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Posted

Hi everyone,

 

New to the forum, joined as I am a bit confused... I bought a second hand 346xp a few years back and after using it a fair bit the last few months it has started to play up so I gave it a full service and tuned the carb. After a few uses it started to play up again. Checked compression and got 125 psi but only after 10 to 15 pulls, 3-4 pulls gave very little.

 

Stripped the cylinder and could see the piston and cylinder bore was scored. Checked on ebay etc. for repair kit and found either 44mm or 44.3mm kits so thought I had better measure what it has now only to find cylinder bore and piston both measure 41.7mm....??

 

Why would anyone fit a smaller piston and where did it come from...?! Seems really odd to me. Is this a standard thing to do? I haven'tffound anything useful on the Webso thought iI would try here.

 

I assume I can just buy the 44.3mm kit, fit it and get the saw working like it should have always been?

 

Any advise greatly appreciated, its the older 346xp the older one.

 

Thanks

Ben

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Posted

Are you sure you measured the bore correctly, the early 346 was 44mm the later one was 44.3, i cannot remember a bore size any different, your not measuring the piston are up??

Posted

According to operators manuals -

 

Early 346xp was 42.0 mm bore ,32.5 mm stroke and 45.0 cc displacement.

 

Late 346xp was 44.3mm bore,32.5mm stroke and 50.1 cc displacement.

 

Changed towards the end of 2007.

Posted

It's definitely 41.7mm, piston and cylinder measured 3 times. I assumed the 44mm was the old one and the 44.3mm the new one but clearly there is a 42mm as well!

 

Can I just fit 44/44.3mm kit as can't find any 42mm for cheap money?

 

thanks

Posted
According to operators manuals -

 

Early 346xp was 42.0 mm bore ,32.5 mm stroke and 45.0 cc displacement.

 

Late 346xp was 44.3mm bore,32.5mm stroke and 50.1 cc displacement.

 

Changed towards the end of 2007.

 

The production change was from 2007 week 19. :wink:

Posted

If your cylinder is good to go put a OE piston back in and get cutting. Figure out why you fried the other one or does it just need new rings?

 

I did a 372 that was 120psi. Put new set of caber rings in and it was 140psi first heat cycle ( less then a min or 2 idle and blips). Dont know what it is up to now after broken in, sold saw.

Posted

Go to my "what's on your bench thread" most cylinders are salvageable and with a meteor piston, it will be near good as new!

The 42mm was a pre NE silverside model, the smaller measurement is wear and ease in the manufacturing

Posted
The production change was from 2007 week 19. :wink:

 

:thumbup1:

 

2007-05 (May) is the first operators manual for the 50 cc 346xp

 

I only looked at March and October last night.:blushing:

Posted

Many thanks for the replies, so I guess it isn't possible to just bolt in a 44mm kit then?

 

The cylinder isn't too bad I think, as I said it does get compression but only after a good few pulls. Maybe a quick hone would be enough, I will check out the section as mentioned by Spud.

 

I think the reason it failed is because we tinkered with the carb - I checked through the exhaust port for scoring only a few weeks back, just before I serviced it and then had the carb 'tuned', and there wasn't any then.

 

Assuming I can get the cylinder sorted then I assume I can just buy the 42mm Meteor piston set off flea bay?

 

Thanks guys

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