Vtr Carb question and random vfr rear caliper question
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From: 34691
Vtr Carb question and random vfr rear caliper question
Ive cut my headers down for a rat rod kinda touch, and of course its loud thats cool with me. It runs like **** and thats not cool with me. I wont pretend, my experience with carbs is limited, for example it took me about 20 minutes to realize I had the vac line hooked up to the vent port lol. But once I straightened that out itll start but runs real bad. i assumed this was gonna happen, I can figure out how to install the jet kit I just have no idea what jets to get? Any advice would be fantastic.
Also if anyone has a bright idea one how to hook this ABS caliper up to a single line that would be cool. Main thing is getting it running right though...
Heres my project build its no way near done but already loads of fun lol! I think the tail may me a touch high but Im gonna wait till i get the bars on and see how it looks. I dont wanna redo it all until its semi complete so I can at least get the whole "look"
Getting a Cbr front end and fitting handle bars is next
Also if anyone has a bright idea one how to hook this ABS caliper up to a single line that would be cool. Main thing is getting it running right though...
Heres my project build its no way near done but already loads of fun lol! I think the tail may me a touch high but Im gonna wait till i get the bars on and see how it looks. I dont wanna redo it all until its semi complete so I can at least get the whole "look"
Getting a Cbr front end and fitting handle bars is next
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SuperSport
Joined: Apr 2011
Posts: 510
From: Edwards AFB, CA
Hey there. Well I have some not so good news for you reguarding the exhaust. You need back pressure for top performance. With the gasses running straight out from the cylinder heads with no pressure build up you can burn up the exhuast valves so no matter how you jet it, it will not run right in my experiance. The VFR caliper now... I belive they used a linked braking system, well on 1998 models I know they did. I would imagine that the other line is for a return to the proportioning valve. You may be able to find a bolt with the same thread pitch of the banjo bolt but shorter so it doesnt thread too deeply into the caliper and put a new crush washer on it so it doenst leak. To me that would be worth investigation but I would only do the above after I found out for sure that is how that caliper works. Maybe if no one on here has any input try a VFR forum and search for the answer or ask the question. Oh and BTW search "Carb Setup" here on the forum and follow the steps, it will get you close to a good starting point.
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Performance isnt a huge concern I have my Z for that. As long as it can get to running ok Ill be satisfied (dont wanna burn anything up though). I see guys running straight headers frequently on the bobber builds...
I did hear about some sort of baffle that goes inside the pipe a while back though, maybe Ill look into that.
I did hear about some sort of baffle that goes inside the pipe a while back though, maybe Ill look into that.
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Superstock
Joined: Jul 2013
Posts: 458
From: Rome, GA
Bobber builds aren't generally using high performance engines though either. Harley engines and even a lot of jap cruisers are built with the fact in mind that some idiot is going to put straight pipes or shotgun pipes on them and can be tuned accordingly. The Hawk is tuned for max performance, one carb on the Hawk is bigger than the one carb they put on the harley 1200 and they only have that one carb where the hawk has two!
While I can appreciate the look of the bike with the bobber style pipes on it wrapped up, trying to mess with the exhaust of an engine like this is like trying to run a two-stroke bike with no exhaust. Alright, well its not quite that extreme, but I personally don't see it being worth the amount of time you will have to invest to get it right.. or the money, as you will either have to buy an O2 meter and sensor, or will have a lot of time and money sunk into dyno runs till you get the carbs set right, or even close enough to right for that matter
While I can appreciate the look of the bike with the bobber style pipes on it wrapped up, trying to mess with the exhaust of an engine like this is like trying to run a two-stroke bike with no exhaust. Alright, well its not quite that extreme, but I personally don't see it being worth the amount of time you will have to invest to get it right.. or the money, as you will either have to buy an O2 meter and sensor, or will have a lot of time and money sunk into dyno runs till you get the carbs set right, or even close enough to right for that matter
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MotoGP
Joined: Jul 2010
Posts: 3,871
From: Phoenix, AZ
48hp bobber build wouldn't exactly be a noteworthy goal...
It's not just "backpressure" but a myriad of things that exhaust engineers know that you need with mufflers and full length pipes... the low pressure caused by the exhaust pulses pulling the exhaust waste gas out for instance. Timing the back pulses to not interfere with the next pulse, etc. Things you can't just tune out of the motor at a slight loss, but will cause you to want to throw it off a bridge.
Or you can embrace the beauty of the twin cans this bike is endowed with and let them hang out for all to see...
It's not just "backpressure" but a myriad of things that exhaust engineers know that you need with mufflers and full length pipes... the low pressure caused by the exhaust pulses pulling the exhaust waste gas out for instance. Timing the back pulses to not interfere with the next pulse, etc. Things you can't just tune out of the motor at a slight loss, but will cause you to want to throw it off a bridge.
Or you can embrace the beauty of the twin cans this bike is endowed with and let them hang out for all to see...
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Ok, so Ill ignore the idiot comment and attempt to keep this on track. (I understand the bike isnt for everyone, good thing Im building it for ME) If you want to talk performance I have a Z in my garage that'll walk all over any hawk you guys can produce, **** fight over? But again thats not what this bike is about, I love the hawk for what it is a quirky grunty V twin with honda build qualitly. Its not gonna be a bobber, its not a cafe bike its not a rat rod its gonna be something in the middle with a nasty attitude! And this is my second one so I came back for more lol. So lets keep the bashing minimal??
Im trying to get some good information here... The pipes are about 1 3/4 inner diameter and the back one has about 4 inches of room to get something in there before a significant bend. I am taking the back pressure issue serious, I thought I could just re-jet it and get away with that. Its fine if that's not going to work I just need to figure out what will. And the way I see it the more heads the better.
Anyone know of any in tube baffles that are 1 3/4 in inner diameter? I found a few but the ones I came across were 2 1/4 diameter. I can cut something down if its to long but cant squeeze it in if its too big, my go to... KY isnt applicable in this situation. Any help as always is appreciated.
-Brian
Im trying to get some good information here... The pipes are about 1 3/4 inner diameter and the back one has about 4 inches of room to get something in there before a significant bend. I am taking the back pressure issue serious, I thought I could just re-jet it and get away with that. Its fine if that's not going to work I just need to figure out what will. And the way I see it the more heads the better.
Anyone know of any in tube baffles that are 1 3/4 in inner diameter? I found a few but the ones I came across were 2 1/4 diameter. I can cut something down if its to long but cant squeeze it in if its too big, my go to... KY isnt applicable in this situation. Any help as always is appreciated.
-Brian
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MotoGP
Joined: Jul 2010
Posts: 3,871
From: Phoenix, AZ
Ok, so Ill ignore the idiot comment and attempt to keep this on track. (I understand the bike isnt for everyone, good thing Im building it for ME) If you want to talk performance I have a Z in my garage that'll walk all over any hawk you guys can produce, **** fight over? But again thats not what this bike is about, I love the hawk for what it is a quirky grunty V twin with honda build qualitly. Its not gonna be a bobber, its not a cafe bike its not a rat rod its gonna be something in the middle with a nasty attitude! And this is my second one so I came back for more lol. So lets keep the bashing minimal??
Here's why I don't think simple baffles will work: When exhaust gas is evacuated, it sends a pulse down the pipes. Once this pulse is partially through the pipe, it creates a low pressure area behind it by the nature of it traveling through. This low pressure area exists until the next full stroke when exhaust is then evacuated again. The low pressure then aids in evacuating the next round of gases by pulling it through and the resulting pulse starts the cycle again. If you have open or short pipes, the pulse just dissipates and leaves no low pressure behind it, so the next evacuated gasses are helped out of the chamber (for lack of a better description). I believe this is what burns up valves is hot gases idle in the chamber more with leaky or open systems (I could be wrong here, though). If baffles and back pressure were all that were needed, race teams would have 6" headers with a small plug and not waste precious weight on a full system. I know you're not looking to race, but it does illustrate why a baffle wouldn't work IMO.
Now, back on topic, let's talk more about that Z that you keep bringing up... what color is it? If it's not yellow, I ain't buyin' the talk
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Superstock
Joined: Jul 2013
Posts: 458
From: Rome, GA
Anyone know of any in tube baffles that are 1 3/4 in inner diameter? I found a few but the ones I came across were 2 1/4 diameter. I can cut something down if its to long but cant squeeze it in if its too big, my go to... KY isnt applicable in this situation. Any help as always is appreciated.
-Brian
-Brian
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Fair enough, and I totally get it. If theres a way to get it running right(ish) with this exhaust thats the look Im after. If I have to bite the bullet so to speak and redesign the exhaust that sucks but there it is. The big problem with that is this SSSA. With the SSSA the rear exhaust port comes smack out right into the shock and further more I have to run it out side of the swinger now so I guess I could run it up to a single can on the right side but strongly prefer to keep the current look. Im fine with sacrificing some performance but of course still want it to haul *** lol.
Wasn't trying to "diss" anyone Ive been riding for 20 years and understand this isnt for everyone. I also accept other peoples bikes that may not be for me... Kinda what riding is about for me at least. Make it yours. That being said, lets be friends we all have a common interest super hawks. Mine just currently runs like ****.
Does anyone have a pipe bender handy? And willing to experiment? Of course Ill pay but cant find anyone local... What I have is a cut weld, messed it up cut weld, its almost there bend the crap out of it thatll do system. And if itll run fair with some baffles and jets it will do lol. But Im not totally opposed to running a can, would prefer a GP style small can down low but might run into the same issue I have now. I guess I need someone thats good at designing a custom pipe set up. Or someone willing to give it a crack.
Heres my Z... I bought her as a pile of rubble pretty much and Im close to done. Still want some levers and stainless lines and Im considering a zx-6 front end but these legs dont treat me to bad so Im focusing on the hawk for now. I went with harley colors cause it makes me chuckle.
-Brian
Wasn't trying to "diss" anyone Ive been riding for 20 years and understand this isnt for everyone. I also accept other peoples bikes that may not be for me... Kinda what riding is about for me at least. Make it yours. That being said, lets be friends we all have a common interest super hawks. Mine just currently runs like ****.
Does anyone have a pipe bender handy? And willing to experiment? Of course Ill pay but cant find anyone local... What I have is a cut weld, messed it up cut weld, its almost there bend the crap out of it thatll do system. And if itll run fair with some baffles and jets it will do lol. But Im not totally opposed to running a can, would prefer a GP style small can down low but might run into the same issue I have now. I guess I need someone thats good at designing a custom pipe set up. Or someone willing to give it a crack.
Heres my Z... I bought her as a pile of rubble pretty much and Im close to done. Still want some levers and stainless lines and Im considering a zx-6 front end but these legs dont treat me to bad so Im focusing on the hawk for now. I went with harley colors cause it makes me chuckle.
-Brian
Last edited by bpw; Nov 26, 2013 at 01:46 PM.
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MotoGP
Joined: Jul 2010
Posts: 3,871
From: Phoenix, AZ
I don't know if you've seen these things:
stainless exhaust tubing 90 degree | eBay
stainless exhaust tubing 60 degree | eBay
stainless exhaust tubing 45 degree | eBay
But they might be easier to work with than trying to find someone with a mandrel tube bender
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Superstock
Joined: Jul 2013
Posts: 458
From: Rome, GA
Heres my Z... I bought her as a pile of rubble pretty much and Im close to done. Still want some levers and stainless lines and Im considering a zx-6 front end but these legs dont treat me to bad so Im focusing on the hawk for now. I went with harley colors cause it makes me chuckle.
-Brian
-Brian
I forgot all about those Kawi's.. You kept saying you had a Z and I kept thinking. I loved my Z car and I miss it horribly.. but theres no way it would "haul ***" compared to a motorcycle
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7 theres an idea! See I hadnt even thought of that. Thanks may be on to something there you guys got my brain going. I was thinking of maybe putting two shorties on the current set up then I thought about how dumb that would look and Id still have the "pulse" problem described prior. So **** looks like I have to go back to the subframe get that where I want it then dink with the pipes.... aaaahhhhrrrrrgggghhh
Thanks, I think lol
Thanks, I think lol
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