HELP!!! I broke it!!! Won't start. Warning LONG!!!

[Gordon in nc]

I will admit that a lot of the stuff in those boxes doesn't get to see the light very often....but when I need a part...most of the time I have it on the shelf. I am tickled that I purchased the XS650 roller because there's a short list of bits I used off of it that saved me time and $$ in the long run. Even though I was a bit tiffed when I first saw the shape it was in...... I got over it pretty quick.

The XS650B is running strong. I still haven't measured the compression but I will get a chance this weekend to do that and report back. I have been kickstarting it just so I'll know how. It's funny the way that each bike I have is a little different when it comes to what you have to do to start it. On the XS I have to give it a "little" throttle before it'll fire. On my BSA unit singles...if you as much as touch the throttle they don't want to start.....motorcycles, you gota love em.

I am chasing a rich condition but it's not bad enough to cause problems and I'll sort it out with time.

I've put 100+ miles on it since the top end work.....I'm feeling better and better about it every ride. (even if they are short). I'm going to leave the stock bars on it...they are almost a dead copy of the BSA B44 VS, VR and SS bars that I have put thousands of miles on so they "feel right" to me. Got the slipstreamer wind screen on the way....I never have liked getting beat up by the wind and use a wind screen ( it's not a windshield or fairing) on all my road bikes.

Hope you guys and gals are doing well......Gordon in NC

 

[5twins]

I'm not sure what condition the carbs were in when you got the bike but if they were all gummed up and had been sitting that way for a long time, that gum and gas varnish can actually eat away at the jet orifices, making them larger. In particular, the needle jet can get eaten away and that causes rich running. Unfortunately, the short style Z-6 needle jet used in the '75 carb set is near impossible to find.

 

[Gordon in nc]

I'm not sure what condition the carbs were in when you got the bike but if they were all gummed up and had been sitting that way for a long time, that gum and gas varnish can actually eat away at the jet orifices, making them larger. In particular, the needle jet can get eaten away and that causes rich running. Unfortunately, the short style Z-6 needle jet used in the '75 carb set is near impossible to find.

5twins, the only fuel that was left in the carbs was just a little in the bottom of the bowls...and yes that did cause a little damage in one of the bowls but as far as I could tell nothing that would cause a problem with jetting. The rest of the carbs insides were in pretty good shape. BUT...if I can't lean it out I'll look at that.

I rebuilt the carbs completely......but I admit I used Keyster kits and I've had good and bad results with them. I do have a set of go-no go pin gauges and checked and comapired everything I could. Of course I was using worn bits as a control. I didn't find anything "odd". One of the main reasons I used those kits.....they had a copy of the short style needle jet. I still haven't put enough miles on it to get it sorted but I can't imagine the bike running better when/if I get it leaned out. I still have the carb kits I got from Mike's.......they were useless and must have been for the MOON model XS's. Most of that stuff wasn't even close to being correct. I was in a hurry and new at it.....so when I found the Keyster's and they had the correct jet (and I couldn't find that any place else)....I went for them.

I'm starting on cleaning up the rims and hubs off my roller......I'm going to clean them up and do a respoke.....then new tires and swap out the primered ones on the bike now.

Rode 30 miles yesterday......nice bike, plenty of power (for me) and it handles a LOT better than I expected.

Take care.....yak at ya later.....Gordon in NC

 

[5twins]

Ah yes, the Keyster carb kit, I'm thinking most like #KY-0489. I purchased one of those for the same reason you did, the included needle jet, but also for the included generic Y-31 needle. I had never heard of that needle before. But there's something you need to know about that Y-31 needle. It is 1mm shorter than your original 4N8. That means it will run richer if set in the same clip slot. Leaning the needles a step may be the solution to your rich running.

 

[5twins]

I should also mention the needle jet, or more specifically, the o-ring on the needle jet. You did put an o-ring on it, right? Without one, or with a bad one, fuel can leak around the outside of the jet instead of just passing through it as it should. That can cause a rich running condition. The o-ring size is 1mm thick x 4mm I.D. I use these .....

http://www.mcmaster.com/#9263k284/=ww6ef2

 

[Gordon in nc]

Yes sir, that's the same kit. Yes, new orings were installed with the jets. BUT.....I didn't catch the needle's length difference. The neddle in the other kit I had was so short....when I laid the Y-31 neddle beside the stock needle I figured I had a match. Yep, should have measured it.

Good......that's an easy fix and we'll see how that goes.

Thank you.....Gordon in NC

 

[5twins]

Yes, that other generic needle is the Y-22, totally wrong and way too short for any of the '74 and newer BS38s, yet they include it in kits for them, go figure. They have been doing it for years. You'd think they would know what the fuck they were doing by now, lol. After all, they make and sell carb kits as a business and to make a living. The only carbs that Y-22 needle may work in are the '73 and older sets. Notice I said "may". There's really no way of telling with the naked eye if the taper is a match for the original 4JN19 used in those older sets. The length does match (40mm from the top clip slot to the tip) but that's all you can be sure of.

Your original 4N8 measures 46mm from the top clip slot to the tip. The generic Y-31 is 45mm measured in the same manner. Stock setting for your needle was slot #4 (from the top). Running the Y-31 in slot #3 should match the lengths for you.

 

[Gordon in nc]

<snip> Your original 4N8 measures 46mm from the top clip slot to the tip. The generic Y-31 is 45mm measured in the same manner. Stock setting for your needle was slot #4 (from the top). Running the Y-31 in slot #3 should match the lengths for you.

Took the XS out for dinner tonight (seafood....well "almost" seafood....we're to far away from the coast and to far out in the sticks to get the real stuff) ....to the next town over, a little over 60 miles round trip....about half way back I was thinking to myself...."Gordon, you're really going to like this bike"

I'm going to put a few more miles on it then check the head bolts again.....while I have the tank off I'll move the neddle clips.

Hope your spring is the BEST ever.......Gordon in NC

 

[usfs68]

Happy trail's Gordon

 

[Gordon in nc]

Well boys and girls....I just wanted to drop in and say the XS is running like a top and thanks to 5twins the rich condition is fixed.

I do have a tiny bit of oil weep....no big deal and I'm pretty sure it's because of my unlearnt, hamfisted way I treated the head gasket and goo. I'll do better next time now that I know what to expect.

The bike is an absolute joy to ride.......I CAN NOT for the life of me understand why anybody would think these bikes vibrate.......just guessing but those folks probably never rode a bike the REALLY vibrates. Put em on a Norton Atlas for a hundred miles or so or my paint shaker BSA B58....THEN ask em if the XS vibrates.

I'm loving it........you all take care and have the BEST summer ever. (or winter if your in OZ)

Gordon in NC

1975 XS650B Runner
1975 XS650B was a parts bike but gathering bits to get it back on the road