D-Mac's rat bike to......cafe bike? Here we go again.

[wibornz]

I would think a two brothers carbon fiber would look sweet.  Just a little fab work.

[veefer800canuck]

I have no idea how it would sound, but a peashooter muffler would look appropriate:



Or maybe a cocktail shaker:

[OU812]

I like the Peashooter.
Like my old Norton.

[bomber]

D-Mac . . . . . . your workmanship is simply outstanding . . . .. would you please come over to the lab and finish up the Buell project that's been living out there for so long?

Well done, indeed!

[Mr.Black]

We need a sound bite.

[mxvet57]

D-Mac . . . . . . your workmanship is simply outstanding . . . .. would you please come over to the lab and finish up the Buell project that's been living out there for so long?

Well done, indeed!

The last time i saw that thing running was the first time i met you.   Remember how long ago that was?  

[bomber]

No.




















;-}

[D-Mac]

I ran the bike for a few minutes today. My goal was to get the engine warm and re-check compression properly. I also wanted to check for proper charging. My aux tank shipped today, so I’ll wait until it arrives before doing a sync and starting to tune.

I did mark off various throttle positions for tuning purposes (I’m stretching things to get a pic of SOMETHING today).


I also added a 2012 Canadian penny to cover up the left side OEM mirror mount. I figure since I’m still Canadian and finished it in 2012 that it was appropriate (I already stuck a 1981 US penny on the right side mount since it’s an ’81 bike and I don’t have a Japanese coin from 1981 lying around).


First, here’s “proof of life” - a video of it running. Bad audio quality from my phone (and I forgot to turn it sideways to capture ‘landscape’):

https://www.youtube.com/watch?v=bAsEVi7gyAE

It idles great. The throttle response was good when cold, but got worse and worse as the engine warmed up (which is when the video was shot) - to the point where it wanted to die under throttle. Classic over-richness. You can hear it bog a bit and see it when I rev it a little. It needed very little choke to warm up (also classic richness, especially since it was really cold in the shop today).

Here’s a plug shot. Yup. Rich. I had already cleaned off the top and bottom plugs before running the bike today. Plug #3 looks the most sooty in this pic, but they’re all pretty similar.



I'm much happier with the compression numbers versus when I checked them before running the bike. When warm (as specified in the manual) the cylinders that were higher before are a little higher (two were in the mid 140s and are approaching 150 now), and the two that were a little low have already improved a lot (from 100 and 115 to 120 and 130 now). So it looks like everything is beginning to even out nicely. As the rings continue to seat, which will take a bit more than a couple of starts in the garage, I expect further improvements.

I verified that it is charging properly. Sweet.

Tomorrow I’m taking the seat to the upholstery place.

My wife nixed the idea of a better garage heater, so it looks like it’s back to saving money for a while.

[Stripes]

 

[davenay67]

I verified that it is charging properly. Sweet.

That was no mean feat for a GS back in the late 70's and early 80's when they were new, so for it to charge properly today is excellent indeed.

[Oddball]

Awesome work.  I have really been enjoying your build thread since it started.

[D-Mac]

Aha!

Quick update: I think might have come closer to solving the rich mix issue with the bike.

To recap, it seems to idle fine, but under partial throttle it's definitely running way too rich - fouling plugs really fast and bogging down as the bike warms up.

I originally set my needles to the 4th e-clip position down. The jet kit suggests 3rd position, which would be a little less rich (since the needle would be higher under partial throttle, letting more fuel through). Honestly, it was so rich that I doubted that one e-clip position would make that much difference. I pulled the carbs and opened them up anyway. Here's what each needle looked like:



Hmmm.....on looking at the current setup of the needles, two things came to mind.

(1) There were no detailed directions for my jet kit other than recommended settings, but it did say "keep stock washers in their positions" so I did that when I rebuilt them. HOWEVER....

(2) I remember reading something somewhere about owners swapping the fat spacer and the washer around because Suzuki jetted these carbs too lean from the factory. I wondered if that had happened to this bike before I got it. If you look at the pic above, just imagine the fat orange spacer being moved to ABOVE the black e-clip, and the small silver washer being moved below the clip. That would lower the needle by nearly the diameter of the fat spacer (minus the diameter of the thin washer) and make it much LESS rich relative to the reverse position in the first pic.

So I swaped the spacer and washer back - to what I now think was stock. Like this:


A quick web search seems to confirm that the fat spacer is supposed to be on top when the GS550s with CV carbs are bone stock. Since I'm rejetting, I'm thinking that I needed to move the spacer/washer back to stock, and I hadn't done that. I also lowered the needle one clip position, and reassembled the carbs.

Unfortunately, I had no time today to put the carbs back in and actually test my thinking. Tomorrow I hope......

[veefer800canuck]

I believe you're barking up the right tree. PO probably did that mod to alleviate the lean running from the factory, as you said.

[D-Mac]

I believe you're barking up the right tree. PO probably did that mod to alleviate the lean running from the factory, as you said.

Yup. I have independent confirmation from the Suzuki GS forum. Sweet!

[D-Mac]

Plot thickens.

Put the carb back on, installed new plugs and fired up the bike for a few minutes.

The Midrange seems better now, but it's still missing when warm and hanging a bit at higher throttle (as before). I pulled the plugs and they are wet with gas - a little dark maybe, too but not nearly as much as before.

Soooo....it's either still fouling plugs (likely) or ignition isn't right (pretty unlikely - it's not a points ignition, plus the missing isn't happening on startup or in an consistent way).

I'm wondering if the float level needs adjustment. It's on spec, but do you think that lowering the front end so much would cause too much fuel to enter the carb bodies? Weird hypothesis I think. I will adjust the fuel pilot screws and try a sync first.

Looking more like I might take it to the dyno.....

[CLAY]

Hanging a bit at higher throttle- the carbs are all balanced, right?

[D-Mac]

Hanging a bit at higher throttle- the carbs are all balanced, right?

Busted. I didn't do a sync today, and and that's what I hope (think) is causing the hanging. No way it's too lean.

On the subject of carb syncs, I've done plenty before and never had a problem. However, when I tried to sync this bike last week, my carbtune wouldn't even register a reading (it's supposed to work fine on this bike too). I have no clue why, but obviously not enough vacuum for some reason. I'm thinking it might have had something to do with the carb needle issue I was having (?) I did drop the carbtune down the stairs during my move last summer   but the little springs and sliders in it seem to work fine. Worst-case scenario - I'll test the damn thing on my BMW, which could use a sync anyway. I read on some forum that the 'non reading' issue can happen if the carbs are really out of whack too. Does seem weird though since Carb 3 (which they others are adjusted to match) didn't show a reading either. Obviously, there HAS to be a vacuum inside the boot if the engine is running! The boot adapters that come with the carbtune SUCK, but I tried some old motionpro adapters I had, and still no go there either. Just weird.

Tomorrow I plan to clean the plugs, let it idle enough to warm it up, and try and sync it/tune it at idle again. I think it I can get the fouling at idle to stop, everything else might actually be fine now (or close anyway).

[Tyrroneous]

What are the little spring loaded valves called that the floats actuate?  I'm having a senior moment and can't remember what they are called...anyway, is there a chance that those little dudes aren't shutting off the flow of fuel?  Did you replace those when you rebuilt your carbs?  

Plot thickens.

Put the carb back on, installed new plugs and fired up the bike for a few minutes.

The Midrange seems better now, but it's still missing when warm and hanging a bit at higher throttle (as before). I pulled the plugs and they are wet with gas - a little dark maybe, too but not nearly as much as before.

Soooo....it's either still fouling plugs (likely) or ignition isn't right (pretty unlikely - it's not a points ignition, plus the missing isn't happening on startup or in an consistent way).

I'm wondering if the float level needs adjustment. It's on spec, but do you think that lowering the front end so much would cause too much fuel to enter the carb bodies? Weird hypothesis I think. I will adjust the fuel pilot screws and try a sync first.

Looking more like I might take it to the dyno.....

[D-Mac]

What are the little spring loaded valves called that the floats actuate?  I'm having a senior moment and can't remember what they are called...anyway, is there a chance that those little dudes aren't shutting off the flow of fuel?  Did you replace those when you rebuilt your carbs?  

Float Seats were replaced. They appear to be working because I can see that the fuel left in the line doesn't drop when the bike+petcock is shut off.

[CLAY]

I don't use the sticks- I use a different style- I'd have to go out to check what it is, but it only does two at a time.  It works well.  

Do you have tubes in the carb holder boots?  How do the tubes attach to the carbs?