BS34 Float Bowl: Stripped Threading

[jonjkim12]

Hey Everyone,

So i've slightly neglected my '77 s360 after recently purchasing a '76 cb750.

attempted to get her back on the road tuned and ready. Set the valves, timing, and boiled the carbs.

After cleaning the carbs in Berryman's i seemed to have left it in too long cause it was caked in the white dust from acid/oxidation. I believe it also further stripped two of the four threads on my left float bowl. The two threads that are stripped at on the same side, and can hold a screw some how, but if you turn it its just turns freely. visually, i can see that its stripped.

i put it all back together always to see the effect. when i started my bike i immediately noticed some white smoke out of my left pipe (not sure if its related, or just from sitting for a few months).

when i took it out for a ride, i noticed when i pulled on the throttle it sounded like it was running with the choke on. barely pulling. if i cranked the throttle to full throttle it bike moved as if it was at 3k rpm even through the tach read 8k rpm.


not sure which symptoms are being caused from sitting and which are because of the stripped thread.

more importantly, any suggestions on the stripped thread? should i just get a slightly bigger screw and make a new thread?

btw: i cleaned the carbs twice. once with Berryman's then again with Pinesol to get rid of the dust that was building up.

please help!

Thanks in advance.

 

[ScottLuke]

Either re tap the threads for a larger diameter one, or run a long bolt through the hole with a nylock on the end.

 

[jonjkim12]

Thanks Scottluke,

going to try the long bolt. But the float bowl slightly leaking on one side wouldn't cause the bike to barely accelerate would it?

the symptoms are hard for me to explain because i've never experienced it before. It can idle GREAT, but for some reason when i take it on the road cranking the throttle and getting it at red line doesn't accelerate the bike the way it should.

it sounds like the choke is on, but its not. super confused here.

 

[xschris]

Did you replace the o-rings for the needle jets?

 

[jonjkim12]

hey xschris,

no i didn't. i normally take the whole diaphragm piece out together and leave it to the side when cleaning my carbs.

i got the longer bolts for the float bowl, i'm going to re-do the entire tune up this weekend and see if that works.

only reason why this is confusing me is because it idles just fine, which is typically my problem. but when i throttle its runs like i forgot to connect the air hose to the manifold (i always forget to reconnect that) but this time i had remembered.

very odd.

 

[xschris]

http://www.mikesxs.net/product/48-5020.html If you have not replace this o-ring it maybe your issue. What about the butterfly shaft seals? When you boil carbs ALL rubber needs to come out

 

[jonjkim12]

really?

i've boiled my carbs a few times now and i never take that part out. i can barely tell from the picture, but is the seal supposed to be one each side of the butterfly rod?

 

[xschris]

Yes, each carb has two seals.

 

[OleDoc]

Does it actually rev to 8000 and not accelerate? That sounds clutch related

 

[jonjkim12]

Hey guys,

I got a bunch of different bolts to fix the stripped float bowl thread. got it all fixed and tight. Went through this morning and redid the valves, timing, filters, spark plugs.

put the carbs back on, no fuel leak. but the white smoke is still coming out of the left exhaust pipe.

the throttle response still isn't what it used to be. she'll start right up and idle forever, but when i give her throttle it's really slow.

Oledoc, yes at 8k rpm its accelerating like its at 4k. i would agree with the clutch speculation, but even in neutral at idle when i blip the throttle its not right.

one thing that just happen was, when i was letting it idle for a while, hoping it just need time, a gnarly spider came out of somewhere. is it possible bugs got in the engine and just made it dirty?

if i feel equal pressure out of both exhaust pipes, it can't be running on one cylinder right?

 

[XSLeo]

With both pistons moving the pressure out the mufflers will be close to the same. The same amount of air is flowing even if one side is not running. Now do both sides feel the same temp? If one side is not running then that side will feel cooler.
Leo

 

[jonjkim12]

ya both headers get pretty hot. with wet fingers, it sizzles when i tap it really quick.

I want to believe its a carb sync issue, but i didn't a bench sync when cleaning the carbs and visually looked about right, so i don't think a slight deviation from perfectly sync'd could cause this much of an issue. I will sync soon.

one other symptom i noticed was that my petcock started to leak (very very very slightly), no dripping, but the last time i was working on it i noticed a slight drip was forming at one of the screws.

i tried running the bike in reserve in case the on position had some gunk clogging it, but even that didn't work.

i am slightly confused by your post XSLeo, so even if one cylinder is down, the pressure at the exhaust can still be equal?

 

[XSLeo]

The pistons move the same volume of air running or not. The non running side may feel close to the same as the running side. One side won't be a lot and the other side zero.
There may be a big enough difference to feel but it won't be a great difference.
Carb sync is very important. With it off one cylinder is trying to run faster than the other.
If both sides are getting warm, then both sides are running.
I'd sync the carbs as the next step.
Leo

 

[jonjkim12]

The more i bitch about my problem here, the more i believe it's a fuel starvation issue.

the only symptom that stumps me the most is that the bike idles as strong as ever (tach needle isn't jumping around), but the throttle just refuses to give me the power it once had.

I'm going to try following the fuel through the bike to see if i can find what's happening. sucks that when i finally get he to idle strong, she refuses to throttle correctly, and i'm hoping the white smoke on the left side will fix itself once i figure out the problem.

 

[jonjkim12]

Thanks XSLeo, XSChris, ScottLuke, and Oledoc.

I'll give it another go over the next two weeks. This forum is honestly the most reassuring thing to have for an XS360/400 rider because people like you guys always respond.

I'll do my best to let you guys know if it's fixed for future riders.

 

[jonjkim12]

Sorry,

I'm over-posting, but i just pulled the spark plug cap off each cylinder one by one to hear how each side was running individually.

While idling, i pulled the left side spark plug cap (side with smoking exhaust) to hear the right side on its own, and the right side running by itself sounded fine.

When i pulled the right side spark plug cap while idling, i hear the left side try to go on its own and then die.

i did the test twice, and the same results both times.

Does that mean my left side isn't making a strong enough spark to go on its own? i know i said before that both headers were hot when running. But this time when i had it running for a short period of time i noticed the left side was a little cooler than the right. But both were still warm.

i've tried replacing the spark plugs on that left side a few times. didn't change anything. could it be the cap?

 

[xschris]

Swap caps and plugs to see it you get the same results. I still think it's the butterfly seals and o-rings for the needle jets. If fuel gets past that o-ring it will bog out the motor.

 

[jonjkim12]

Thanks XSChris,

I'll give it a try today. I was considering sending my carbs off to a professional rebuilder. Through it costs and arm and a leg, i want to make sure the carbs are goods....and because taking apart the butterfly pieces is inviting me to break/lose parts.

 

[xschris]

The needle jet o-rings are easy to do. Just slide out the jets. If they slide out easy or the o-ring is dry and hard they leak. The butterfly seals are a bit harder. But if the bike idles well they may be good enough.

 

[jonjkim12]

Hey xschris,

Guess i gotta take off the carbs again and see haha. I'll take a look this weekend. But when cleaning my carb, a lot of the jets didn't budge when i lightly tried to remove them, and i noticed the PO tried to pull them with force so now i'm afraid of bending the brass.

but at this point, i might as well try.