break in question

Another Bucker said:

I've vac and pressure tested per factory service manual before and after the rebuild. Still think it is strange no leak was found when it scored the piston and jug. I have convinced myself since that first failure was caused by lean/epa mandated carb setting [from the factory] and stale 87 octane 50:1 fuel mix plus operator not shutting it down when it started to over heat. Now I'm having second thoughts on my diagnosis. Maybe I'm being paranoid but my other new saws didn't need as many adjustments during their break in period. Are the piston and jug [cylinder] seated during factory assembly? Does the Intellicarb not like holding adjustment with out limiters?

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Another Bucker said:

Hello to all. Excellent site. I've been lurking for months...anyway I've had to install a new top end on my brother's ms290. Factory parts rebuilt carb, vac and pressure tested good before and after, removed carb adjustment limiters, and started to break in. The saw is on the third full tank of fuel and I'm still having to fine tune the carb more than I would have thought. I set it pretty rich on the high side for the first tank but by the end of that tank it turned more rpm but still had a rich burble at wide open out of the cut. Second tank half way gone had to back the high out an eighth of turn to keep that same burble. Third tank 3/4 gone same thing [another 8th or 16th] richer still. High side out about a turn and a half. Is this typical for a rebuild?

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Another Bucker said:

Thanks for the help on everyone's favorite saw Fuel and Impulse lines hold pressure and press on firmly. Any tips on pressure and vac testing carb? Attached is a pic of the plug. It looks ok to me but what do you think?

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Another Bucker said:

I've vac and pressure tested per factory service manual before and after the rebuild. Still think it is strange no leak was found when it scored the piston and jug. I have convinced myself since that first failure was caused by lean/epa mandated carb setting [from the factory] and stale 87 octane 50:1 fuel mix plus operator not shutting it down when it started to over heat. Now I'm having second thoughts on my diagnosis. Maybe I'm being paranoid but my other new saws didn't need as many adjustments during their break in period. Are the piston and jug [cylinder] seated during factory assembly? Does the Intellicarb not like holding adjustment with out limiters?

Click to expand...

Another Bucker said:

Hmm... I just went back and reread a pile of threads about limiter caps. Lots of people recomend moddifing the limiters so you can keep them but have full adjustment on the mixture screws. Seems I've been lucky with other saws adjustment screws not vibrating out of tune. Guess I got hung up on the removal part.

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