HELP PLEASE! Bike Cranks but wont Start.

[smoothbomber23]

Hello, I'm new to this forum and also new to motorcycles in general. I appreciate what you guys are doing here as it will most likely prove to be a HUGE help. Three weeks ago I purchased my first motorcycle, a 1986 GS450L, from a guy who put a mac 2-1 exhaust on it and said he rejetted the carbs. He also said he replaced the valves. I rode it around for a few days in the city and noticed it wasn't running well, I had a hard time getting above 35mph! I thought it must have been a carb problem so i removed the carbs to clean them to find them pretty much mangled inside, took them to a shop and they needed replacement. Unfortunately the original carbs are discontinued from mikuni so I ordered the new/used carbs on ebay and put them on with no problem. When I went to start the bike it cranked and cranked but wouldnt turn over. I ran the battery dead and hooked it up to my car (with it off) and tryed to crank it again but it wouldnt turn over. I decided since the carbs were used they were probably just dirty and needed to be cleaned so I took them off and cleaned them and put 125 main jets on them for the exhaust (original are 115). I also replaced the spark plugs and the O-rings that go from the carbs to the motor. I finally put everything back together and hooked it back up to my car because the battery was dead and it just cranked and cranked and wouldnt start. Both bowels have fuel in them from priming and the choke was out, but i also tryed with the choke in and couldnt start it. Any ideas on what is going on would be greatly appreciated and i'm sorry the post is so long i just didnt wanna leave anything out.

Thanks
-Thomas

 

[jed.only]

internal combustion engines require 4 things to work. air. fuel. spark. and compression. when an engine will not start, likely it is attributed to the absence or deficiency of one of the 4 items i listed.

 

[omaharj]

Hello!!!
The gurus will be by in a minute. In the meantime,let me guess. 2 into one means you need to rejet new(used,new to you) carbs. Instead, I'd say go back to stock pipes and rerejet. Anyway. here comes the knowledgeable folks.

Welcome to the GSR--We like pics! RJ

 

[omaharj]

internal combustion engines require 4 things to work. air. fuel. spark. and compression. when an engine will not start, likely it is attributed to the absence or deficiency of one of the 4 items i listed.

I was typing while you were posting

 

[asetech]

Have you checked spark? are the plugs fuel fouled? Are you running pods or the factory airbox?

 

[robertbarr]

You have two sets of carbs, and the bike won't start with either.

Drain each carb bowl into a container (like a clean tuna can, or something of the sort). Examine the quality & volume of fuel that drains out.

The next time you have the spark plugs out, check the engine compression. Then check spark with the usual techniques, before putting the plugs back in.

 

[Steve]

Not starting when cold is a classic symptom of mis-adjusted valves. Most likely, the intakes are tight, but it could be any of them.

.

 

[Smokinapankake]

Consider, too, that if the butterfly valves are completely sealed off, no gas/air mixture will get to the cylinders, hence no fire. This is easy to adjust as it is controlled by idle adjustment screw, on the bottom, between the middle two bowls. Being a new to you set of carbs, there's no telling how they are adjusted.
Ask me how I know this......

 

[BassCliff]

Greetings and Salutations!

Greetings and Salutations!

Hi Mr. smoothbomber23,

I would add that, unless you have the jetting all dialed in for pods, these bikes need a properly sealed airbox installed on the carbs in order to run. It's not very easy to get these bikes to run with nothing on the carbs to restrict the air intake. Have you checked the float height? If you do have an airbox, did you put too much oil on the air filter? Have you tested for good spark? Have you tried new plug caps? OK, let me just shut up and give you the mega-welcome, which will get you started on your Suzuki GS adventure.

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.


Thank you for your indulgence,

BassCliff

 

[Guest]

Did you use the prime function on the petcock to fill the float bowls of the new to you carbs?

 

[smoothbomber23]

WOW!!!!
I never expected replies that fast! This forum is an awesome tool! The butterfly's being closed makes a lot of sense and I will give that a try tomorrow. Also the guy that had the bike prior to me mangled the carbs when trying to fix them so i can only imagine the way the valves look so i may have to pull the head off and look at those, at least to do a clearance check (how easy is this?). I'm gonna start simple with the butterfly adjustment and post again tomorow to see what the results are. I think im gonna keep the mac 2-1 for now because of money but does anyone have any thoughts on the jet change from a 115 to a 125? Is that a good jump for the exhaust?

THANKS A LOT!!!!!!
-Thomas.

 

[Guest]

That's a good start for the mains. I rebuilt that same bike for a friend and have the manual. If you have any questions just ask.
Your motor uses shims for the valve adjustment. Basscliff has a tutorial on his website for this process.

 

[BassCliff]

Also the guy that had the bike prior to me mangled the carbs when trying to fix them so i can only imagine the way the valves look so i may have to pull the head off and look at those, at least to do a clearance check (how easy is this?).

Hi Mr. smoothbomber32 (Thomas),

Valve adjustments are a little tedious, but pretty easy to do. You'll find a tutorial on my website for my 850G, but the concept is the same. Also Kerry Burton, from the GSTwins.com forum shows how to adjust the valves on his later model GS500, but the procedure is the same. The video is here:

http://video.google.com/videoplay?docid=-2015554469142545363

I would strongly urge you to get a manual for your bike. At least a Clymer (or Haynes), but preferably a Suzuki Shop Manual.


Thank you for your indulgence,

BassCliff

 

[smoothbomber23]

I figured out the problem. It was something dumb! The breather hose that goes from the head to the airbox was disconnected from the airbox. I guess this happened when i slid the airbox back to remove the carbs. Other then that then that the new carbs with the jets make the bike run way better then the old carbs. Next up is the valve clearance task. I read the DIY and watched the video so I'm ready to tackle it. Thanks everyone who helped me out with my problem!!!
THANK YOU
-Thomas

 

[four_shot]

congrats and welcome....I cant wait till I have to start chasing gremlins on my bike. winter is way too long.

 

[Nessism]

I figured out the problem. It was something dumb! The breather hose that goes from the head to the airbox was disconnected from the airbox. I guess this happened when i slid the airbox back to remove the carbs.
THANK YOU
-Thomas

Glad your bike is running better Thomas but the problem was not the breather - only issue that will cause is fogging some oil and blow by gases on the ground.

Fingers crossed that the bike keeps running well.

 

[Guest]

The float bowls finally primed themselves.

 

[thatbikerguy]

When he said that he was new to motorcycles in general... I was gonna suggest turning the petcock to the on position.

Been there before...:-$

 

[smoothbomber23]

The bowls were primed for sure because i undid the drain plugs on the bottom and got gas everywhere, (and yes reprimed them after they became empty) but also the engine was totally flooded so i think letting it sit had something to do with it also!!!!! Thanks Again Guys.

-Thomas