075 Help needed

[Waggie]

Hi guys, I have recently purchased 2 power units 1 was an 075ave and 1 was an 051ave (or at least that was listed in the sale advert, the first was a simple strip down clean and replace usual parts crank oil seals and bearings plus all gaskets fully assembled this beauty fired and run like a dream ticked over superbly and accelerated to max revs without missing a beat. Stripped down the 051 to have a look and found the it to was an 075ave just had the wrong filter cover on, however this proved a lot more troublesome having re-build it using the same parts again (crank seals and bearings plus all gaskets and also stripped and rebuild the carb, tried to fire her up only to find when I engaged the starter it snatched back violently, so needed to investigate further, I have invested in a Stihl test set (cost me £100 pic below) but I think it will prove well worth it, I have tested the ignition armature and the readings are as stated in the manual (1 ohm on primary and 8700 ohm on the secondary) so good to go, this is fitted with an electronic switching unit, so no testing needed as the manual stated when I did the spark test. So having cleaned everything and re-assembled her I tried to fire it up, and still have the same problem, that is when I engage the recoil starter it snatches back extremely violently. So guys, has anyone any ideas where to go from here??

I should also say that when I rebuilt the crank and bore assembly I did lightly coat all components with a light grade oil.[/color]

 

[muttley9050]

Had this problem with an 051 and i was advised to check all screws in the recoil casing were present and tight. I already new they weren't as I thread was bad. I fitted an insert In the thread and the recoil wa much better.

[Sawchip]

I assume with the description you gave that the flywheel has been off to do the work....is it back in the correct position ?

[Big Beech]

My 064 can also hurt the pinkies if not pulled over like a man, the 090 breaks your hand if pulled lamely!!!!

This is I think down to the timing issue, and as noted above may be relevant if the fly wheel has been off and incorrectly refitted.

[NoRush]

I have 2 075 and both have decomp buttons. 1 stays in till started the other pops out every time you pull it snatchers like a git if you not carefull