and coolant hose.
5. Remove the cables from the spark plugs. The cables should be removed by holding the boot portion.
6. Remove the ignition coil.
7. Remove the power steering oil pump and bracket.
8. Remove the intake manifold.
9. Remove the heat protector and exhaust manifold assembly.
10. Remove the coolant pump pulley and the crankshaft pulley.
11. Remove the timing belt cover.
12. Remove the timing belt tensioner pulley.
13. Remove the timing belt.
14. Remove the head cover.


15. Remove the cylinder head assembly. The cylinder head bolts should be removed by using Special Tool, Cylinder Head Bolt Wrench (09221-32001) or equivalent, in the sequence as shown in the illustration in two or three steps.
16. Remove the gasket pieces from the cylinder block top surface and cylinder head bottom surface. NOTE: Make sure that the gasket pieces do not fall in the engine.

INSTALLATION

1. Clean all gasket surfaces of the cylinder block and the cylinder head.
2. Install a new cylinder head gasket onto the cylinder head assembly. Apply sealant to the gasket and do not reuse the old cylinder head gasket.


3. Install the cylinder head bolts. Starting at top center, tighten all cylinder head bolts in sequence as shown in illustration, using the Cylinder Head Bolt Wrench (09221 - 32001) or equivalent. Repeat the procedure, re-tightening all cylinder head bolt to the specified torque. (torque spec is Cold Engine 105-115 Nm (76-83 ft lb) )
4. Install the timing belt tensioner pulley.
5. Install the timing belt on the camshaft sprocket, making sure that the tension side is tightened by turning the camshaft sprocket in reverse, all timing marks are in alignment.
6. Adjust the timing according to "Timing Belt"
7. Install the rocker cover and tighten the bolts to the specified torque. Tightening torque: Rocker cover belt:

2.5-3.5 Nm (25-35 kg.cm, 2-3 ft. lbs.)

8. Install the timing belt cover.
9. Install the new intake manifold gasket and the intake manifold. Tighten the nuts and bolts to the specified torque.
10. Install the new exhaust manifold gasket and the exhaust manifold. Tighten the exhaust manifold attaching nuts to the specified torque.
11. Install the surge tank and tighten the nuts bolts to the specified torque.
12. Install the power steering oil pump and bracket.
13. Install the ignition coil.
14. Install the air intake hose.
15. Connect the vacuum hose, fuel hose and water hose.
16. Install breather hose.

You need to remove the fuel tank and then the engine. You then remove the top head by removing the four bolts holding the head and cylinder jug on. slide the jug upwards off of the piston. To remove the piston you will need to separate your case

This is the complete procedure from the service manual on how to replace the timing belt start to finish, start over to assure u get it right, if u mess up the engine will be damaged

Removal for 1.6L engines : ONLY 2006 to 2009 CARS


Engine removal is not required for this procedure.

1.Remove the engine cover.

2.Remove the RH front wheel.

3.Remove the 2 bolts and RH side cover.

4.Temporarily loosen the water pump pulley bolts.

5.Remove the alternator drive belt

6.Remove the air conditioner compressor drive belt

7.Remove the power steering pump drive belt

8.Remove the 4 bolts and water pump pulley.

9.Remove the 4 bolts and timing belt upper cover

10.Turn the crankshaft pulley, and align its groove with timing mark "T" of the timing belt cover. Check that the timing mark of camshaft sprocket is aligned with the timing mark of cylinder head cover. (No.1 cylinder compression TDC position)

11.Remove the crankshaft pulley bolt and crankshaft pulley

12.Remove the crankshaft flange

13.Remove the 4 bolts and timing belt lower cover

14.Remove the timing belt tensioner and timing belt.

15.Remove the bolt and timing belt idler

16.Remove the crankshaft sprocket

17.Remove the cylinder head cover.

(1)Remove the wire harness bracket

(2)Remove the ignition coil.

(3)Remove the PCV (Positive Crankcase Ventilation) hose and the breather hose from the cylinder head cover

(4)Remove the engine cover bracket

(5)Loosen the cylinder head cover bolts and then remove the cover and gasket.

18.Remove the camshaft sprocket.

Hold the portion of the camshaft with a hexagonal wrench, and remove the bolt with a wrench and remove the camshaft sprocket.

INSTALLATION:

1.Install the camshaft sprocket and tighten the bolt to the specified torque.

(1)Temporarily install the camshaft sprocket bolt

(2)Hold the portion of the camshaft with a hexagonal wrench, and tighten the bolt with a wrench
Tightening torque :78.5 ~ 98.1N.m (8.0 ~ 10.0kgf.m, 57.9 ~ 72.3lb-ft)



2.Install the cylinder head cover.

(1)Install the cylinder head cover and bolts
Tightening torque :7.8 ~ 9.8N.m (0.8 ~ 1.0kgf.m, 5.8 ~ 7.2lb-ft)

(2)Install the engine cover bracket

(3)Install the PCV(Positive Crankcase Ventilation) hose and breather hose to the cylinder head cover.

(4)Install the ignition coil.

3.Install the crankshaft sprocket

4.Align the timing marks of the camshaft sprocket and crankshaft sprocket with the No.1 piston placed at top dead center and its compression stroke.

5.Install the idler pulley and tighten the bolt to the specified torque.

Tightening torque :42.2 ~ 53.9N.m (4.3 ~ 5.5kgf.m, 31.1 ~ 39.8lb-ft)

6.Temporarily install the timing belt tensioner

7.Install the belt so as not give slack at each center of shaft. Use the following order when installing timing belt.
Crankshaft sprocket →idler pulley →camshaft sprocket →timing belt tensioner

8.Adjust the timing belt tension.

(1)Loosen the tensioner pulley mounting bolt and apply tension to the timing belt.

(2)After checking the alignment between each sprocket and each timing belt tooth, tighten the mounting bolt and one by one.

Tightening torque :19.6 ~ 26.5N.m (2.0 ~ 2.7kgf.m, 14.5 ~ 19.5lb-ft)

(3)Then recheck the belt tension.
Verify that when the tensioner and the tension side of the timing belt are pushed in horizontally with a moderate force [approx. 49N (11lb)], the timing belt cog end is aprox. 1/2 of the tensioner mounting bolt head radius (across flats) away from the bolt head center.

4)Timing belt tension measuring procedure
(by a sonic tension guage)
Rotate crankshaft in clockwise direction to set 1st piston on top dead center (TDC) and rotate crankshaft in counterclockwise to 90° then measure the belt tension in the middle of tension side span (in arrow direction of above illustration) by free vibration method.


9.Turn the crankshaft two turns in the operating direction (clockwise) and realign crankshaft sprocket and camshaft sprocket timing mark.


10.Install the timing belt lower cover with 5bolts

Tightening torque :7.8 ~ 9.8N.m (0.8 ~ 1.0kgf.m, 5.8 ~ 7.2lb-ft)

11.Install the flange and crankshaft pulley, and then tighten crankshaft pulley bolt. Make sure that crankshaft sprocket pin fits the small hole in the pulley.

Tightening torque :137.3 ~ 147.1N.m (14.0 ~ 15.0kgf.m, 101.3 ~ 108.5lb-ft)

12.Install the timing belt upper cover with 4 bolts.

Tightening torque :7.8 ~ 9.8N.m (0.8 ~ 1.0kgf.m, 5.8 ~ 7.2lb-ft)

13.Install the water pump pulley and 4 bolts.

14.Install the power steering pump drive belt

15.Install the air conditioner compressor drive belt

16.Install the alternator drive belt

17.Install the RH side cover with 2 bolts

18.Install the RH front wheel.


Tightening torque :88.3 ~ 98.1N.m (9.0 ~ 10.0kgf.m, 65.1 ~ 72.3lb-ft)

19.Install the engine cover with bolts.


Tightening torque :3.9 ~ 5.9N.m (0.4 ~ 0.6kgf.m, 2.9 ~ 4.3lb-ft)

Remove impeller using a 10mm socket. It is a standard thread so nothing special needs to be done.get back to me if need more info

Assuming that you have already removed the heads and dealt with the clearance problems of the lower-rear head bolts on both banks (you have to remove and install the heads with the lowest-rear bolts in the head -- secured with something like rubber bands -- in order to get the clearance needed):

To install:

1. Rotate the crankshaft counterclockwise 45 degrees. The crankshaft keyway should be at the 9 o'clock position viewed from the front of the engine. This ensures that all pistons are below the top of the engine block deck face.
2. Rotate the camshaft to a stable position where the valves do not extend below the head face.
3. Position new head gaskets on the cylinder block. Install new bolts in the lower rear bolt holes on both cylinder heads and retain with rubber bands.

New cylinder head bolts must be used whenever the cylinder head is removed and reinstalled. The cylinder head bolts used on these engines are a torque-to-yield design and cannot be reused.

1. Position the cylinder heads on the cylinder block dowels, being careful not to scratch the surface of the head face. Apply clean oil to the new cylinder head bolts, remove the rubber bands from the lower rear bolts and install all bolts hand-tight.
2. Tighten the new cylinder head bolts as follows:
1. Torque the bolts in sequence, to 22-30 ft. lbs. (30-40 Nm).
2. Rotate each bolt in sequence 85-95 degrees.
3. Rotate each bolt in sequence an additional 85-95 degrees.
3. Position the heater return hose and install 2 retaining bolts.
4. Rotate the camshafts using the flats matched at the center of the camshaft until both are in time. Install suitable cam positioning tools, on the flats of the camshafts to keep them from rotating.
5. Rotate the crankshaft clockwise 45 degrees to position the crankshaft at TDC for No. 1 cylinder.


The torque pattern follows:

left bank:
8 9
4 5
2 1
6 3
10 7


right bank:
9 8
5 4
1 2
3 6
7 10

My advice dont do it your self the new crf motors are quite complicated and unless you are experienced i wouldnt attemp it.