Loud Knockin on my VFR700. Transmission?

Good job keeping that 86 intact and on the road. I was going to say from those pictures of the drain plug dont even bother with that motor it is shot. Also thanks for the follow up.

 

Hi, I'm here in Houston too (I just joined vfr world) and I have the exact same thing going on with my 1986 VFR750! I have also met the same frustrations here in looking for parts for our bikes! Sams didn't even tell me the truth apparently, they said they only carry bikes '02 and newer! I would love you forever if you could point me in the direction of a good used engine! I love this bike and would hate to let it sit like this, but it's not as easy as going around the corner to pick up an old Ford 300 for my truck, which are a dime a dozen.

Not too proud to beg at all! ray:

 

I went to Sams a couple weeks ago and he is closing his shop. He's moving his parts to a warehouse and will sell online only. It's a moot point as he didn't have any parts for my bike anyway.

Some local shops that don't have any parts:
Union Cycles on Long Drive, Houston
Houston Cycle on Red Bluff, Pasadena
Lands Cycles on Bayou Drive, Channelview

With just a 2 year run on our bikes it's really hard to find parts. Some things can be ordered from the dealer, but big parts like an engine your gonna have to ship in.

 

Sam does have a nice collection of old bikes, though. Several Nortons, BSA's, Indians and even a Bultaco. I've only seen those in pics until I saw his.

 

Did you find out what was wrong with the old engine ? If I'm not mistaken the metal on the magnet can't be bearing shell metal, because white metal is NOT magnetic.
You can do a quick & dirty bearing check by taking the plugs out & use a rod down on the piston crown, then with the sump off push on the big end & then in the opposite direction with the rod.

When the noise got really loud, did the gear changing or staying in gear get worse ?

 

Haha! You just named all the places on my hit list!

Union Cycles are great folks: He taught me how to save my dying plastics!
Houston Cycle is another great place: Tigger is knowledgeable and always willing to help! Even if it's just to offer a laugh
Lands Cycles I have only talked to by phone because I just found out about them last weekend, but the lady I spoke to seemed nice enough!

I was engine shopping and found a guy who was parting out his project bike. It was a '94 rc36, and he put a cbr600rr swing arm in place of the standard single sided. I got there and was going to give him the $300 he was asking for the engine straight off, but I remembered my friend's words "Always offer less than what you can pay, then you'll reach the right price by compromise."
I offered him $225 for the engine and he gave me the whole bike and everything with it for $300. I was worried at first until I found out the reason was because he just got a new Ducati.
Now I'm stuck in a dilema...
The RC24 needs an engine, which the RC36 has, but the RC36 is only missing plastics and a seat. In addition, the RC36 has a higher compression ration, but less power from what I understand. I'm all for upgrades and mods here or there, but I don't want to damage the nature of either bike! I'd rather stick to the original parts for each, except for that swingarm, which I understand to be an improvement, but time will tell and I may swap that back to the original too. It's not that I haven't got another engine period, I'm just being picky, lol! I know you can't always have your cake and eat it too, but can I just this this once? Pretty pretty please! PUH-LEASE!!


I've got no clue what is wrong with the old one, but mine has the exact same shavings in the oil. It was the sight of those that let me know something was seriously wrong, and the noise wasn't just, well... noise.
I would be just fine with doing that piston test but I don't fully understand what you mean. I'm sure you're making perfect sense, it's just that I might need the "for dummies" version, lol! I used to know cars and trucks like the back of my hand, but even that's been a while since the last time I did anything serious. I understand that motorcycles are somewhat similar, but I never learned the proper names for things under the hood. I was a backyard mechanic, a "tinkerer", I just named them "thing 1," "thing 2," "thing 3," etc... As you could imagine, the list of "things" got pretty long and confusing. It's a wonder I ever got it all back together, lol! I'm just know learning the proper names for "things" and though I know what you mean by piston crown, but I don't know what you mean by "sump", "the big end", or "the opposite direction" which makes me wonder if I know what you meant by the original direction, lol!

As far as the gears are concerned, my bike stays in and swaps gears just fine. The clutch lever got really stiff though. Now it's normal again, but I think that's just because it's been sitting. Until I get a new engine for it, I'll be just fine with running whatever tests you'd like on it, I don't think it can get any worse, lol! Just lemme know!
Thanks everyone for your time and God Bless!

 

The piston is connected to the con rod (connecting rod) by the little end or wrist pin to Americans, the other end of the con rod is connected to the crank shaft via the Big end bearing. So with a rod through the plug hole you can push down on the piston.

The big end bearing can usually be accessed via the bottom of the end in you car/truck motors they is a sump or oil pan bolted to the bottom. The VFR has a small one on the bottom of the engine where the sump plug or oil drain plug is located. The first describes what it is the second describes what it's used for !

So if you take the sump off, you can see the big end bearings, so should be able to push & pull them with your fingers. They should NOT move if you wiggle them. You can try pressing on the rod through a plug hole, then try pushing up on the bottom of the big end of the same cylinder, again it should not move on the crank bearing.
You might be able to see visually if there is any damage to the sides of the big ends.

Hope that explains it better.

 

I haven't touched the old engine since swapping it out. I'm focused on a front end swap right now.

The transmission functioned the same as before the knocking started.

 

I don't think you can swap the 36 engine into the 24 bike if that's what you were contemplating.

I also wouldn't put much faith in the compression ratio specs either. They vary in real life, usually a bit lower than spec.

What's wrong with the 36? I'd try and fix it up since it has better suspension and radial tires in common sizes.

The cbr600rr arm and shock are good inexpensive parts at maybe $30 each, (I have 2 shocks and one arm in my parts pile). The shock has a lot more adjustability than the stock SSSA shock. Then again, the SSSA has a certain cool factor. I wonder why he swapped it?

Getting back to you 24, when is the last time you synched the carbs?
Did you clean the magnet on the drain plug the last time you changed the oil?

 

Entheos Life 88, why don't you start a thread like I did with details on your bike and a video if possible. Maybe we can figure it out. Put a link in this thread so I will see it.

 

Thanks a bunch! That helps a lot, and I should be able to post pics or vids of the test this weekend! I don't have a bunch of other things to do, just waiting for the right parts to come along, lol! It'll be an RC24 engine, and though it'll be different from Jason WW's in a few ways, it sounds like the exact same trouble.

:frown: that engine swap was exactly what I was thinking when I went to go get it. I wound up with a whole bike, but after getting disenchanted with the idea of a motorcycle salvage yard, I took refuge in the hope that if all else failed I could just stop being picky and swap them out. Ah well, neither one seems to need too much to get going, and I really don't mind the idea of having two of these bikes one bit, lol!
I think he (the po) was going for a streetfighter/racer, so the cbr gave a "non-stock" look that didn't sacrifice functional performance. That's my guess. But for all practical purposes, the 36 is a complete bike mechanically, it just needs lights and fairings. He took it apart to part it out, so that's what has taken me this long, I'm putting it back together with the service manual(which I thank the Lord for daily, lol). That said, if I could find the lights, the plastics, and a seat, I'd be riding it right now. Oh, and a rear fender too. I'll take your word and stick with that cbr swingarm then, I know better than to pretend I know too much of what I'm talking about on here, lol! It's a real nice look too, I like the single-sided well enough, but I love those wide tires so much that if it were a woman we'd be married!

On the 24, I haven't synced the carbs. I've cleaned them, and run sea foam regularly, but I didn't know there was a such thing as syncing until you mentioned it. Take it from me: Ignorance ain't bliss, you get the same trouble you just don't see it coming first! As glad as I would be to have the problem be that easy to fix, that knock hints at something bigger. Sounds like I'm riding on a jackhammer! But I'll try syncing them before I pull apart that engine! I can say that I clean the plug every time I change the oil, OCD can't stand the oil on the outside of the plug getting onto the wrench, then my hands, then my clothes, lol! I can't say if there were shavings on it before or not, as this is the first time I went in with the intent to look for them. Good question.

I can definitely do that, I just didn't know if my situation was different enough to warrant a new thread, lol! I can put up everything tonight!

 

The thing with synching up the carbs is that 3 of them can be pretty close, but one might be more closed than the others and get less fuel so it's not supporting the load evenly (for lack of a better explanation) and causes a knocking sound similar to wore out bearings.

There are videos and tutorials on the web on how to do it. You basically start with a warmed up engine. Tap vacuum gauges to the vacuum ports (threaded holes) in the head. If you have 4 vacuum gauges, you can tee them together and make sure they all read the same, then connect one to each cylinder intake.

The front left carb (cylinder #2) is the main one and it's controlled by the big idle adjustment knob. The other 3 are adjusted to it. Your trying to get the same vacuum reading on all 4 cylinders. That way you know all 4 are firing equally. There are specialty synch tools out there that work better and quicker. I built a simple manometer that let's me compare vacuum between any 2 cylinders. One line stays attached to #2 and the other line gets moved to each of the other cylinders until they all pull vacuum equally.

Synching will usually get rid of the knocking sound. Unless of course you do have a bearing that is wearing out and letting a connecting rod move more than it should.

The rod bearings fit tightly to the rod and has just enough clearance for a thin film of oil to form between the bearing and the crankshaft. Usually 0.004-0.012 of an inch. This film both lubricates as well as absorbs the shock of the piston slamming down. When the bearing wears, the gap gets bigger and the oil film can't do it's job so the connecting rod is able to move too much and creates a knocking sound.

Mohawk was saying to use a rod to push down on the piston and another tool to push up on the connecting rod to try and feel this extra slop in the bearing.

Before I replaced my engine, I removed the oil pan and rotated the crank by hand. I moved each connecting rod to it's halfway point and then watched carefully as I rotated the crank just a little back and forth. I was looking for slop in the rod bearing, but I couldn't see any. The rod on the far left side is really obscured so it might have had some slop but I couldn't see it. The service limit for the big end of the connecting rod is 0.016. Any bigger and it's considered bad and needs to be replaced. That's such a tiny amount of movement I'm not sure I could even detect it.

 

If you are able to remove your oil pan (just remove the front two pipes first) you can check the screen in the pick up tube. I found a ton of little shavings and such trapped in the mesh screen. If your bike has that then you'll know your engine is a lost cause.

 

Here is a link to the rc24 question...
http://vfrworld.com/forums/mechanics-garage/41879-1986-vfr-engine-rebuild-swap.html#post395188

 

I'm sorry! I hadn't seen these when I made the thread! I'll give this a whirl first thing in the morning! I should be able to post results around breakfast time! Thank you so much for your time!