Jonsered 630 non starter

[highlandspanner]

Hi all, I`m a newbie and a forum virgin so please be gentle with me. Here in nw Scotland which is v. remote and hard to scratch a living i`ve started a small engine repair service after completing a correspondence course from the good ol` US of A. (I know it`s chicken feed to you lot but it was all that was available- there`s nothing over here and you`ve got to start somewhere, nobody`s born doing anything). Anyway, business is reasonable up until now, and I apologise for bringing that old chestnut to the fore again-got a Jonsered 630 Super that was not running, never been touched in 10 years, pulled the carb off (Tillotson) which was gunked up managed to get a new genuine diaphragm/gasket and float needle kit from US, stripped, cleaned, blew thru everything, installed new kit, new s/plug, clean fuel and pulled the rope and you guessed it --nothing except an arm like Popeye. Looked on here and read a few threads about said machine. Intrigued about the not using the new supplied gasket between the carb and block. Something about impulse passage?? totally over my head with that. The original gasket is the same thickness (like thick card) as the new one but slightly wider-should I reuse that, there was reference to a thin paper type original gasket on the forum. Got spark, plug is wet, so should I be hinking about a vac leak somewhere? Customer says v. difficult to start and won`t idle. Should I just concentrate on cooking?? Thanks in advance

 

[o8f150]

if you have fuel and spark,,check compression,,,,,, it also might be flooding out too

 

[Cantdog]

Hey Highlander.....the deal with the carb to isolation block (manifiold) gasket is that most aftermarket gaskets are not large enough around the outside to completely cover and seal the impulse corridor. This is mostly a concern on the older Jonsereds but may be as well on the 630. But my guess is that if you have spark and your plug is wet, it is either a compression issue or perhaps your sparkplug is done. I have had them fire fine out side but would not fire under compression. I am also someone who hates to overlook the obvious. As a whole (humans) we always assume a complex issue when often it is not. Make certain of your plug by either using a new one or one of known goodness. (Simplest first!!) There are a number of probable issues but eliminate the easiest first. There is help here and you will get it....

 

[MechanicMatt]

Basics AIR FUEL SPARK

Compression at least 125 psi, would like to see more

Fuel start 1 1/4 turns out on the screws

Spark plugs are cheap always try a "known good" one

good luck, and when you do get her running share what you found. Keep telling your self your gonna get it, don't ever doubt your self.

 

[Chris J.]

Owahrudoon, muhn? Welcome to AS!

I was going to offer a Jonsered 630 Service Manual, but I don't have one :msp_thumbdn:.

Aw ra best!

 

[vhmtach38]

When you reinstalled the carb kit. Did you hook the atmospheric fuel metering diaphragm to the underside of the cover? Because if you didn't it will push way down on the fuel metering arm and needle and let in too much fuel.
This happened to me once on your same model. And only one turn out on both high and low needles to start then adjust accordingly. Good Luck!

 

[highlandspanner]

When you reinstalled the carb kit. Did you hook the atmospheric fuel metering diaphragm to the underside of the cover? Because if you didn't it will push way down on the fuel metering arm and needle and let in too much fuel.
This happened to me once on your same model. And only one turn out on both high and low needles to start then adjust accordingly. Good Luck!

Hi folks, sorry not replied yet, but been working away. Anyway story so far-installed new carb kit and hooked the metering diaphragm to the arm that lifts and drops the needle, (did have flooding issues-thanks vhmtach38), got 140 psi compression, got fuel at spark, screwed high and low needles 1 turn thru to 11/4 turns, checked air gap, tried new sparks-did notice when testing for spark on c/head that spark was blue but not massive. Saw ran for a few secs very fast then died again. Could a dodgy coil be causing me grief (dodgy coil could also be the story of someone`s life-literally!) . Anyway as far as I`m aware there is fuel, spark, compression and still no bang-any clues? To top it all off the weather`s miserable and the midges are hungry

 

[vhmtach38]

try lowering (bending) your metering arm a hair lower at a time to adjust your fuel input

 

[highlandspanner]

Hi folks, guess what? Went to have another look at saw and thought what the heck I`ll give it one last pull and lo and behold it spluttered into life! Alot of fuel spurted out of the muffler and away we went. Amazing! Ithink hooking the metering diaphragm onto the needle jet arm and then leaving it overnight ettled things down enough for starting. The only problem now is a pool of chain oil puddling evey time I leave it standing. Suggestions anyone-we`re on a roll now. Big, big thanks to all especially vhmtach38
What a fantastic feeling it must be to share knowledge-maybe I`ll find out soon.:yourock: