engine starting problem

[Guest]

hey guys,

cleaned my carbs and reinstalled them. set the pilot screw 2.5 turns out. when i press the starter the bike begins to fire but doesn't catch. when i apply some throttle and start it doesn't even catch. any ideas?

[tc.young]

oh relevant info,

it is getting fuel and spark and will fire when given starter fuel

it's a '85 gs700ef

[Steve]

First of all, GET RID OF THE "STARTER FUEL".

Next, learn the proper technique for starting a cold engine.

Let's start with basics. Have you adjusted the valves? Should have done that while waiting for your carbs in the 'dip'.

You did dip your carbs, yes?

Turn the idle mixture screws out to 3 turns, instead of 2.5, until you get it running well enough to be able to fine-tune the mixture.

Set the "choke" lever to about half-way.

Turn the key ON.

Pull the clutch lever (unless you have disabled the "safety" switch).

Push the starter button.

Regulate engine speed with the "choke" lever. Keep the revs under about 2500 by moving the "choke" lever toward the right.

As the engine starts to warm, it will speed up.

When the "choke" lever is almost all the way to the right, you can test the throttle response. NOTE: this is the FIRST time you touch the throttle.

When the bike is fully-warmed up, slowly turn the idle mixture screws in until you hear the engine start to slow down a bit, then back the screw out about 1/8 turn, move to the next screw. You might end up back at 2.5 turns, but the richer mixture will help get it going on a fresh clean and rebuild.

.

[tc.young]

well got it started. was listening to the engine it's only firing on 2 cylinders, the two outside ones. any ideas why guys?

[tc.young]

and the answer to all the above questions was yes.

[tc.young]

well after fidling around with it more bad news. it was firing on the outside two cylinders so i sprayed took apart the two middle ones again and cleaned them. then reassembled and put back together. turned it on, both outside ones were still firing but not the middle two. then while it was revving it made a sound and died. compression tests show 60psi on 1,2 and 4 and 3 is zero. any ideas what could have caused this? overheating?

[SqDancerLynn1]

First a mistake many make is ? Did you open the throttle wide open when doing the compression test ???
Next step would be to check the cam chain timing

[tc.young]

wot when checking compression, made that mistake once.

didn't check timing assumed it was right.

[1_v8_merc]

You probably have a bad coil or dirty connection...

Look on basscliffs website to run some quick coil/wire tests.
You will obviously need a digital voltmeter

Cylinders 2+3 are wired to the same Coil.
So you might simply have a loose wire or dirty connection.
Another common problem is corroded wire Boots(the boot that connects to your spark plugs)

Which brings me to my next point....check your spark plugs yet?

[tom203]

wot when checking compression, made that mistake once.

didn't check timing assumed it was right.

New to you bike? assume nothing, except that someone likely screwed up!

[tc.young]

New to you bike? assume nothing, except that someone likely screwed up!

yea made that mistake once before and now again.

i replaced the plugs.

anyone know if the top end can be removed in frame? bottom feels alright so if possible i'll keep it in place, open the top and take a look.

[Steve]

... anyone know if the top end can be removed in frame? bottom feels alright so if possible i'll keep it in place, open the top and take a look.

Top end can be removed with engine in place, but please make sure it's necessary before going through all the work and expense.

.

[koolaid_kid]

That is a pretty drastic step to take when you have not even finished investigating and troubleshooting yet. It's your bike, but I'm just saying.

[keman]

zero on #3... shine some light in through the plug hole to check if you can see any obviuos damage. Valves can get so far out of adjustment that they never fully close, or worse, collide with the piston and get damaged.

If this were my bike. I'd take the cam cover off and check the valve clearences for ALL of them. I am guessing that #3 may be way off. Remember, these valves TIGHTEN with age.


What was the noise it made before it died? Pop, Bang, metal to matal, thud, clunk, fizz,... Try to describe it for us.

[tc.young]

just seeing what my options are, still have brakes to fix. gonna double check valves, derust the tank and redo carbs again. then check timing and that cct. then go from there.