Engine stutter on deceleration
 

I just bought a '98 SH with 22K miles and the previous owner mentioned that the bike sometimes has a stutter/hesitation on deceleration.... its weird, at any operating temp, I'm going along at a steady 3,000-4,000 rpm and can accelerate just fine, and once in a while when I lay off the gas and let it decelerate a little, the engine seems to stutter a little like its dieing, and I can feel the hesitation in the handle bars like something in the block is coming up at me. If I then lay on the gas and accelerate, it goes back to running normal. The previous owner said there had been posts on here about it and said it seems to be something normal for the SH. Any advice? I see the previous owner of my bike had posted a couple times about the CCT... having last owned a '01 CBR F4i, and having the cct replaced on it because of the noise, the hesitation the bike seems to have once in a while is nothing to do with the cct.

Does this happen on hard braking or just normal decel?

Engine stutter on deceleration
 

Normally not braking when this happens... its sorta like the bike is hiccuping... I'm going along at a steady 3,000-4,000 RPM and lay off the gas and it sorta hiccups like something is bogging down the motor, and if I accelerate, it goes away... its very infrequent.

How many miles does it have on it? Does it still have the pair and all the emmissions equiptment still hooked up? Do you know when the last time the carbs were sync'ed?

Bike has 22K miles. The carbs were recently sync'd I believe. The emissions equip. was all removed.

It might be a slide sticking for a sec but besides that I'm not sure what else to tell you.

I talked to my regular mechanic about it a little bit ago, he said its not doing anything abnormal. I guess I won't worry about it, the bike runs great otherwise.

Well it doesn't sound like a major problem so you shouldn't have any problems. Like I told you it kind of sounds like the slides are hanging up for a sec.

It actually stutters, we're not talking about popping on decel. Mine has pair removed and is rejetted but its a little *off* and in the 3k and lower range it pops on decel and at steady-state cruise it has a miss/stumble to it that I attribute to the tune and TPS volts not being 100% correct....and I dont know how much is the cam profiles either.

I wouldn't worry about it..

It also sounds lean on the bottom and rich on the top..... the cams have nothing to do with it....

shim your carb needles and see if the stutter goes away? (being too lean down low)

Not to steal the thread but I always thought it was rich down low because if I cruise for a minute and wrap the gas, it stumbles real hard before it takes off and occasionally after cruising in a high gear/lower rpms, it will stall on decel and hiccup when restarted. Figured it's loading up.

It does it when I let off the gas while in 2nd gear btwn 3,000 and 4,000 rpm. If I lay back on the gas when it does it, it stops and runs normal.

The popping on decal is usually a sign that it is a little lean, try pulling the choke out just a little bit and see if it goes away. You can also check the higher rev's the same way-pull the choke out, once again just a little, and if it gets better it's lean or if it gets worse, it's rich.

I would check the TPS setting first.

Sorry to echo what has already been stated, but check the TPS. In my experience I have found that the TPS sensor off leads to a surging affect at any throttle setting.

The carbs being out of sync can have this affect also.

Although when my hawk has been out of sync she will stumble at idle, and be fine throughout the rev range. Hope this helps.

It may be the TPS but unlikely. It is a problem and needs to be addressed probably best of taking it to a competent tuner with a dyno. A few hundred dollars and will be a different bike.

A stumble at steady state cruise will mean a lean condition. I have had mine very rich and it runs fine however with lean mixtures the hawk does not run well at all and your symptoms are a prime example of a lean condition.

But he said the problem wasn't at steady cruse but when he closed the throttle. That's why it sounds like a slide hanging up to me. That and if it was lean the problem wouldn't go away when he gets back on the throttle but should get worse.....

So throughout the summer I have had a problem like this. My bike is 04 model and has done 3.5k. The bike would occasionally miss a beat after running out of town and then travelling through traffic. Now in winter the same thing happens but cuts out needing to restart. It only does it in these circumstances and otherwise runs fine. After restart the fault has gone-(until the next time.) Very baffling seems llike a fuel issue anyone any ideas?

Hi Guys,

I faced the same issue on my 2002 VTR, I removed the 2 hoses ( see part 25 there !).

I reduced these hoses length to 10 cm (4 inches) and I putted those back.

It fixed the "plop" at 3500 - 4500 rpm at the deceleration.

I hope it will help.

Best regards

(Please forgive my bad english, I'm a frenchie... I'll improve my english, but it takes some times ;))

Your English is great...keep at it!
Are those the famed overflow hoses that need to be rerouted?

Yes, it is exactly that hoses.

With the hoses, the engine may miss some beats (or makes some "Plops").

With the hoses rerouted & cutted to 4inches, it works fine.

One other thing, on stock VTR, the TPS (Throttle Position Sensor) is not calibrated. You must have 490 to 510 Ohm between the A & B pin (information take from the VTR'99 official Honda workshop book, french version). (Generally on stock engine you have something greater than 600 ohms !!!)

I thought re-routing those hoses was an odd fix, cause they are overflow drains and shouldn't affect the function of the carbs, but this seems to confirm the affect. I wonder if they are subject to suction on decellaration and are partially colapsing, as they are soft, causing a pulse of turbulence in a bad place. when you re-route or shorten, they are less likely to collapse. Anyone else got any ideas?

Other than that it worked with a re-route on mine... No idea why thoo... It's not very logical as you said happytrack...