Kawasaki ATV Forum banner

BF750 knocking noise

27K views 19 replies 10 participants last post by  JVDChuck 
#1 ·
It has roughly 3k miles on it and I just had it fully serviced with new valves/adjusted and carb cleaned about 150 miles ago. I just cleaned the air filter today and the machine was running flawlessly until the ride back from a hard/fast ride when we stopped at a sandpit/water hole to mess around a bit and had to pull 2 wheelers out of 2ft of water/sand.

The wheeler continued to run fine until we all started leaving to head back. They all left hard in front of me so I came onto the brute pretty hard and the engine seemed to sound a little louder than normal but I didn't really think anything of it.

A little ways down the trail, the brute started getting even louder on WOT and soon a knock started to begin. I was going up a long gradual hill and it seemed like I had to go WOT to make it up it and by the top of the hill, it was knocking pretty good.

So I decided to limp back as far as I could before the knocking got really bad. Even at idle. So I parked it and got the truck.

It seems to be coming from the right side of the wheeler. Almost like a piston slap noise but I'm not quite sure. I checked the oil level and that seems to be right in the middle of the dipstick (hard as hell to see) and it's not burning any oil out the exhaust. The brute will idle fine, just knocks softly until you give it some throttle.

I'm not sure what the problem is. Any ideas?

Thanks,
Drew
 
See less See more
#4 ·
I have heard clutches knock that sounded like an engine noise.This might be worth checking out especially if the noise is on the right side.
 
#5 ·
funkey knock

Check the clutch and belt for sure. Mine has made some sounds from hell that ended up being a trashed belt or primary weights smacking around. Its worth a shot. good Luck!
 
#6 ·
Get yourself a mechanics stethoscope and find out exactly where the noise is coming from b4 tearing the engine apart. If u cant find a set... a wooden dowel or broom handle will do; this will amplify the noise and make it easier to isolate where the noise is coming from.
 
#11 ·
they havent called me yet, but he sounded pretty sure it was the crank bearings. idle noise was there but rev it a little and ouch, its horrible. did the same losing power then started makin noises from hell that just kept getting worse. hopefully hear from them possibly yet today or tomorrow.
 
#12 ·
got my brute back today, $3100 later. VERY happy it was warrantied. almost sounds like it has a little valve tick now tho, could it be just cuz the bearings are all new and tight or should i take it back and have the valves adjusted? I can do it too i guess. What ya'll think?
 
#13 ·
U r sure it's a knock right....not a ping like pre-ignition? did u take a drink while yous were playin in the water hole? not an expert by anymeans but I sounds like johns right; sounds like it's the crank if it gets worse
under load. May b it'll b worth bringing it in to the shop and getting them to troubleshoot 4 u.
 
#14 ·
ouch! $3100!!!
a local dealer charged 2K for another bike with a smoked crank.
mine is currently sitting because of the exact same symptoms.
mine will idle like a kitten but a soon as i go its not a good sound...well here, listen yourself!



what i need to know is:
whats normally replaced? just the crank and bearings? assuming nothing else got taken out by the carnage?

what i want to do is save some money and take the motor to him instead of the whole bike. he complained about how bad it sucks getting the motor out.
 
#15 ·
I was told the problem was the rear cylinder crank bearing, basically the rod bearing. I would think that as long as the bearing didnt go to pieces you could get by with new bearings on the crank and rods, a new wrist pin in the offending piston and a good cleaning. If the crank is ok and the cylinders arent scored i would think it would be pretty straight forward. Since mine was warranty he said they replaced just about everything: new rings, bearings, gaskets, seals, etc. PM me if you have any specific questions or anything. O where are you located?
 
#16 ·
i get a clanking noise fomr the front right i think. mines only a month old 2009, bout 20 hours, 300 miles, when i got my first service after the break in they said it was nothing. but it's getting louder.. like a random clanking noise heard best when cruising between 10-25 mph specially over rougher terrain. at higher speeds ic an't hear it proly cause the wind, engine, and trans or whatever get louder. is this bad? did i get screwed? i should stil have a year warrenty i think but it's hard for me to move around.
 
#18 ·
it's more when i give it gas i hear it. as soon as i let upo on the gas it pretyt much stops. and it might happen more on rough terrain but i'm not sure.. thats annoying cause it's brand new, only had it for a month and cause brought it in for the break in service just 10 hours/100 miles ago and they said it was nothing to worry about. but it's getting worse. on and off. i get it the most after switching gears alot. if i leave it in 2wd for a long time it seems to go away sometimes. i have no clue what it is and noone else seems to :/ i can't tell if i'm losing power on it yet but i've been able to hit 70 in it and i'm 250 lbs so it sounds like it's performing properly.
 
#19 ·
County/ warranty

County, you are entitled to your warranty. They they have an obligation to honour that warranty and service that bike. Don't let them talk you into letting it go, be aggressive if you have to. And get them to include their recommendations on the invoice, if they're not willing to accommodate you as a CLIENT...You just bought a new bike man, whether you paid additional for the warranty or it was incorporated into the price, YOU PAID FOR IT....
On that note, don't get too aggressive and start shoving the guy....LOL.
If they still say it's nothing and they make reference to your concern and recommendation on the invoice, you have it on record that they neglected to fulfill that obligation. Let's say it is the crank and it fails after the warranty has expired, you've got a document that proves they were negligent... Good luck man...... Or tell them you're going to bring up the issue with head office.....
 
#20 ·
Get them to check your belt first. A buddy I work with had the same thing. Took it in they told him it was the tranny and ran up a bill of $600 taking the machine apart then they realized his belt was shot and causing the noise.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top