help guys zxr400 problems

[Andrewc2oo5zx...]

hiya guys, ive run into few problems with the rebuild of my zxr400, it seems to rattle when running, when u throttle up it goes quiet, its been in garage for check they checked the cam chain and tensioner and it aint them, what garage did tell me was that , where the spark plugs are, there are about 12 bolts, a couple were threaded and he sed this is the cause of the rattle, now ive tapped them out but haven t put it backk together again, im just wondering what else cud be wrong if anything???? also the casing that goes on top of this, the long one lol with four holes that the spark plug leads sit in, there are four bolts and one has sheered off and is now fucked, the other three are solid and it seems to be sound, just wondering if this is potentially lethal as its there fr a reason, i just want to get it runnin so i can ride it to garage about 60 miles away coz the one close is shit, any ideads will be ver welcome
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zxr's and cbr's

SUNDERLAND AFC

[bidman]

Well i'm struggling tothink which 12 bolts you mean , do you mean the 16 bolts that hold the cams down, if so these all need to spot on with a torque setting, if these come loose and your cam decides to start wobbling about, your in trouble. As for other causes of the rattle check the exhaust downpipes, make sure they are all secure this has been a cause of rattling on a few of the zxr's I have had and make sure you check your tappets to make sure they are all in good order. The four bolts on the rocker cover are faily important as they stop any rubbish getting into the cams and stop any oil being sprayed out. try gettin the sheered off bolt out and re-tapping it just to be on the safe side
I have rebuilt many zxr engines and I have always replaced the cam chain and tensioners for good measure, it really isn't such a hard job and with the cam chain only being 20quid it does seem silly not to replace if your giving the engine a bit of an over haul anyway. Check the left hand side spring loaded tensioner and see how far up it has come anymore than 20mm and i would recommend replacing the cam chain.
Let me know how it goes, or if you need any more help, Dan
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Don't ride it, RAG IT!!

[Andrewc2oo5zx...]

Yeah thats the ones i mean, the 16 i mean, theres 2 bolts in these 16 that are loose, so can i tap thse out and just put bolts back in, im sure this is where the rattle is coming from, but also ill sort the exhaust out coz one of the downpipes is half screwed on and half off, i shud have mentioned that the cam chain has been replaced over the last 200 miles, so im positvie its not that, ill tap out the sheered off bolt and fix that,, how much would it cost for a top end rebuild???, im totally clueless mechanically but really willing to go it ago, any suggestions agin mate id be very grateful, also please dont laff but what are the tappets and are they expensive>>>>
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zxr's and cbr's

SUNDERLAND AFC

[bidman]

Ok just make sure that when you re-tap these make sure you put them in nice and tight and that the threads are going to pull out when you come to torque setting them.
It shouldn't be the cam chain then really not if its been replaced already.
A top end rebuild would usualy mean, new pistons, rings, perhaps a rebore new gaskets and resetting of valve seats and new valves, it depends on how for you want to go with it i have included a rough cost of all the parts below;

new pistons - around 40quid each, including rings, circlips, pin etc...
rebore - around 10quid per barrel, (very unlikely you need this done though)
gaskets - 20quid for a full set
reseating valves and new valves - i think around 15quid for each valve and re-seat.

I think if you strip the top end down clean it all out and put it all back together with just a new gasket set it'l be more than enough, hope this helps, Dan
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Don't ride it, RAG IT!!

[Andrewc2oo5zx...]

and as for torque setting???? how wud i perform this operation lol
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zxr's and cbr's

SUNDERLAND AFC

[bidman]

Hi you'l need a torque wrench and just tighten the nuts untill the reading on the dial of the torque wrench reaches what is recommended in the manual , Dan
____________________
Don't ride it, RAG IT!!