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Flat spot in rev range

x01660

x01660

On a Connie in a neighborhood near you
Member
EDIT: The PO Sent the carbs out to Steve in FL to have the drain tubes put in. He also told me about some foam that he put in the airbox to help with something. Perhaps that's the issue?

So here's a new issue that has cropped up:

For the past couple of days, when I go to rev my engine FAST, there's a flat spot right around 3k. Not sure if I never noticed before, or if it was doing it. I've attached a video. Is this normal?

Also, I've noticed that my shifter has been a bit... "crunchier" on upshifts. I have started wearing new boots, so maybe its that, but it still seems a bit off. I changed my oil yesterday (oil, no filter).

Any thoughts would be most appreciated. Thanks!


-x01660
 
Last edited:
Sounds like the PO had the 2 Minute Mod from Shoodaben Engineering installed. It requires user "tuning" with a piece of foam blocking roughly 1/2 of one of the openings into the airbox right close to the front of the swingarm. If you have the 2MM and do not have the foam piece installed, you will be running too lean. Also, make sure the airbox has no splits along the seams. I noticed the engine was not up to temperature in your video which could maybe factor in to what you showed us.

I'll assume you are skilled at rev matching while shifting and spare everybody the lecture. Crunchy shifts can be due to tires not being optimally inflated, particularly the rear tire. I ran like 40/42 F/R. Brakes dragging, toasted wheel bearings, throttle cable adjustment. Or...clutch related issues such as worn lever bushings, needing bleeding to get rid any air in the system, master and/or slave cylinder seals leaking. I sure went through an adjustment period when I got new boots a few years back but it was all about not allowing the shift lever to fully return to center of travel on upshifts causing me to not get the next shift :mad:.

It looks like you have a 2005 so it's getting up in years and may suffer from "deferred maintenance". Valve clearances been inspected/adjusted lately?

You said "no filter" but I think you must mean you didn't change the filter, just the oil. I always wanted to slap a Kawasaki engineer every time I changed the filter in my C10s because it's such a messy operation.
 
brooke.benfield said:
Sounds like the PO had the 2 Minute Mod from Shoodaben Engineering installed. It requires user "tuning" with a piece of foam blocking roughly 1/2 of one of the openings into the airbox right close to the front of the swingarm. If you have the 2MM and do not have the foam piece installed, you will be running too lean. Also, make sure the airbox has no splits along the seams. I noticed the engine was not up to temperature in your video which could maybe factor in to what you showed us.

I'll assume you are skilled at rev matching while shifting and spare everybody the lecture. Crunchy shifts can be due to tires not being optimally inflated, particularly the rear tire. I ran like 40/42 F/R. Brakes dragging, toasted wheel bearings, throttle cable adjustment. Or...clutch related issues such as worn lever bushings, needing bleeding to get rid any air in the system, master and/or slave cylinder seals leaking. I sure went through an adjustment period when I got new boots a few years back but it was all about not allowing the shift lever to fully return to center of travel on upshifts causing me to not get the next shift :mad:.

It looks like you have a 2005 so it's getting up in years and may suffer from "deferred maintenance". Valve clearances been inspected/adjusted lately?

You said "no filter" but I think you must mean you didn't change the filter, just the oil. I always wanted to slap a Kawasaki engineer every time I changed the filter in my C10s because it's such a messy operation.
Click to expand...

Thanks for responding!
  • Yes. The owner did do the 2 minute mod. I've also been riding pretty hard. I wonder if I disloged the piece of foam. I'll have to check.
  • I bought a part from a member yesterday, and we noticed that there was a zip tie that was holding the rubber clutch cable to some other cables. And when I turn the bars all the way to the left, it was holding the clutch open partially due to the angle. I wonder if I got some extra air in the clutch that I need to bleed out. I'll have to check that.
  • Tire pressure is what the OEM pressure says it should be. But I'm also a heavy dude. Right around 300 lbs. And I ride two up occasionally. I'll have to check that pressure
  • PO was pretty good about maintenence. Valves were adjusted at 42k, and I'm at 48k now. So I think I'm good.
  • Yes. I meant that I just changed the oil and not the oil filter. Though my oil filter bottom looks like a metal car filter, as opposed to the one with the 17mm bolt. I think he mentioned upgrading to a twist off, but I'm not sure. I'm planning on swapping my oil out relatively soon (gonna do 1k miles, then add Seafoam, ride for 30 miles, then change the oil again) so I'll get in there and see. Getting the belly pan off was a pain, but it'll be easier next time!
  • I do have a NASTY habit of holding the shifter up or down instead of releasing the shifter. I'm getting better, but I hope I didn't hurt anything.
  • I just got back from a ride, and it seems to be a bit better when the bike warms up. Specifically the crunchy upshift and the flat spot.
I think that covers everything. Looks like I'll be pulling fairings and doing a complete check up next weekend!! Kinda scared about the fairing, lol. But I'm sure I'll manage. šŸ˜Ž

-x01660
 
Fairings are easy. Got some long bolts & some short bolts. Don't get them mixed up.
Also be careful to put the correct size smaller bolts so you do not poke a hole in your lower plastic antifreeze bottle. it happens a lot.
Murph has got the kit for the spin on oil filter. I did mine it was easy. Best mod you can do on your bike

Dean
 
x01660 said:
Thanks for responding!
  • Yes. The owner did do the 2 minute mod. I've also been riding pretty hard. I wonder if I disloged the piece of foam. I'll have to check.
  • I bought a part from a member yesterday, and we noticed that there was a zip tie that was holding the rubber clutch cable to some other cables. And when I turn the bars all the way to the left, it was holding the clutch open partially due to the angle. I wonder if I got some extra air in the clutch that I need to bleed out. I'll have to check that.
  • Tire pressure is what the OEM pressure says it should be. But I'm also a heavy dude. Right around 300 lbs. And I ride two up occasionally. I'll have to check that pressure
  • PO was pretty good about maintenence. Valves were adjusted at 42k, and I'm at 48k now. So I think I'm good.
  • Yes. I meant that I just changed the oil and not the oil filter. Though my oil filter bottom looks like a metal car filter, as opposed to the one with the 17mm bolt. I think he mentioned upgrading to a twist off, but I'm not sure. I'm planning on swapping my oil out relatively soon (gonna do 1k miles, then add Seafoam, ride for 30 miles, then change the oil again) so I'll get in there and see. Getting the belly pan off was a pain, but it'll be easier next time!
  • I do have a NASTY habit of holding the shifter up or down instead of releasing the shifter. I'm getting better, but I hope I didn't hurt anything.
  • I just got back from a ride, and it seems to be a bit better when the bike warms up. Specifically the crunchy upshift and the flat spot.
I think that covers everything. Looks like I'll be pulling fairings and doing a complete check up next weekend!! Kinda scared about the fairing, lol. But I'm sure I'll manage. šŸ˜Ž

-x01660
Click to expand...
Your bike has been upgraded to a spin on oil filter.
 
What oil are you using ? Mine gets difficult to shift when it's overdue for an oil change . Kinda notchy feeling .
 
x01660 said:
Thanks for responding!
  • Yes. The owner did do the 2 minute mod. I've also been riding pretty hard. I wonder if I disloged the piece of foam. I'll have to check.
  • I bought a part from a member yesterday, and we noticed that there was a zip tie that was holding the rubber clutch cable to some other cables. And when I turn the bars all the way to the left, it was holding the clutch open partially due to the angle. I wonder if I got some extra air in the clutch that I need to bleed out. I'll have to check that.
  • Tire pressure is what the OEM pressure says it should be. But I'm also a heavy dude. Right around 300 lbs. And I ride two up occasionally. I'll have to check that pressure
  • PO was pretty good about maintenence. Valves were adjusted at 42k, and I'm at 48k now. So I think I'm good.
  • Yes. I meant that I just changed the oil and not the oil filter. Though my oil filter bottom looks like a metal car filter, as opposed to the one with the 17mm bolt. I think he mentioned upgrading to a twist off, but I'm not sure. I'm planning on swapping my oil out relatively soon (gonna do 1k miles, then add Seafoam, ride for 30 miles, then change the oil again) so I'll get in there and see. Getting the belly pan off was a pain, but it'll be easier next time!
  • I do have a NASTY habit of holding the shifter up or down instead of releasing the shifter. I'm getting better, but I hope I didn't hurt anything.
  • I just got back from a ride, and it seems to be a bit better when the bike warms up. Specifically the crunchy upshift and the flat spot.
I think that covers everything. Looks like I'll be pulling fairings and doing a complete check up next weekend!! Kinda scared about the fairing, lol. But I'm sure I'll manage. šŸ˜Ž

-x01660
Click to expand...
If you have 2 minute mod jetting, you will need to block appx 2ā€ of the right side airbox inlet at the rear of the airbox .
 
Steve in sunny Fla said:
If you have 2 minute mod jetting, you will need to block appx 2ā€ of the right side airbox inlet at the rear of the airbox .
Click to expand...
I just checked it this morning, and it looks like the foam block is blocking the entire right side of the airbox. I'll adjust it to the side to let more air in and see if that fixes the problem. About to go on a 200 mile ride, 2 up, so I'll report when I get back.

Thanks!

-x01660
 
The TY wrap on the clutch hose will have nothing to do with the flat spot in the rev range. It was just making it hard to pull the clutch lever, then trapping pressure in the slave cylinder. I would look a lot closer at the hose where it was kinked for any damage. Leaks, cracks in the rubber, swelling with the lever pulled to the grip. I have heard that replacing the hose/metal line/ hose clutch line is a challenge.
 
Cra-z1000 said:
What oil are you using ? Mine gets difficult to shift when it's overdue for an oil change . Kinda notchy feeling .
Click to expand...

I am now using some Yamalube 10W40 that I had laying around the house. I just ordered some Motul 7100 and the spin on oil filter for my bike, and I'm gonna change the oil in a week.

The oil that I took out was jet black. Super worn. I'll add some Seafoam to this oil about 30-50 miles before I do my oil change, then switch to the Motul.

That should fix the problem, hopefully. :)

-x01660
 
Jpd11958 said:
The TY wrap on the clutch hose will have nothing to do with the flat spot in the rev range. It was just making it hard to pull the clutch lever, then trapping pressure in the slave cylinder. I would look a lot closer at the hose where it was kinked for any damage. Leaks, cracks in the rubber, swelling with the lever pulled to the grip. I have heard that replacing the hose/metal line/ hose clutch line is a challenge.
Click to expand...

It was only applying pressure when I was at full lock on the left side... I looked at it, and there are no visible kinks or swelling. Clutch pull feels normal, and now it doesn't bind when at full lock to the left.

-x01660
 
Flat spot is gone. Moved the foam over a bit and it's a lot better. Shifter also feels a lot better. Will report more when I get back. Gotta keep moving!!

20230916_110747.jpg
-x01660
 
Ok. I just swapped out my oil again with some Motul 10W40, and WOW what a difference. The notchiness is completely gone. Butter smooth shifting. I know what oil I'll be sticking with going forward. Expensive stuff, but worth it.

And I did have a spin off filter, so that's a LOT better and its changed.

I do need to mess around with that foam block. Maybe get a new one to mess with the size. It seems its shifted and I've got a NASTY flat spot I'm trying to sort out. But I'll mess with it.

Thanks, everyone!

-x01660
 
Did you drain everything. You have 2 drain bolts under your pan both need to be drained, Plus your spin on filter. First time I changed my oil I knew nothing about that 2nd drain bolt.

Dean
 
deanbuffington909409 said:
Did you drain everything. You have 2 drain bolts under your pan both need to be drained, Plus your spin on filter. First time I changed my oil I knew nothing about that 2nd drain bolt.

Dean
Click to expand...

There are two drain bolts, eh? Oh boy.....

I only saw the one that was near the spin off filter..... bike took 3L of oil.... And the oil in the window is red (Motul color)....

Where's the other bolt, and how much oil comes out of that one?

Mind you, I changed my oil about 200 miles ago, so this is pretty fresh oil that was in there before today....

-x01660
 
I changed mine twice before I found out about the other bolt. If I remember correctly there is only about 7 to 9 oz of oil in that 2nd bolt. Some one posted a picture of the oil pan and had the bolts circled that were the drain bolts. That was a big help.

Motul is great oil, You can not go wrong with that.

Dean
 
Reading your past notes;
I just checked it this morning, and it looks like the foam block is blocking the entire right side of the airbox. I'll adjust it to the side to let more air in and see if that fixes the problem.

Flat spot is gone. Moved the foam over a bit and it's a lot better.

I do need to mess around with that foam block. Maybe get a new one to mess with the size. It seems its shifted and I've got a NASTY flat spot I'm trying to sort out.

Did you compress the foam or trim it?
If you compressed it (Moved the foam over a bit) it may have expanded again and is covering more of the opening.
ie; It has to be trimmed to size.

Ride safe, Ted
 
connie_rider said:
Reading your past notes;
I just checked it this morning, and it looks like the foam block is blocking the entire right side of the airbox. I'll adjust it to the side to let more air in and see if that fixes the problem.

Flat spot is gone. Moved the foam over a bit and it's a lot better.

I do need to mess around with that foam block. Maybe get a new one to mess with the size. It seems its shifted and I've got a NASTY flat spot I'm trying to sort out.

Did you compress the foam or trim it?
If you compressed it (Moved the foam over a bit) it may have expanded again and is covering more of the opening.
ie; It has to be trimmed to size.

Ride safe, Ted
Click to expand...

The PO actually had tape wrapped around the foam, in an attempt to keep it set in a location. I'm gonna go to Home Depot today to get some replacement foam.

Is there a specific type/name/brand of foam that I should be looking for?

-x01660
 
Well, I pulled out the foam that was in the airbox... This is what was in there:

20230921_142035.jpg


So I went to Home Depot, looked high and low for some foam, and was unsuccessful... But I found this:

20230921_142106.jpg


Cut a piece of it and stuck it in the airbox, blocking about 1/2 of it.

Flat spot is GONE!!

We're good to go. Thanks!

-x01660
 
I cut the foams in the armchair recovery cousins with a kitchen saw knife

1695360953-20211116-084009.jpg
 
X01660 can you post a picture of where you installed the foam?
You're photo (with the extra piece of foam taped on) is setting off alarm questions in my head.

ie; Many install the foam wrong, or remove the plastic piece in the air box.

Ride safe, Ted
 
connie_rider said:
X01660 can you post a picture of where you installed the foam?
You're photo (with the extra piece of foam taped on) is setting off alarm questions in my head.

ie; Many install the foam wrong, or remove the plastic piece in the air box.

Ride safe, Ted
Click to expand...

I'll go out in a bit and post.

The piece of foam is installed on the throttle side of the bike. It was sitting in the right side chamber of the air box, sticking about 20% out. When I pulled it out, I saw that it was taped together like that.

I then got that sponge, cut it with my pocket knife to the right size, and stuck it in the right side chamber.

I'll get some pics when I got out in a bit.

-x01660
 
Steve {or someone} "please" correct me if I'm saying this wrong.

It's been a long time since I did mine. So, this is from memory.
As I recall; You put the foam in the right airbox inlet with the arrow on top and pointing "towards" the engine. Once installed, it cannot move. or expand to cover more of the (right) inlet.

Looking at yours. The foam has been widened and it has dust on the arrow.
I think the dust should be on the end, with the arrow on top.
The foam was originally 2" wide.
It should block more than 2/3 of the right inlet.

On yours, I think you could remove the tape, discard the extra foam, check the width, and it should slide in perfectly. (I think that 1 3/4" was the width that normally worked the best).

Additionally, there should be a plastic piece in the airbox inlet. (Don't recall what it's called)
It's held in with 2 screws.
Some people used to remove it or cut it to get more air into the airbox.
Is yours there, or has it been removed?

Ride safe, Ted
 
Last edited:
Looks pretty good. Hopefully the width is about 1 3/4"?
On your airbox; (At some time in your bike's life) Someone drilled holes in the side to get more air into the air box. They are now covered with tape. Be sure that they are sealed good.
Next; Look at the cover on the other side of the airbox and be sure that there are no holes drilled in it.
If yes, Be sure that they are sealed good.

NOTE: While your there, look at the front-lower edge of the airbox.
You will see a seam line where it was assembled.
Inspect it there and see if there is a crack?
If there is a crack, air is getting in thru that crack and it needs to be resealed.

Ride safe, Ted
 
connie_rider said:
Looks pretty good. Hopefully the width is about 1 3/4"?
On your airbox; (At some time in your bike's life) Someone drilled holes in the side to get more air into the air box. They are now covered with tape. Be sure that they are sealed good.
Next; Look at the cover on the other side of the airbox and be sure that there are no holes drilled in it.
If yes, Be sure that they are sealed good.

NOTE: While your there, look at the front-lower edge of the airbox.
You will see a seam line where it was assembled.
Inspect it there and see if there is a crack?
If there is a crack, air is getting in thru that crack and it needs to be resealed.

Ride safe, Ted
Click to expand...

Yes. That's about how wide the foam is. The flat spot is gone completely. Though I am a bit confused as to why it started to begin with, as it was fine when first got the bike. That said, it did start happening after I plugged up my H pipe outlets (it was rusted out completely), so I wonder if the diference in air flow had something to do with it.

The PO gave me a STACK of parts with the bike, and an airbox is included in that stack. I may take a look at that one and see if maybe its in better condition. But as it is, I'm good. And if it ain't broke.... šŸ˜Ž

-x01660
 
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