Intake boot problems

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towtruckpimp

towtruckpimp

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Dec 21, 2010
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in a van down by the river
Sorry if this is a duplicate post but I'm on iPhone and search not working. I have put the forth one on it and same problem. I rode it for maybe an hour and a half and then wam! It split again. Is there something wrong or something I can do to mod it.

It's a 03 model.
 
Double check all your motor mounts, especially the upper mount that bolts to the cylinder head. Excessive vibes will tear one fast.
 
Ok did that all mounts good. My mech just adjusted valves and it still backfires. So I bought new carb rebuild kit had him rebuild carb and still doing that. I know he is a good mech because the local dealer subs out some jobs to him when they are overloaded. Anymore suggestions. He thinks that is the reason they keep splitting. Weird part is this last one split on the top in the thickest part of the boot.
 
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Check your timing. Could be a mechanical backfire caused by improper valve timing. Which would more then likely be from a worn timing chain.
 
could be. No real reason to run 93. It just burns hotter and will actually ping if its not really required. If you have stock bore and stroke and compression, low grade should be used......and it cheaper.

Still check your motor mounts and make sure the boot it mounted right and the airbox boot is too. That carb should be sitting in nice and tight when its all bolted up.
 
DeadLastRacing said:
could be. No real reason to run 93. It just burns hotter and will actually ping if its not really required. If you have stock bore and stroke and compression, low grade should be used......and it cheaper.

Still check your motor mounts and make sure the boot it mounted right and the airbox boot is too. That carb should be sitting in nice and tight when its all bolted up.
Click to expand...

YOU NUCKING FUTS?? it burns cleaner cooler and smoother! if you insist on that give me facts or personal experience because ive been working on these motors for 5years and have never found a aplication were to much octain makes a "ping" i call bs on your statement.

make sure there is no water in the carb, that can cause a back fire also. check you plug make sure its not dirty or gunked up.
 
i had a little slice that i couldnt see and my quad did the same thing.....take the boot off and carefully look at it for cracks the smallest one could do it.
 
Was going to bring up the spark plug, but weston beat me to it. High octane fuel wont ping. Low octane will, especially in higher comp engines. My dad's maxima NEEDS supreme, regular pings and goes through it like **** through a goose. My 8.1 isn't a high comp engine and I almost always run reg in it. I have reprogammed it, but because of knock sensors and lower comp engine, it handles the reg fuel fine. But put supreme in it and it is way more efficent.
 
Ok I know it's split no doubts about that. Gonna go ahead and do timing chain and all its components. Next thing I am un decdeided on boring it or to just do a port and polish. Any ideas. I'm not a fan of boring due to the fact that I live in the south and do a good bit of river riding with it. I know that it thins walls and if I get it hot then that sudden splash itto the water could crack them. I read on here someone did a port and polish job and got some impressive numbers out of that.
 
DeadLastRacing said:
could be. No real reason to run 93. It just burns hotter and will actually ping if its not really required. If you have stock bore and stroke and compression, low grade should be used......and it cheaper.

Still check your motor mounts and make sure the boot it mounted right and the airbox boot is too. That carb should be sitting in nice and tight when its all bolted up.
Click to expand...

Had my facts backasswards. Good catch guys. Working on a few hours of sleep a day. My brain is gettin goofy.
 
Hi everyone, I'm his mechanic.......
Anyway, here's the deal, like towtruck stated 4th intake boot!
What the engine is doing is small backfires which jolts the carb backwards towards the airbox, on idle its not as bad, but still backfires, running the bike hard makes some serious backfires which basically blows the carb backwards hard which then splits the intake, the last intake boot lasted all of 30 mins!!!!
Tomorrow going to give it a compression check (bike doesnt smoke) and get the cylinder head off and look at the valves..
I know for sure the camchain is worn out, you can hear it!
Anyway guys, I'll keep you posted.....
 
Compression at 132psi, tore it down, going to get valves out wednesday, and also going to put new piston rings in while I got it tore down this far.
I'm leaning toward broken valve spring or pitted/burnt valve.
 
Sorry for the long delay,,,,,

Here's the update, I checked the valves which were ever so slightly out of round, so I changed them, and all valve in/outer springs, the springs had little tension.
Replaced the timing chain and replaced piston rings.....
Slight port on the cylinder head with minor skim of cylinder head.
Hand valve lap and new valve stem oil seals and all upper gaskets.

New intake boot, fresh fuel, fresh oil and filter and spark plug....

Oh it sounds so nice on idle now without backfires......

Let it run for 20 mins with the occassional rev with fan blowing on the engine, let cool down and re adjust the valves.....

Rides super sweet to half throttle, havent ran it hard yet trying to let the rings settle in for a good few engine cycles........

Looking fwd to this Sunday to see how it performs.....
That will be $6598 for the rebuild Ben, plus time spending typing this!!! lolol.
Phil.
 
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