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I picked up a 1979 750K back in November. I worked on it a bit.

In June I was put it all back together and tried to start it. Bike started and ran for but I couldn't keep it running. (Figured it was the carbs as it didn't run for a year or two).

Tried again the next day ... and it started once then next time I heard a small noise and the the next time all I go was a spinning starter.

So talked to a Honda shop and they said probably the starter clutch so I picked up a repair kit and found 3 broken springs in the clutch. Replaced all rollers and springs got excited ... hit the starter and again all I get is the sounds of a starter running.

Took it out the next day and pulled it behind a truck. Nothing. Rolls like the clutch is engaged.

The put it in gear If you pull it backwards you here the sounds of the engine and all parts moving. Push if forward and it pushes like nothing.

pulled out the the two out side plugs. hit starter bot pistons are moving up and down.

Bike appears to have compression when pulling backwards but none when pushing it forward in gear.

What's next to check?

Help!
 

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Have you checked that the cams are turning?
 

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Three things to check. First check compression on all 4 cylinders. Second check for a big fat blue spark at all 4 plugs. Third, if the first 2 show ok, remove, completely disassemble, and clean the carbs, replace any worn or broken parts. Jets don't wear, I'm mostly talking about 0-rings and gaskets, and maybe the float needle valves. If it has CV carbs, check the diaphragms. Handle them VERY carefully.

When you get everything back together, make sure you have gas going to the carbs, and the float bowls are actually filling up. There should be drain screws on the bottom of the float bowls.

If you have compression, spark, and fuel, you only have one thing left, and that is timing, both ignition and valve.

If it has points and a movable backing plate, you can set the ignition timing. If it were the valve timing, there wouldn't be much you could do about that. But if the valve timing were off, or the cam chain broken, that would show up on the compression test, so if compression is good, valve timing is ok.
 

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Well it seems like there is no compression when I push it forward in gear but there seems to be compression when I pull it backwards.

I'll have hopefully more time to look at it next week.

Thanks appreciate the support.
 

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Not sure, but the timing chain slack adjuster may be loose and this is making the engine "out of time". This is why there is no compression forward BUT compression going backwards.
I had a CB350 and while messing with things I didn't understand (at the time) I managed to get the timing chain slack on the WRONG side of the timing chain adjuster and your issue sounds just like my problem.
 

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Joep and I have been in conversation about this same idea ..

Funny how my Goldwing forums are giving me better help than my 750 forum ... LOL ...
 

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I was going to say that it sounded like the same problem that I had when i replaced a timing belt in one of my mom's cars. I fixed the timing and it ran just fine after that. It sounds like you already have it covered so...
 

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I really appreciate the help ... I Love my goldwing and nothing compares to the ride of a wing on the open road.

But I live in a nice very scenic area of Southwest Wisconsin that has mile and miles of fun twisting roads.. Although I have no problems putting the wing through the twists. It's nice to have something a bit more nimble to play with.

I have always had a passion for the old CB750's and Loved the lines of the K models.

So I picked this bad boy up last November.


Now I have a boner to get it on the road. Haven't had time to work on it until now ... that was frustrating ...

Thanks again for the help.
 

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Great bike!
 

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If it ran ... LOL
 

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Hope you've located a manual for the DOHC's by now. I agree with Dave about checking for the cams turning. I can't imagine a scenario where eight valves are open at the same time if the timing chain is entact.



You may want to access the clutch and verify that it's turning when you push the bike forward while in gear.



Those motors were very robust, Honda used the same basic lay-out for the 750/900/1100 with only bore/stroke and head changes... :gunhead:
 

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Yes I have a manual, and yes I have checked the clutch and all spins when I push it forward.

Originally there was an issue when I purchased it with the cam chain being loose. But It only ran for a few moments it ran very rough and I couldn't keep it running enough to tighten the chain.

I've been searching for a replacement engine just in case but I'm sure I'll have this running shortly.
 

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You may have to pull the valve and timing cover to line-up the marks, tobe able to static time the cams/crank,(as in a rebuild,or cam change). Once you are close and get the engine running you can try the self tensioner proceedure in the manual...:gunhead:
 

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I do have a new chain and I have a set of gears just in case ... I picked them up last winter just in case ... Got lucky on an OEM deal. Thought good to have on the shelf for the price I paid.
 

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Well found the problem ... broken cam chain ...

So biggest question ... can you access the bottom sprocket via the oil pan! would make putting the new chain on much easier.
 

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Don't know, the manual may show if there is a slipper/guide on the bottom or not. On my 900 I was able to attach bothe chains together and pull the new one in, as I worked the old one off/under/around the bottom crank sprocket. Of course I was younger and had more patienceback then... :gunhead:
 

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I've heard of cam chains replaced by attaching the new to the old using a "soft link" (google it) But I have never done it like that.
If it were me,,,,,, I would pull the engine, split the cases, use nos parts, and do it right.

...... It's a lot of work and ain't cheap.
 

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That won't work the pulling one chain attached to the other one .. as it was broken at the bottom and just lifted strait out ..
 

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Look cool .. so much fun ahead.

 
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