Who can fit a Release compression valve on my CR500R

Henka · Dec 9, 2005

Who can fit a Release compression valve on my CR500R 1992. like the world series Drivers used on their 500 2 stroke's. and how is it done?. I know that they use to drill for it just above the carb. but who has the stuff i need for it.

Tony Eeds · Dec 9, 2005

Welcome to the site :cool:

Be sure and go to your User CP and update information relating to your location, type of riding, etc.

I am going to move this thread to the CR / KX / RM / YZ (2-Stroke) Discussion forum so it will get more views.

Grab a spot on the couch, crank up a new post here and tell us a bit about yourself. How long you have been riding, what kind of riding you prefer, where you are located, etc.

Also, please don't double post.

Again, welcome to the site, and shout if you have any questions!

Masterphil · Dec 9, 2005

Is there some physical problem why you can't start it without one? It just seems like you are trying to overcomplicate one of the simplest motors that is used today. Have you tried this starting technique, It works well with 4 strokes and big-bore 2-strokes:
Push lever down until it stops.(This brings the piston just before TDC)
Push down just a little farther, it feels like it goes though a notch. (This is bringing the piston just past TDC).
Let the kick starter return to the top of the stroke.
Imagine that you are kicking your foot all the way to the floor. You don't want a snappy quick-kick, but a fast, continually accellerating powerfull kick.

If there's some other reason why you want a decomp release on it, I'm all ears.

Papakeith · Dec 9, 2005

Drill for it just above the carb? I've got to admit I'm lost on this one.
The only type of compression relief that my 98CR500 had was a notch of sorts that is machined into the cylinder wall to relieve compression a bit while kicking it over. I had no problems with mine in that configuration. Heck I even started it barefoot a time or two.

I wonder if we are talking about the same things here.

COLEMANAPP · Dec 9, 2005

I have an '02 Husky 360 that is fitted with what they call a decompression head. Its basically an compression release valve fitted to the head of the bike and has a vacuum hose that runs to the intake manifold.The valve is open til the motor fires and the vacuum from the motor closes the fitting. The fitting is just forward of the spark plug. THe actual parts to make the auto decompression is cheap, vacuum hose and the lawnmower decompression fitting. The biggest problem with using it is that you can't just drill a whole into the head and expect it to work. The head on my bike was cast with the fitting. If you really wanted to test it, you could get an extra head and see what you could do.
My 360 was notoriously hard to kick with a really short kickstarter. With the decomp head, its easy as a 125.

Henka · Dec 9, 2005

Compression Release modification

made by Accu-Products for easy starting of big bore motocrossers and quads. Start your bike as easy as a 125 by simply pressing the thumb lever mounted on the split clutch perch. Wiseco called me when they developed the KX500 piston because they were burning out starter motors on the dyno. They sent me the KX500 jug and I visited them to see the development work continue, there dyno was loving it and your feet will too! Also used by David Hand on his Honda CR500 while competing in the AMA 500cc Nationals a few years back. He said, "I like to save my energy for the race, not starting my 500!" You must send in your cylinder for the machining and installation of the sleeve thru the water passage. It has no adverse effects on performance. Great for Suzuki 500 Quads. Too bad Service Honda 500 don't come stock with these. All World Championship WORKS 500's used compression releases if you look closely at old photos.

Henka · Dec 13, 2005

I don't have big problems to start it. I just want to make it easier. I have raced in MX. and of for almost 30 years now so i now how to start a Bike. it's just so ****ing hard when you are exhausted. and get it to stall.

steve.emma · Dec 14, 2005

just my 2 cents here. there is a guy here in new zealand that converts cylinder heads to use the victa lawnmower decompression release valve like the other guy said. it seems to be very common on the husky big bore 2 strokes. and is supposed to make them a heck of a lot easier to start.
dont know about starting a 500 but i get tired starting my 250 after a long day trail riding!

gpoints · Jan 29, 2006

Anyone have the accu-procducts compression relief mod done? We've got an '85 cr 500 that will not start cold or warm unless we tow the thing. :ahhh:

TimberPig · Jan 30, 2006

gpoints said:
Anyone have the accu-procducts compression relief mod done? We've got an '85 cr 500 that will not start cold or warm unless we tow the thing. :ahhh:

Are you sure that it isn't other problems with that bike? It sounds more like something else is amiss with it. Are you sure it is that you can't crank it fast enough to start it and not other issues?

Low compression, bad reeds, fuel system issues, and electrical issues could all make it hard to start.

gpoints · Jan 30, 2006

TimberPig said:
Are you sure that it isn't other problems with that bike? It sounds more like something else is amiss with it. Are you sure it is that you can't crank it fast enough to start it and not other issues?

Low compression, bad reeds, fuel system issues, and electrical issues could all make it hard to start.

-Compression is good (too good)
-Reeds are brand new
-Fresh Fuel
-Timing is perfect
-We have a fat blue spark

We've had other "Big Bore" bikes like a YZ 400, YZ465, IT400 & IT465.

There could be "other problems" with the bike but the bottom line is the bike is just too hard to kick over. The only way I can describe it is it's easier for me to crank my RM250 by HAND than kicking the 500 with my foot.

Honda revised subsequent designs to make the 500's easier to start but those advancements don't help us much.

motometal · Jan 30, 2006

I'm with Farmer, yes they are a bit harder to kick than some others, but if it's tuned right it should be a single kick affair, hardly enough to make you tired. Maybe you need a bit of jetting work. I rode a ktm 495 back when I weighed like 120 lbs and never had a problem, that was with a left side kicker. BUT if I would have had to kick it 20 times each time i'd go to start it, yes that would have been a bummer.

TimberPig · Jan 30, 2006

gpoints said:
-Compression is good (too good)
-Reeds are brand new
-Fresh Fuel
-Timing is perfect
-We have a fat blue spark

We've had other "Big Bore" bikes like a YZ 400, YZ465, IT400 & IT465.

There could be "other problems" with the bike but the bottom line is the bike is just too hard to kick over. The only way I can describe it is it's easier for me to crank my RM250 by HAND than kicking the 500 with my foot.

Honda revised subsequent designs to make the 500's easier to start but those advancements don't help us much.

How close is the jetting set? How is the inlet needle and seat? If it isn't sealing well, it can flood the cases, making it harder to start. How fresh are the crank seals?

The mid 80's CR 500's were well known as hard kicking bikes, and the later designs with the bleed off ports to aid in kicking helped somewhat, but it should start easier than that. If it is in mechanically good shape, and properly tuned, it should kick hard, but you should still be able to start it by kickstarting. In his tips on CR 500's Eric Gorr lists some head mods to smooth the powerband and they should also help make it somewhat easier to start, if you haven't read them, you can read them here
Honda Tuning Tips
There is no way it should be that hard to start that you have to pullstart it. It should be able to be started with a good firm kick on the kickstarter. I'm not trying to say a decomp button wouldn't be worth having, just that it sounds like the bike is starting harder than it should, and the decomp valve alone may not be the answer.

REARWHEELSLIDER · Jan 30, 2006

Oh, be a man and put some balls into kicking the machine over. What are we, ballerinas?

If the bike needed a decomp switch, it wouldve came stock with one. If my grandpa could kick over his husquarvarna 650 two stroke in 1979, you shurley can start your bike.

No offense, just dont want to see another perfecly good two stroke cylinder head go to waste!

rws

VintageDirt · Jan 30, 2006

I don't remember Husqvarna making a 650 2-stroke :think:

I think I remember your grampa though. Is he that fast guy that wore line-man boots, jeans, work shirt, Buco helmet, tank commander goggles, and red suspenders?

gpoints · Jan 31, 2006

TimberPig said:
How close is the jetting set? How is the inlet needle and seat? If it isn't sealing well, it can flood the cases, making it harder to start. How fresh are the crank seals?

The mid 80's CR 500's were well known as hard kicking bikes, and the later designs with the bleed off ports to aid in kicking helped somewhat, but it should start easier than that. If it is in mechanically good shape, and properly tuned, it should kick hard, but you should still be able to start it by kickstarting. In his tips on CR 500's Eric Gorr lists some head mods to smooth the powerband and they should also help make it somewhat easier to start, if you haven't read them, you can read them here
Honda Tuning Tips
There is no way it should be that hard to start that you have to pullstart it. It should be able to be started with a good firm kick on the kickstarter. I'm not trying to say a decomp button wouldn't be worth having, just that it sounds like the bike is starting harder than it should, and the decomp valve alone may not be the answer.

The jetting may be off on the slow jet but its hard to get a plug reading or do jet troubleshooting on a bike you have to drag to start; that's where the decomp-head comes in.

The bike is definately harder to start than it should be, I just want to get some reviews on the decomp mod.

Thanks for the link, I'll read into it. :cool:

gpoints · Jan 31, 2006

REARWHEELSLIDER said:
Oh, be a man and put some balls into kicking the machine over. What are we, ballerinas?

If the bike needed a decomp switch, it wouldve came stock with one. If my grandpa could kick over his husquarvarna 650 two stroke in 1979, you shurley can start your bike.

No offense, just dont want to see another perfecly good two stroke cylinder head go to waste!

rws

Given your logic ("if the bike needed a decomp switch, it wouldve came stock with one." ), why add a free-flowing exhaust or revalve your suspension? The jetting is near perfect from the factory too, right?
I mean, if it needed it, it would've come with it stock, right?

Who can fit a Release compression valve on my CR500R

Henka

Tony Eeds

Godspeed Tony.

Masterphil

DRN's Resident Lunatic

Papakeith

COTT Champ Emeritus

COLEMANAPP

Henka

Henka

steve.emma

gpoints

TimberPig

gpoints

motometal

TimberPig

REARWHEELSLIDER

VintageDirt

Baked Spud

gpoints

gpoints

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Who can fit a Release compression valve on my CR500R

Godspeed Tony.

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COTT Champ Emeritus

Baked Spud

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