Not so blown engine

[ohgoodtimes]

Alright, so I went and picked my bike up from the mechanic who told me my engine was blown and would not start etc. So I took it home and sure enough it started. Now the bad thing is when it starts it shoots straight to full throttle with the throttle being closed. I have to shut it down immediately after starting in fear of it hitting the red over reving and breaking stuff more. Any suggestions as to where to start my search for the culprit?

 

[tkent02]

Throttle partway open?

I bought a 250 dirt bike once with the throttle slide in backwards, the throttle would only go halfway down, it would not start until we pushed it to about 6,000 RPM, then it took off like a shot, dragging a bunch of drunks after it. Hilarious, if painful.

So maybe this "mechanic" put something together wrong?

 

[lucabond]

Do a bench sync on your carbs, that should get you in the ball park.
Good luck,

 

[ohgoodtimes]

with the bench sync at 2 turns out it was kind of running, but only with full choke. at 1.5 turns out it can run to about half choke. I let it actually run out and it isn't going over 4-5 k on the initial start. checked for vacuum leak by sealing the top of the air box and the bike died. Is this going to be a fuel problem then?

 

[ohgoodtimes]

update, the rpms change along with me spraying carb cleaner. wont stay running though

 

[earlfor]

Sounds like a set of half frozen carbs and/or a seriously screwed up throttle linkage/cable setup. I would pull the carb rack off the bike, and at the minimum, check the slide operation with my finger, then check the cable free play and friction.

Earl

 

[Nessism]

I'd fully rebuild the carbs, replace the intake pipe O-rings and then go from there.

 

[ohgoodtimes]

throttle works fine in opening and closing, at least from the outside I can't see what is going on inside. If I add any throttle though it kills the motor. I am thinking the carbs need a good cleaning after sitting for 8 months. I know there are a few things they need such as o rings for the bowl drain plugs. I guess I will be pulling them off and going from there. Oh and the intake o rings are fairly new

 

[Guest]

You don't have intake o-rings

 

[earlfor]

Oh and the intake o rings are fairly new

As chef said, 83's dont have intake "O" rings. Possibly you meant the intake induction rubber boots are fairly new? If the bike has been sitting for eight months with gas in the bowls, it a sure bet the carbs need disassembly and a thorough cleaning.

Earl

 

[Nessism]

Actually, the '83 does have the o-rings. Funny how Suzuki went back to O-rings for the 3rd generation 750 after deleting them on the 2nd gen.

 

[teet]

+1 on carbs plus linkage checks- including the choke.

While on the bike, you can also check this.

Check your choke slides are not sticking. Also loosen the idle screw on the bottom of the carbs.

It could be contamination in the carbs, etc.

Looks like pulling the carbs and cleaning them, with special attention to reassembly is in order.

Did your "mechanic" have the carbs apart? And does he have any more "blown up bikes" in his shop? I could use a few of those

- JC

+1 on JC's post.


Sounds to me almost like a choke issue...but a complete cleaning is definitely in order.

Jeff (teet)

 

[ohgoodtimes]

He didn't have the carbs off from what I can tell. I am going to agree with the cleaning and that is what I am going with. As far a cable play and movement the choke and throttle both seem to be functioning normally from the outside, but the problem more than likely lies inside. I did leave gas in the carbs with stabil in them while it sat, so after cleaning I am hoping to see a huge improvement.

 

[duaneage]

The throttle rotate about 1/8" before the cable tightens, this is a safety feature meant to ensure the throttle closes all the way and turning the bars does not raise the engine speed. The choke likewise should allow all four to close and the actuator rod should have play in it. About 1/4" movement is acceptable on the choke control and it should open completely.

 

[first timer]

I would bet the carbs need a good cleaning, are they the black ones or silver? Bring the bike on over here we can do a carb clean on her. Or I can show you how to take them apart and you can do the rest at your leisure. You should do a search for robert barr and his o-rings kits, if you order tonight you might have them by saterday. I would recomend dipping the carbs if they are not the black ones other wise we will have to try spray cleaner first and see if it work. The Dip will strip the black paint off the carbs.

I would go one step further and guess that you were getting lower cr numbers because one of the slide in the carbs is hanging and not letting the cylinder breather fully to get a good cr test. We can do a cr test at my place too if you want. The throttel cable does not directly operate the slide so you could have a free operating throtel and have a hanging slide.

I'll be around this weekend drop me a line.

-R

 

[Guest]

http://www.cycleorings.com/