my gas tank sucks

[RobertWichert]

In searching for the cure to my "Stumble Bumble" (full report to follow) I have discovered that deep in the CVK carburetor there is a little plastic P.O.S. that seems to hold the needle down on the slide by spring pressure from the big spring above. Interestingly enough, if you do not seat this little P.O.S. correctly, it can rotate "one notch" and block the slide lifting hole. With the slide lifting hole blocked by the little P.O.S., the bike doesn't go over about 3,500 RPM, and has little or no power. So what keeps this little P.O.S. from turning a notch when I take one of my famous crash and burn excursions? That spring is pretty wimpy if you ask me. Any insight from the carburetor guruistas? -- Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 ===============================================

[Fred Hink]

Never heard of this problem before. I have a carb on my bench and just took it apart to have a look. There are indexing bumps inside the slide near the needle holder that index the plastic keeper from blocking this port. I d say that there is no way that the plastic part can block this hole. You may have fixed your stumble but it most likely wasn t caused by this plastic piece blocking the vacuum port. Fred http://www.arrowheadmotorsports.com From: RobertWichert Sent: Thursday, April 25, 2013 8:49 AM To: klr Subject: [DSN_KLR650] CV Carb Plastic P.O.S. In searching for the cure to my "Stumble Bumble" (full report to follow) I have discovered that deep in the CVK carburetor there is a little plastic P.O.S. that seems to hold the needle down on the slide by spring pressure from the big spring above. Interestingly enough, if you do not seat this little P.O.S. correctly, it can rotate "one notch" and block the slide lifting hole. With the slide lifting hole blocked by the little P.O.S., the bike doesn't go over about 3,500 RPM, and has little or no power. So what keeps this little P.O.S. from turning a notch when I take one of my famous crash and burn excursions? That spring is pretty wimpy if you ask me. Any insight from the carburetor guruistas? -- Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 =============================================== [Non-text portions of this message have been removed]

[RobertWichert]

That little P.O.S. did not cause any problem until I did not seat it correctly, Fred. And I can verify unequivocally that it CAN AND DID block the hole. I failed to seat it in those nice little notches that I did not notice so it was not seated correctly, by me, and it did WAY block the hole. Try it, you won't like it. One reason that it CAN block the hole is that the little P.O.S. has about eight little arms, so being wrong a bit is eight times as likely as if it had a hole for the hole, if you know what I mean. Not to spoil the report, but I took the carburetor apart looking for the stumble bumble and when I put it back together I did not notice that there were notches (which I think are pretty wimpy) so I just dropped it in. The bike ran really lousy. I took the carburetor apart and lo and behold! The little P.O.S. was not down in the notches but was blocking the hole! When I put it down in the notches, all was well and good. Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 ===============================================

On 4/25/2013 8:02 AM, Fred Hink wrote: > Never heard of this problem before. I have a carb on my bench and > just took it apart to have a look. There are indexing bumps inside > the slide near the needle holder that index the plastic keeper from > blocking this port. I d say that there is no way that the plastic > part can block this hole. > You may have fixed your stumble but it most likely wasn t caused by > this plastic piece blocking the vacuum port. > Fred > http://www.arrowheadmotorsports.com > > *From:* RobertWichert > *Sent:* Thursday, April 25, 2013 8:49 AM > *To:* klr DSN_klr650@yahoogroups.com> > *Subject:* [DSN_KLR650] CV Carb Plastic P.O.S. > > In searching for the cure to my "Stumble Bumble" (full report to follow) > I have discovered that deep in the CVK carburetor there is a little > plastic P.O.S. that seems to hold the needle down on the slide by spring > pressure from the big spring above. Interestingly enough, if you do not > seat this little P.O.S. correctly, it can rotate "one notch" and block > the slide lifting hole. With the slide lifting hole blocked by the > little P.O.S., the bike doesn't go over about 3,500 RPM, and has little > or no power. > > So what keeps this little P.O.S. from turning a notch when I take one of > my famous crash and burn excursions? That spring is pretty wimpy if you > ask me. > > Any insight from the carburetor guruistas? > > -- > Robert Wichert P.Eng. LEED AP BD&C > +1 916 966 9060 > FAX +1 916 966 9068 > > =============================================== > > [Non-text portions of this message have been removed]

[Fred Hink]

Robert, To continue this discussion, I don t doubt you had a performance increase. If the POS as you describe it is not down on those notches then it can t be down on that hole. Please explain to me how you feel this plastic piece if not indexed correctly and is on top of the indexing notches can cover that vacuum port. Since this plastic piece if not indexed correctly is raised by the index notches is also raised from the base of the slide where the vacuum port is. Unless I am misunderstanding you, I don t see how this is possible. The problem I see by not having the plastic piece indexed is that it is not holding down the needle in the slide and could cause it to float slightly causing a jetting issue in the midrange. I have seen this problem (pinched diaphragms) since CVK type carbs have been around. There is a lack of power and the slide only opens part way. Most often there has been someone inside the carb previously (or on an old bike it has just worn out) and has not got all of the diaphragm in the grove where it is supposed to be. This causes a vacuum leak and the slide can not open like it is supposed to. Most often the diaphragm is cut by tightening the cover and may or may not work as intended after that. By making sure that the diaphragm is in the grove it is supposed to ride in, you may have fixed your problem. If the diaphragm edge was cut, then it may also have a slight air leak there. Not trying to argue with you but to explain to others that may not know the inner workings of their carburetors. Fred http://www.arrowheadmotorsports.com From: RobertWichert Sent: Thursday, April 25, 2013 9:21 AM To: Fred Hink Cc: klr Subject: Re: [DSN_KLR650] CV Carb Plastic P.O.S. That little P.O.S. did not cause any problem until I did not seat it correctly, Fred. And I can verify unequivocally that it CAN AND DID block the hole. I failed to seat it in those nice little notches that I did not notice so it was not seated correctly, by me, and it did WAY block the hole. Try it, you won't like it. One reason that it CAN block the hole is that the little P.O.S. has about eight little arms, so being wrong a bit is eight times as likely as if it had a hole for the hole, if you know what I mean. Not to spoil the report, but I took the carburetor apart looking for the stumble bumble and when I put it back together I did not notice that there were notches (which I think are pretty wimpy) so I just dropped it in. The bike ran really lousy. I took the carburetor apart and lo and behold! The little P.O.S. was not down in the notches but was blocking the hole! When I put it down in the notches, all was well and good. Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 ===============================================

On 4/25/2013 8:02 AM, Fred Hink wrote: > Never heard of this problem before. I have a carb on my bench and > just took it apart to have a look. There are indexing bumps inside > the slide near the needle holder that index the plastic keeper from > blocking this port. I d say that there is no way that the plastic > part can block this hole. > You may have fixed your stumble but it most likely wasn t caused by > this plastic piece blocking the vacuum port. > Fred > http://www.arrowheadmotorsports.com > > *From:* RobertWichert > *Sent:* Thursday, April 25, 2013 8:49 AM > *To:* klr > *Subject:* [DSN_KLR650] CV Carb Plastic P.O.S. > > In searching for the cure to my "Stumble Bumble" (full report to follow) > I have discovered that deep in the CVK carburetor there is a little > plastic P.O.S. that seems to hold the needle down on the slide by spring > pressure from the big spring above. Interestingly enough, if you do not > seat this little P.O.S. correctly, it can rotate "one notch" and block > the slide lifting hole. With the slide lifting hole blocked by the > little P.O.S., the bike doesn't go over about 3,500 RPM, and has little > or no power. > > So what keeps this little P.O.S. from turning a notch when I take one of > my famous crash and burn excursions? That spring is pretty wimpy if you > ask me. > > Any insight from the carburetor guruistas? > > -- > Robert Wichert P.Eng. LEED AP BD&C > +1 916 966 9060 > FAX +1 916 966 9068 > > =============================================== > > [Non-text portions of this message have been removed] [Non-text portions of this message have been removed]

[RobertWichert]

Well, Fred, I beg to differ. And, I am always ready to admit my errors... So here goes. The diaphragm was not cut, for sure. When I put it back together the second time everything worked great. So unless the cut healed itself (it could happen!) it was not cut before, during or after the repairs. The diaphragm may not have been in the groove, but I tighten everything down gorilla-tight, so if it was not in the groove, I would have cut it badly. I did not have a performance increase. I took the carb apart and I put it back together wrong and the bike ran lousy. I attribute the lousy running to having the P.O.S. blocking the slide lifting hole because when I carefully disassembled the carburetor, the P.O.S. was not down on the notches and it was blocking the hole. It could have moved when I disassembled it, but I don't think so. I remember distinctly not giving a S. where I put the P.O.S. when I installed it the first time. I just dropped it in. I never thought about it having notches, which it has as you correctly pointed out and I found out when I looked at it critically after I disassembled it the second time. I then installed it correctly and the lousy bike became normal. QED. You are right about the needle being high if the P.O.S. is not down all the way. So yes, it could cause problems but since the needle isn't really that tapered, I don't see that little change as being enough to make the thing run like a Honda 50. What I think was happening (without X-Ray vision, I can't be sure) is that the slide was not rising as much as it should be rising due to the restriction in the lifting hole. But I could be wrong. So, regardless of the reason, here is what I suggest be given as advice to those not knowing the inner working of the CVK carburetor for putting the CVK carburetor back together. BE SURE TO GET THE PLASTIC NEEDLE RETAINING PIECE SEATED PROPERLY ON THE NOTCHES IN THE SLIDE SO THE LIFTING HOLE IS NOT BLOCKED BEFORE REINSTALLING THE SPRING. IF YOU ROTATE IT, YOU WILL SEE AND FEEL IT CLICK INTO PLACE. I think you will agree that this is good advice, no matter what. But as I said before, my years of experience have taught me that I can be wrong and if so, I try to learn from my mistakes. Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 ===============================================

On 4/25/2013 8:51 AM, Fred Hink wrote: > Robert, > To continue this discussion, I don t doubt you had a performance > increase. If the POS as you describe it is not down on those notches > then it can t be down on that hole. Please explain to me how you feel > this plastic piece if not indexed correctly and is on top of the > indexing notches can cover that vacuum port. Since this plastic piece > if not indexed correctly is raised by the index notches is also raised > from the base of the slide where the vacuum port is. Unless I am > misunderstanding you, I don t see how this is possible. The problem I > see by not having the plastic piece indexed is that it is not holding > down the needle in the slide and could cause it to float slightly > causing a jetting issue in the midrange. > I have seen this problem (pinched diaphragms) since CVK type carbs > have been around. There is a lack of power and the slide only opens > part way. Most often there has been someone inside the carb > previously (or on an old bike it has just worn out) and has not got > all of the diaphragm in the grove where it is supposed to be. This > causes a vacuum leak and the slide can not open like it is supposed > to. Most often the diaphragm is cut by tightening the cover and may > or may not work as intended after that. By making sure that the > diaphragm is in the grove it is supposed to ride in, you may have > fixed your problem. If the diaphragm edge was cut, then it may also > have a slight air leak there. Not trying to argue with you but to > explain to others that may not know the inner workings of their > carburetors. > Fred > http://www.arrowheadmotorsports.com > > *From:* RobertWichert > *Sent:* Thursday, April 25, 2013 9:21 AM > *To:* Fred Hink > *Cc:* klr DSN_klr650@yahoogroups.com> > *Subject:* Re: [DSN_KLR650] CV Carb Plastic P.O.S. > > That little P.O.S. did not cause any problem until I did not seat it > correctly, Fred. > > And I can verify unequivocally that it CAN AND DID block the hole. I > failed to seat it in those nice little notches that I did not notice so > it was not seated correctly, by me, and it did WAY block the hole. Try > it, you won't like it. > > One reason that it CAN block the hole is that the little P.O.S. has > about eight little arms, so being wrong a bit is eight times as likely > as if it had a hole for the hole, if you know what I mean. > > Not to spoil the report, but I took the carburetor apart looking for the > stumble bumble and when I put it back together I did not notice that > there were notches (which I think are pretty wimpy) so I just dropped it > in. The bike ran really lousy. I took the carburetor apart and lo and > behold! The little P.O.S. was not down in the notches but was blocking > the hole! When I put it down in the notches, all was well and good. > > Robert Wichert P.Eng. LEED AP BD&C > +1 916 966 9060 > FAX +1 916 966 9068 > > =============================================== > > On 4/25/2013 8:02 AM, Fred Hink wrote: > > Never heard of this problem before. I have a carb on my bench and > > just took it apart to have a look. There are indexing bumps inside > > the slide near the needle holder that index the plastic keeper from > > blocking this port. I d say that there is no way that the plastic > > part can block this hole. > > You may have fixed your stumble but it most likely wasn t caused by > > this plastic piece blocking the vacuum port. > > Fred > > http://www.arrowheadmotorsports.com > > > > *From:* RobertWichert > > *Sent:* Thursday, April 25, 2013 8:49 AM > > *To:* klr > > *Subject:* [DSN_KLR650] CV Carb Plastic P.O.S. > > > > In searching for the cure to my "Stumble Bumble" (full report to follow) > > I have discovered that deep in the CVK carburetor there is a little > > plastic P.O.S. that seems to hold the needle down on the slide by spring > > pressure from the big spring above. Interestingly enough, if you do not > > seat this little P.O.S. correctly, it can rotate "one notch" and block > > the slide lifting hole. With the slide lifting hole blocked by the > > little P.O.S., the bike doesn't go over about 3,500 RPM, and has little > > or no power. > > > > So what keeps this little P.O.S. from turning a notch when I take one of > > my famous crash and burn excursions? That spring is pretty wimpy if you > > ask me. > > > > Any insight from the carburetor guruistas? > > > > -- > > Robert Wichert P.Eng. LEED AP BD&C > > +1 916 966 9060 > > FAX +1 916 966 9068 > > > > =============================================== > > > > > > [Non-text portions of this message have been removed] > > [Non-text portions of this message have been removed]

[Fred Hink]

I have tried to measure the rise or depth in this notch but I am not able to because it is not a stepped notch but rather a ramped notch. Meaning that the transition from the middle needle holder to the notches at the base is gradual and I could not get my calipers to get me a reading as to it s depth through the transition. Anything is possible but it would be hard to position this holder on top of that ramped step and have it stay there for long. I wasn t inferring that you had cut your diaphragm but was adding this as an explanation as to what has happened to those I have experienced in the past. I guess we will have to agree to our disagreement here. As long as your bike is performing to your expectations, that is all we can hope for. ps. plug for my Mikuni carb kit......... No Diaphragms! Fred http://www.arrowheadmotorsports.com From: RobertWichert Sent: Thursday, April 25, 2013 10:13 AM To: Fred Hink Cc: klr Subject: Re: [DSN_KLR650] CV Carb Plastic P.O.S. Well, Fred, I beg to differ. And, I am always ready to admit my errors... So here goes. The diaphragm was not cut, for sure. When I put it back together the second time everything worked great. So unless the cut healed itself (it could happen!) it was not cut before, during or after the repairs. The diaphragm may not have been in the groove, but I tighten everything down gorilla-tight, so if it was not in the groove, I would have cut it badly. I did not have a performance increase. I took the carb apart and I put it back together wrong and the bike ran lousy. I attribute the lousy running to having the P.O.S. blocking the slide lifting hole because when I carefully disassembled the carburetor, the P.O.S. was not down on the notches and it was blocking the hole. It could have moved when I disassembled it, but I don't think so. I remember distinctly not giving a S. where I put the P.O.S. when I installed it the first time. I just dropped it in. I never thought about it having notches, which it has as you correctly pointed out and I found out when I looked at it critically after I disassembled it the second time. I then installed it correctly and the lousy bike became normal. QED. You are right about the needle being high if the P.O.S. is not down all the way. So yes, it could cause problems but since the needle isn't really that tapered, I don't see that little change as being enough to make the thing run like a Honda 50. What I think was happening (without X-Ray vision, I can't be sure) is that the slide was not rising as much as it should be rising due to the restriction in the lifting hole. But I could be wrong. So, regardless of the reason, here is what I suggest be given as advice to those not knowing the inner working of the CVK carburetor for putting the CVK carburetor back together. BE SURE TO GET THE PLASTIC NEEDLE RETAINING PIECE SEATED PROPERLY ON THE NOTCHES IN THE SLIDE SO THE LIFTING HOLE IS NOT BLOCKED BEFORE REINSTALLING THE SPRING. IF YOU ROTATE IT, YOU WILL SEE AND FEEL IT CLICK INTO PLACE. I think you will agree that this is good advice, no matter what. But as I said before, my years of experience have taught me that I can be wrong and if so, I try to learn from my mistakes. Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 =============================================== On 4/25/2013 8:51 AM, Fred Hink wrote: Robert, To continue this discussion, I don t doubt you had a performance increase. If the POS as you describe it is not down on those notches then it can t be down on that hole. Please explain to me how you feel this plastic piece if not indexed correctly and is on top of the indexing notches can cover that vacuum port. Since this plastic piece if not indexed correctly is raised by the index notches is also raised from the base of the slide where the vacuum port is. Unless I am misunderstanding you, I don t see how this is possible. The problem I see by not having the plastic piece indexed is that it is not holding down the needle in the slide and could cause it to float slightly causing a jetting issue in the midrange. I have seen this problem (pinched diaphragms) since CVK type carbs have been around. There is a lack of power and the slide only opens part way. Most often there has been someone inside the carb previously (or on an old bike it has just worn out) and has not got all of the diaphragm in the grove where it is supposed to be. This causes a vacuum leak and the slide can not open like it is supposed to. Most often the diaphragm is cut by tightening the cover and may or may not work as intended after that. By making sure that the diaphragm is in the grove it is supposed to ride in, you may have fixed your problem. If the diaphragm edge was cut, then it may also have a slight air leak there. Not trying to argue with you but to explain to others that may not know the inner workings of their carburetors. Fred http://www.arrowheadmotorsports.com From: RobertWichert Sent: Thursday, April 25, 2013 9:21 AM To: Fred Hink Cc: klr Subject: Re: [DSN_KLR650] CV Carb Plastic P.O.S. That little P.O.S. did not cause any problem until I did not seat it correctly, Fred. And I can verify unequivocally that it CAN AND DID block the hole. I failed to seat it in those nice little notches that I did not notice so it was not seated correctly, by me, and it did WAY block the hole. Try it, you won't like it. One reason that it CAN block the hole is that the little P.O.S. has about eight little arms, so being wrong a bit is eight times as likely as if it had a hole for the hole, if you know what I mean. Not to spoil the report, but I took the carburetor apart looking for the stumble bumble and when I put it back together I did not notice that there were notches (which I think are pretty wimpy) so I just dropped it in. The bike ran really lousy. I took the carburetor apart and lo and behold! The little P.O.S. was not down in the notches but was blocking the hole! When I put it down in the notches, all was well and good. Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 ===============================================

On 4/25/2013 8:02 AM, Fred Hink wrote: > Never heard of this problem before. I have a carb on my bench and > just took it apart to have a look. There are indexing bumps inside > the slide near the needle holder that index the plastic keeper from > blocking this port. I d say that there is no way that the plastic > part can block this hole. > You may have fixed your stumble but it most likely wasn t caused by > this plastic piece blocking the vacuum port. > Fred > http://www.arrowheadmotorsports.com > > *From:* RobertWichert > *Sent:* Thursday, April 25, 2013 8:49 AM > *To:* klr > *Subject:* [DSN_KLR650] CV Carb Plastic P.O.S. > > In searching for the cure to my "Stumble Bumble" (full report to follow) > I have discovered that deep in the CVK carburetor there is a little > plastic P.O.S. that seems to hold the needle down on the slide by spring > pressure from the big spring above. Interestingly enough, if you do not > seat this little P.O.S. correctly, it can rotate "one notch" and block > the slide lifting hole. With the slide lifting hole blocked by the > little P.O.S., the bike doesn't go over about 3,500 RPM, and has little > or no power. > > So what keeps this little P.O.S. from turning a notch when I take one of > my famous crash and burn excursions? That spring is pretty wimpy if you > ask me. > > Any insight from the carburetor guruistas? > > -- > Robert Wichert P.Eng. LEED AP BD&C > +1 916 966 9060 > FAX +1 916 966 9068 > > =============================================== > > [Non-text portions of this message have been removed]

[James W. Flower]

Thanks Jeff, very helpful.