Problem with a STIHL 131R Kombi motor

[farren272]

Hi all,

This is my first post here, so be gentle :-)

I have a STIHL 131R Kombi engine, and it's recently started to get hard to pull over. If I remove the spark plus it's smooth as silk, and I have checked that the pull-cord itself is fine, so what else might be causing the issue?

When it does start, it seems to run perfectly fine.

Cheers

Farren

[Mick]

Hi Farren, and welcome to TGMF.

What you have there is a kombi unit with a 4-MIX engine. The main cause is the tappets needing adjustment, if you're lucky that will be all that's required to sort the problem.  Engine is fitted with a automatic decompressor which can't work properly if the tappets are loose.

If you're unlucky the decompressor which is part of the plastic camshaft has failed or fallen apart, as has been know to happen.

I would check the tappet clearance first.

Valve clearance
Inlet valve: 0.10 mm
Exhaust valve: 0.10 mm

[farren272]

Many thanks Mick,

I will make that my first port of call then. I've only had it since Feb so I'm hoping it's nothing too serious! :-D

Thanks again, and I'm glad I found this forum!

Farren

[Mick]

No problem, let's hope it's nothing more serious than that.

By the way, you will need a special feeler gauge to set the valve clearances on these engines, a standard one is too wide to fit between the recess in the end of the rockers. There is a way around this, but the genuine ones are very cheap. 

Example, https://www.lsengineers.co.uk/setting-gauge-stihl-part-no-4180-893-6400.html

Also make sure the cover gasket is good, ideally you should replace this gasket when you remove the cover, but you can get away with it if it's in good condition.

Also there's a vid here showing how to do it.

https://www.youtube.com/watch?v=jAylJAcF-iA