Technical Discussion Topics related to Technical Issues

flat spot

Old 11-12-2012, 05:10 PM
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flat spot

I've had my VTR for a while now. The two of us are getting on fine and becoming great friends. I've put over 3 thousand miles on it since I bought it in July. I have done the CCT replacement with manual CCT. I did the RR swap with a R1 unit. Very large and a bit tricky getting it to fit and all but that head ache is taken care of. Found a set of two brothers carbon slip ons and installed them. And, I did the TPS adjustment, left it at 503 ohms.

I'm not sure if I'm getting used to the bike or if it just doesn't have the roll on power it had. Is it possible I didn't tighten the screws enough and the TPS slipped and is not giving me the power at top? If I managed to let the timing gears slip a tooth during cct replacement, would that cause top end sluggishness? 1st, 2nd and 3rd are eye ball peeling in terms of speed but once I get to the higher gears at higher speeds the bike just feels a little flat. Any ideas?
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Old 11-12-2012, 06:34 PM
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Sounds like a tooth off on one or more of the cams.
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Old 11-12-2012, 06:35 PM
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Twist funny you mentioned this. I just went to a 2 into 1 exhaust, did hawks carb set up and and the same symptoms.......higher rpm. higher gears, slower accel than before. But i figure that i need to go to bigger mains because of a foam air filter with cut off flap with the single exhaust.

Anyway, what I was getting to is that I put 93 octane in for a couple of tanks and now it's running much better on top. Now i'm not sure why, but some of the carb experts on here may be able to explain, but it's worth a try for you, esp considering the **** fuel we're getting today. I'm still going to larger mains and pilot to see if i can get back to 87 oct , but till then. It's 93 for me. About a dollar more a tankful may be worth if there are no adverse side effects.
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Old 11-12-2012, 07:02 PM
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As any mechanic will tell you, if you make a change that should have a specific result and that doesn't happen you go back and check your work.

Years ago I rebuilt my top end and went to the track, it pulled like a raped ape till it got to the higher RPM's where it seemed to hit a wall. I looked at everything except my rebuild, then complaining to an old hand he said "hey ******* check your work" he was right, the cam was off and it was only my pride/arrogance that prevented me from seeing it!
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Old 11-12-2012, 09:21 PM
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Originally Posted by HRCA#1 View Post
As any mechanic will tell you, if you make a change that should have a specific result and that doesn't happen you go back and check your work.

Years ago I rebuilt my top end and went to the track, it pulled like a raped ape till it got to the higher RPM's where it seemed to hit a wall. I looked at everything except my rebuild, then complaining to an old hand he said "hey ******* check your work" he was right, the cam was off and it was only my pride/arrogance that prevented me from seeing it!
do you have a hawk that is stock in terms of cams and carburetion and so forth? I don't have anything to compare against so I'm not 100% sure.

How should it pull in 5th gear at 3000 to 6000 rpm with a roll on?
5th gear from 4000 to 6000 with a roll on?
Shifting from 5th at 5000 to 6th gear and rolling on to 5000rpm?
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Old 11-12-2012, 09:23 PM
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Originally Posted by HRCA#1 View Post
Sounds like a tooth off on one or more of the cams.
most likely the front? check both of course.
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Old 11-13-2012, 07:33 AM
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Originally Posted by VTRsurfer View Post
Most of the punch is from 5,000 rpm up. It should pull steady from 3500 in 5th or 6th, but it won't snap your head back. If I'm in 5th or 6th, I downshift to get the revs up to around 5000 if I'm passing someone. Then it goes like a rocket.

When riding the canyons I enter corners with the revs no lower than 4500. 5000+ is best for accelerating out of a corner.
thank you for that. I must be getting used to the bike. At highway speeds in 5th and 6th at 5000 it pulls but not the eye ball peeling kind of acceleration of 4th or 3rd. If I am in 6th and running at 70 or 80 and open it up it pulls steady just not hard. If I drop it to 5th it is blast off time. So, I am getting paranoid with all this talk of slipping a tooth? I really don't want to start taking things apart unless I have to. Either that or I have a inate desire to work on the bike and make changes.
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Old 11-14-2012, 11:19 AM
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An easy way to test the bike it take it to 60mph in 6th.

Go WOT and you should hit 80mph in 1.5-1.75 secs. This is what a completely stock bike will do. So if it takes longer you have issues somewhere.
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Old 11-14-2012, 11:33 AM
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Wouldn't he have problem's in lower gears and rpms also with a tooth off, not just when he's pushing it?

Twist, have you cleaned, synced, and tuned your carbs? And changes to the airfilter? The slip ons could make it run differently, and maybe your mind is exacerbating the flat spot because you were expecting something different. Dont be afraid to tear it down again, at least if you do you will have peace of mind.
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Old 11-14-2012, 11:43 AM
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Originally Posted by aja View Post
Wouldn't he have problem's in lower gears and rpms also with a tooth off, not just when he's pushing it?

Yes he would but doing it this way puts the largest load on the engine and any issues will be more evident IMHO.

It is just a "quick" check but it starts at the bottom of the power band and the engine should just continue to pull harder all the way to the HP peak.
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Old 11-14-2012, 04:19 PM
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I took the bike out for a little run before I read 8541hawk's reply, thanks hawk! Here's what I did: I got the bike warmed up on surface streets about 10 min then took it onto the freeway accelerating and shifting through the gears normally. I got it to highway speed, 70 to 80 mph and ran it there for about 8 to 10 miles. I then wicked it open and observed the response. Not head whipping but not bad either. It ran up to 100 very quickly. I then slowed down to 80 again, settled in for a few miles and dropped into 5th and wicked it open. Very satisfactory response. Not like 1st to 2nd but nice. I let the bike settle back to cruising speed again and let it stay there for a good 10 to 15 miles and tried the process again. In the end, I think I've been getting used to the bike and getting paranoid. The bike is fine. As a matter of fact, as I remember, after I put the new cans on the bottom end acceleration got better, or so it seemed. I hate to admit it but I got used to the bike and 90 feels like 60. When I slow down to the speed limit I can't even use 6th gear. I'm thinking of switching to a 16/42 sprocket configuration. Any advice of a good combination to take advantage of the long legged 6th gear?
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Old 11-14-2012, 11:29 PM
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8541, that [email protected] gear sound interesting. I will try it next time. As for 6th gear I hardly use it. I only get a strong pull at about 80+(in 6th). Running 16/42 renthals alum. rears. Got about 64K on her and use Premium. Leaded gas runs almost like a tune-up. Must have carbon build-up on the pistons? Honda tech at previous 60K tune-up told me to use only premium gas. Do notice a diff when last running 87 oct. Getting about 43mpg on long rides(not corrected for gearing), but consistant. My VFR700 gets about 55 mpg(stock gearing). Been using her mostly for long rides(save gas), but not nearly as fun.

Working on my spare carb with FPjet kit and set-up with 48s purchased from forum member. Will reference your carb write-up as I go along for my stock carb(got second set of 48s to put in). Will be running 16/43 on my spare set of rears. DID gold chain. And my other spare with factory 41.
(SORRY FOR ANY THREAD JACK)

Last edited by Onomea; 11-14-2012 at 11:56 PM. Reason: consideration
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Old 11-15-2012, 06:56 AM
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Hondas are notoriously undergeared usally running something like .9:1.0 in 6th which is an overdrive and therefore the need to downshift to get her to go.

I run a 43 rear for the sole reason of bringing that ratio back to rougly 1:1 maybe slightly over and gets her long legs a little shorter.

Let me add that I spend almost 0 time on freeways where that overdrive would be most useful in just laying down the miles and using as little power/fuel as possible.

Last edited by HRCA#1; 11-15-2012 at 06:59 AM. Reason: afterthought
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Old 11-15-2012, 10:07 AM
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Vid

Originally Posted by 8541Hawk View Post
An easy way to test the bike it take it to 60mph in 6th.

Go WOT and you should hit 80mph in 1.5-1.75 secs. This is what a completely stock bike will do. So if it takes longer you have issues somewhere.
I would be grateful if you would post a vid of your speedometer while the needle sweeps from 60 to 80 in 6th gear. I'll use a stopwatch to time it. 1.5 seconds is brutal, to say the least. Thanks
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Old 11-15-2012, 10:15 AM
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Originally Posted by zxbud View Post
I would be grateful if you would post a vid of your speedometer while the needle sweeps from 60 to 80 in 6th gear. I'll use a stopwatch to time it. 1.5 seconds is brutal, to say the least. Thanks
Well you did get me the stock spec is 2.7 sec : Motorcycle Performance Numbers & Street Bike Quarter Mile Times at Sport Rider

I guess I'm getting old, or just way to used to my set up that will pull a 60-80 roll on (with stock gearing) in well under 2 secs.
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Old 11-17-2012, 10:50 PM
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Originally Posted by 8541Hawk View Post
Well you did get me the stock spec is 2.7 sec : Motorcycle Performance Numbers & Street Bike Quarter Mile Times at Sport Rider

I guess I'm getting old, or just way to used to my set up that will pull a 60-80 roll on (with stock gearing) in well under 2 secs.
I'm going to try the little test to see how my VTR stacks up. I still haven't done the mod you wrote up but am planning on it. I'll try the test again after that and see what kind of difference I find.
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Old 11-18-2012, 07:49 AM
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Originally Posted by 8541Hawk View Post
Well you did get me the stock spec is 2.7 sec : Motorcycle Performance Numbers & Street Bike Quarter Mile Times at Sport Rider

I guess I'm getting old, or just way to used to my set up that will pull a 60-80 roll on (with stock gearing) in well under 2 secs.
no guessing about it. Either you are getting old, or you're dead.....anyway that's my rationalization.haha

accord to those SR stats, you may well have, not just the fastest superhawk, but the fastest bike of all @ 1.5sec from 60-80. Congrats!

And now since tweety blindly supported your claim, and offered his own challenge, he's gonna have to put a nitrous bottle and 15/44 gearing on his vtr to achieve this under 1.75 sec. roll-on time.

This is gonna be fun........
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Old 11-18-2012, 08:09 AM
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Yeah I'm known for just making **** up......
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Old 11-18-2012, 08:36 AM
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Originally Posted by 8541Hawk View Post
Yeah I'm known for just making **** up......
Woke your *** up huh! ha I thought you'd be on your way to the bikini state to vie for your steak dinner.

not saying your making **** up. Could be your timer needs re-calibrated or maybe your speedo has tourettes.

we believe ya..honest!
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Old 11-18-2012, 03:21 PM
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Originally Posted by 8541Hawk View Post
Yeah I'm known for just making **** up......
I don't think hawk is the kind of guy to make this up, and there is no reason for him to try to impress anyone. Don't forget, these bikes are known for having personalities of their own. If hawk has a stock bike and knows what the hell he's doing tuning the bike, I think his bike will do what he claims it will.
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Old 11-18-2012, 05:08 PM
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I really don't have a dog in this fight but I will say that in my time on this site neither 8541Hawk or Tweety has ever said anything that they couldn't support with facts and/or data.

There are others that believe what they believe and will take it to their graves however they rarely let little things like facts get in the way of those beliefs.

We ride normally aspirated motorcycles so the variables of temp,barometric pressure, air density and altitude all come into play, not to mention the tuning we do as individuals and even the tire pressures we run.

So if the man say's his bike will do X I'll take him at his word until I have facts that say it won't.
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Old 11-18-2012, 09:59 PM
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Originally Posted by twist View Post
I don't think hawk is the kind of guy to make this up, and there is no reason for him to try to impress anyone. Don't forget, these bikes are known for having personalities of their own. If hawk has a stock bike and knows what the hell he's doing tuning the bike, I think his bike will do what he claims it will.
Originally Posted by HRCA#1 View Post
I really don't have a dog in this fight but I will say that in my time on this site neither 8541Hawk or Tweety has ever said anything that they couldn't support with facts and/or data.

There are others that believe what they believe and will take it to their graves however they rarely let little things like facts get in the way of those beliefs.

We ride normally aspirated motorcycles so the variables of temp,barometric pressure, air density and altitude all come into play, not to mention the tuning we do as individuals and even the tire pressures we run.

So if the man say's his bike will do X I'll take him at his word until I have facts that say it won't.

First off, the main problem here is not soley tied to this particular issue just in case you haven't realized this yet. It is instead that there is a history of Hawk getting on my *** with his insults for some time now on several other non-related issues. He typically tries to disguise his cuts with "IMHO" and other bullshit conciliatory remarks and thinks that somehow makes his malicious comments justifiable.

If you guys or anybody else chooses to hold his hand, then have at it because I can deal with adversity. Personally i ain't goona swallow **** that smells bad to me and i don't need or want anyone patronizing me.

Now let's keep it objective, not subjective, because i ain't interested in this alpha-dog hagling **** with you guys, hawk or anyone else here. My intent is and always has been to share info. learn and enjoy with a group of riders who have some common interests based around the SH.

So..........from my understanding of hawk's challenge, it's riding along in 6th gear, start counting as you wack the throttle open at 60mph and time til 80mph. And, if an OEM hawk is unable to achieve 1.75 sec to 80mph, something's wrong with it.

Now these sport rider stats I believe are taken from graphed quarter mile runs which negates the time lost for cracking the throttle and time lost for accelating from a static speed.

read these stats for every bike, then take your own bike out and wack the throttle wide open as you start counting, and answer for yourself if you can in good conscience justify Hawk's claims.



Yamaha Motorcycle Performance Numbers & Yamaha Street Bike Quarter Mile Times at Sport Rider
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Old 11-22-2012, 06:00 AM
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Thin Skinned

Originally Posted by 8541Hawk View Post
Yeah I'm known for just making **** up......
Nah, just a little testy maybe

Here's a roll on account kinda scares me today even several years later. Entering I-4 in Plant City where the 3 lanes curve right at the ramp and I'm in 6th gear of the 2000 ZX-12. There is a semi in the middle lane and the right line I'm merging into is clear for a short way, enough room to overtake the semi and hammer down in the center lane. So I nail it in 6th and quickly move from the right to center in front of the truck but I didn't notice the fast moving car passing the truck in the left lane and turns out it wants the center lane, too. I must have looked in the mirror or something just long enough to miss seeing the car which is now directly in front of me in the center lane and now I'm going 100 or more and nearly rear end the car. What a mess that could have been .

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Old 12-21-2012, 07:22 PM
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Originally Posted by twist View Post
I don't think hawk is the kind of guy to make this up, and there is no reason for him to try to impress anyone. Don't forget, these bikes are known for having personalities of their own. If hawk has a stock bike and knows what the hell he's doing tuning the bike, I think his bike will do what he claims it will.

The whole issue here is my bike is far from stock. Yes I said stock gearing but other than that, well things have been changed.
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Old 12-21-2012, 10:08 PM
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Originally Posted by nath981 View Post
no guessing about it. Either you are getting old, or you're dead.....anyway that's my rationalization.haha

accord to those SR stats, you may well have, not just the fastest superhawk, but the fastest bike of all @ 1.5sec from 60-80. Congrats!

And now since tweety blindly supported your claim, and offered his own challenge, he's gonna have to put a nitrous bottle and 15/44 gearing on his vtr to achieve this under 1.75 sec. roll-on time.

This is gonna be fun........
You are aware that about the only thing stock on my bike is the stickers, right?

A stock bike puts out 112 bhp at the crank, or around 105 at the wheel, my bike puts out 130-135 at the wheel depending on what dyno you put it on... And it's also substantially lighter than stock, with more front weigth bias, and a longer swing arm and wheel span... End result, when I whack the throttle open, my bike isn't fighting for traction as much, it just goes...

So yeah, I'm really going to need a nitrous bottle, huh?

I'm well aware of yours and Mikes issues, and I'm not blindly supporting anything... I haven't put a stopwatch on it, so theres no data to prove it... But compared to a handful of local riders with bone stock engines, I'd say 1.7 is reasonable, if a stock bike does 2.7... Basically, I can pass them anytime I like, any gear, without effort... They can pass me and pull out a lead, going WOT, and I'll just go past them...
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Old 12-22-2012, 06:03 AM
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Keep on topic fellas. Help twist w/ his issues or the thread gets closed.
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Old 12-22-2012, 06:21 AM
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Originally Posted by Wolverine View Post
Keep on topic fellas. Help twist w/ his issues or the thread gets closed.
Yep, i agree.

Hey Mod's why not create "Bitch" thread so the "Mine is better than yours; your wrong; i know more than you; blah blah blah" bitch-en can be done in a useless thread and everyone else can just ignore the thread.

Happy days!
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Old 12-22-2012, 03:42 PM
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Thumbs up

'Im not sure if I'm getting used to the bike or if it just doesn't have the roll on power it had.
Sometimes we go looking for problems when they are not there. This can be even more so after doing any recent mechanical work.

How should it pull in 5th gear at 3000 to 6000 rpm with a roll on?
5th gear from 4000 to 6000 with a roll on?
There's not much in these two. At either 3000 or 4000 in 5th gear you have to expect the bike to not be as punchy as having it in a lower gear.

By all means experiment and see what kind of timings you get from 60-80 in various gears. If nothing else, at least you have some figures that you can use as comparison for any future work/mods you may do to the bike.



(:-})
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