Cracked transfer, What can i do?

[jmssaws]

I doubt it would have ever caused a problem. Nothing rides on that part of the cylinder.

 

[jmssaws]

Is a 064 cylinder still available?

 

[Stump Shot]

Have you tried just a bit of pressure behind the bridge to see if it will pop back into alignment as you go?

 

[Brewz]

It could be welded and plated again if you really wanted to save it. That would be at the cost of a new one over here.

haha, I'm not that keen.

God knows where I would get it done here anyway.

 

[Brewz]

Have you tried just a bit of pressure behind the bridge to see if it will pop back into alignment as you go?

What do you think

 

[Brewz]

I doubt it would have ever caused a problem. Nothing rides on that part of the cylinder.

Thats what I thought.
The ring runs half way down it
Its at the end of the stroke so its moving slow.

I plan to fill the gap just so there is minimal leakage and then port it.

I just ordered new Cabers for it.

 

[drf256]

As long as there is enough ring support I think you're fine. How is the intake at that part of the bridge?

If you clean it very well and leave a small space between the bridges, I bet you could use aluminum brazing on that. The capillary action will pull it into the crack space. It's the "weld aluminum with a propane torch" crap they sell at car shows. Its available on amazon from Hobart.

It melts @ 700*F IIRC. So enough to withstand cylinder heat, but not enough to warp jug or pop the plating.

I plan on trying it to modify 026 ports.

 

[Chainsaw Jim]

Chainsaw Jim cut the hell out of the lowers on a 372xp against all advice. Turned it into a decent runner by thinking outside the box.

Thank you for bringing that up, but I'd say decent is an understatement. That saw made great gains considering I didn't raise the transfers or exhaust, and the mistake of the giant freeport gap. Lol
I did a Dolmar 5100 that same exact way minus the freeport and it was a very good runner too.

The main part of the bridge is pushed into the transfer channel, away from the piston.

Here it is now that I have released the pressure on the crack

View attachment 25764

You don't want the channel you ground into it to be smaller at the bottom like you have it. That will kill your velocity. Either make the channel even or wider at the bottom.

 

[big t double]

Is a 064 cylinder still available?

yes

 

[Brewz]

You don't want the channel you ground into it to be smaller at the bottom like you have it. That will kill your velocity. Either make the channel even or wider at the bottom.

I was planning on filling the channel with devcon as it is on the exhaust side, not the intake like a bridge port should be

 

[Chainsaw Jim]

I'd run it before using any epoxy or jb weld. That small of a finger shouldn't have any affect on direction. Actually a finger port on the intake side will help pitch the flow upwards instead of at the backside.

 

[Iron.and.bark]

haha, I'm not that keen.

God knows where I would get it done here anyway.

No one here in oz that I could find wanted to touch a closed top cylinder

Nz cylinders do a fantastic job, but unless it is for a project or very rare cylinder around $450 Aussie plus shipping ain't great. USA chrome is cheaper, but shipping is higher (but cheaper overall..)

 

[Brewz]

I am thinking of going with drf's idea of using some aluminium braze to weld up the crack and then fill and smooth it.

That should help prevent movement as well

 

[Brewz]

Today, I decided to just get the job done and filled the groove in the transfer bridge with Type F devcon which is really good stuff.
I used a fine point bit and ground down into the crack a bit deeper and roughed it up to help the devcon stick

Filled it this morning, left it to sit near the fire to cure and then ground it down smooth.
It worked great!

I forgot to take a picture.

I wanted the 064 all back together so I could make bench space and I wanted to see how it ran.
I took the front off the muffler baffle, opened out the side port hole and fitted up a well opened up dual port front cover off an 066.

The pull rope is really short which makes it a bear to start.
I am going to add a longer rope and give it a run on the weekend.
Then I might delete the gasket, raise the exhaust a couple deg, drop the intake a couple deg, open out the intake and exhaust ports a bit and test it again.

What the saw is really going to need is an unlimited coil and flywheel.
I have an aftermarket unlimited coil that I used on an 066 red light but no flywheel.

Anyone got one?

 

[Brewz]

Will run it in some timber on the weekend to get it nice and hot.

Fingers crossed, but I am confident.

to be honest I dont see myself selling my 066 and I dont need 2 x 064's so I will probably sell this one and build the other one up with the unlimited coil and bing carb

 

[Mastermind]

Hi folks
I have a really nice KS Stihl 064 cylinder here that has had the spark plug thread repaired.
The thread repair is good, but whoever did it left a chunk of something hard in the motor and when they fired it up it jammed between the piston and the transfer bridge.

It totaled the piston and cracked the transfer bridge.

View attachment 25658

I was planning on porting a cylinder but figure if this one can be saved and made to run well somehow, I will use it.

What would people recommend?

Shame its on the exhaust side

I have been told it can be ground out

I've got a 064 top end you can have for shipping.

 

[Brewz]

Fantastic!

Thank you so much, that will really help me out!

PM on its way

 

[stihl saws]

As long as there is enough ring support I think you're fine. How is the intake at that part of the bridge?

If you clean it very well and leave a small space between the bridges, I bet you could use aluminum brazing on that. The capillary action will pull it into the crack space. It's the "weld aluminum with a propane torch" crap they sell at car shows. Its available on amazon from Hobart.

It melts @ 700*F IIRC. So enough to withstand cylinder heat, but not enough to warp jug or pop the plating.

I plan on trying it to modify 026 ports.

That stuff works amazingly well for small stuff. Like he said it's gotta be super clean though.

 

[Terry Syd]

Can't the 064 be fitted with an 066 jug with a bit of work (mostly elongating the base holes)? Perhaps an AM big bore kit for an 066 on the lighter 064 cases - what would be the displacement for a BB 066 jug?

 

[Brewz]

Hi Terry
Yes that has been done and I have all the bits ready to build one myself.

Jason is building them to run a husky 288 piston and has them making between 9 and 10 hp.

All I'm missing to do the job is a lathe