Engine rebuild

[DavidG]

Had my Honda motor re boarded with new over sized piston & rings. After putting it back together it runs but a lot of smoke & not much power. Any suggestions?

 

[MRCo.]

First reaction is its bored too much for the ring diameter. You are bypassing oil, giving smoke. Bypassing compression in to the crank case, losing power. Oil from the crank case breather at all?

 

[RoperGuy]

Would try making your air/fuel bit richer would be running lean I u haven't adjusted

 

[DavidG]

How would I do that? I thought that mixture was pre set and couldn't be adjusted.
I had it professional boarded out, with the correct cylinder to piston clearance.

 

[RoperGuy]

I think fist you should look into an compression test

 

[bertsmobile1]

Tip the oil out.
Go to Walmart and buy a quart of the cheapest oil you can find.
run the mower who in heavy grass to put a load on the motor.
This will help seat the rings which would appear not to have happened.
If it does not clean up in 10 to 15 minutes take the engine back for warrante repairs.

 

[motoman]

Boring/piston fitting is an exact science. I have been burned at a so called "pro shop" which could not hold the proper tolerance. I hope this is not true in your case. Careful measurement accross the piston skirt must be compared to the true bore diameter. There used to be some clearance checks made with a feeler gauge inserted between bore and piston. A spring scale hooked on the feeler gauge must show the specified withdrawal force. I only mention this so the professionals can comment and perhaps save you a tear down to measure the piston. If you are "sure " of the piston diameter you should get someone to carefully measure the bore and compare. No thicker oil film will solve an overbore problem IMO.

 

[ILENGINE]

Every time I take an engine for boring I also take the specs from the manufacturer with me so they know how to measure the piston skirt, cylinder clearance. If they don't measure the clearance according to the manufacturer they can really screw stuff up.

 

[bertsmobile1]

Every time I take an engine for boring I also take the specs from the manufacturer with me so they know how to measure the piston skirt, cylinder clearance. If they don't measure the clearance according to the manufacturer they can really screw stuff up.

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I gave up on geting them bored and now do it myself.
Problem is very few people get mowers bored so very few shps have the faintest idea of how to do the job and in particular how to mount the cases.
Most car engines are bored by bolting down either the sump or the head so when confornted with a mower engine rather than make up an L block closing plate to bore the engine they just fit it by the head bolts and you end up with an oval bore.

 

[Rivets]

My first question is, did you check the ring end gap in the newly bored cylinder before installing? Your cylinder my be bored correctly, but you received and installed the wrong rings. Second question, are the rings installed in the correct order and proper edge facing up? Third, did you replace the piston also? Can you post the following info:
1. All numbers for the engine.
2. Part number for the ring set.
3. Part number for piston.
4. What diameter was the cylinder bored to?
5. Was the block washed and cleaned multiple times before reassembly.
6. Are you sure the rings were staggered when install?

This will help us diagnosis possible problems.