18 replies to this topic

[mark68502]

Bought an 87VFR700 last year that had been garaged for 10 years. Joined VFRD at that point but have been mostly a lurker since then.

Learned quickly that you should NOT bother replacing side panels until you can start the bike! (Ok, so I didn't really "learn" the lesson, I just ran out of money... lol)

Anyway, started fiddling with things and learning my way around this bike and here's where we are

1. Im definitely in over my head.
2. This is NOT a problem - its how I learn.
3. Spent alot of time with miracle oil, pb blaster and what-not
4. The engine can now be turned over (by hand) but there is ALOT of pressure when piston 1 reaches TDC. Its WAY more than when any of the other pistons goes through compression even with all the plugs out
5. Took the top end off to assess the damage from a battalion of mice that were living in the airbox.
I am suspecting the valves are not working quite right on that cylinder - they suffered the most from the mice and show alot of surface corrosion - but I CAN manually turn past that point so... wondering if anyone has a magic mirror and can ask it what the likely meaning of this little problem is?
6. Much to my surprise, I seem to have got the cams put back on right. Shop manual really DOES help!

Edited by mark68502, 03 April 2012 - 09:04 AM.

[WestOfBen]

I would try turning it over by hand with all plugs removed. By my reasoning this would allow you to test whether things are hitting other things, like valves hitting pistons slightly and it might give you a feel for bearings. After that I would invest in a compression tester, or find someone who can do this for you. Squirt a little bit of light oil in the cylinders (with the plugs out).

All of this may be wrong of course. VFRD Gurus please correct me so that I might learn also!

[coffeebrake]

You tore into a top end with zero experience?

My advice is to stop right now before you ruin something expensive or rare, sell the bike to someone with more wrenching experience, and go get yourself an 80's air-cooled parallel twin to rebuild instead. You will learn so much more if you start with a simpler machine. And you will find the process so much more rewarding if you get a rideable motorcycle out of it, which you might not with this VFR. If rodents actually damaged the valves, I have to wonder if this bike is a practical project.

You could pick up a Ninja 500 or Vulcan 500, or a Honda CM400, or CB450, a KZ400, or an XS400 that "needs work" for super cheap. Just make sure piston rings and carb parts are available for it.

I am by no means being mean to you. I'm sharing my hard experience. I completely tore apart and re-assembled a little twin engine, taking it from the frame and splitting the cases to check every single tolerance, before I ever tackled a top end job on a bigger bike. My mistake was choosing a little twin without making sure I could get the parts I needed. What I did right, was take apart (and re-assemble correctly) a very simple engine instead of a relatively rare, heavy, water-cooled, and cramped V-four.

[YoshiHNS]

How did the mice get to the valves? Airbox is easy and I know that's not too uncommon, but the valves?

[coffeebrake]

I assume the bike was left with the carbs off?

[kgsmotorcycles]

Will not any vfr 750 engine 86-97 slip straight in? At least any RC24 engine anyway..86-90
Buy them cheap with carbs on.... saves a fortune and time.

[wlodek1980]

looks like you misalligned top end and now bending valves on cyl1

[mark68502]

I would try turning it over by hand with all plugs removed. By my reasoning this would allow you to test whether things are hitting other things, like valves hitting pistons slightly and it might give you a feel for bearings. After that I would invest in a compression tester, or find someone who can do this for you. Squirt a little bit of light oil in the cylinders (with the plugs out). All of this may be wrong of course. VFRD Gurus please correct me so that I might learn also!

I think thats good advice, since thats where I started. :)

You tore into a top end with zero experience? My advice is to stop right now before you ruin something expensive or rare, sell the bike to someone with more wrenching experience, and go get yourself an 80's air-cooled parallel twin to rebuild instead. You will learn so much more if you start with a simpler machine. And you will find the process so much more rewarding if you get a rideable motorcycle out of it, which you might not with this VFR.

Small twins are great for learning! Learned carbs & electrical on a small v-twin and resurrected an 81CB750 for my daily rider. This is definitely more of a mechanical adventure but for $300, I can afford to explore a little. Cams don't worry me too much but I have no desire (yet) to drop the engine or go any deeper.

How did the mice get to the valves? Airbox is easy and I know that's not too uncommon, but the valves?

I know right!? They ate / pissed their way right through the filter and then the urine just dripped down into everything. I think they were probably gentically enhanced super-evil mice or something... :)

Edited by mark68502, 03 April 2012 - 07:40 AM.

[mark68502]

looks like you misalligned top end and now bending valves on cyl1

Bent valves is what it feels like. Could be that the PO damaged #1 but it was stiff before I dug into the top end and after re-assembly it feels just like it did before, except that it is smoother on 2, 3, and 4 than it was at first...

[mark68502]

I assume the bike was left with the carbs off?

No but the airbox was not capped.