So my bike runs now that I hav it together and everything buuuuutt, it runs bad and idles bad, also spits gas out of the front carb like a mist. Fiatracer and myself concluded that I probably did not get the valve timing right. That is the only thing I can think that would make has most out of the carb. Does this conclusion sem correct?
For sure, double your cam timing.
i thought i had it right. i mean it is pretty simple. tdc1 for the front, align the cam gear dots with the sleeves.....and repeat for rear but use tdc2....
You know what thought did, he farted m but shite himself instead! You are out of time , at least on the front cylinder. Ask me how i know , I did in on the rear cyl. . It was 1 tooth off,
yea... i was having a problem, i think on the rear though, but i could not get the cam gear spot to be perfectly vertical when lining it up. it was impossible. it was damn close but not perfect....
Before I tore mine down, I noticed that one cam on each head was about a half tooth off from aligning with the timing marks.
I was worried that my cam chains were stretched, but it sounds like this isn't terribly uncommon.
Quote from: Jimustanguitar on September 20, 2012, 08:24:24 AM
Before I tore mine down, I noticed that one cam on each head was about a half tooth off from aligning with the timing marks.
I was worried that my cam chains were stretched, but it sounds like this isn't terribly uncommon.
That's how mine was exactly
I took a handfull of pictures so that I could refer to them for reassembly. It looks like one cam in each head is slightly off.
Very nice :) I think today I will try and fix it after work, but I'm going to check how far off I was with a screwdriver in the spark plug whole and line the cams up
Your definatly off, no cigar! try again .
So I checked the timing..... It is not off. It was right on the money.... Does anyone have any other ideas on what it might be? It still sucks air in but it also pushes air out too
Hard to tell from the pics but it looks off.,
Quote from: Rick G on September 20, 2012, 11:42:20 PM
Hard to tell from the pics but it looks off.,
Those aren't my pictures! They are not off though I made sure.
Now it's the front carb that is shooting out gas, do I need to check the rear timing too? I don't sw why I would but What do I know
Heartless, did you have your cams out of the heads?
Quote from: fret nut on September 21, 2012, 01:22:39 AM
Heartless, did you have your cams out of the heads?
Well when I rebuilt the motor I did. I don't need to take them out yesterday
Quote from: Hartless on September 21, 2012, 09:09:07 AM
Quote from: fret nut on September 21, 2012, 01:22:39 AM
Heartless, did you have your cams out of the heads?
Well when I rebuilt the motor I did. I don't need to take them out yesterday
So this is the first it's been running since the cams were installed? If so, it seems likely the cams are not timed correctly. It's not unusual for the marks to be off slightly due to chain stretch but this sounds like more than half a tooth off.
As a quick check, turn the motor anti-clockwise to TDC compression (NOT exhaust) stroke on the front cylinder using the "T" mark on the flywheel. Which way are the cam lobes pointed? Now turn the motor another 290 degrees in the same direction to put the rear cylinder at TDC compression. Which way are the lobes facing? A couple of pics may be helpfull.
Quote from: Rikugun on September 21, 2012, 11:07:55 AM
Quote from: Hartless on September 21, 2012, 09:09:07 AM
Quote from: fret nut on September 21, 2012, 01:22:39 AM
Heartless, did you have your cams out of the heads?
Well when I rebuilt the motor I did. I don't need to take them out yesterday
So this is the first it's been running since the cams were installed? If so, it seems likely the cams are not timed correctly. It's not unusual for the marks to be off slightly due to chain stretch but this sounds like more than half a tooth off.
As a quick check, turn the motor anti-clockwise to TDC compression (NOT exhaust) stroke on the front cylinder using the "T" mark on the flywheel. Which way are the cam lobes pointed? Now turn the motor another 290 degrees in the same direction to put the rear cylinder at TDC compression. Which way are the lobes facing? A couple of pics may be helpfull.
They are facing outward on the front and at the same time the rear is facing inward
Do you mean the rears faced outwards when you turned the motor to TDC for the rear cylinder? If so, would you say the valve timing is correct plus or minus half a sprocket tooth? Are there any mechanical noises that shouldn't be there? Ticking from pistons and valves meeting for instance?
If not, is it running on the rear cylinder? Can you feel heat developing in the rear exhaust soon after starting like in the front header pipes?
How long since those carbs have been on a (good) running motor?
QuoteI'm going to check how far off I was with a screwdriver in the spark plug whole and line the cams up
Do you not trust the flywheel marks? Did the screwdriver method and the flywheel marks agree?
Quote
Do you mean the rears faced each other when you turned the motor to TDC for the rear cylinder?
yes
QuoteIf so, would you say the valve timing is correct plus or minus half a sprocket tooth? Are there any mechanical noises that shouldn't be there? Ticking from pistons and valves meeting for instance?
yes, no everything sounds good
Quote
If not, is it running on the rear cylinder? Can you feel heat developing in the rear exhaust soon after starting like in the front header pipes?
yes
QuoteHow long since those carbs have been on a (good) running motor?
they were on my other motor before it went south, so about six months.
QuoteI'm going to check how far off I was with a screwdriver in the spark plug whole and line the cams up
QuoteDo you not trust the flywheel marks? Did the screwdriver method and the flywheel marks agree?
yes i do, but with the way it is misting the gas out of the carb and forcing air back out of the carb, i was sure that the cam timing was off and wanted to see if the marks might be a little off.
Quotebut with the way it is misting the gas out of the carb and forcing air back out of the carb, i was sure that the cam timing was off
I'm unclear as to what's been done to this engine. Are the heads what you've been running or is this a different engine? Is it possible you have some bent valves? Have you performed a compression test or leak down test?
I'm not exactly sure what you mean by "misting the gas out of the carb" or how much but I guess what is important is it's only on one. Are you observing the carbs with no airbox or with the lid and element out? When I've done that I noticed the accel pump stream is no longer a stream when the engine is running but rather looks more like mist inside the air horn. Are both accel pump nozzles functioning? Did you drain the carbs before letting them sit for 6 months?
Its very frustrating for me ! I'd love to jump in the truck and drive over to your house and look at it!
I put a new crank and rods in my engine. Yes I drained the carbs but I'm going to clean them again. It is not squirting a stream of has straight up,just a mist constantly flowing straight out of horn enough to hit me in the eye while I was standing next to it. Heads were good last time I used them.
Though I might have separated the head and cylinder when putting it back on, if it has a bad head gasket could that be the cause?
QuoteIts very frustrating for me ! I'd love to jump in the truck and drive over to your house and look at it!
Well shoot on over! It sure as h ee double hockey stick is frustrating me!
Is it gas or coolant misting from the carbs? :P
I would think breaking the gasket seal between cyinder and head may be bad. :(
Heartless, if you put your hand over the carb does it suck or does it blow? Or does it do both? Accelerator nozzles are functioning properly and pointed down the throat of the carbs?
When the cams were out did they get mixed up EXH for INT etc.?
I would think that with the valve covers off and a socket on the crank you could slowly turn each cyl over on compression stroke (@ TDC) and verify that all the valves are opening & closing at the proper time. Close observation may reveal the cause...
Sent from my iPhone using Tapatalk
I thought that was Adam was doing but this statement has me thinking something is still very wrong...
Quotejust a mist constantly flowing straight out of horn enough to hit me in the eye while I was standing next to it.
QuoteThey are facing outward on the front and at the same time the rear is facing inward
When I questoned this you corrected yourself but I want to be sure you are clear the two pistons are not at TDC at the same time. After doing the front the crank has to be repositioned to align the rear cylinder cams. I would quadruple check the timing - as Fret pointed out it is easy to mix up the cam sprockets orientation. Also, is it possible valves were bent after an initial incorrect timing when the starter was used?
When I put my hand over the carb it sucks and blows.
I was clear that they are not both at tdc at the same time, and have been following my book when setting the cam timing. The timing was set correctly initially so I don't think it would bend the valves. If I get a chance this week I am going to pop the carbs off and I'll be able to check the valves a little easier and such.
And I did take the covers off and rotate it by hand. It's when I started it afterwards to try and figure it out again that it shot has in my eye
QuoteWhen I put my hand over the carb it sucks and blows
It's supposed to - suck, squeeze, bang, blow. ;D Which carb is doing the misting, sucking and blowin'? ??? 8) Or is it both? Did you ever do a compression test? And did you say both cylinders exhaust get equally hot more or less simultaneously?
Are you sure this isn't just carb issues? With Visions, 86 and one third percent of the time it's carbs. :P If you think it's electrical - it's carbs. If you think it's carbs - you're right. But the problem is much worse than you first thought. Once in a while it's the starter or stator but then it's right back to carbs. :) :D
Quote from: Rikugun on September 23, 2012, 10:03:13 PM
QuoteWhen I put my hand over the carb it sucks and blows
It's supposed to - suck, squeeze, bang, blow. ;D Which carb is doing the misting, sucking and blowin'? ??? 8) Or is it both? Did you ever do a compression test? And did you say both cylinders exhaust get equally hot more or less simultaneously?
Are you sure this isn't just carb issues? With Visions, 86 and one third percent of the time it's carbs. :P If you think it's electrical - it's carbs. If you think it's carbs - you're right. But the problem is much worse than you first thought. Once in a while it's the starter or stator but then it's right back to carbs. :) :D
It's the front carb, and I have the exhaust loosely on hat in case I have to take the engine from the frame again. The bike is running on both cylinders and I haven't really run it
Long enough to be able to tell If ones hotter than the other.
Checked all the valves and they are moving freely, but I think I will check the clearances tomorrow.... The frot cylinder isn't even getting hot. I took the pipes off and there is barely any exaust coming out leading me to believe that the intake valves aren't opening and/or closing enough
The cam timing procedure does have you spin the engine ccw, you caught that it wasn't clockwise, right?
I'm sure you did, but I know that's a mistake that I would make :)
Yea. I tried all ways haha
Quote from: Hartless on September 24, 2012, 10:43:06 PM
Checked all the valves and they are moving freely, but I think I will check the clearances tomorrow.... The frot cylinder isn't even getting hot. I took the pipes off and there is barely any exaust coming out leading me to believe that the intake valves aren't opening and/or closing enough
Why would the valves not open? Aren't these the heads you were using before? Did you change shims when you swapped cranks? Did you crank the motor over when the cam timing was wrong?
Earlier you stated both cylinders were running now it seems the front isn't getting hot. I'm now feeling Rick's frustration. :(
Start with the basics. Finish assembling the bike including the exhaust. Check your valve clearance. Ensure both cylinders have spark. Beg borrow or steal a compression gage and use it. Clean the carbs and try again to start it.
My thoughts are starting to lean towards no compression due to an open valve. Perhaps one of them doesn't have any clearance and is being held open by the heel of the cam. If you cut new valve seats or lapped them a lot, you'd definitely need thinner shims.
Like everybody else is saying, check your compression and measure your clearances. I think that will tell the tale.
Quote from: Jimustanguitar on September 25, 2012, 10:50:07 AM
My thoughts are starting to lean towards no compression due to an open valve. Perhaps one of them doesn't have any clearance and is being held open by the heel of the cam. If you cut new valve seats or lapped them a lot, you'd definitely need thinner shims.
Like everybody else is saying, check your compression and measure your clearances. I think that will tell the tale.
This is what I am thinking as well. I have started with the basics, then put it back together as repeat. The only thing I have my done is use an actual compression checker and check valve clearances. The valve caps fell off and I'm guessing I did not put them back on correctly, that I did but apparently not. By hand it feels like its getting compression, but not enough and at least one of the valves is staying open and air is pushing back out the intake
No need to get frustrated! I should be the one frustrated!!!!
You stated that the rear cams face inwards.
According to the manual, the rear cam lobes should face outward, away from each other. The fronts should face inward towards each other.
I have mis-timed my Vision before resulting in one cylinder blowing out the carb.
My mistake was that I was too focused on aligning the punch mark on the cam (not the gear) without realizing that the cams have two punch marks each, one for installation in the front cylinder and one for installation in the rear.
If you make sure the cam lobes are facing the right direction and the punch mark on the gears are alligned the punch marks on the cam will fall into alignment.
If all is aligned and you are still getting blowback you must have a partially open valve that is either sticking, not shimmed properly, or not seated.
Quote from: VisionMeister on September 25, 2012, 11:52:59 AM
You stated that the rear cams face inwards.
According to the manual, the rear cam lobes should face outward, away from each other. The fronts should face inward towards each other.
I have mis-timed my Vision before resulting in one cylinder blowing out the carb.
My mistake was that I was too focused on aligning the punch mark on the cam (not the gear) without realizing that the cams have two punch marks each, one for installation in the front cylinder and one for installation in the rear.
If you make sure the cam lobes are facing the right direction and the punch mark on the gears are alligned the punch marks on the cam will fall into alignment.
If all is aligned and you are still getting blowback you must have a partially open valve that is either sticking, not shimmed properly, or not seated.
What I meant was when I had the front cylinder at tdc the rear cylinder lobes faced inward. I'm double and triple checking again after work today
Quote from: VisionMeister on September 25, 2012, 11:52:59 AM
You stated that the rear cams face inwards.
According to the manual, the rear cam lobes should face outward, away from each other. The fronts should face inward towards each other.
OOOPS! There ya go, we had it backwards. That's probably it afterall. Nice catch Vision Meister. :)
So when the front cylinder is at tdc, the rears should be facing inwards? My haynes does not even reference where the cams should be for the rear when the front is at tdc. I just figure since they rotate opposite the lobes would be opposite.. Am I wrong?
approximately so.
Check wikipedia for Yamaha Vision.
Humber, in Europe, has been so kind as to load pdf files of all available yamaha service manuals.
These are easy to download and store in my documents and don't take much memory.
This is where I had my timing problems. I had an old harcopy manual that had missing pages (misprint) right at the cam timing section. I did this on two separate Visions I was working on at the same time, so I got a lot of practice.
Quote from: Hartless on September 26, 2012, 08:50:24 AM
My haynes does not even reference where the cams should be for the rear when the front is at tdc.
That's because it's relatively unimportant so don't focus on that. What is important is after the cam is set on the front (TDC, lobes angled in, marks aligned etc.), turn the crank another 3/4 of a revolution and start looking for the rear TDC mark at the small inspection cover on the alternator cover. Rock the crank a little back and forth until you find the crank marks and align them. Then align the cam marks with the lobes angled out on the rear cylinder. Then adjust the valves, clean the carbs and go riding. :)
Quote from: Rikugun on September 26, 2012, 06:10:53 PM
Quote from: Hartless on September 26, 2012, 08:50:24 AM
My haynes does not even reference where the cams should be for the rear when the front is at tdc.
That's because it's relatively unimportant so don't focus on that. What is important is after the cam is set on the front (TDC, lobes angled in, marks aligned etc.), turn the crank another 3/4 of a revolution and start looking for the rear TDC mark at the small inspection cover on the alternator cover. Rock the crank a little back and forth until you find the crank marks and align them. Then align the cam marks with the lobes angled out on the rear cylinder. Then adjust the valves, clean the carbs and go riding. :)
QuoteThat's because it's relatively unimportant so don't focus on that
:) thats what I was trying to say in a sarcastic yet un sarcastic manner. haha
everything is lined up correctly and the only thing i havnt checked in regards to cams is the valve clearences, which is going to have to wait another week because i will be hunting!
Quote from: Rick G on September 20, 2012, 08:56:47 PM
Your definatly off, no cigar! try again .
I'm reassembling my cams today (Jim, not Hartless). My bike ran before I had head gasket failure a month or two ago, and I have no reason to believe that my valve timing was off before (except that the idiot PO messed up everything else :) ) The pictures of timing marks are mine from before the tear down and I'm comparing to them for reassembly.
Anyway, my timing marks line up the exactly same way still. Moving one tooth is more off than where I already am. I did notice that there is a timing mark on the cam itself though (visible from above) and they all line up absolutely perfectly (they align even better than in the pictures, my angle is off because of holding the light and camera). *** edit - I made the attached pictures less huge. sorry about that ***
Am I ok?
Jim, are both pics of the rear cylinder?
These are both pictures of the front. You can see the rubber grommet for the carb heatshield on the intake picture.
The front cam lobes face towards each other at #1 TDC, and when rotated CCW 290 deg to #2 TDC the rear cam lobes face away. This is correct per the manual.
After several rotations in both directions, my timing marks are still landing in the same places and I've triple checked the ccw 290 deg relationship with each other.
I think I'm ok to put her back in the frame.
OK, got it. I was having a hard time orienting myself. The ability to post large pictures is a good thing I guess but it sometimes seems awkward navigating around them. :o It sounds like you've got a handle on the cam timing procedure.
If you screw it up you can re-time with the engine in the frame, as long as you were not so far off you bent a valve. OKI was a tooth off the first time I did it,
Quote from: Rick G on October 01, 2012, 04:00:01 PM
If you screw it up you can re-time with the engine in the frame, as long as you were not so far off you bent a valve. OKI was a tooth off the first time I did it,
When did you catch the problem - had you tried to start it? I'm guessing it will run with one tooth off?
I caught it while the bike was still on the stand , on first start. I recognised it immediately and shut it down and pulled the rear valve cover , the timing cover and proceeded to re-time.
Any updates? I hope you got it!
I think Rick was relating a story from an early experience he had with cam timing. :)
I was asking Hartless if he got back to his Vision yet. I'm curious what he found :)
OH, why didn't you say so!? :P :-[ My bad ;D But since you brought it up I'm curious too.
Yes Rikugun, that was in 2005, the first time I had the engine out of the frame , due to a bad rod bearing. It's really an easy engine to do , as it comes out the bottom, as opposed to levering a CB750 out of the frame and struggling to carry it (with a friend) across to the bench!
At my current age and fitness level the Vision motor would present the same challenge as a 750. :( :o Earlier in the summer I assembled a Bultaco 125 motor to put back in the frame. Individually all the parts seemed light enough. But once assembled it was as if it was fused to the bench. I couldn't get over how heavy that thing had gotten just sitting in my basement all these years. :) :D ;D
This is a little off topic for the thread, but relevant to some of the latest posts...
I built a wooden stand to put under my engine while I worked on it. Originally I just wanted something to keep it off the concrete floor, but I also wanted something to hold the engine steady so I could torque the heads without it rolling around (since the engine doesn't sit flat). I built it with scraps in about 10 minutes with a friend who had the idea of raising it with some 2x4's so that I could roll the floor-jack under it. Sure enough, it worked just like we hoped. Lifting it took no muscle, and with one of us balancing it and the other pushing and pulling to get it aligned just right, reinstalling the engine was pretty stress free. Easier than the last few times I've done it on other bikes.
That's clever.
that is pretty clever! but as to whether i have gotten anywhere with my bike that would be a negative. I have not had a chance to work on it as i was hunting :) i will let yall know when I do check it out. i do have to admit, i was re reading this thread and i didnt even notice that you guys were talking about the timing mark on the actual shaft of the cams, i did not even know that it existed. so that is definitely be what i check first
so, the rain season has finally arrived here in Portland, Oregon (later then usual!) and I plan on taking another look at my bike tomorrow. my luck, I will finally get it going good and just in time for the rain! oh well better than nothing.....if i do :D
So, I finally have began investigating my problem further and have came to a conclusion that there is a stuck valve. I am going to swap in my spare head and see what happens!
A stuck valve in a V probably indicates valve piston contact. Any contact indicating marks on the top of the piston?
Quote from: QBS on December 18, 2012, 03:20:36 PM
A stuck valve in a V probably indicates valve piston contact.
Maybe...but not always. It may well be a gummed up, sticking valve that needs removing/cleaning or replaced...or it could be a :-\ Ah well, we shall soon know when Hartless removes his head ....... from the Vision that is :o ;D :D :D :D :D :D... ;)
8) ....... TIGER ....... 8)
Quote from: Tiger on December 18, 2012, 03:28:31 PM
Quote from: QBS on December 18, 2012, 03:20:36 PM
A stuck valve in a V probably indicates valve piston contact.
Maybe...but not always. It may well be a gummed up, sticking valve that needs removing/cleaning or replaced...or it could be a :-\ Ah well, we shall soon know when Hartless removes his head ....... from the Vision that is :o ;D :D :D :D :D :D... ;)
8) ....... TIGER ....... 8)
I think this is more likely the case then it hitting the piston. This happened directly after I put the motor back together and the symptoms happened immediately. (spitting gas out of the carb) I did check the cam timing and it was off.... But it turned
By hand freely before I ever ran the engine. I originally had a different head on and it would not turn all the way and I figure now it is because the cam timing was off. So HOPEFULLY I should be able to swap out the original head and be riding soon!.... But I have made MANY similar statements In the past and.... Well here I am talking about it Again!
I've seen bent valves that were not stuck. Stuck valves are usually the result of carbon or varnish in the valve guide.
Have subscribed. You had me at hello.
This is like one of those vision version of the mentalist.
I got similar symptoms to you and thought it might be a valve as well. Put some upper cylinder lubricant in the fuel. It turned out to be a combination of minor things. In order of importance, these were:
1. Failing spark plug. Replaced with non resistor plugs
2. Failing resistor spark plug caps. Replaced with new NGK's.
3. Once it was running again, Carbs way out of balance. - Rebalanced.
4. Sticking float valve causing overflowing to front cylinder.
Now she starts really easy and pulls like a train. Still needs tweaking but at least rideable.
Good luck
That's so true with many Visions - it's often a host of problems with overlapping symptoms. Working through them all is a process and can take some time to get right. :) ;)
QuoteNow she starts really easy and pulls like a train. Still needs tweaking but at least rideable
That's always nice to read - another Vision well on it's way! :D
Quote from: pinholenz on December 23, 2012, 05:36:34 PM
I got similar symptoms to you and thought it might be a valve as well. Put some upper cylinder lubricant in the fuel. It turned out to be a combination of minor things. In order of importance, these were:
1. Failing spark plug. Replaced with non resistor plugs
2. Failing resistor spark plug caps. Replaced with new NGK's.
3. Once it was running again, Carbs way out of balance. - Rebalanced.
4. Sticking float valve causing overflowing to front cylinder.
Now she starts really easy and pulls like a train. Still needs tweaking but at least rideable.
Good luck
That is originally what I suspected and I changed all that, but to no effect... :(