New and confused

[Bobber82badd]

Hey guys, I have a 82 XS650 Bobber. I bought it just a few months ago and am relatively happy. However, I have some questions I need guidance with. My bike backfires quite a bit when decelerating. Now it idles great, and works well so I don’t know if this backfire is because I am running straight pipe or if there is a carb issue? Have new filters and have been running high test gasoline. Any help would be appreciated

 

[Bobber82badd]

This is the old gurl

 

[650Skull]

Before getting into the carbs, Change the pods for UNI filters. Those, on the bike now, disrupt the air flow for the slide/diaphragms and fuel delivery. Yes the combination of the pods and pipes make for difficult tuning and can be the cause of the backfiring..........Maybe some baffles inserted will also help to create some pressure for easier tuning.
second post by 5twins shows the best type of UNI's
http://www.xs650.com/threads/carb-jetting.283/page-9#post-548837

Backfiring can also be caused by an air leake around the manifolds or timing could be off. Check for leaks by spraying some WD40 around the manifolds with the bike idling.

Rear brake isn't situated very well. That brake stay should be longer or attached to the lower part of the frame. Where the stay attaches to the brake plate it should be near the 5 0'clock position and this will mean the brake actuator can also be at the 6 0'clock position and will be more affective. The position of the actuator isn't best for getting the best out of your rear brake.
Should be in this position to get the best out of the brake


Do you have a Manual and are you mechanically mined? or if not do you learn quickly. Some history about capabilities and experiences with bikes or such can help us get a handle on where your at.

 

[Bobber82badd]

Okay awesome, I grew up working on cars but haven’t done much with bikes. I like to think i understand and am able, I didn’t think the drum was set properly. The stabilizer bar they had broke on me the first time I took it out and I just put that to get me by. I drive my bike daily as my only means of transportation. I’m going to try swapping the filters hopefully sometime this week. And hopefully can relocate my rear drum. Thanks for the help

 

[650Skull]

noticed the brake arm had a bend in it. make you change your pants when it happened???

 

[figure8]

I agree with skull on starting with changing the pods, and also installing baffles. From my own experience putting in baffles made it much easier dialing the carbs in. The pods he suggested may be best, but your already tight on space with the hardtail. I would suggest buying the uni pods offered from TC Bros. Same design just not quite as long as the ones 5twins suggests. I can provide a link for the pods I mean if needed.

 

[5twins]

I think the angle of the photo is deceiving, there may well be plenty of room for the longer filter. But if not, UNI also makes versions that mount at a slight 15° angle. With those, you could turn them down and/or out if need be .....

https://unifilter.com/online-catalog/clamp-on-air-filters/

Your model has the last and most E.P.A. mandated carbs on it. They were borderline too lean on the stock bike right from the factory. Any changes made to intake and exhaust will effect them badly. Some jet changes will be required. You'll need to check and see what sizes are in the carbs now, maybe the last guy didn't change anything. Here's a chart showing the stock sizes. Your carb set is the last in the list .....

 

[Bobber82badd]

When it comes to carbs I get lost. I don’t know how to test or do anything with them. Since driving my bike this season I tried tightening the clamps from my filter to my intake and it tightened a bit, since tho it seems to be backfiring more. Before it never did at an idle and no it is at an idle, and the backfire is occurring in the exhaust on the right side. Bottom end seems to pull hard however wen I get going it seems to spit and sputter a bit when reaching top end. Is this a sign of not enough fuel or not enough air? How do I tell the difference and is there anything easy to try without the air filters because they will take me a few days to get... any knowledge is appreciated .

 

[gggGary]

A heads up: the odds are fairly high that you are experiencing lean stumble, and every ride is deepening the hole you are eating in the top of the piston. This isn't rare, a lot of guys have holed pistons in Xs650's running lean. I have seen several holed pistons in my garage nearly always aftermarket pipes nad filters without changing jetting. $30-40 bux worth of jets or an engine overhaul, choose wisely.
Those are mighty short pipes, it'll run better with mufflers, a cheap option is stock sportster mufflers, often found for $10-20 a pair.

 

[Bobber82badd]

So this is going to sound rediculous but I went over all my bolts tonight and my exhaust had loosened a bit... tighten it up and the backfire is gone... still going to get new filters and see how it runs. Hoping the air leak was the problem. So thanks for the recommendations fellas. Appreciated