Decomp valve
Decomp valve
Have give a quick thumbs up to Larry W for the lovely job he did on 2 heads
Here's one.
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On the bike.
Here's one.
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On the bike.
Last edited by mr500 on September 24th, 2011, 6:05 am, edited 1 time in total.
Keep it real, Keep it steel.
Re: Decomp valve
Beautiful - I wonder would it clear the side of my large Clarke tank.
Steelie Build Done
Gen 1 CR500 AF Complete - SOLD
Gen 1 CR500 AF Complete - SOLD
- Roostius_Maximus
- Site Admin
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That head is like the ones I do also, most of the side mount ones didnt clear the big tanks, I had always installed them stair up before because of that. I did sell some side mount stuff that didnt need to be welded also.
I have a strait up install R casting head ready to go if you need one
I have a strait up install R casting head ready to go if you need one
http://www.youtube.com/user/500bigbore
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
Decompression
I still have a couple needs for upgrades throughout the fall and over the winter and this may well be one of them. I will contact you when I get ready to do this. Here is one thing I do not understand - if low compression causes difficult starting ( I experienced this first hand) then why doesn't a decompression valve have the same effect?Roostius_Maximus wrote:That head is like the ones I do also, most of the side mount ones didnt clear the big tanks, I had always installed them stair up before because of that. I did sell some side mount stuff that didnt need to be welded also.
I have a strait up install R casting head ready to go if you need one
Steelie Build Done
Gen 1 CR500 AF Complete - SOLD
Gen 1 CR500 AF Complete - SOLD
Who said its easier to start?.. Decomp means it's only easier to Kick!
Maybe its cos the mixture is going out the decomp valve and not back into the crackcase via the rings?
One thing i did notice is it's harder to find TDC wiith the valve in.
BIt like an xr400.
Better to find TDC first then push the button.
Maybe its cos the mixture is going out the decomp valve and not back into the crackcase via the rings?
One thing i did notice is it's harder to find TDC wiith the valve in.
BIt like an xr400.
Better to find TDC first then push the button.
Keep it real, Keep it steel.
Although my bike needs some jetting time spent still, I find the big difference on the decomp valve is it allows the motor to spin over a bit quicker. They still like an open throttle and a damn good kick, but with my still weak right knee I'd otherwise be leaning the handguard against a tree and having to stand on the peg for every start I think.
- NightBiker07
- Posts: 1942
- Joined: April 16th, 2008, 8:59 pm
- Location: USA
You use the decomp to get some kick momentum before returning the full cylinder compression. if the decomp stuck on, it would never start, similar to a low compression issue.
I dont understand how these work though. A lever operated one stays open until you release the lever. but how are you supposed to kick the bike and deactivate these decompression valves? I must be missing something here
I dont understand how these work though. A lever operated one stays open until you release the lever. but how are you supposed to kick the bike and deactivate these decompression valves? I must be missing something here
2000 CR250, pipe, filter, Vforce
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
these are a poppet style valve, you push it in and it "snaps" down...
when kicked they will stay open, but upon the first good pop or fire from the cylinder it kicks them shut. Sometimes if the bike pops/fires it will kick them shut before it starts and you need to reset the valve again to kick again. My Valve is on the right side of the cylinder head, so when i reach for the kickstarter its right at my fingertip to push in, it seems a little more natural on this side to me as i only need to use the one arm to get the kicker and the valve. Some people have rigged up cables to allow a bar mount hot start lever from a 4T to be used to bump it open, some of these setups are pretty damn sweet.
There are several different manufacturers of the valves, including some chainsaw designed ones... (STIHL)
AV&V
Goodson
S&S
Screaming Eagle
all make the same sort of style but i haven't got any clue what is best...
when kicked they will stay open, but upon the first good pop or fire from the cylinder it kicks them shut. Sometimes if the bike pops/fires it will kick them shut before it starts and you need to reset the valve again to kick again. My Valve is on the right side of the cylinder head, so when i reach for the kickstarter its right at my fingertip to push in, it seems a little more natural on this side to me as i only need to use the one arm to get the kicker and the valve. Some people have rigged up cables to allow a bar mount hot start lever from a 4T to be used to bump it open, some of these setups are pretty damn sweet.
There are several different manufacturers of the valves, including some chainsaw designed ones... (STIHL)
AV&V
Goodson
S&S
Screaming Eagle
all make the same sort of style but i haven't got any clue what is best...
- NightBiker07
- Posts: 1942
- Joined: April 16th, 2008, 8:59 pm
- Location: USA
Got it. I know the 4 stroke hotstarts will stay open as long as you hold the lever.Gmbond wrote:these are a poppet style valve, you push it in and it "snaps" down...
when kicked they will stay open, but upon the first good pop or fire from the cylinder it kicks them shut. Sometimes if the bike pops/fires it will kick them shut before it starts and you need to reset the valve again to kick again. My Valve is on the right side of the cylinder head, so when i reach for the kickstarter its right at my fingertip to push in, it seems a little more natural on this side to me as i only need to use the one arm to get the kicker and the valve. Some people have rigged up cables to allow a bar mount hot start lever from a 4T to be used to bump it open, some of these setups are pretty damn sweet.
There are several different manufacturers of the valves, including some chainsaw designed ones... (STIHL)
AV&V
Goodson
S&S
Screaming Eagle
all make the same sort of style but i haven't got any clue what is best...
The more i read into these, the more i want one for my bike.
Would you have any pics of a cable rig on one of these? that would be really nice to have. I just cant visualize hooking a cable to that little thing, especially if you push IN on the button
2000 CR250, pipe, filter, Vforce
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
compression release
How to get a hold of Larry W? he is at lwiechman@charter.net
Last edited by cbx1170 on December 4th, 2011, 4:26 am, edited 2 times in total.
- 2strokeforever
- Posts: 1524
- Joined: November 13th, 2009, 1:04 pm
- Location: Vernon B.C Canada
ya it could, mine does it every once in a while, also with a little throttle it will run with it open, i didnt pass soundtest so i held it open with my knee, and richened up the air screw, also put it in gear and kept a little load on it with the clutch, and backed away from the tent the bike was suposed to be parked underif the decomp stuck on, it would never start
this let me scrape thru
it wasnt too loud really, but the random bing noise coming from the pipe was pushing it over the limit
im gonna get a washer that fits between the silencer and pipe for next time in case theres issues
the 450 will have less power and will be harder to start, and will be heavier, but to make up for it it will require more maintenance.
4stroke=dead fish
4stroke=dead fish
- Roostius_Maximus
- Site Admin
- Posts: 4641
- Joined: November 16th, 2007, 3:24 pm
- Location: Mt Nebo, Manitoba, Canada
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I started making them when I blackened my foot almost this bad...
http://www.youtube.com/user/500bigbore
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
It bloody well should start easier. There's not much bloody point if it doesn't. It shows it to be an ill thought out design, however pretty it might be.mr500 wrote:Who said its easier to start?.. Decomp means it's only easier to Kick!
Maybe its cos the mixture is going out the decomp valve and not back into the crackcase via the rings?
One thing i did notice is it's harder to find TDC wiith the valve in.
BIt like an xr400.
Better to find TDC first then push the button.
Does your bigger tank still fit?
I posted my Auto Decomp pics and info in July 07, on CR500riders . SH and Roosty seemed to have got into them, then.
Mine, you just kick the bike, and it goes. No levers, buttons , TDC finding, or anything to mess with. Fit any tank you want. I don't try to sell them on sites, as I've more than enough to do, but I've done quite a few for people who have sought me out. Unless I'm 'snowed under', if a OZ owner sends his parts (head, and carb) to me by Express Post, they get the finished job back, in less than a week from when they sent their stuff.
What is an ill thought out design? What am I missing when you say that? Its late and I might not get it right now...It shows it to be an ill thought out design, however pretty it might be.
Id like to see your design, or sell me the plans to do myself?Mine, you just kick the bike, and it goes. No levers, buttons , TDC finding, or anything to mess with. Fit any tank you want. I don't try to sell them on sites, as I've more than enough to do, but I've done quite a few for people who have sought me out. Unless I'm 'snowed under', if a OZ owner sends his parts (head, and carb) to me by Express Post, they get the finished job back, in less than a week from when they sent their stuff.