Running rough

[crybinsk]

Hey guys you've been really helpful so far. So I've moved on from electronics now I'm on engine. I have a 77 xs650 with a 72xs1 engine. The bike idles nicely and shifts into gear perfectly fine. But as soon as I start to drive it feels sluggish and in first I get a puff of smoke. Only got it up to 3rd but always feels very sluggish. Where should I start? The guy who owned it before me said he did a carb clean and changed parts. He also put a new petcock and fuel line. Sparks look new and there is gas. Basically I'm asking where should I start? And what you think might be going on.
Thanks

 

[nj1639]

On stock carbs you can check the brass slides to see if they're functioning properly.
Get to the intake side of the carbs and look in the throat. Lift the slide up with one hand and cover the oval opening at the top of the carb opening with yer thumb. Let the slide down while still covering the oval.
Slide should descend slowly. If it drops fast then the rubber diaphragm attached to the slide top may have a hole.
Costs nothing to check but time.

Carb ID is critical. I've a '77 but running '78 carbs. Know what you have.

 

[crybinsk]

On stock carbs you can check the brass slides to see if they're functioning properly.
Get to the intake side of the carbs and look in the throat. Lift the slide up with one hand and cover the oval opening at the top of the carb opening with yer thumb. Let the slide down while still covering the oval.
Slide should descend slowly. If it drops fast then the rubber diaphragm attached to the slide top may have a hole.
Costs nothing to check but time.

Carb ID is critical. I've a '77 but running '78 carbs. Know what you have.

Thanks I'm just learning. Not sure what carbs are on it right now.

 

[5twins]

Well, it seems you have what we call a "bitsa" on your hands there, lol (parts from different years). As mentioned, you'll need to I.D. the year of your carbs. Jetting is based on the carb set year, not the year of the bike. Here's a chart I made up listing the stock jetting for the various years and carb sets .......

If the P.O. installed aftermarket rebuild kits, the jet sizes may be wrong, as well as the needle. The '76-'77 kit in particular is pretty bad. It's been sold with the wrong jet sizes for many years ('78-'79 sizes).

Show us some pics of your carb set and we can help I.D. it for you.

 

[crybinsk]

Ya I'm starting to think it might be a bitsa shit. Lol. I hope it's a joke. Here are the pictures

 

[crybinsk]

Ok I found out some info. The carb is the original 1971 xs1. The carb kit he used was a 73 xs650

 

[crybinsk]

He said the engine is all xs1

 

[Jim]

Ok I found out some info. The carb is the original 1971 xs1. The carb kit he used was a 73 xs650

Those are linked carbs. '71 didn't have linked carbs. Not positive on the year, but linked carbs came later. '75 or '76 maybe?

 

[5twins]

No, you have a '76-'79 carb set. The early carbs are separate units, each with it's own throttle cable. The later '76-'79 carbs are bolted together as a "bank" and the two carbs are linked together by a linkage. They only use one throttle cable. I can see that in your pics, along with the angle bracket along the lower front that connects the two carbs together. You also have the butterfly shaped plate on top between the two carb tops. Early separate carbs wouldn't have those.

But now you need to determine whether you have a '76-'77 or '78-'79 set. You can start by looking at the float bowl. The earlier set will have a drain nipple on the bowl and possibly a drain bolt with a screwdriver slot in it ......

The later bowl ('78-'79) won't have the drain nipple or the screwdriver slot in the drain bolt .....

But, bowls are easily swapped. To really be sure which set you have, you'll need to look at the intake bells. Both will have the slot at the top but the '76-'77 set will only have 2 round holes near the bottom. The '78-'79 set will have 4 holes. The two larger ones are the float bowl vents, moved internally from the inner sides on the earlier set ......

 

[Jan_P]

Sparks look new

Is that new spark plugs or verified good sparks at the right timing Point ? With Strobe light ?
Is it with points ?

 

[5twins]

And if the P.O. really did install '73 rebuild kits, then the jets sizes, pilot jet type, and needle are wrong as well.

 

[crybinsk]

Ok so I bought this bike to fulfill a desire to learn how to wrench. Looks like I'm going to get that. Yes it has a screw and a nipple. I've included another picture. As for the sparks the PO said he put cables but just cleaned the old ones. I assume the issue with the carb is why it's running like crap right 5twin? I'll start by taking them off and check the spark plugs. I'll respond when I have them off. I really appreciate the help

 

[crybinsk]

Here it is

 

[crybinsk]

It is running so that has to be somewhat of a good sign

 

[crybinsk]

Sparks look new

Is that new spark plugs or verified good sparks at the right timing Point ? With Strobe light ?
Is it with points ?

Spark cables new spark plugs are old. Going to pull them out tomorrow. It's not points it's electric but that's coming from PO. I plan to do the strobe but I thing now that I'm reading the posts that it has something to do with the carb. But I'm sure you suggestions are a factor as well

 

[Wingedwheel]

If you pull the small round upper cover off the left side of the engine and post a pic someone can identify your ignition.

 

[crybinsk]

If you pull the small round upper cover off the left side of the engine and post a pic someone can identify your ignition.

That would help. Thanks

 

[5twins]

OK, I can see the drain bolt but not whether or not it has a screwdriver slot in the head, also can't tell if there's a hose nipple on the bottom of the bowl or not. Need a better angle (looking up from the rear). This is a '76-'77 set. The "tells" are the two round holes in the intake bells, the external float bowl vents (inner side of each carb), drain bolts w/ screwdriver slots, and the hose nipples on the bowl bottoms .....

 

[crybinsk]

OK, I can see the drain bolt but not whether or not it has a screwdriver slot in the head, also can't tell if there's a hose nipple on the bottom of the bowl or not. Need a better angle (looking up from the rear) .....

View attachment 349456

Ok I'll do that when I get home

 

[5twins]

Getting the carb set in and out is one of the 650's "Rubik's Cubes", lol. It can be done without removing a manifold if you remove the top butterfly plate and the throttle cable bracket, and also that big cover nut on the cam chain tensioner. Then you can "work" the carb set out the right side with lots of twisting and turning, lol.