Need some information on issues with vacuum

Howdy all! Long time lurker, first time poster from Colorado!

So I've been trying to chase down an issue. This is a 2002 Honda Silverwing with 17002 miles on it. I get a 150~ RPM jump at idle all the time. I went to synchronize my throttle plates, and the dual vacuum gauge is just jumping in "Late valve timing or leak at manifold or heat riser." I changed my oil, changed my oil filter, changed my spark plugs to OEM, changed my variator rollers to 21G Dr Pulley sliders. I changed the hoses all around the top of the engine that deal with vacuum and fuel, and even the fuel pressure regulator. I can still smell a raw fuel smell on starting the bike sometimes.

I should mention- This bike was laid down pretty hard by the last owner, I replaced a damaged body panel on the left side of the bike if you're looking at it from behind when I bought it. I also bought the lower frame and replaced that, as the old one was slightly bent in on one part of a bar. (Getting the entire engine off and on was not as hard as I expected!)

I should mention that this bike drove me here from Florida to Denver. I-70 was wild on this thing. I feel like the tire size makes it not for interstate travel lol. But can anyone tell me why I still experience this issue with vacuum, or ways I can track down leaks or some cool trick I can use to get my bike good on vacuum and get my plates synched?

Thanks in advance. You guys have posted tutorials that have greatly advanced my mechanical understanding of these machines, and I'm hoping someone can help me now!

-Nick

Easiest way to find a vacuam leak (assumimg all componanrs are visible) is to spray each item individually (with the engine running) with carb' cleaner & listen for change in engine note.

Smell of petrol from exhaust on start up is 'normal' on models without exhaust sensor bud

Good to know the smell is normal. I'll go pick up a can of carb spray tonight for sure. I've not tried to change the boots on the intake manifold, do you by chance know if anything around it like the fuel injectors might have like a o-ring that eventually gets dissolved or falls apart or something?

You might have a look at the fuel pressure regular. I believe that there is a test procedure in the service manual. Something about raw fuel in the vacuum hose. Someone on this site will chime in and add to my post.

Thanks for the reply! So the FPR is a OEM replacement I just put on five days ago. I think it should be okay. One thing I can say: when removing the FPR, I had to grip the fuel rail to get leverage. I don't think anything got knocked loose, but we'll find out this weekend when I get the time to take the entire front body panel set off

You guys are great!

Idle is surging up-down or is just to high? 150RPM?

Usually a vacuum leak is constant and it will idle up. Spray is a great way to locate a leak use straw in small sprays to pinpoint the area.
Another thing to check is throttle cables for slack a tight cable could be causing an issue.
Boots are above throttle plates they won't cause a leak but could make it idle rough. Throttle body bolts directly to head there are 2 O-rings there.

It goes up and down, but it seems to mostly do it at idle. I'm for sure gonna try the spray. As far as the slack in the throttle cable, how can I test that? I'm not sure what it would normally feel like for comparison

There are two cables for safety reasons. One pull opens other closes throttle but it should do this by itself.  A little slack at grip before RPM increases is normal. There are adjustments on cables near housing. Slid rubber boot back and nut threaded part are there.  You can adjust slack from there.

Sticky cables can be lubed with a tool that pushes lube into cable housing.

Got it. That makes sense. Thanks man! You sound like you do this all the time!

Here is a vacuum diagram at throttle body and cables .  There are adjustments there too. If you removed engine maybe these are off. [/ur

After seeing the boots looks like I'm wrong these could be a vacuum leak . I'm a Honda car wrench. DUH

Hey, the TSM! I paid a hundred bucks for one of those bad boys, it's saved my butt a few times

There you go. Then you already have what I posted.   You will figure it out.  Keep us posted . I'll help anyway I can.

This is the area where there is a leak. I'm not sure what exactly is leaking, I replaced a lot of the hose in this area, and it seems it's leaking where the intake manifold meets the throttle body, the metal and the plastic. It doesn't look too far apart to me, but what should I do here? Which of these places is this most likely to be?

Could the inside diameter of the new vaccum hose be too big?

No, this problem was precedent to the new hoses, unfortunately. I sprayed ALL around the throttle body where it meets the black box. It only seems to stall once I spray where I'm aiming the nozzle in the first picture, on top of that area.

Does anyone know what the sensor is on the left side of the throttle body in the second picture? I'm having a hard time locating it in the manual

So that's the Throttle Position sensor, and that black box behind the throttle body is the air cleaner box. Does anyone know why a leak might occur in that area?

An air leak between the airbox and the throttle bodies should not matter; only an air leak downstream of the butterflies will affect the FI/air-fuel mixture.

That's strange, because the only place it's changing RPMs when I spray is in that exact location. Nowhere else nearby that makes it do this.

Do you mean that you're spraying the area immediately behind the air screws bud ?

If so I'm wondering if the srews are sealed with O rings ? & if so they may have been damaged during the initial adjustment, having been in the same position for several years & possibly hardened

The Bern, you may be onto something. I bought a throttle body/air box/ air cleaner box set from Italy, used, in great condition this morning and got it rush shipped here. When it gets here, I'll try to get a video of it idling, a video of me replacing it and a video of it running after for further diagnosis. I have a 1080p Sony camcorder and a girlfriend that can hopefully help me with that

One question you experienced guys might be able to answer. What does a slipping clutch feel like, and are there any engine-related symptoms that could come from that?

I found it. When I took the throttle body off, I noticed the throttle position sensor is actually cracked and broken. I'd assume this happened randomly at some point. Spraying directly into the cracked area while the engine is running causes it to stall. It is FOR SURE the throttle position sensor

well done bud

Appreciate the help all ^_^ I will let everyone know how it goes after new parts get on it

Nice job, three thumbs up.

Good trouble shooting.  Getting a little noise from the rear when taking off slow is normal.  Has your V light come on? (slipping).

Nope! No V-light, but it sounds like a squeal every time I take off now, even if I bullet train out of park. I changed the variator face because it had a groove in it about six months ago and put new sliders (21g) in from Dr. Pulley. It's been fine up until about two or three weeks ago when the noise and squeal started.

I should also mention I changed my final drive gear oil last summer.

Some clutches are just like that.

I hand sanded my clutch shoes and drum several times yet the noise would return after a day or so. Even disassembled the clutch, cleaned & lubed the shoe pivots and changed the springs to white Malossi springs. Nothing resolved the problem. Finally the squealing noise was eliminated once and for all when I installed my old Dr Pulley HiT clutch. Haven’t had a problem since.

Could be that the OEM clutch assembly was just “never right”. Or maybe the pads needed some time on a belt sander. There’s not much else you can do to tweak the clutch.

Try coating the pads with magic marker, then you can see the wear pattern on the different shoes when you pull it apart again. If a shoe or shoes aren't seating evenly with the drum that’d sure contribute to the squeal. Obviously the high points on the pads will wear off the magic marker first. Sand down those high points to get the pads to seat as completely as possible. But be aware that those shoes won’t ever contact the clutch bell along 100% of of the pad surface. Like ‘ol time drum brake shoes there’s a lead edge and a following edge to the wear. 

That’s my 2¢.

Tim

Bro that is the most ingenious way I've heard yet to identify clutch issues... I will take it apart this weekend and check. I had to order a new outer pull tool that's gonna be here this weekend.

I'm a Swing Newby myself but I did not think you needed a special tool for the rear hub unless you wanted to take off the spring? Which I've heard was a difficult job.

terrificobjects wrote:

(Snip) I had to order a new outer pull tool ...

There are two special tools associated with the Driven Pulley. The Clutch Outer (clutch bell / clutch drum) removing tool. And the torque spring compressor tool. 

The torque spring compressor tool is easy enough to DIY with a length of all-thread, a piece of wood to serve as a base, a ~3” PVC pipe dome (cap) and a couple of nuts. After drilling a center hole for the all-thread you’ll need to slice about 1/3rd off the side of the pipe dome. That will allow access to the torque spring circlip once the spring is compressed.

For a DIY method to remove the clutch bell use the Search function here to find a couple of posts explaining how to assemble a gear puller set to fit the Clutch Outer.

So I wanted to follow up- I put the new throttle body on last weekend, there is a definite amount of power present in the bike now that was missing before. Here's a picture of me working on it:

I have a new muffler gasket too, for the slip on muffler where it meets the exhaust pipes. I'm doing that today then riding up to the mountains with my girlfriend for some fun time

Hey Terificobjects -
Did your idling problem get solved with replacing the throttle position sensor? I have the same idling issue on mine. Sometimes it does around 1200rpm idling, other times more like a 1000rpm idling. Gees up and down while idling.

Anders L wrote:

Hey Terificobjects -
Did your idling problem get solved with replacing the throttle position sensor? I have the same idling issue on mine. Sometimes it does around 1200rpm idling, other times more like a 1000rpm idling. Gees up and down while idling.

Well, last activity for "Terificobjects" was on Mon Jul 06, 2020 10:49 pm according to his profile

Try to adjust your idle speed up to 1300rpm when hot(make sure you are turning correct screw *), have you had any changes in fuel consumption or general rough running, maybe got it that way? Some possibilities may be a, incorrectly adjusted air bleed/synchronization screws, vacuum leak, extremely dirty air filter, dirty injector or a bad fuel pressure regulator. Maybe as easy as pouring some fuel injector cleaner in fuel tank and going on a long ride.

* Sometimes air screws are turned by accident, affecting synchronization, and/or too far out, a good general setting for both airscrews is 1.25 out to a max 1.5, if set over 1.5, it could affect the press regulator and or TPS idle position setting slightly. In any case count initial turns on air screws, they should be very similar, adjust idle speed with center screw, not air screws.

Any electrical/adjustment issues with the TPS, will usually give you a "MIL" light (Malfunction Indication)