having some wierd bike issues

I believe it's now time to make the call, this thread is officially....


THREAD JACKED

 

Threadjacked, yeah. So how is the bike running now?

 

While waitin',nothin'wrong with discussin' compression.

Great discussion. :thumbsup: I think it's been a great education for everybody, myself included. I've put the Thermo text back on the shelf. I see Jamie's point regarding the fact that we are dealing with a cold engine and making assumptions that we are not adding heat when we squeeze that cold air mixture. The whole discussion of valve overlap, ram effects and scavenging is facinating and I want to thank GreyVf750f for those points. I was trying to touch on those in mentioning the assumption that air had no mass or momentum in the adiabatic case. But I stand corrected by Jamie’s realization that I was describing 'operating pressure' and not 'cold pressure testing'. Still the whole “compression pressure” discussion is cogent and not that far off from the subject at hand. I mean that no matter how hard you try to get the carbs perfect they ain't gonna work if your "pump done broke". Now we all need to agree that Matt's Vf500 is going to have to have all cylinders within 10% and above 140 psi(?). More than likely around 175 psi. I don’t have a factory manual for the Vf500, so maybe someone with a factory manual could read us chapter and verse of what Mr. Honda says is acceptable. I do have a Clymers Vf500 manual and Mr. Clymer says Compression on a Vf 500 should be between 142-199 psi.

Sooo, Matt’ew,me boyo, give us a t’rill an’ tell us all if ye’ would, what the cylinder pressures are before ye’ go out to play wid' your toy made new.


Meanwhile, what we are waiting for is the result of rebuilding Matt's 86 Vf500f carbs . There was necessarily going to be a dead spot while he fought the good fight getting those fresh Kaitin 31A's dialed in. He has to work too, so it will take some time for him to sort it out. In the meantime I don't think a discussion/argument :argue: on how to calculate cylinder pressure at low piston speeds and cold temperatures is a bad way to pass the time. :smile: And it was a great reminder that we might want to make sure that Matt's Vf 500 is pumping like it should before he tests out his virgin Kaitins. :smile:

DKC

 

not yet still cleaning the tank things have been going slow wiht work and then going to see my boys has'nt left much time to work on the bike

 

Not a problem boy'o. That's what arguing about how to "calculate cold cylinder compression pressure" is for. Take care of your work and your kid's first. The bike will fit itself in in its own time.

 

By all means Matt, take care of those two new youngun's first.
Priorities in life are the ones you love, not the things you love! Things are just 'things'!
Without the ones you love in your life, all the 'things' in the world are just useless junk.

 

Amen to that one!

Didn't realize you had a couple new guys. Take care of all the family stuff first, as if you really need me to tell ya that!

 

How's the weather been treating you?

Had to drop by to tell you that there is another guy complaining that his Vf 500 has surging problems. His thread is 'Cam lobe flattening '85 Vf 500' thread started by 'TinkerinWstuff', Wish you could get into the discussion regarding your outcome. Hope you get the bike on the pavement before winter shuts off riding. And, by the way, how is the wife treating you? Miss your substitute. You need to take her for a fast ride?

 

Hmmmm....I hope that isn't Matt's issue.

You got the bike running yet?

 

i should have it running by this weekend and give y'all the ride report i doubt thats whats going on with my bike (lobe flatting) but if it is or does i've already called dave dodge up and will be sending the motor off next winter for a extreme motor build the goal is 90hp on 93 octane :thumbsup:

 

DKC - I've been working really closely with Matt on his bike. I can tell you that the cams are not his problem. When the rockers go bad it's accompanyied by quite a bit of ticking and knocking sounds - he would have mentioned that. I think TinkerinWStuff has a few things going on, his bike was quite a bit more neglected than Matt's.

 

amen to that brotha :biggrin:

 

Don't be too surprised if you do not see an improvement, or that it actually makes less peak hp, with the use of 110 octane fuel. Octane is simply a rating of a fuel’s ability to resist detonation and/or preignition. It is possible to "over octane" your engine and it will actually run worse than it does on pump gas. Give the VP U4.2 a try and I'm sure you will be pleased. In my experience this fuel will get you a gain somewhere in the ballpark of 5%......of course 5% of 29.8 isn't gonna make you smile that much....but it is realistic to see a 1-1.5 peak hp increase. The best I have gotten is a 6.5% increase in peak hp, but 6.5% of anything over a 100 peak hp is substantial. :biggrin:

 

Surging is almost always a problem with the carbs. That's where Matt's problems were coming from too I'm pretty sure.

In fact, one of my 500's has been suffering from the same thing recently. It looks like the sync is to blame there, I just haven't had the time to get it sorted out yet.

 

very interesting you got me now i want to know whats causing that

 

Surging can be caused by a few things, but the most common are carb related. In my experience, which is like talking to yourself when it comes to forums, is usually caused by a lean condition which results in increased rpm's even though, the throttle is held in a constant state. The surging is the result of intake vacuum/velocity fluctuation. A lean condition can be associated, with inadequate fuel supply, an air leak ( internal or external to the carburetor), an internal carburetor jetting issue (i.e. inability to adequately provide enough fuel to the intake airstream - carb pilot, needle or main jet flow issue reasulting in a lean condition, depending on which circuit is being employed at the time of the surging) or poor ignition performance (i.e. timing advance/retard issue). To troubleshoot such an issue via the internet is equivalent to grasping at straws. Systematically narrow down the possible causes until a solution is reached. There are no free lunches.

 

Just thought you and 'Tinkerin' might help each other

If you read what I wrote I never suggested or implied that Matt had cam/follower issues. I was putting forth the "surging" issue both Matt and 'Tinkerin' complained about as the reason they might gain some advantage from contributing and involving themselves in each others threads. You are conflating the fact that I gave Matt the title of "Tinkerin's" thread (something 'flattening cam's' something something) with my suggesting that Matt somehow had cam problems. I just wanted the two of them to maybe gain from the coincidental coterminous "surging" issue. And for my money I place a higher causal value on the missing "adjustment springs" that I think Jamie had to mail to Matt because his were missing after the dealer installed his jet kit. Strangely coincidental that they went missing when the surging started to become a problem??? But then, who's to say what the root cause of Matt's surging was after having shot gunned the Carbs with a complete rebuild (by Squirrelman??) and who knows what else?

Any whoo, I'm just as curious about the outcome of Matt's adventure (misadventure???) with 'surge control' as the rest of you. I also still want to know what kind of mileage he gets with his Keitin 31's. Similarly, I think that 'Tinkering' could gain from what Matt has learned/been taught along the way. And that Tinkerin is probably in the best position to offer advice considering that he is figuring out his way around the 'surging' problem even as we sit here reading and writing to each other.

So, in closing I'd like you all to know that my '84 Vf 500c got 45 mpg driving at mostly 80 to 90 MPH ("Everyone was driving that fast, Officer") on LA's freeways last weekend. So I have a feeling that my aged romper would be gettin' near 50 mpg if I were straight driving the freeways on it from fill up to fill up, even with those fat Keitin 59's on it. And that extends my cruising range out to 130 miles and better :thumbsup:.