My engine sounds bad

[Anonymous]

So a few months ago, my 93 Kat 600 (stock) was just drinkin' down the fuel like crazy and dying when at stop...so I just recently pulled the carbs, dismantled them, and cleaned them thoroughly...new fuel lines, filters, new Mobil 1 syn oil...new OEM plugs.

Bike idles well now at 1500, does not die at stop.

However it sounds and still feels bad. Instead of the vrrrrr!!! when you open it up, its more louder like whaaaa!!! and feels as if the engine is making a clattering noise, small crackles when closing throttle from a fully open position. (ya I'm sure you guys can really tell what that sounds like )

What could this be? I have never touched the engine. Could this be due to a plug not getting the electricity it needs?

HELP WANTED

(on 6th gear, 6000 rpms, 70 mph)

[HS2020]

Mine does that when I close the throttle. Can you smell fuel in the tailpipe? I think most of the time the crackling you are hearing is unburned fuel getting pass and igniting where it shouldn't? Does it sound like a sewing machine on steriods when running? Idle at 1500 is fine. It should be no higher than that but no lower than 1100.

Then again what do I know my bike only has 2 gears I have been told.

[Anonymous]

A sewing machine on steroids sounds about right....but one that has been kicked a few times.

[HS2020]

Well I think we need to get cyber in here on this one. I do believe that your valves need to be adjusted, the carbs synced and that should be just about it. Mine sounds a little like that. I also think that our yr bikes have shims in them. That is all I can come up with right now.

[Court93kat]

Ok.. sewing maching sound.... sounds like the cam chain tensioner to me. My 93 600 is making the same noise right now. It could also be the valves. Yes, they have the shim system which is more of a pain than the adjustable type, but not too bad as long as you go by the book step by step your first time.

Crackling in exhaust... the fuel mixture is not right. In my opinion it is too rich on the mix. I am sure someone else will verify this. Did you adjust the flat head screw on the bottom of the carb by the bowls? That is the air/fuel mixture screws. If you took your carbs apart for cleaning, they most definately will need to be sychronized. Just synch'ing the carbs will make a big difference, but I think the crackling is in the mixture.

We will see when others answer how well I have diagnosed your bike.

[Anonymous]

I'm headin to the garage as we speak.............

[The CyberPoet]

OK, after-fires (popping, crackling in the exhaust on decel or on closing throttle from high RPM's) is from the mixture in the idle circuit being too lean under those conditions. Bike ships lean, and if you add an aftermarket exhaust can or headers, aftermarket airfilter (even the EMGO which looks like the stock one but drafts slightly more air), you're leaning out the mix even further. The crackling sound is unburned fuel igniting when hits the exhaust. Richening up the idle circuit will stop it from happening.

The sewing machine noises are common for the pre-98 Kats, especially if they've had cheaper car oils much of their life and done hard time (i.e. - high temps, longer rides, etc), or been regularly pushed past the service interval for oil changes. Typical car oils boil off too readily and tend to form gunk (think grease plus varnish from boiled-off oil-remains) which can clog the spring at the cam chain tensioner. The initial problem is that the cam chain runs loose because the tensioner isn't keeping up; in the long run this can cause journal wear issues at the cams because they are being slopped around a bit.

Fixes are down to two:
(A) The factory way - replace the cam chain tensioner spring, clean out the tensioner wheel, and check the cams & cam chain for being in spec or out of spec, replace as necessary;

(B) The "it might be worth a try" way -- flush the engine with either an engine flush product like gunk five minute engine flush (for the time the package indicates) or with a very light weight oil (straight 10 weight or 5w10) with a high detergent content for fifteen minutes, and hope it cleared out the gunk. Both will require dumping the oil cooler contents afterwards; if you use the engine flush product, you may be well advised to pull your clutch basket first to ensure the flush doesn't deteriorate the fibers in your clutch pads (I haven't had it happen on past wet-clutch bikes that I've done it to regularly in the mid-80's, but I don't want to tell you that it won't). Another oil change afterwards is also mandatory.

The 98+ Kats increased the oil pump volumes to try to help offset this tendency to build up gunk at the cam chain tensioner (among other issues), and by the 2001 model, the engine was moving almost double the oil per minute of the pre-98 engine designs (8.8 gallons/min vs. 4.9 gal/min).

One of the other thing you want to do is seriously consider the use a JASO-MA spec oil to help avoid gunk formation. The JASO-MA spec includes much stricter limits on how much the oil can evaporate due to boil-off over the full service life, and higher shear-viscosity requirements, meaning it shouldn't produce gunk in the same way regular car oils will under the higher strain of an air-oil cooled motorcycle.

The other thing you may want to consider is your riding habits that involve shutting the engine down extremely hot. If you go out for longer rides, try put-putting a bit for the last mile or two (say 6th gear at 50 mph) to help the engine shed excess heat before parking it, instead of tearing into the parking lot/driveway at 10k RPM...

Finally, check/clean your oil cooler. If it's covered with bugs, dirt, debris, bent fins, it won't be shedding heat well, and that means the oils in the engine passages will be running hotter (and thus the whole engine will be running hotter). It too will benefit on an older bike if you flush the engine with an engine flush product, since any varnishes on the inside of the cooler passages will be stripped away (and thus no longer act as an insulation blanket).

Cheers
=-= The CyberPoet

[Anonymous]

Here is some further info:

My bike is completely stock...no jet kit..therefore no air/fuel mixture screws. It idles very steady after cleanin the carbs...so do I still need to sync the carbs?

Thanks you guys for the posts...

[The CyberPoet]

Here is some further info:

My bike is completely stock...no jet kit..therefore no air/fuel mixture screws. It idles very steady after cleanin the carbs...so do I still need to sync the carbs?

There are still air/fuel mixture screws on your Kat's carbs; they are just covered up by small metal surface plugs in the carbs that I guess haven't been removed yet. Two questions come to mind:

(A) Did you disassemble the carbs? If so, yes, sync is required.
(B) How long has it been (miles/years) since it was last sync'd? If the answer is 3 years, you probably want to have it done anyway.

Cheers
=-= The CyberPoet

[floxera]

I have a 98 engine that I think is may have the same problem with the cam chain tensioner. It sounds like a "sewing machine on steriods". When I first start the bike in cool wheather 40 degrees F the slapping or clicking noise is pretty loud. At idle 1400rpm the noise isnt that loud at 2000 rpm "sewing machine" As the engine warms up the noise becomes quieter almost faint but still there. Also when I roll off the throttle and start braking from a high rpm say 9000 it really sounds like the engine internals are slapping around. Like the engine doesn't want to slow down as quickly as my braking.

What do you guys think? cam chain tensioner or ??unknown???

I checked the valves twice all the clearances are good.
I switched to full synthetic motorcycle oil 10w40.

[floxera]

very light weight oil (straight 10 weight or 5w10) with a high detergent content

Can you recommend a brand CyberPoet?

[The CyberPoet]

very light weight oil (straight 10 weight or 5w10) with a high detergent content

Can you recommend a brand CyberPoet?

A light-weight high-detergent 10 weight? I'm not really sure... It's what many of the Europeans do instead of using Engine flushes (personally, I've normally done the engine flush routine). Perhaps Mobil's Drive Clean 0w20 would work, but I'd be hesitant to recommend a zero-basis oil for this purpose (too much to risk). My guess is that if you go visit your local automotive parts retailer, you'll only find a single kind of straight 10-weight oil on their shelves, if they carry any at all. Either way, remember that you don't want to rev it, just want it to get hot and liquify the sludge, carry it away. Ditto with an engine flush -- get the regular oil hot first, before you add the flush product, then follow the recommended directions.

Good Luck!
=-= The CyberPoet

[Dartanion]

The 98+ Kats increased the oil pump volumes to try to help offset this tendency to build up gunk at the cam chain tensioner (among other issues), and by the 2001 model, the engine was moving almost double the oil per minute of the pre-98 engine designs (8.8 gallons/min vs. 4.9 gal/min).

Cheers
=-= The CyberPoet

Will the newer oil pump fit on an older motor?

Also, crap forgot my question

[The CyberPoet]

Will the newer oil pump fit on an older motor?

No. Different designs.

Cheers
=-= The CyberPoet

[Anonymous]

Sorry still learning.....can someone point out the air/fuel mixture screws?

http://www.ronayers.com/fiche/300_0286/carburetor/carburetor.cfm

(stock 93 kat 600)