Engine change not as straightforward as thought

Hi guys, can anyone on here advise me on the following problem. Bought a 1986 VFR with a very grumbly engine so bought another engine also from a 1986 bike, heard this engine running in the donor bike, sweet as a nut, low miles, perfect. Just finished installing this "new" engine but could'nt get it to start, no sparks then i notice the old engine has a cam pulser the new engine does not. Question is this do i change the front cylinder head which will then allow me to fit the cam sensor or possibly change the cdi unit or any suggestions from you guys, many thanks in anticipation.

 

That sucks. The best way oot of this is to change the head as you thought. Your other option is to swap oot the electronics and the dash as the tachometer will require the secondary signal to operate correctly. Will run at half speed withoot it.

 

You won't like this.
As soon as a lot of you young guys have a engine problem the first thing you want to do is GET ANOTHER ENGINE. You never think about REPAIRING what you have.
The problem you are having now is because you just thought it would be EASY plug and play. WRONG!

You grow up with plug and play toys and video games.
You need to learn how things work.

Now to fix your problem.
"Bought a 1986 VFR with a very grumbly engine"

Now what does that mean? You need to find out what is wrong with that other ORIGINAL engine. If you are willing to change cylinder heads to address the pulser on the cam problem you should be able to do the work to find out what is going on with the original engine.
The fact that the engine you bought has "pulsers" on the cam does not mean it will not work.
You need a workshop manual for your motorcycle.
The "pulsers"(as you call it) may just be a cam sensor for the computer .
The sensor can also be crankshaft mounted. IS it? You need to find out what the Pickup on the cam does.

Now they call a magneto a "pulser" but a pulser on the cam ...no Because the cam only turns at 1/2 crankshaft speed.

You need to get the workshop manual and find out what the device on the cam does do. The replacement engine may just have an extra sensor if it is a newer model.

BTW...HOW MANY MILES are on the original engine???? Very important.

 

I his defense, almost everything for the engine is discontinued and what can be purchased is a bit on the expensive side. I have been in search of a full set of rod and crank bearings for a gen 2 for years. Almost have a full set but what a pain.

 

oh great guru Donald......... you need to take a pill or something.... big freaking deal if he wanted to change the engine out..... why do you care...the title to his thread wasn't " please chastise me for doing something , not the way you would do it" the old engine is no longer even a thought for him. he has the other one in and was asking for advice on what he needed to do ......

And he said the "new" engine was from an 86 as well

 

Many thanks

Thank you for the lecture Donald, firstly i was not brought up in the plug and play era, i'm 50 years of age, secondly i did,nt buy the second engine thinking it would be easy plug and play you condescending t--t. Finally the reason for the request was in hope that somebody out there may have encountered the same thing, were i to have more free time i would pull the thing apart and sort it. Unfortunately Donald guys like you are about as much use as a chocolate torque wrench.

 

Thanks Toe cutter, will pull the cylinder off at the weekend and swap em over. Who is this Donald guy, a real ar-e wipe.

 

Cheers Crustyrider, guys like Donald are about as much use as a dose of the pox.

 

Hi First strike
I just went through changing engines on an 86. I had read that there were two different engines and that I was to look for the same side covers, in my case brown kinda fake magnesium look. I am not sure but you may only need the proper ignitor box. Obviously the color of the side cases doesn't make a direct difference but from the factory it was a way of indicating which one you have.

Mine was a plug and play type of installation. Like it was said, parts and some gaskets can be hard to get. So why dick around with replacing components on a motor with 50k miles. My compression was low and had a top end noise.

Good luck in getting yours running

 

Sorry if I seemed accusatory.
I guess I should have asked the miles first then asked if a repair was possible.
As far as parts being hard to get that seems odd considering all the motorcycle engines that never get repaired ,only thrown in the salvage yard.

I would still get a shop manual and find out what the device is on the cam shaft.
Also by having the workshop manual you could check for other possible issues and to tell which engine would be the best to work with.
Good luck.

 

Donald makes a good point. alternately, you could also repair the original motor, and have a ready to go spare in case something goes wrong.

I may be doing this with my second VF700 engine soon. just because its a learning experience.

 

vfr 750 update

Firstly many thanks to all of you guys who posted on my thread and secondly apology to Donald, bit stressed out last night. Home from work this evening pulled cylinder head off original engine, only 25 mins with engine out then cylinder head off engine in frame a good 60 mins or so, remove front exhausts, radiator etc. swapped heads and now have sparks, unfortunately not enough time to reset valve clearances and put all back together but looks very promising now. The pick up on the inlet cam front cylinders talks to cdi box along with crank pick-ups so not having this pick up was the problem. Just to drone on a little more, the condition of the valves and pistons in the "new" engine is amazing obviously very low miles so the plan is to machine the cylinder head to allow the fitting of the pick-up as the outline shape is already cast in the cylinder head. Regards to all

 

Could you please post a photo of the cam pick up version and the non cam pick up version? Thanks. Would like to see a clear shot of that cam pick up.

Can you also tell us the year of each version? Thanks again.

 

I believe he said what year they were in his first post....

 

I could be wrong, but i believe ALL US-model '86 VFR700F/750 bikes had the front cam pulse generator, while the '87 F2 models eliminated it with slightly changed wiring harness and different CDI.

UK bikes could be different, but still it seems that all '86 F models would have the same 3 pulser setup, with changes only coming on the '87 F2 bikes as here in USA. ?????