Thank you 5T and Jim. I will let you know how it works out. 
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Van Islander's TX650A - Quest for a Daily Rider
- Thread starter TX650A Van Islander
- Start date
Vee
XS650 Enthusiast
Hey guys total noob question here. I already checked the tech section and searched around but couldn't find the answer I was looking for. Figured this would be a good thread to post the question to.
So I'm putting back together my re-jetted bs34 carbs. I'm at the point where I'm putting my needle valve? Jet? /fuel mixture screw with the rubber grommet, washer, spring and brass needle and I'm wondering how tight do I go on this thing? I've heard some people say until you feel "light tension". I've heard others say "until you feel it stop". Well I've tried the light tension method and when it's time to back them out it almost seems like they are too loose. When I try the "full stop method" I start hitting a little bit of tension with my tiny screwdriver and I start to get a sound of the spring almost "krinkling" when I'm tightening. I get scared and back off. I'm not reaching a point where it comes to a stop at all because I'm afraid of I may damage the needle. Any help on this would be much appreciated!
So I'm putting back together my re-jetted bs34 carbs. I'm at the point where I'm putting my needle valve? Jet? /fuel mixture screw with the rubber grommet, washer, spring and brass needle and I'm wondering how tight do I go on this thing? I've heard some people say until you feel "light tension". I've heard others say "until you feel it stop". Well I've tried the light tension method and when it's time to back them out it almost seems like they are too loose. When I try the "full stop method" I start hitting a little bit of tension with my tiny screwdriver and I start to get a sound of the spring almost "krinkling" when I'm tightening. I get scared and back off. I'm not reaching a point where it comes to a stop at all because I'm afraid of I may damage the needle. Any help on this would be much appreciated!
Are you sure you got all the old parts out, the old washer and o-ring? If not, having double the parts in there could be overloading and over-tensioning the spring, and that's why it feels funny and is making noises. Normally, the mix screw screws all the way in pretty easily until it stops. You don't make it super tight, just screwed in until it stops. If it's properly in all the way, without any extra parts in there, the tip of the mix screw will stick out into the main bore about a MM or so. You can see it here at the top in this pic .....
Vee
XS650 Enthusiast
The needles, springs, flat washers and rubber grommets are original so I'm positive I don't have any extra parts down there. Thanks for the picture. I suppose I'll just tighten until I see about a mm and hope for the best.
Vee
XS650 Enthusiast
Finally hit that stop point so that problem is solved; on to the next. So I watched a video on Mr. Miyagis xs650 about doing a kind of carb sync hack using the butterfly flaps. He just uses pieces of welding rod the same size and places them in both flaps and tries to get roughly the same amount of pressure on the rod applied by each butterfly flap by adjusting that screw that holds both carbs' throttle points. My issue is that when I try this trick only my right side butterfly flap loosens and tightens. Is this an issue? You should both of them be loosening and tightening? I will attach a picture below to give an idea of what the technique is.
Attachments
Vee
XS650 Enthusiast
Thank you, will give it a whirl when I’m back in the garage.
If you have the carbs off, you don't need to insert any rods, just hold the carbs up to a good light source. First, back the idle speed adjuster screw on the left carb way off so it's not touching the cable arm. That will allow both plates to close fully if they're in sync .....
And that's all you do, fiddle with the sync screw between the carbs until both plates close up fully and you don't see any light around their edges. Here's a shot with the left carb off .....
..... and with the right carb off .....
..... and finally, synced .....
Then dial the idle speed adjuster screw back in until both plates crack open just a hair.
And that's all you do, fiddle with the sync screw between the carbs until both plates close up fully and you don't see any light around their edges. Here's a shot with the left carb off .....
..... and with the right carb off .....
..... and finally, synced .....
Then dial the idle speed adjuster screw back in until both plates crack open just a hair.
What I do!
But; adjust the left with the idle stop screw so there is a THIN sliver of light showing under it, then use the synch screw between the carbs, set so the sliver of light showing in both bores match. I think this improves acuracy a bit over having the butterflies touch the bore cuz it keeps all the adjustment linkages tensioned against the springs like they will be in use. when done turn in the idle screw about a half turn, cuz the motor will need a bit more air flow to idle.
Checks with a vacuum gauge set on the running motor show this gets synch VERY close, seldom more than a 1/16th turn of the screw needed to bring the gauges into agreement, most of that prolly more engine cylinder health than carb settings.
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This thread has become a fabulous tutorial / refresher course on fettling carbs and loads of other stuff.
Should start your own thread. Van Islander has his voyage documented here. If you start your own it may be easier for you and others to chronicle your journey.
Vee
XS650 Enthusiast
Great techniques! You're right Willis. I will start another thread, sorry about that.
All good Vee - these are very good and important questions to which we all now have the proper answers. I hadn't yet considered the fine tuning of my new '76/'77 carbs vs the original independent '74 carbs. It leads to the next question which I had not thought of until now - I can still use the dead cylinder method for tuning with these linked carbs, correct? I guess that is just going to be about air mixture adjustment considering the idle speed has been synchronized with the carbs off of the bike?
Finally I can report some great news on this carb body with the stuck broken off needle. I got it out and will proceed with reassembly today!
First I tried heating up the body and tapping it out, having sprayed in lots of lubricant and letting it sit. No luck. Next I tried the suggestion of drilling a hole from the other side, with the goal to punching it out from the other side. I took it to a machine shop friend of mine (I don't have a drill press and wanted everything to be centred and straight). He set it up on a milling machine and got only about 4 mm down into the carb and hit a wall - a very, very hard wall, which resulted in a few dulled drill bits. Hmmm.
I brought it home and yesterday and unsuccessfully tried to drill the first hole more with a new drill bit. A few bits later I gave up that idea.
I then successfully drilled it out from the air mixture screw entry hole side - very carefully at low speed with a variable speed drill and 3/64" drill bit. I used some WD40 lube, drilled a little bit, blew it out with compressed air, inspected, picked at it with a sharp thin pick, and repeated the process about 3 or 4 times. It seems like the seat is ok, but visually not as clean as the other carb which is perfect. The photos below show a bit of it, and the tiny brass tip which fell out. The screwdriver is pointing to the drilled hole which only went down 4 mm.
I'm hopeful its ok. Installation and trial will tell.
First I tried heating up the body and tapping it out, having sprayed in lots of lubricant and letting it sit. No luck. Next I tried the suggestion of drilling a hole from the other side, with the goal to punching it out from the other side. I took it to a machine shop friend of mine (I don't have a drill press and wanted everything to be centred and straight). He set it up on a milling machine and got only about 4 mm down into the carb and hit a wall - a very, very hard wall, which resulted in a few dulled drill bits. Hmmm.
I brought it home and yesterday and unsuccessfully tried to drill the first hole more with a new drill bit. A few bits later I gave up that idea.
I then successfully drilled it out from the air mixture screw entry hole side - very carefully at low speed with a variable speed drill and 3/64" drill bit. I used some WD40 lube, drilled a little bit, blew it out with compressed air, inspected, picked at it with a sharp thin pick, and repeated the process about 3 or 4 times. It seems like the seat is ok, but visually not as clean as the other carb which is perfect. The photos below show a bit of it, and the tiny brass tip which fell out. The screwdriver is pointing to the drilled hole which only went down 4 mm.
I'm hopeful its ok. Installation and trial will tell.
Installed the new carbs and air boxes yesterday. Next step is replacing the leaking camshaft seals.
Thx for the update @TX650A Van Islander , glad the bike is getting put back together. Hopefully spring will come early for everyone and we can get the bikes back on the road.
Man I love that exhaust...wish I could still find a setup like that somewhere.
Thanks. I lucked out because that exhaust was part of the bike when I bought it. I thought this exhaust was sold on Mike's or another online vendor?
Next up is replacing the camshaft seals and gaskets for the oil leaking inside and outside of the breaker cover housings. I forgot I needed to get new o-rings. Does anyone have the o-ring dimensions (item #24 in the photo)? I'm hoping I can find them locally.
You can see from the photos where the gaskets were leaking and it looks like these gaskets spread out away from the centre of the housing, possibly causing the leaking?
You can see from the photos where the gaskets were leaking and it looks like these gaskets spread out away from the centre of the housing, possibly causing the leaking?
