VF750F starting issues

Hi All, i am new here i have been reading heaps of post and there is some really good advice out there, now i need some please.
I recently got a 1984 VF750f which had sat for a bit, i did all the basics to get it running again, which it did for a few weeks but i always had an issue that when it got hot it wouldn't restart it would sound like a flat battery, but an hour or so later started sweet. I thought it was the starter motor so i got a second hand one and a new battery, installed them started bike and i ran it for about 10 minutes turned it of and tried to start it again and all i got was clicking from the solenoid!! I put the multimeter on the relay and it reads consistant on each terminal also when ipush the start button i get the same reading at the starter motor terminal. i try to put a screwdriver across the 2 terminls on the solenoid to see if that would run the starter but it does nothing doesnt even spark? It appears someone has tinkered with the wiring at some stage and has added a switch for the fans, also when the kill switch is on or off and i push the start button it operates the same but when the bike was running and i switched the kill switch of it would stop the bike as it is supposed to. any advice or thoughs on what i maybe?? thanks

 

you may heve a bad ground to the engine. also, i've had to replace brushes in the starters a couple times... does exactly what you describe when the brushes go south. no big deal, the brush plate is available online, or a decent auto parts store may have them. I got mine at napa, but i don't know what you have there.

 

Clicking solenoid...check charging voltage...test alternator...change R/R...rinse and repeat.

 

Hi, appears to be the brushes in the starter motor. Anoys me becuase this is the second hand starter i brought from a wrecker who told me it was sweet, started bike once and they turned to dust! So with new ones, the issue of it not starting when hot wll go away? thanks

 

yes, the problem will go away with new brushes.

 

cool! Thanks

 

I guess I misread the post. Usually when someone says the relay is clicking, they mean that it is clicking repeatedly. As if it is not getting enough power to hold latched. This happens quite a bit with the VFRs, due to the rampant R/R failures.

Brushes are very fragile and tend to just break down over time. I wouldn't hold this against the wrecker, as brushes are considered consumable and are cheap and easy to change. It would probably be a good time to clean the commutator while you're there and make sure that all of the old brush residue is removed, so that the new brushes don't get damaged. Also, it is good practice to seat the brushes properly so that you get good contact.

Good luck.

 

Hi thanks for the advice hopefully can get parts soon and sort it have a ride in a week

 

Hello NK74. Good to see a fellow Kiwi here with a VF750F. I've been sorting one out too over the last year. Getting parts here is a bit of a mission. Only managed to find 1 being wrecked in the whole country! For new parts I found CMS parts good for stock, price and freight costs. Parts take about 1-2 weeks to arrive.
Try this. Honda Vf750f 8319750 Interceptor Usa parts list partsmanual partsfiche

 

Hi Rainman thanks for the tip, i managed to get some brushes from local bike shop. Problem i have now is it keeps turning them to dust any ideas what could cuase this? the starter motor gets real hot. Took it for a ride about 6 weeks ago and it blew a head gasket, got a new set from Aus at a good price too, just got it back together and took it for a ride earlier went well apart form the starter motor issue any help appreciated.

 

Hi NK74 When you say they turn to dust. Do you mean the brushes are actually wearing shorter with only a few starts? With the new brushes does it start OK when the bike is hot?
I haven't heard of this before and I'm only guessing but I wonder if the starter is not disengaging after the bike starts - So the starter is still getting spun all the time - that would wear brushes quickly and make the stater hot. Also it may be worth getting your old starter motor and put new brushes in that and see if the problem goes away.
What part if the country are you in?
Good to hear its going well other wise - I took my Gen 1 out today too! :smile:

 

Hi, yeah wears them down real fast, starts sweet when new. What you say makes sence as it has done it to 2 different starter motors, any ideas on what would cause it to stay engaged? electrical, mechanical?? Im in Hamilton:smile:

 

I don't think it would be electrical as that would be very noticeable - it would be like riding with your thumb on the starter button all the time, so it will be mechanical if it is happening.
Unfortunately I haven't been working on motorbikes for very long so don't know my way around the starter gear setup. If it was a car I would point you in the right direction but not the motorbike :frown:

Fortunately there are heaps of experts on this site who will be only too happy to share their knowledge.....they may even say I'm way off target with guessing it may be staying engaged.

I'm in Palmerston North.

 

thanks for the comments all helps in trying to suss these things out:smile:

 

Hi, right this is doing my head in now! I took the bike for a 15 minute ride, when i got home i stopped the bike and it wouldnt start. It is the original issue when it heats up it wont start after it cools it starts. The battery, solenoid and starter motor brushes are all fine, what could this be and what can i do to prevent it??

 

So when bike is warm, it acts like a weak battery and doesn't turn over? If so, try boosting it to see if it works.

I take it that you determined the starter is not spinning when the engine is running. Are the brushes still getting shredded? Disassemble starter and clean the armature.

If the bike is turning over fine, but just not starting, you'll have to determine if it is a spark, or fuel problem. If it is a no spark problem, try spraying the ICM with an upside down canned air product, to cool it down.

 

Hi Karazy, yep when engine warms up it is like the battery is weak and when it has done this in the past it has shredded the brushes. I then stripped the starter motor and cleaned all parts and put in new brushes and it did the same thing, also i put in a different starter motor and the same thing happened. I left the side cover off and started the bike to see if the starter motor was operating correctly, and it did what it was suppose to. Also to check the solenoid i put the multimeter on it to see it wasnt running power through it once motor started and it was working correctly.

 

So when you have the left cover off you could see the darter gear disengaging after the starter was released?
Have you got access to a DC clamp meter. If so you could see how much current is being drawn hot and cold.
Have you tried jumper leads off a different battery when warm. Batteries can do odd things and maybe yours is breaking down when warm. Worth a try if not.
The motor isn't getting tight when warm? Does it run just the same over a 1-2 hr ride?

I thought I had starter motor issues with mine a while back but it was the cam chain jumping position on the cam shafts causing issues. I don't think this would be your problem though as its not temperature related

Good luck

 

I would check your r/r if you havent alredy. I would also check your battery voltage immediattely after a ride. I would really suspect the previous owners wiring and check all those connections . Good luck. Will be interested to hear what it turns out to be.

 

Hi will check those as there has been some changes in the past to the wiring, i will definitely put up the solution to the problem when i find it.