My Vf1000 frustrations

I'm curious if you have solved the problem. I just purchased 2 VF1000 and one of them is acting up almost like yours.
Thanks, Golden

 

Ignition Problem

Techno, did you ever sort this problem out? I have just joined this forum and was reading your problem, and boy does it bring back memories. I raced a VF1000 road race sidecar for 7 years, had an engine failure and through a spare in only to have it demonstrate all the same symptoms yours did. turned out even though the engine numbers of these 2 motors were only a couple of hundred apart Honda in there wisdom had changed the ignition rotor design. they had lengthened the raised section (trigger) on the rotor which causes a higher than normal pickup voltage to be generated which is how the rev limiter is activated, thus causing the rev limiter to work around 25-2700 rpm. When I got back from S.A. (I live in Victoria) I found the difference, swaped the rotor and away she went after spending all weekend in Mount Gambier and not getting to race.
Cheers TAZ

 

Thank you VERY MUCH !!! sidecar42 ! I have had my VF1000FE (-84) since new from 1985 and have driven with it about 100 000 km´s. It has burned too much oil for years and that´s why I decided to purchase a better used engine. So I found a 6 000 km driven (as they claimed) FF engine (-85) from Germany and bolted it on. Holy s**t the engine started well but could only reach about 2500 rpm´s just like the guy´s who started this thread. I did look after everything but could not find the reason. Fortunately I finally found this thread and made the change as sidecar42 did and voila ! Problem was solved, now it runs great without any hesitation at all !! My autumn is saved ! Hopefullly the thread beginner did get his engine run before tearing it for parts.

 

Amazing! I've seen the gap mentioned in the service manual but all of the engines I've checked were ok so I stopped worrying about it. It's great to know that this could be a possible cause for that kind of problem!

 

It is not the gap between the trigger and the 2 picups but the length of the raised trigger on the outside surface of the starter clutch. The earlier version has 5 or 7 mm (sorry I don´t remember how much) shorter trigger than the later version. This caused the rew limiter kicking on about 2500 rpm´s. The carburettor slides went crazy up and down (it made me crazy also !) and it refused to gear past 2500 rpm´s. After I released the gas everything was just fine ! Very frustrating thing but fortunately I got great advice from sidecar42 ! Again many thanks to him !

 

Hey Bro, NEVER dump her. I feel your frustration but your getting some choice and expert advice here from some serious users. Hang in there She will be worth it. Best of luck.

 

First off.. You had a 1984 right? Then you put in a 1985 engine right? That is the problem. The 1984 wiring harness is NOT the same and the 1985 for the CDI boxes. The 1985 has ONE CDI box. The 1984 has TWO CDI boxes. Read that again. Also which 1985 engine? Is it gear driven cams like mine or does it have a cam chain? Here is the good news. The wiring harnesses are very similar and the part of the harness where the CDI box connects can be modified to fit either box. The timing of the 1984 and 1985-86 is DIFFERENT. Now back to basics. First STEP is to do a compression check on the 1985 motor. Then ( I know you will not like this) take the carbs off and remove the float bowls and find out which size jets you have for the main jets and the slow /pilot jets. write those down. Is the 1985 engine a 49 state engine? Look on the front side of the engine and if the carb float bowl vent goes directly to the aluminum pan that holds the carbs....then it is a 49 state version. the jetting for the 1984 and 1985 needs to be checked. If you try to run the engine WITHOUT the INTAKE......air filter or without the mufflers it will run horrible or not at all. It needs the restrictions to run right and be rich enough. So get these two things looked into. 1. the CDI boxes TWO 1984 or 1985 ONE box. 2. The 1984 probably has .. 49 state= 150/145 mains the California model has #112/110 MAINS. The 1985 has 49 state and Canada= 125/125 mains The California has 122/120 mains. The pilot air screw adjustments are different for all of those models also. But find out which engine you have FIRST!!!

1984 and 1985 CDI boxes do not interchange!!
It will run ,but not right.

 

What is that supposed to mean?????

BTW....You were right about the 500 having a valve train problem.
Still not clear what was missing. The retainer or one keeper or both keepers.
Let me know if you find out.

 

Thanks for everyone's replies. I am glad that there has been some info sharing as a result of my problems.

The "rev limiter" theory has a lot of merit as that is exactly how I would describe it.

As for my bike, I still have it, of sorts. I gave up on getting the later model motor to fit. I concluded that it was an electrical issue. I ended up fitting the original motor back in and did a deal with my local mechanics college to give it to them for a few years. They will pull it apart a few times and try to get it running again. I have promised to pay for/source any needed parts. After a couple of years (when it qualifies for classic rego here) I will get it back, hopefully fully functional again.

I still have the newer motor for sale if anyone in Aust is interested.

Cheers

Techno.

 

None of this makes any sense.
"pull it apart a few times"

 

Im having the same problem with my 85' vf1000r. I have cleaned and rebuilt all four carbs and the bike seems to sputter alot and wont really rev past 8k. Sometimes it will get good power, but sometimes it loses power. It idles good and runs good below 6k rpms, but sputters alot above 6k and i can't get the full potential out of my honda. I'm thinking it may be the cv slides in the carbs (diaphrams), I don't think they are opening up all the way. I have replaced them, but i'm still having the same problems. I actually had it running with the gas tank to the side and airbox off and i pulled the slides up in the carbs gently with my fingers and reved the engine and it seemed to run like it should! So i'm not sure what the problem is or how to get the slides to open up like they should. Any suggestions or solutions? It tends to run differently when i have an air filter in it. If i put a filter in it, then it will rev up to 11k like it should, but it revs slowly up there and doesn't have as much power as it does without a filter. I've tried just about everything but i dont know whst i should do.

 

Of coarse it will run better with a filter in it.
It is in effect like a manual choke or if you put your hand over the intake. It will get more gas.
The stock intake and filter will have the most choking effect.


But it is hard to talk about any of these problems with out ALL the facts.

What kind of exhaust system?
Is the intake stock?
What are the main jets size and idle jet size?
Is the stock spring in the slide?
Is the needle stock?
Does the needle in the slide have washers under it?

What is the float level set to?????

BTW the 1985 VF1000F and the 1985 VF1000 R cdi boxes are NOT interchangeable because the valve opening timing is different.

The "F" model has two black boxes and he "R" model has only ONE black box.

 

Did you resynch the carbs?

 

The early V4's never run worth a hoot without the filter, so if yours is better with it out then you certainly have something going on. Keep the filter in place from now on as you will want to use it.

I'd almost suspect a fuel delivery problem with this bike. Maybe a bad fuel pump or relay or even a bad float needle/seat or two. Vacuum slides not opening won't cause the sputtering problem, just a general loss of power or rough feeling. Sputtering sounds like it's starving for fuel to me.

 

stock exhaust, stock intake except i've been experimenting with the filter, i've used a different filter then the stock one. All the carburetor components are stock. How do you set the float level? And I dont ever remember seeing any washers under the needle in the slide when i rebuilt the carbs though. it is the R model with one black box but i set the valve opening times for the carbs so that they will all open at the same time. Is it supposed to be like that?

 

How do you resynch the carbs? Im not a carburetor expert but i've rebuilt several single carburetors. Should i have an expert experiment with it?

 

yes its probably only making half the power it should, it ran the same when it had the stock fuel pump but the fuel pump went out and i replaced it with an aftermarket inline fuel pump for 4 and six cylinders from advance. The floats and needles seemed to be in good condition though. It doesnt really sputter to much, it just has a slow rev at rpms above 6000.

 

Of course it will run better with the filter in, but NOT because of choking effect, it has a lot to do with intake resonance. The intake has a tuned length just as exhausts do, and CV carbies are very fussy about resonance, if your trying to rev it and watch the slides it won't run correctly anyway because the airfilter/airbox can't be there so you can see the slides functioning. We spent many months with the dyno to get my sidecar to run cleanly without an airfilter (modified slides, emulsion tubes,main jets, air bleed jets etc) it's not just a matter of choke effect, yes you'll get more fuel but you restrict airflow. The valve timing verses black box (CDI) is irrelevant we had HRC cams and still ran the standard CDI's (so I couldn't over rev it, my wife got tired of me destroying engines). Another cause I have had for spluttering is moisture in the CDI's (they are not sealed) You have rebuilt the carbs? are you aware the front and rear slide springs are different as are the main jets and needles? We also had a problem once when a camchain tensioner failed and the chain jumped a tooth on the inlet cams (only for some reason) and it then wouldn't rev, also check you ignition pickup for resistance and check the airgap between the rotor and pickup. Just remembered check the filters in the seats, when you remove the needle and seats there should be a small screan filter on each seat, these can clog over time causing fuel delivery problems to.