'Nother Dumb Question!

Barbara · Posted: January 27, 2009, 2:29 pm Post subject: 'Nother Dumb Question!

Hi Guys,

(Toldja I liked this board...)

So I've been looking at my XS manuals (3), and can't find a thing in any of them about the "compression release" on the early models. I'm simply curious, but if anyone has an original bike that still has the comp release, would you please post and tell me about them?

No, I don't want one--the comp releases on the BSA's keep me plenty busy--I'm just curious, because the books seem to ignore their existence.

Thanks, Guys. (I hate the vacuum of ignorance....especially in my own head!)

xsjohn · Posted: January 27, 2009, 2:43 pm Post subject: Re: 'Nother Dumb Question!

Barb........holds exhaust valve open I spose.........xsjohn

woodman · Full Member Joined: Oct 12, 2008 Posts: 256

I had a new XS1 in 1970 and a 73 TX650 later and I swear I dont recall either having one. That was 39 years ago and maybe Im getting senile. Are you talking something like my 78 XT500 single has ? Just cause I dont remmeber doesnt mean it wasnt there Question

TeeCat · Posted: January 27, 2009, 2:51 pm Post subject: Re: 'Nother Dumb Question!

Hi, Barb -

The gal pictured below, my '73 "mild cafe", has an original compression release. It's essentially a "trigger" or small lever right behind the front brake lever that, as I understand it, mechanically (via cable) opens an exhaust valve and simultaneously engages the electric starter; the open exhaust valve makes it easier for the electric start to spin the motor.

ine works, but I always kick her because the electric start draws a lot of juice, and it's fairly primitive, so I'm cautious with it.

Hope this helps!

TC

Retiredgentleman · Posted: January 27, 2009, 5:33 pm Post subject: Re: 'Nother Dumb Question!

From what I have read, the 72 XS2 and the 73 TX were the only models that had the decompressor. That is why the left exhaust valve cover is a different size and shape; Yamaha just left it that shape on later models. I would be curious to see a close up picture of both the outside and the inside of the cover with that device.

JeffM · Posted: January 27, 2009, 6:10 pm Post subject: Re: 'Nother Dumb Question!

72 and 73 only. I have read the starter motor was uprated in 74 so the release was dropped. The starter motor on my xs2 didn't work when I bought the bike and it starts easily without, so not a priority. The minature brake lever on the right grip is amusing and kinda cute... it pulls a cable and there is the starter switch inside.
The pre-decompressor heads had 3 bolt cover on all valves, the four bolt cover was for the decompressor and it was never changed back. The cover itself is an ugly thing! it is like a big alloy horn sticking out of the head. the cable rotates a shaft that goes through (you can see it in xsjohns post) the cover and rotates a cam to lift the rocker and open the exhaust valve. The rocker arm is extended on this valve.

Barbara · Posted: January 27, 2009, 10:45 pm Post subject: Re: 'Nother Dumb Question!

Hi Guys,

Thanks! I knew it had to be something like that, but I've never managed to find that exploded drawing that xsjohn found. Having my BSA singles which have the comp release levers, (and two G80 Matchlesses) I am familiar with them, I just couldn't picture it on a Yammie twin--and I won a bet with myself---I was thinking that they would somehow combine it with the starter button, I just couldn't figure out how.

Pretty neat! One of those would be fun to play with..... Laughing

Pure-Pork · Posted: January 28, 2009, 12:56 pm Post subject: Re: 'Nother Dumb Question!

I have a 72 motor in my 78 special with the release assy valve cover intact, and a 72 XS that also had the release.assy complete when I bought it. I took the cable and lever assy off to get rid of the clutter it caused. They kick start well anyway

xs1961 · Posted: January 28, 2009, 7:27 pm Post subject: Re: 'Nother Dumb Question!

..Yamaha realised decompressors were for girlies.... Cool

xsjohn · Posted: January 28, 2009, 7:43 pm Post subject: Re: 'Nother Dumb Question!

Schwarzenegger would probably classify all compression releases and electric starts as girly men devices……probably the XS650 also…. Laughing

xsjohn

jayel · Posted: January 28, 2009, 8:34 pm Post subject: Re: 'Nother Dumb Question!

do you really think that H-D Arnie rides has a kicker? however he does have a sidecar so watch what you say, Barb might be listening

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

try and kick over a high compression HD and you'll think they are great. Either that or you biuld a lower compression motor to make life easier.

xsjohn · Posted: January 28, 2009, 8:46 pm Post subject: Re: 'Nother Dumb Question!

Are we insinuating that Barb is more of a man that we are.......... Laughing

xsjohn

jayel · Posted: January 28, 2009, 9:12 pm Post subject: Re: 'Nother Dumb Question!

she might have more sense than some of us.....

yes with a old high comp. motor you better have a good spark retard or a compression release, put your knee into your chin real quick if you didn't go over the bars and you wondered why old bikers limped

me I like my E-start

xsjohn · Posted: January 28, 2009, 9:23 pm Post subject: Re: 'Nother Dumb Question!

"""""she might have more sense than some of us.....""""

That's obvious... Laughing

xsjohn

Tomterrific · Posted: January 28, 2009, 10:25 pm Post subject: Re: 'Nother Dumb Question!

Hi Barb,

Here is picture that shows fairly well what the compression release would look like on the engine.

www.trickphotog.com/XS650Web.jpg

Tom Graham

Barbara · Posted: January 29, 2009, 1:20 am Post subject: Re: 'Nother Dumb Question!

Thanks, Tom,

That's kinda cool, if redundant.....oh, and about kicking over a bike...I thought my B44 BSA singles were bad, until I got my first Matchless. I thought that was a challenge until I got my first and only BSA Gold Star DBD34. Without a decomp device, that engine would put me right over the bars and land me head first in front of the wheel!

I *love* decomp levers, and I wouldn't have a single larger than 250cc without one! However, like BSA and Triumph (and Norton, too), the XS is happily a twin, and therefore much more civilized. For years I kicked the '77 to start it---and then figured out how to adjust the voltage regulator and thus gained use of the electric starter.

It does seem almost 60-ish British to fit a compression release/electric starter, doesn't it? As compared to an up-graded starter/electrical system, that is. I guess that's why they interest me..... Laughing

I like things that are unusual, even if they don't quite work the way they were supposed to.....and don't any of you guys take that personally, OK?

HA!!

xs1961 · Posted: January 29, 2009, 5:32 am Post subject: Re: 'Nother Dumb Question!

Anything in Ive got that doesnt work as it should be is usually my womans fault...Ahem... Embarassed

xsjohn · Posted: January 29, 2009, 11:45 am Post subject: Re: 'Nother Dumb Question!

We definately need more women on the site........I'm tired of taking all the blame........

xsjohn

jayel · Posted: January 29, 2009, 12:18 pm Post subject: Re: 'Nother Dumb Question!

stick with what you're good at john, lol

xsjohn · Posted: January 29, 2009, 12:23 pm Post subject: Re: 'Nother Dumb Question!

Trust me I would if I could just figure out what that was........... Crying or Very sad

xsjohn

Barbara · Posted: January 29, 2009, 3:45 pm Post subject: Re: 'Nother Dumb Question!

C'mon, John---the more you "needle" us, the better our carbs work...... Laughing

And yes, we do need more women around here---there are several of us on the Britbike sites where I hang out. What's the deal? I can't be the only oddball......I hope.

xsjohn · Posted: January 29, 2009, 3:50 pm Post subject: Re: 'Nother Dumb Question!

Barb.........You are definately not the odd ball.....the rest of us are just the girly men..........:lol:

""News Flash""....Cyclist found dead along the side of the road in NC.....cause of death .........electrocuted by home made heat suit.......

xsjohn

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

Why aren't there more girls riding the XS, It's not as if it's just a mans bike and where are all the wives and girlfriends whose husbands or boyfriends have bought them their own 650...........heard this a lot on this site ........."i'm going to get my misses an XS650"

What Happened to 650rider.com?

Yamaha xs650