Topic: Stumped

[my78k]

Hey guys, I appologize in advance as this will likely be a long post but I can't figure out what has gone wrong and I am a little nervous about tearing in to the motor too deep if I don't need to...btw it's a 78 750K

Here's my situation: After cleaning the carbs over the winter and a few other small jobs I put the bike all back together and fired it up. (it's important to note that this bike was left for dead for 14 years uncovered and unprotected in a driveway in southern Ontario where the winters and summers can be pretty harsh...needless to say it was basically like bringing something back from the dead). When I put it away it ran about 5 out of 10 (wouldn't idle w/o choke etc.). I had already done the oil change and plugs long before starting it up the first time. When I put it all back together (after the winter)  it ran more like a 7. I was hoping to get it up to a 9 or so by doing some further maintenance like valve adjustments, cam chain tension etc.

I had it fired up and wanted to get it up to temp so was letting it idle for a while with periodic revs when it started to backfire etc. The cam chain has always been noisy so there was the usual clatter etc. But the popping got a little worse so I turned it off. I know the carbs are clean although they are probably way out of sync.

I waited a few minutes and tried to start it back up...and now it will only barely start and sounds like crap with absolutely no power. I basically have to hold it at 1/2 throttle just to keep it idling!

I figured I should check the cam chain tension so I did as prescribed and set it to 15 degrees past TDC and ensured that the tappets on cylinder 1 were loose...loosened the retaining bolt and undid the tensioner and did not hear any click or something similar. Started it back up and it sounded exactly the same...like crap! I can't check the tappets right now as the feelers I have are straight and can't get them in through the valve covers properly.

So I guess what I am looking for is a way of trouble shooting to figure out what the hell went wrong...

I checked for spark on all 4 cyl's and that is fine...the carbs should be fine as I just cleaned them and installed new fuel filter. I had set the timing back in the fall with a timing light.

Could it be that Cam chain snapped or slipped or something??? It sounds from previous posts that I have read that I should have heard a click or similar sound when I loosened the cam chain screw...

HELP?!?!?

The weather is turning gorgeous out and although it's not ready for the road it's atleast great wrenching weather and I always take it around the neighbourhood for kicks...

Any thoughts are welcome!

Dennis

[Lumbee]

 CARBS, CARBS, CARBS!!!  I know thats not what you want to hear, but from everything your saying it sounds like carbs.  I just brought a 750 back to life and on the 4th cleaning I finally got the carbs to run right, and they looked great befor the 1st cleaning.  Have you completly disassembled the carbs and soaked the carb bodies?

Cam chain is not a weak point on this motor.  Is it possible it "jumped a tooth" and is out of timing?  I guess, but not likely.

[byidesign]

   Hope you have a manual, as you can adjust cam tension
        without getting into the motor, also go.{see FAQ's}pages

 I would agree, Bad gas, and dirty carbs.
    you may try fresh clean gas in the tank, and open,
       the bowl drains,and let it run through until
        fresh,and try again.{also flushes out the bowls} if you get a noticable
          difference, {it's carb cleaning time}
             you will have lasting headache's if you don't clean them
           in the long run.
               hope it helps
                      Bruce
           

[dusterdude]

im wondering if some or all of the plugs fouled on it.

[my78k]

Thanks guys....I do know how to adjust cam tension w/o opening engine as that is how I did it...I was just surprised that I did not notice any difference after or any noise while adjusting it...any way to tell if the adjuster is stuck?

I replaced the plugs last year and only have a few hours on them but for the few bucks I guess I could try replacing them.

Could I have put in too much stabilizer? or something else go wrong like that?

Also like I say I have not been able to adjust the valves...could that have anything to do with it? Anyone been able to adjust theirs with regular straight feeler guages?

[TwoTired]

Anyone been able to adjust theirs with regular straight feeler guages?

Sure.  But, only after taking a pair of pliers and making a 30 to 40 degree bend in them about 1/2 inch from the tip.

Cheers,

[Lumbee]

...I bet alot of your engine noise is coming from the clutch plates not the cam chain...thats pretty common.  When I first got mine I was paranoid about the noise coming from the engine, and though it was the cam chain, but it wasn't.  Keep in mind an air cooled dry sump motor doesn't have much to dampen noise coming from the engine...

[Sam Green Racing]

If the carbs are not in sync, you will find it causes a lot of noise from the primary chains, not the cam chain.

Sam.

[eldar]

Well I will let you in on something with the cam chain. Take the tensioner off and clean it. Oil gets in there and gums up. It is stuck, I would bet the farm on that. So set the enigine to adjust the cam chain, take off the tensioner and pull it apart and clean it. Be carefull as you clean it cause the spring will shoot out. Once clean, put it back together and back on the engine and then loosen the screw and it will go about its business.

Now for the running part. Clean the carbs as suggested but you dont need to soak. What you want to do is make sure the passages are clean. You dont evene have to pul the bodies completely apart for this. Now once you have the main areas cleaned up, get out your pliers and a piece of cloth. Put the cloth around the low speed jets and squeeze with the pliers and twist them while pulling. they will come out after a herculean struggle. I actually had to wiggle mine a bit VERY GENTLY to get the crud to loosen up. Clean these and clean the little holes. Carb dip does not clean these holes worth crap in most cases.

Now put the jets back in and bench sync the carbs using a small drill bit to set them to about the same setting. Adjust your lows speed mix screw to about 1.5 turns out. Remember OUT MEANS RICHER, IN MEANS LEANER on our bikes. this is opposite to the 76 and earlier carbs.

Set your floats to 14 - 15 mm from the gasket surface. Manual says 14.5mm +- .5 so that means 14 - 15 mm. Oh before yo uset the floats, cvlean out the valve seats and check to see if you need new valves for the floats.

Put these cursed things back on and hook up all the cables and filter.

Make sure your points are clean and dressed and timing is set.

Take out those plugs and clean them too.

Put it all back together and turn on your fuel and hit it. You should get something out of this, but this is your starting point. You may actually want to check your valves after you set the cam chain.

This should get you on the track though.

[Objectionableone]

Ditto above. Clean carbs, Clean points and Correct timing

[HondaMan]

If the engine is running unevenly you will hear lots of clatter from the primary chain, down in the cases. Don't worry about that noise until it's running well again.

The camchain tensioners do stick, especially when they haven't been adjusted in a long time. Turn the engine to the adjustment point, going only forward direction, loosen the camchain adjuster locknut-bolt about 1 turn, then tap firmly on it with a plastic hammer or brass hammer (use a 3/8" ratchet extension for the tapping if you can't get the hammer in there). This usually lets 'em move. Then tighten the bolt & nut back down before moving the crank again.

Worst case: remove the tensioner and unstick it by hand, then put it back on. It's not tricky or mysterious, just a plunger that's held in place with the little lockbolt and nut.

The problem sound like carbs or plugs. Or both, like the guys above said...BTW, the gas preserver usually gums up the float valves real bad in these bikes. Don't use it. Just drain the tank and carbs instead.

[my78k]

The part that really suck here is I did clean the carbs over the winter (a much more thorough job than before when I did it in the fall) I pulled the idle jets and cleaned them...got the wire through and everything. I hate the thought of pulling them again but guess I don't really have a choice...

[Bob Wessner]

Also, make sure all passages are clear (compressed air source). I feel your pain. I got to know my carbs way better than I ever wanted to before getting them sorted out.

[eldar]

Well clean em again I suppose. Make sure you have a filter on the fuel line. When you pull the lows, make sure you clean the port for them also. If you did not do that before, that crap could have replugged the holes. ALso make sure you set the low speed mix screws and you have cleaned the float valves. Dumbest thing that happened to me was that my #2 float was not closing and it would flood out the cylinder like nuts but would not go out the overflow tube. Real odd since I know the tube was not plugged. make sure the slides are set the same too.