Compression release?

How easy is it to start up a 500 with a compression release?

I am kind of curious what folks say. For the four stroke it has a compression release on the bar and once upon a time a cable to a ramp thing at the kick starter. I only use the lever to get the engine to a particular spot before kicking.

You have some 90cc Husqvarna chainsaw don't you. 385 perhaps how much easier does that make starting?

I know it is a Husqvarna forum but the Honda system on outdoor power equipment that raises the exhaust valve a bit until the thing runs works real well.

I have a 82 cr500 with a chainsaw button about an inch down the back of the cylinder .
Stock internal rotor ignition . Stock worn out 44mm carb
Choke on . Push kicker through twice . Click decomp . Get it just past tdc . Kick the kicker right through it's stroke .
Hasn't ever not started in the last couple of years .
Can start it left legged if needed . Given the choice I stand on the folded up ramp and kick it right footed
Put it in the barrel . Putting it in the head is for the uneducated
Not a fan of victa auto compression releases . For one they are ugly as sin . The are naturally open all the time so the chamber is open to air . Also there is enough vacuum at kicking speeds to close it . Aswell as they make it hard to find tdc

Decomp is grest . Also is less wear/stress on crank cases and kickstart gear train

SilverstreakNZ that's on the rear of a 500 air cooled cylinder?

Does a compression release make the 500 feel like a 125 when you kick it?

silverstreak,
I am considering putting a decomp on my 500. How large a hole in the cylinder liner does it require? Any particular brand you prefer? Any pictures or info would be appreciated.
Thanks, Steve

The thru hole should be smaller than the size of the valve on the compression release incase it ever breaks it can't get into the cylinder. That's my plan. The threaded hole for the chainsaw release is 10.1 mm.

Mine is ac . The decomp is stock blue button one from any husqvarna chainsaw .
The hole should be smaller . Like 3or 4 mm . Just any size smaller than the valve head on the decomp .

Yes I know , husky forum but wanted to share this anyway . I agree with silverstreaknz , put in the cylinder . Pictures are from an 81 Maico 490 . As you see , Maico put theirs in the cylinder , offset on an angle , my guess to clear the carb . They came stock with a 14 mms comp release and drilled and tapped all the way thru the liner . The top of the hole measured 24 mms to top of the liner . Beware that compression releases are can have different lengths and if too long can hit the piston when open .
Since Maico tapped their comp release hole all the way thru , carbon can be cleaned from the hole with the correct tap or make your own tool to clean the threads out of an old spark plug as I did . I was told some 490 owners are replacing the 14 mms releases with 18 mms compression releases that came on the 83 490's .
I will say that the 83 490 is easier to kicker than the 81 490 . Neither feels like a 125 but you can feel the difference , especially if you forget to open the compression release .

I have some brand new Suzuki type compression releases like the one above with the sparkplug thread. I have some 70's cylinder heads with this extra threaded hole. This new cr cable setup is on eBay. I also have some adapters that have the sparkplug thread with the 10 mm thread for the chainsaw compression release also from eBay. There available in different lengths sparkplug thread wise. Search for compression release.

Yea someone drilled my barrel to that extent . Only had a broken off spark plug in it when I got the bike . I turned up a piece of steel to fit the two together .
There is enough meat to drill a 4 mm through the bore then take the 10 mm drill 2/3rds the depth and cut a thread for the decomp .

I wouldn't say it kicks like a 125 because the ratios are still less than ideal . In that you have to find tdc and kick all the way through to below the peg to spin the motor over twice m but it now will spin over twice and that's what makes it start

That's what I use . This one needs the tiny hole enlarged and prolly anothe hole drilled opposite it
So they are tunable to an extent also

Obviously you need someone to get an end mill and make a flat surface through some fins

Free from the husqvarna chain saw shop

Put a spacer on it if it has too much thread for your hole .

I figure a counterbore or sweep with a small pilot should work. Drill a small thru hole first then sweep the outside. This gives a flat surface for the washer on the cr to seal. Probably rotary file the fins for clearance to get to the meat of the cylinder. Or plunge an end mill. Your right. I just hope there's enough meat/ thickness on the cylinder wall to thread this in.

they are real easy to kick if you have a buddy do it for you.

There's plenty of meat there to work with

My son was starting it, but the riding area has a hill at the car. Roll it, put it in second and pop it. I only stalled it three times in years.

Looks great silverstreaknz.

Next time you assemble it burnish some moly paste into the pores of the sleeve and piston skirt.

Old photos . It's getting a piston shortly . That piston is on its 3rd ring .

I've been looking at the compression release option for my buddys 420 Auto there are some with a shorter thread reach,I wonder if you you will get the same effect if you make the thread hole just deep enough to open the release and then a smaller hole in to the cylinder or head will it still give the desired decompression. I'm thinking if you go through the cylinder with a smaller hole there would be less chance of a ring snagging the hole.

Why is it bad to put one in the head? I installed a chainsaw type one in the head of my 1983 Yam IT490 and it seems to work fine.

Has any one done the drill through the barrel to the exhaust port which eases kicking compression but the opening hole is too small, 2/3mm perhaps, to effect running?

"Has any one done the drill through the barrel to the exhaust port which eases kicking compression but the opening hole is too small, 2/3mm perhaps, to effect running? "

I have a 420 cylinder that has that feature. It could be original for all I know. The 420 cylinders look like the casting from the 430 air cooled with some machined off the top and bottom, of the two I have to examine they were not done the same way.

That hole I see in Yamaha RD400 twin street bikes.