1980 GS1100LT Resto/Mod - Won't start..

[Guest]

Hey all, some of you may recognize this bike from late last season when I got it mostly put together. I have not been able to get it running yet. It has a dyna 2000 with the 2.2ohm coils. I have verified that my static timing is set to 40 degrees and I see a spark on all plugs. The left coil is powering cylinders 1/4 and right is 2/3. I primed the carbs, verified that they are getting fuel and fuel seems to be getting to the cylinders also. Occasionally the bike will let out a menacing backfire when trying to start, but never gets running.

Carbs - BST36SS 1989 gsxr750. I jetted them with a 1997-2001 Bandit 1200 dynojet kit. I believe these carbs are much the same, but at this point i'm hoping that there's a fundamental difference so I can just buy a holeshot kit that magically fixes everything. Also worth noting, the dynojet kit I used had diaphragm springs that were too long so I cut them down slightly and evenly across the board, the carb slides move freely, but I also have a feeling that this is more of an exact science.

Kit I have installed - http://www.dynojet.com/pdf/3154.pdf . I used the DJ150 mains and 32.5 pilots. All sync ports on the carb lids are sealed. There are no vacuum leaks.

I have spark, air, and probably poorly metered fuel with above said. Before I run out and get the holeshot kit, any advice contrary would be great.

Hope you're all doing well and getting ready to enjoy another great riding season.

-John

[ShadowFocus603]

Does the backfire sound like its through the carbs? Either way I'd check timing and valve clearance.

[yoshisakan]

Not through the carbs no, it's definitely through the exhaust. I just replaced the valve guides and all that, valve clearance is good. Also replaced the head gasket and head studs. Everything is definitely correct there.

[chef1366]

You should of used the DJ kit 3136.
These carbs wear out at the needle and emulsion tube since the slide guide wears out and creates a lot of slop.
Check the emulsion tube for an oval opening at the top of the jet where the needle goes in.

[yoshisakan]

Chef - Which part of the kit I used do you suppose would keep the bike from not starting at all? I want to have a plan before tearing the carbs off and getting fuel everywhere.

The spring difference is very concerning to me. The kits for the 1100 and 750s say to keep the stock springs and the ones I'm using now are stiffer/have a faster return rate requiring more force to move the carb slide.

[posplayr]

40 degree static time?

[yoshisakan]

Here are the instructions I followed: http://www.dynaonline.com/skins/down...uct/DDK3-3.pdf

It says stock compression motors run well with 40deg total timing.

[posplayr]

Here are the instructions I followed: http://www.dynaonline.com/skins/down...uct/DDK3-3.pdf

It says stock compression motors run well with 40deg total timing.

When I lined up the timing plate, I rotated the engine in a clockwise direction. Is that the correct direction?

total means initial (static) plus all mechanical. I think static is about 12 deg and has a timing mark. When you rotate the advancer you should be at the total mark. You can confirm a that with a timing light as well. The manual should explain. There are gixxer manuals for free download at gixxer.com in the oil cooled fourum sticky.

[yoshisakan]

Oh, so you think since the timing to spark at 40deg on the timing plate, that is actually 28deg off? It does say to align the mark to the "full ignition timing that you want to select." That leads me to believe that the static timing is set to include the advance.

[posplayr]

Static=initial
total=static+mechanical

[yoshisakan]

I think in this case they are referring to total timing as initial + advance, which should be about 40 deg for stock compression. 13deg is the initial timing for this motor, at 8000rpm the advance is 22deg, for a total of 35deg.

[posplayr]

Not sure I should ask, but why did you not buy the proper dual filters for those carbs? They not fit?

[yoshisakan]

Not sure I should ask, but why did you not buy the proper dual filters for those carbs? They not fit?

They actually are the correct ones, I had to work a little magic with 45 degree elbows to make them sit lower because of how low the pigel fuel valve sits. My tank needed an adapter plate that sits about 1/2" lower and that's really the cause of the problem.

[yoshisakan]

I'm up at the ass crack of dawn today, so I'm going to reinstall my stock carb springs and see what happens.

[yoshisakan]

Update: I reinstalled the stock carb springs and now the bike is back firing through the carbs, which I suppose is a step in the right direction. Also I looked at the old needles and they have some gnarly grooves dug out in the end close to the circlip. I still think this thing should start even if it runs like crap. Thoughts?

Turn out my carbs are actually from a 1995 Katana 750. More research to be done here.