Need help installing piston

[arlen]

I tried to install the piston upgrade on my Makita 6401 to make it 79 cc.
I was able to remove the old piston and cylinder.
I installed the new piston and tried to install the cylinder.
I lubricated the cylinder and piston with two stroke oil.
I wasn't able to get the ring into the piston. I tried using a screwdriver to compress it no luck. I tried a hose clamp to try and compress it so I could push the cylinder over it no luck I would up breaking the piston ring.
So I need to order two rings [ one extra ] than try again.

I have a few questions

1] What size it the wrench for removing the cylinder screws ?
2] how much tork to tighten up the cylinder in inch pounds ?
3] Can I use the old gasket if it is in good shape ?
4] Is there a gasket for the exaust muffler to cylinder ?
5] How to I get the piston with ring in the cylinder ?
6] Does anyone have a shop repair manual in pdf ?

 

[cjnspecial]

Here's what you need to compress the piston rings....

http://www.baileysonline.com/itemdetail.asp?item=10429&catID=

 

[doc874]

I tried to install the piston upgrade on my Makita 6401 to make it 79 cc.
I was able to remove the old piston and cylinder.
I installed the new piston and tried to install the cylinder.
I lubricated the cylinder and piston with two stroke oil.
I wasn't able to get the ring into the piston. I tried using a screwdriver to compress it no luck. I tried a hose clamp to try and compress it so I could push the cylinder over it no luck I would up breaking the piston ring.
So I need to order two rings [ one extra ] than try again.

I have a few questions

1] What size it the wrench for removing the cylinder screws ?
2] how much tork to tighten up the cylinder in inch pounds ?
3] Can I use the old gasket if it is in good shape ?
4] Is there a gasket for the exaust muffler to cylinder ?
5] How to I get the piston with ring in the cylinder ?
6] Does anyone have a shop repair manual in pdf ?

Man that sucks! In the end its going to cost you more to buy two more rings then the cost of a plastic ring compression tool. Never pays to rush a job like that and doing your homework is invaluable.

 

[LouieIV]

I'm no expert, but as far as getting the cylinder and piston together you need a ring compressor (linked). You might be able to find one at an auto parts store or a small engine repair shop. Be careful with that screwdriver, you don't want to damage the cylinder.

Sorry I can't help you with anything else.

-LouieIV

 

[arlen]

Here's what you need to compress the piston rings....

http://www.baileysonline.com/itemdetail.asp?item=10429&catID=

For a 79 cc piston will a 60 mm ring comprssion work or do I need 79mm ?

 

[Nitro-Fish]

For a 79 cc piston will a 60 mm ring comprssion work or do I need 79mm ?

You'll be fine, cc's and mm's are two different things all together. The kit in the picture (worth every penny) will do most saws that you will ever work on.

 

[cjnspecial]

For a 79 cc piston will a 60 mm ring comprssion work or do I need 79mm ?

It's a 52mm piston so one of the clamps in that set will take care of it.

 

[Taxmantoo]

Is there a locating peg in the ring groove?
If so, did you find it and make sure the ring gap went over the peg?

 

[Fish]

Yes, it sounds like you have either the wrong ring for the piston, or have
tried to install it wrong regarding the locator peg.

I never use rings compressors...........

 

[Jacob J.]

One of the long-time mechanics at a rival Stihl dealer, who I'm friendly with and is one of only 55 Gold-level techs in this service area, uses his fingers exclusively to slip the rings into the bore while installing pistons.

That being said, he's got the thickest callouses on the ends of his fingers that I've ever seen. I don't want fingers like that.

 

[madrone]

I use my teeth.
:monkey:

 

[Hugenpoet]

I use my teeth.
:monkey:

So do I, but only for compressing steaks and chops.

 

[Fish]

That being said, he's got the thickest callouses on the ends of his fingers that I've ever seen. I don't want fingers like that.

They are good for other things too.

 

[arlen]

Is there a locating peg in the ring groove?
If so, did you find it and make sure the ring gap went over the peg?

first time I have replaced a piston and cylinder on a chainsaw.
2nd time I have ever replaced a piston.

So what are you talking about:monkey:

Thanks David

 

[Haywire Haywood]

Look at your piston's ring groove. At some point there will be a little pin in it. The curved ends on the ring will ride on that pin. It's there to keep the ring from turning on the piston in use and getting hung in the ports. If you don't have it lined up, the pin will keep the ring from seating in the groove and it'll be impossible to install the piston in the cylinder.

Ian

 

[Fish]

Here is a pic.

Poor, but a pic

 

[Fish]

Ok here........

 

[cbolyard]

You can compress the rings with your fingers, but it can be a real PITA to do... I've done it several times on snowmobiles. If you plan on doing a lot of work on your own saw, then the ring compressor would be $ well spent.

 

[Fish]

Actually, I use more fingernail, and it really quite easy.

Of course with my religous habits, my hands are steady as a rock.

 

[AZLOGGER]

Ring locating pins are most always located on intake side of piston,(side of piston opposite exhaust side locating arrow on top of piston)).