First Engine Rebuild 1985 VF700F

So the last time I posted I was trying to figure out why my motor would quit under load but was able to rev and run ok in neutral.

I found several things including a burnt out regulator, clogged carbs and, last but not least, I found that I was under by (on average) 50 psi on all four cylinders.

After seeing that I, maybe hastily, decided to attempt my first engine rebuild.

I have now broken the motor down to where the only part left to remove from the crank case is the clutch. I am kind of stuck here until I can find the wrench to remove the lock nut that holds the clutch spring plate.

If anyone knows where to find this tool or how to get the nut off with out it i would appreciate it.

Here are a few pictures of where I am now.

 

i believe that all you need is the correct clutch basket holding tool and then the correct socket to fit the nut. I do not know where to find the clutch basket holding tool...send a pm to squirrelman or jamie daugherty at this site and they should be able to provide a source for this item.

 

Been there done that

Hey

I am putting finishing touches on my motor,Changed pistons,gears,rods,crankshaft,camshaft,rocker arms,engine block (taking 700C block and changing it to 700F block),all the bearings and I am just now putting the camshafts in and then I am done after 7 months work.I will try to help you best as I can.I had the simular problem with my bike and I found gasoline in my oil.

Best regards

Gunnar

 

You can put a leather belt around the basket to pinch it tight. Then use an impact gun with proper socket. If the other gear that turns the basket gear is still there you can swedge a flat blade screw driver between the teeth and lock it that way. Also can use some rope in any cylinder. Push it through the spark plug hole to wedge the piston/crank tight on the compression stroke. Then use an impact wrench.

 

Hey there,

So I also had found gas in the oil. That was another reason why I decided to break it down. Just out of curiosity, what was the cause of your having gas in the oil? I am hoping that I have a cracked rings and not warped cylinders.

I tried to break that lock nut using a rachet strap and jamming the main clutch gear but I found that the whole shaft and clutch spring assembly was turning.

I also appreciate the suggestion to ask jamie daughrety I got the idea to remove my fuel pump from him.

 

Howdy all; I am in the planning stages of rebuilding my 5th gen VFR motor. I am happy to see that we have some guys that have the tenacity, or maybe insainty, to take the plunge and get into a major project. I have gathered the majority of parts and gaskets and I also purchased a spare motor so the bike wont have to be down as long. I am sure I will run into my share of roadblocks once I get started. Anyway good luck with your rebuilds,I hope that you plan on posting updates as you are going along. thanks eddie

 

The reason for gas in the oil was that the compression was bad on the 1st cylinder and it didn´t run on it the engine ran just on the 2,3,4 cylinders.At first I synchronized the carbueators and then it ran on all four but the compression was still bad on the 1st cylinder.And when I open the engine the 1st cylinder was totally ruined so I changed the block and also lot of other things also.But I can begin by taking out the sparks and see how they look they should be with a little grey,not black

Best regards

Gunnar

 

So...what was the cause of your low compression? From the looks of the piston tops it doesn't look like it was consuming mass oil. Have you checked out the heads?

 

I have not yet pulled the valves out of the heads. I also have not yet been able to separate the crankcase (waiting on a tool from Honda).

My valves look ok but I won't know for sure until I pull them and I don't yet know about my rings.

So, in short I don't know yet but I am hoping to have the tool I need in a week and I will let y' all know.

 

Just a little advice from a long term tech...it's best to figure out where the compression is being lost before you tear down. It's a little late for a leak down...but there's just as good a chance it was going past the valve seats as by the rings. Did you check the valve lash for a tight clearance before you pulled the heads? That could explain your low compression.

If it were me...I'd make $amn sure the problem isn't in the heads before I went to the massive work of tearing into the bottem end. You just don't want to go there unless you have to.

A quick and dirty way of checking valve seal...get a can of carb cleaner and spray into the intake and exhaust ports adjacent to the valves. If it runs out through the seats into the combustion chamber that valve is probably leaking. If it holds the fluid the valve is almost certainly OK.

It seems to me gas in oil usually comes from a leaky carb bank...It's possible, but I wouldn't necessarily assume it's from a piston ring problem.

 

Hey I heard you can build a sweet stroker motor by putting a 750 crank in that 700 block. I have the extra parts let me know if interested.

 

i had a similar problem with gas in the oil on my 750, turned out my carbs were dumping WAY too much fuel (my fault), once i fixed my carb issue the fuel issue stopped

 

Hey there,

So the first thing that I checked before I started tearing my motor apart was my carb floats and needles. The rubber tips on the float needles were pliable with no visable damage and the floats were at the correct spec. I was really hoping that my carbs had something to do with all of my problems however I could not find anything wrong.

At any rate once I am done with the motor, I intend to replace my carb slides and also depending on whether or not I have to have my cylinders bored possibly rejetting the carbs if it is neccesarry.

 

If your compression was only 50PSI there's very likely something going on internally.

Sometimes just inspecting floats and needles doesn't tell the whole story about leaking gas. There's also float level...kinda important 'specially when the carbs don't sit level as on your carb bank. It only takes a teeny bit of 'whatever' between the seat and needle to allow gas to dump into the cylinder(s)...rust from the fuel tank...gas line rotting internally, and it can disappear before you have a chance to inspect. Or the needle can stick or bind in the seat as the carbs are filling up. A suggestion...you can bench test the carbs by putting fuel to them off the bike and letting them sit overnight...sometimes you can spot a leak you didn't anticipate.

Post your progress. If you have any questions, post 'em. It's been awhile, but I've had MANY of those older V4's apart back in the day...mostly for transmission problems.

 

Hey there all,

So my motor is back in its frame. After I ripped the motor apart I took it to my local engine shop and had them gauge the cylinders and check out the head and they found nothing that was anywhere close to being out of spec.

Needless to say I was pretty pissed because now I have to go back to hopefully finding the problem elsewhere.

While I was having my motor checked out I completely tore down my carbs and rebuilt them. I also made a great ebay find of about a dozen CDI boxes and a half dozen regulators so I replaced my original ones.

I figured while I had the motor out I might as well replace my fork seals and front and rear wheel bearings. And then I figured that since I had gone that far I might as well rip the bike down to the frame and repaint it.

So my motor project turned into a fame off restoration . . . what can you do.

Anyway here are some pictures.

 

WTF!!! wow that looks like a job you've got good luck! :thumbsup: