What's on your bench today?

[Rich2484]

My corsa was in the shed today. Bag of nails in engine sound. Head gone and needs a new one. Think the car will go scrap yard.

[GardenKit]

I assume you've checked the guts of the spark plug are all intact?

You assume correctly

[GardenKit]

Is the screw that holds the throttle valve or the choke valve missing? Other than this, perhaps someone has dropped one of the airfilter backplate nuts down the carb (unlikely) or the big end bearing has started to break down!

 

It may be we were right but the saw continuied to run and the cover has since been replaced!

 

No, carb is intact. Big end and small end appear good. I think a backplate nut may have done a little more damage

Metal embedded in piston is ferrous.

 

I think you probably were right after all.

 

I supplied this saw new 13 months ago, my stickers are white, and I put them on the cover. This cover has only a bit of sticker left on it and its yellow, a local competitors colour.

 

Now this customer used to buy his saws there, so this is from an older one, possibly one of his scrappers. I'll bet one of his guys swapped it when it would not stay on. I have asked him to try to find out.

 

I just have to get to the bottom of a problem such as this.

[spudulike]

Take a close look at the indentations in the piston and see if they are rounded, sharp, symetrical! My money is still on that damn air filter cover screw - I think it is semi circular so should give a rounded indentation here and there if the end broke off - the thing just looks and sounds like the one I have!

 

Is there any play on the ends at all - also got a Stihl 028 with a buggered big end that has bad damage a bit like that!

[GardenKit]

Take a close look at the indentations in the piston and see if they are rounded, sharp, symetrical! My money is still on that damn air filter cover screw - I think it is semi circular so should give a rounded indentation here and there if the end broke off - the thing just looks and sounds like the one I have!

 

Is there any play on the ends at all - also got a Stihl 028 with a buggered big end that has bad damage a bit like that!

The indents do look like they were caused by the lug from the screw. I am waiting for him to produce the original cover, but am pretty sure thats the cause. I,ll let you know when I find out.

cheers

[Blaisey]

Cracking thred Tons of great info

Thanks.

[spudulike]

Been out in the workshop with the dremmel:thumbup: Yup, a bit of porting.

346XP 50cc cylinder, done a muffler mod on it, now the lower transfers are blended in to the crankcase cut outs, the exhaust port has been opened up, the inlet has been opened and the upper transfer rear has had a very slight amount of metal taken off.

 

All the edges have been radiused just leaving a custom gasket to be made to get the squish right.

 

Should go like a train when done:thumbup:

[rxe]

An 090 that I got for peanuts last year. Basically sound, but when I tried to tune it, was unresponsive and erratic. Sat on a shelf for 6 months, but as the starter pawls on my other 090 broke, I thought I'd better check it over.

 

- Pressure test - good. Vac test - held 750 mbar for 5 minutes, even with me pulling it over. Perfecto.

- Some scuffing on the exhaust site, looks like it has been running lean, not a disaster, compression is good, rings appear undamaged.

-So it must be the carb. On undoing the fuel inlet, I realised the whole thing was packed with sawdust. A complete strip down, new kit, and a session in the ultrasonic bath restored it to shiny goodness.

- There was no fuel filter in the tank. One has been added...

- The air filter and front AV mount are toast, on order.

 

Reassembled and pulled it over. Started on the 5th pull, sounded good, but I wasn't going to try tuning an 090 in a built up area at 11:30 at night...

[spudulike]

The ported 346XP runs - got it together last night and fitted a black unlimited coil tonight - you can see the number 14,100 on the blue limited coil - that is the maximum revs the coil will run at before capping the revs.

 

Not good on a saw that is now capable of running at much closer to the maximum revs of 14,700rpm hence fitting the black coil - it also makes taching the saw much easier.

[ecodao]

Everyday you teach me something new Spud..

 

thanks

 

steve