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-   -   Help shes refusing to start (https://www.vn750.com/forum/11-vn750-general-discussion/104661-help-shes-refusing-start.html)

Will750 09-19-2019 08:05 AM

Help shes refusing to start
 
Hello guys and gals. Im will from the wet misserable windy island of ireland. Iv Been riding for years but this bike is braking my heart. I have finaly took the plunge and registered on this fourm as i have been a ghost it the back ground for some time now. So please this is my first post so go easy on me.😁.
Right first off i need some help from all ye wonderful people. I got this 1986 vn750 as a project with a blown crankcase. This has been replaced along with clutch plates, gear dampers an the likes. Valves have been reseated, timing is spot on. All marks line up correctly. Ear shave completed on the bike as she was a us import. Carbs cleaned and recieving fuel. The problem im having is when i try to start it. She turns over and over but wont catch. Carbs give a bit of a blow but thats as far as she will go. The concern i have is that when i am turning it over the starter motor stops all of a sudden and theres a clunk when it stops. As if it locks up and stops dead. When i try again it does the same thing. Turns over for a bit and then stops with the clunk. Is this the sign of a bad starter motor and is that why it wont start. Any help very much appreciated.

mmart 09-19-2019 09:21 AM

Welcome, what shape is the electrical system? Good battery? Sparks? Etc?

Thorn 09-19-2019 10:45 AM

Welcome aboard!
I've spent a lot of time holding in the start button, and I've never had it 'clunk'. or do anything that I'd describe as a sudden stop. I don't think the starter motor is to blame. Sounds more likely that a valve is interfering with a piston or something. Are you able to turn the crankshaft manually without interference?

Will750 09-19-2019 02:13 PM

Hi and thanks for the welcome. Sorry for the late reply im still trying to figure out how to work the site. Yes i can turn the crank shaft manualy no problem at all. Im currently as i type this, cleaning the carbs again. So i think the best thing i can do is post a video so you know what i mean. Sorry for the noob stuff but as soon as i have the carbs done i will start it and show you. As for the electrics. From what i can tell everything seems to check out. All lights work where there suppose to all earths have been checked and rechecked. I am at withs end at this point.

Will750 09-19-2019 02:14 PM

Also the battery is brand new. And theres a nice blue spark from all 4 plugs.

Will750 09-20-2019 08:25 AM

Quote:

Originally Posted by mmart (Post 1279937)
Welcome, what shape is the electrical system? Good battery? Sparks? Etc?

Quote:

Originally Posted by Will750 (Post 1279951)
Also the battery is brand new. And theres a nice blue spark from all 4 plugs.

all electrics seem to be in good shape. New battery aswell.

mmart 09-20-2019 09:22 AM

Quote:

Originally Posted by Will750 (Post 1279977)
Quote:

Originally Posted by mmart (Post 1279937)
Welcome, what shape is the electrical system? Good battery? Sparks? Etc?

Quote:

Originally Posted by Will750 (Post 1279951)
Also the battery is brand new. And theres a nice blue spark from all 4 plugs.

all electrics seem to be in good shape. New battery aswell.

Gotcha, if you feel the starter is the issue, Maybe try to push start it? That’s easier in 2nd gear but the bike needs to be rolling a bit to get it in a higher gear than 1st

Just a thought

Spockster 09-20-2019 09:39 AM

First thought was one of the carbs filling the cylinder with gas - hydro lock. Any plugs that are really wet? Oil smells like gas?

Any chance the camshafts got mixed up? Valve timing would be off.

Will750 09-20-2019 09:46 AM

Quote:

Originally Posted by Spockster (Post 1279983)
First thought was one of the carbs filling the cylinder with gas - hydro lock. Any plugs that are really wet? Oil smells like gas?

Any chance the camshafts got mixed up? Valve timing would be off.

the plugs were wet but not drenched. All cams and chains set according to the haynes bible. Its like as if it stops drawing power and just stops dead. Then when i hit the start button again she cranks few a few seconds and stops again. I will be installing the carbs again today after cleaning for the second time. Battery is fully charged also. Could an intermittened starter relay cause this ? I will post a video as soon as i try it

Spockster 09-20-2019 10:45 AM

Quote:

Originally Posted by Will750 (Post 1279985)
the plugs were wet but not drenched. All cams and chains set according to the haynes bible. Its like as if it stops drawing power and just stops dead. Then when i hit the start button again she cranks few a few seconds and stops again. I will be installing the carbs again today after cleaning for the second time. Battery is fully charged also. Could an intermittened starter relay cause this ? I will post a video as soon as i try it

Wet plugs can point to a flooding carb with a sticking float. If it was the front cylinder, could also be leaking gas though the petcock vacuum line. So check that hose, it should be dry at all times. Gas can leak through there constantly, even on the 'off' setting, this fills the cylinder and crankcase with gas.

Could be a dead spot in the starter armature, but, do you notice the any of the lights brightening as if the current draw dropped? Same applies to bad starter relay. If the light stay slightly dimmer, the starter is still trying.

You can test for a bad starter relay, jump across the two largest terminals, see if the starter cranks normally.

There's another starter relay inside the junction box, those do fail occasionally.

If you keep hitting dead-ends, the battery should be load tested, regardless of age. Is this a wet cell or AGM type?

About the cams - I mean could the cams have been swapped front to rear? The marks can be set, but if the rear cam is in the front, it would never work.


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