tuning my bs34's, ended with red exhaust...

[jonandjones]

I have been battleing tuning my carbs for awhile now. I jetted up on my pilot jets last night. 42.5 to 45 137.5 on mains. I started the bike alittle hard starting, popped every now an then. Raise rpms to around 1500 to get ready for adjustments did the dead cylinder trick. But the bike would stay running when I lowered the rpms. So I hooked back up the plug and figured I would let it warm up a bit. Well the exhaust whent from blue to purple and then the purple kinda whent away and I noticed a red color so I shut off my shop light and the exhaust was red!! So I shut the bike down. Even before I turned on the lights... Well I pulled the carbs off again and there they sit on my bench tore apart... 1980 bs34s brass float.

 

[jonandjones]

This all happened within about 3mins of running

 

[littlebill31]

I glanced at some of your post's, so please forgive me if I ask something that was answered. But, in my opinion I would put a stock jet needle and needle jet back in if you haven't all ready. And 2 up on the stock pilot/mains, and get the bike running correctly.
I have pods and cut exhaust and run 45 pilot/145 mains, 3 turns out on the mix.
It's always best to get a bike running, and tuned, with stock equipment before changing to "upgraded" items such as those Dyna things. If the bike is not performing stock, then when you try to put on, so called, "performance parts", it's gonna run even worse and probably fry something.

 

[jonandjones]

(Sorry long winded rant warning) I agree truth be told I didn't buy the tune needle kit for performance. Mikesxs call them dyno tune kits or something. I went to buy pjs and mains for jetting and noticed the kit that came with a few differnet jets and guidlines for tuning. Depending on what your running mod wise. I read on my forums how aftermarket adjustable needle are the great. Turns out maybe the ones from mikes aren't so great. Im still confused as hell on the pj issue that I have a forum going on elsewhere. I had the bike running great with mikes needles and 135 main and 42.5 pj in the vm22 style. I know not supposed to be there but idles good mid good top end is good all pulls hard all the way through redline. Its just my pipes turn blue not red but I just thought its running hot. But I know them pj don't belong in there so I'm trying to get what is supposed to go in there and get it to run. I just picked up a full xs out of a backyard yest for 100 I think I'm going to pull them carbs and clean them rebuild and try on thus bike. When I bought this bike the motor was shot got it apart it had a melted piston. While i was rebuilding to motor i brated it out and fabed some new parts for it. Was hopeing the motor would go back together do some adjusting and ride.Maybe them carbs are the devil. Still I hate to give up on them. I'm going to put stock needles in ill try 135 on the mains 45 pj cause I run foam pods, 3 turns on the mix and see. Sorry for the long rant just really frustrated...

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[5twins]

If you have aftermarket straight pipes, they're probably single wall. It's not uncommon for them to turn colors, maybe even glow red at night, even if the carbs are in tune. If they're the original double wall headpipes then, yes, you have a problem. And yes, sometimes a carb set is just plain no good, screwed up inside somehow and not fixable.

 

[jonandjones]

They must be.... going to give it one more shot. I have pipes off of another xs that r just the pipes no mufflers. I was lookin at them last night quite abit thicker must be double wall. Should I put them on? Maybe make some baffles to put in the ends with some turn downs? Just wondering what is the average oparating temp of an xs motor? Just curious

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[littlebill31]

I would try it with the pipes. You never know, it might run ok. Normally you would need larger jets for open pipes, but it's worth a shot.
I think the running temp is like 225 degrees F. I think.

 

[jayel]

is the timing set correctly?

 

[CDNTX650]

Who cares if your pipes blue....my aftermarket xs-1 replica pipes are blueing and the bike pulls clean up to 6500rpm so far. Plugs are good color. What do you plugs say? Get it running on stock jetting first. I have pods with stock jets (want to do very very thin shims though as it's typically bs-34 ever so slightly flat in the mid range)

Go by how the bike pulls and what your plugs say.

 

[jonandjones]

The blue doesn't really bother me. I just thought it meant the motor was running hot. But beans the exhaust is single wall aftermarket. I can see why the pipes get hot so fast. I'm going to try different pipes and different carbs I think mine r have something screwed up inside. Maybe revisit them later.

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[jonandjones]

Littlebill you say you run 145 main and 45 pilot and 3 turns. Cut exhaust. Should I would that be a good place for me to start I have that setup. Is your topend stock?

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[littlebill31]

First, all carbs are different. One set-up might not work on another bike. Altitude, exhaust, pods, tolerances in the engine, sanding the jets, ect. can effect the bike. There is no specific "kit" or "recipe" for them.
That being said, I have a stock engine, pods, and exhaust cut where the stock foot pegs would be. I found the 45/145/3 turn out set-up to work well for me. I am at sea level though, but the 34's are a little more forgiving in that department. The 3 turns out is a good place to start with the jets, but you still need to do the "dead cylinder method" to properly set the mix correctly.

 

[Tomterrific]

Retarded timing. JL gave you a big reason pipes turn red at idle. The mixture burns in the pipe rather than completely in the combustion chamber.

TG

 

[littlebill31]

Retarded timing. JL gave you a big reason pipes turn red at idle. The mixture burns in the pipe rather than completely in the combustion chamber.
TG

It is good to check the timing. Even though you have a TCI, it can still go wacky.