Intake Manifold HELP!!

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ksowin87

ksowin87

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Alright... the other day i was riding and heard a popping noise coming from the top of the motor. I looked around and found that the intake manifold was ripped in the center. Every time the engine popped the rip on the manifold opened up then closed... So I thought that was the problem. So I got a new one from a bike shop on ebay, repalced it, and it ran great!...for about 5 Hours!! Until it started to make the popping noise again!! So i looked at the NEW MANIFOLD and it was ripped the same as the old!!! For now i contacted the dealer to see if i could get a replcement... but i have a feeling that is not my only problem...

After i put the new one on i also cleaned the carb. and when i started it up it ran fine(no popping)... then after a while the idle speed began to increase... I tried adjusting it but no luck...but then later went back to normal...

So I was wondering what u guys think? Not sure what I should be looking into next...I just want to ride again!!!

Thanks!!!
 
Yup, what beastly said, you have issues with the engine moving around. 1st check is the top mounts up under the tank. Mine was so bad when I got it that the bolts that hold the cute lil cover for the throttle linkage on were rubbing againt the frame! Check em, replace if broken & tighen ALL of the bolts in the engine to chassis. Then routinely check every couple rides, I do. You couldn't get your idle to stabilize because of the vacuum leak (intake boot).
 
ksowin87 said:
Alright... the other day i was riding and heard a popping noise coming from the top of the motor. I looked around and found that the intake manifold was ripped in the center. Every time the engine popped the rip on the manifold opened up then closed... So I thought that was the problem. So I got a new one from a bike shop on ebay, repalced it, and it ran great!...for about 5 Hours!! Until it started to make the popping noise again!! So i looked at the NEW MANIFOLD and it was ripped the same as the old!!! For now i contacted the dealer to see if i could get a replcement... but i have a feeling that is not my only problem...

After i put the new one on i also cleaned the carb. and when i started it up it ran fine(no popping)... then after a while the idle speed began to increase... I tried adjusting it but no luck...but then later went back to normal...

So I was wondering what u guys think? Not sure what I should be looking into next...I just want to ride again!!!

Thanks!!!
Click to expand...
When I had rebuilt my warrior and ran the motor everything was fine. When i put on the hood and started the bike back up it idled very high. I couldn't adjust it or any thing. The problem was the throttle cable had no free play in it. So I adjusted that and it idles normal now. Try that for your idling problem.
 
Help again!

OK... I checked out all of the engine mounting bolts and turns out there was like an 1/8th of an inch clearance around most of the bolts... the diameter of the shafts were too small... the holes on the frame were not ovaled so I replaced all of the mounting bolts with the correct size (10mm dia shaft) and now the motor is all snug... So then I replaced the intake boot with the new OEM Yamaha one and put everything back together... All the bolts were snugged up including the air box. Took er' out a few times since then and she is runnin good although the other day I was watching the intake boot and saw it vibrating (compression and tension in the axial direction) and was wondering if this is normal? I know that is it is supposed to move but not sure how much so I took a vid for u guys to take a look at... Let me know. I dont want to rip another intake boot!

http://www.youtube.com/watch?v=KrGQE1VMXic&feature=g-upl&context=G2c9cb70AUAAAAAAAAAA
 
No way to stop some vibration, that's part of the reason that it's rubber to begin with. You have a solid mount engine with no vibration dampners, that energy is gonna go somewhere. I'd only be concerned if there was an evident "pull" on the boot.
 
So that movement in the Video is OK... it just looked like a lot of movement to me... Just wanted to be sure... Thanks!:tup:
 
Can you put a vacuum gauge on it? A gauge will tell more of a story.

To me, it looks and sounds like either you have a lot of valve timing overlap (some type of race cam) or the cam timing is off. The intake manifold looks like it is swelling with back pressure. (I did watch your video.)

I'd start with a vacuum gauge and then the cam timing marks. It also sounds like the valve rockers are loose. I'd even check and readjust the lash.

Good luck, keep us posted.....

-Rhyno
 
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After posting the last post, I felt that this should be added....

For a typical High Performance cam to bring "the Sweet Spot" to a specific rpm range, not only will the valve duration change but also the timing of the grind.

Basically to get a high rpm performing cam, both the intake valve and exhaust valve will be open at the same time. One valve will be closing while the other is opening, but both will be open. This is what is referred to as "Valve Timing Overlap."

The low RPM manners will suffer and it will run "dirty" while in the low RPMs. There will be a lot of unburned fuel. This unburned fuel can accumulate in the intake boot and port and eventually ignite, causing your rubber intake boot failures. It will be stronger in the upper rpm range, though.

So basically, what I am seeing, is you are getting some intake manifold pressure from both valves being open, at the same time.

You could also get this from the original cam timing being off. Meaning a stretched chain, one tooth off in either direction, etc.

Here's my $ .02, for what it's worth. It's just an internet diagnosis.....

Like I said in the previous post, a vacuum gauge will tell more of a story.

-Rhyno
 
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Thanks I will Have to check that out... Not sure if I have an aftermarket cam or not(Bought it that way). I dont have a way of measuring the vacuum... but i will check the timing and adjust the valves...
 
Ok, sorry, not bein a douche but fuel does not accumulate in the intake boot & ignite there. If timing is off then yes you will have a pop back up through the intake but this is not camshaft profile related. If the cam timing is incorrect then it's possible that the intake valve could be open while the ignition fires but it's going to be running horribly if at all. If intake valve lash is too tight then it's possible that the valve is not seating properly & allowing compression to pass back into the intake tract but it likely won't run if it's bleeding off that much compression. Wish I could see your vid but my mobile web hates youtube.
 
When the intake valves close, at any RPM, fuel and air come to a stop,(Where's it gonna go? The valve is closed....) accumulate and depending on the velocity or RPM, have a small amount of pressure. (The internet is full of this explaination, just Google it......:haha:)

Which is a reason as to why High RPM engines like to have their Intake Runner volume increased. (Porting???) "More room to accumulate," which leads to a denser charge when the valve opens.

Fuel in a mist versus fuel by the drop, is a form of accumulation. Especially if we don't know the OP's current jetting.

I'm not here to argue cam profiles, I listened to what the OP said and asked. The symptoms and etc.

Ask your favorite mechanic to explain Valve Timing Overlap and how raw or partially burned fuel can be ignited by the exhaust pulse.
(Maybe Google will be able to answer that, too......:haha:)

Cam timing and ignition timing are different.....


Remember, this is an attempt (and an Internet Diagnosis) to help ksowin87, not to mis-lead him and tell him that it is normal to have brand new rubber intake boots pop.

That's poor and inaccurate advice.

ksowin87, take it for what it's worth......

-Rhyno

As for you being a Douche or not, boils down to your choices. Everybody is one, now and then......:haha:
 
I didn't tell him it was normal to have the boot to "pop" I told him that it was normal to have vibration from the solid mount engine & see some flex in the rubber boot as a result of this.
As far as camshaft profile is concerned, I'm fairly well versed, sir, thankyou. Rougher cams with more overlap do make engines run dirtier, yes, yes some combustion chamber gasses will be pushed back into the intake tract before the intake valve can close but to say that they ignite in the intake boot or runner is an untruth.
 
OK... so ultimately I need to check the valve timing and adjust the valves? The Quad does run really well... there is just that vibration of the boot. Don't want to rip or pop another one.

And Thanks again, all of u for tryin to help me get this sorted out! :tup:
 
That much movement is a tad bit much, set the valves and I bet that solves the issue. As for the stock boot tearing thats just a stock weak point.
 
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