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Can a GXV120 be rebuilt?

#1

R

Ralph63

I took it to my local Honda dealer, he told me to forget about trying to rebuild the motor, actually said cant be done, started showing me new models.

I want to fix it.

Hard to start cold, but impossible to start once warm.

Seems to have lost compression, I was thinking a hone & rings, or maybe a burnt valve.

Ive rebuilt many auto engines before, im sure I can handle a mower engine with some guidance.

Its an old model, made in japan, HR194 / GXV120-1199573

can someone tell me if its an A1, A2 etc for parts reference?

having trouble uploading photos.

Mark


#2

M

mechanic mark

<a href="http://www.amazon.com/Honda-GXV120-GXV160-Engine-Service/dp/B00HUZAK7G" target="_blank">http://www.amazon.com/Honda-GXV120-GXV160-Engine-Service/dp/B00HUZAK7G</a>        Absolutely yes,purchase this manual, valuable information for your engine rebuild.


#3

R

Ralph63

<a href="http://www.amazon.com/Honda-GXV120-GXV160-Engine-Service/dp/B00HUZAK7G" target="_blank">http://www.amazon.com/Honda-GXV120-GXV160-Engine-Service/dp/B00HUZAK7G</a>        Absolutely yes,purchase this manual, valuable information for your engine rebuild.

thanks for that, I cant purchase from amazon, can give me a description of the manual so I can search for it?


#4

B

bertsmobile1

Honda sell their manuals on both evil pay and Amazon.
Other than that they can be ordered through a Honda dealer but they are more expensive that way and take a lot longer.
Yes they can be rebuilt but not by a dealer where is become uneconomic.
There is 4 - 6 hours in it plus parts plus machining by which time the rebuild exceeds the replacement price
There are 4 oversize pistons available and 2 undersize con rods.
A full gasket kit is around $ 40 ( AUS ) so it costs me around $ 200 to rebuild one in parts & machining.
As such there are 6 of them in the graveyard waiting rebuild or plifering.


#5

R

Ralph63

Honda sell their manuals on both evil pay and Amazon.
Other than that they can be ordered through a Honda dealer but they are more expensive that way and take a lot longer.
Yes they can be rebuilt but not by a dealer where is become uneconomic.
There is 4 - 6 hours in it plus parts plus machining by which time the rebuild exceeds the replacement price
There are 4 oversize pistons available and 2 undersize con rods.
A full gasket kit is around $ 40 ( AUS ) so it costs me around $ 200 to rebuild one in parts & machining.
As such there are 6 of them in the graveyard waiting rebuild or plifering.

thanks burt, just found one EBay but $56USD, think ill wait for a better deal.
I just rang my boring guy, he cant do the Honda bore because of the size and shape of the engine housing, he doesn't have the jig anymore, only does bike motors now.
So I hope the std piston can back in.
I might start pulling it down now, ill post how it goes.


#6

B

bertsmobile1

thanks burt, just found one EBay but $56USD, think ill wait for a better deal.
I just rang my boring guy, he cant do the Honda bore because of the size and shape of the engine housing, he doesn't have the jig anymore, only does bike motors now.
So I hope the std piston can back in.
I might start pulling it down now, ill post how it goes.

That is the price from Honda.
Unless you find a used copy, that is what you are going to pay


#7

R

Ralph63

So this is where its at.

Ive moved ahead without the shop manual.:ashamed:

Two head bolts were loose so gasket was leaking. No compression.

I nearly put it back together but decided to pull the flywheel off, the key was sheared so that explains the misfiring which I didn't mention before.

Ive gone this far so may as well keep going, new rings at least. I read in a forum I should buy the Honda rings with the 3 piece oil control rings?

Now how to split the case to remove rod from crank. Back to the sand pit.



gxv120 lid off.jpgGXV120 head gasket leak.jpgGXV120 head 1.jpgGXV120 cylinder.jpgGXV120 crank keyway 1.jpgGXV120 flywheel keyway 1.jpg


#8

B

bertsmobile1

So this is where its at.

Ive moved ahead without the shop manual.:ashamed:

Two head bolts were loose so gasket was leaking. No compression.

I nearly put it back together but decided to pull the flywheel off, the key was sheared so that explains the misfiring which I didn't mention before.

Ive gone this far so may as well keep going, new rings at least. I read in a forum I should buy the Honda rings with the 3 piece oil control rings?

Now how to split the case to remove rod from crank. Back to the sand pit.



View attachment 33882View attachment 33883View attachment 33884View attachment 33885View attachment 33886View attachment 33888

Same way as you do any head, criss cross across the cases 1/4 turn then again 1/4 turn then whip them all out
Put a dab of paint on one bolt head and the cases then remove all of the loose bolts in a clockwise mannar from the marked hole.
OR if you already have the gasket kit, trace the gasket on a corn flakes packet then push the bolts into their hole.
Polish the pto shaft with a wire wheel.
You are going to replace the oil seal in any case but you do not want to damage the running surface on the case.
I hold the shaft in some hardwood in my big vice then tap off the smaller case.


Finding loose head bolts is not uncommon.
I have a Kanga Loader in here at the moment with a GX 670 that is trashed because the owner has put in several hundred hours with loose head bolts , warping both heads , erroding the barrels & burning one exhaust valve.
If I can weld & machine the heads and machine the barrels the parts bill will be around $ 500 and the labour well over $ 1000.


#9

R

Ralph63

Having a bugger of a time getting the cutting disc off the crank!

ive also noticed some end play in the crank.


#10

B

bertsmobile1

Having a bugger of a time getting the cutting disc off the crank!

They can rust in quite solid, penetrant, heat and more penetrant.


#11

R

Ralph63

They can rust in quite solid, penetrant, heat and more penetrant.

yep its moved about 10mm but a struggle all the way.


#12

R

Ralph63

They can rust in quite solid, penetrant, heat and more penetrant.
Its off, crankcase split, piston out (3 piece oil ring type) crank out.

Do I change the lower main bearing?

where do I buy gasket kit, rings & seals?


#13

R

Ralph63

I was bored so I decided to give the head a porting job.
before I started you could not see into the ports from the combustion chamber. I wish I took a before photo, Its a huge difference, maybe some one has an original head laying about?

this is my 1st go at the inlet port to take the sharp corner out.
inlet port 1st cut.jpg

Final cut.
Inlet port final cut.jpg

Exhaust 1st cut to take the corner out.
exhaust port 1st cut.jpg

Final cut.
exhaust port final cut.jpg

Don't know if this will make a noticeable difference but Ive got the tools so no harm in having a go.

Except for Bert, I feel like I'm talkin to myself in this thread but whatever I'm having fun.


#14

BlazNT

BlazNT

Your views are high so people are reading. I personally try not to cause confusion by piping in when someone is already taking care of it.


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