Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 250 & 400 => Topic started by: SRwitt on September 06, 2005, 11:01:36 AM
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Some of you may remember a couple of posts from me a while back about my bike not running right.
Well this last weekend I got the time to tear it down so I can start into the engine. What I found was when I changed the oil for the first time after I bought it I didn't pull the right plug to drain the oil, I pulled the one right above the header on the front of the oil pan not the one dead center on the bottom. Long story short didn't drain all of the oil, refilled it and boom way too much oil in the engine. Soo anyone have anythings to watch for as I tear into the engine to adjust valves,and check the condition of my cylinders. I would have probably just blown the rings right? Should I be able to just replace the rings and get it going again as long as the cylinders aren't all scratched up there is only 9000 miles on the engine.
Thanks,
Shawn
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It depends on how much oil was actually in the bike. If you had enough to hydrolock it, you may have bent the rods. I don't believe the starter would have enough power to do that, though. If the engine actually -started- and ran for a bit before 'BOOM', you may have problems.
If the engine didn't start, you -may- be able to drain the oil and refill it with the proper amount and then go about your business as if nothing happened.
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Well the starter was able to crank it over, I was riding when I lost two of the cylinders #2, #3 are very low on compression 50psi or so. The bike has run since then just not very well. It won't idle has to be around 3500- 4000 to stay running, no power but no loud noises or anything were ever made just a sudden loss of power while riding it.
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Head gasket, more than likely. At least, that'd be what I'd check first.
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Thank you for your suggestions, I will be tearing the engine down over the next day or two and will get back.
Shawn
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Well the engines apart
The cylinder walls look fine no noticible scoring or anything like that.
There is a lot of carbon build up on cylinders 2 and 3 way more than on #1 and 4 , #2 and #3 were the two cylinders low on compression.
The head gasket looked like it needed replacing everything else looks fine.
What should I do next anyone know?
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Buy a 442 cc kit and put it back together! :beers:
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Buy a 442 cc kit and put it back together! :beers:
Well, that'd be ideal, yes... :lol:
I'd clean up all the parts, removing the carbon and such, and start putting it back together. While you've got her apart, check your cam chain tensioner and valve adjustment. She'll probally run better than ever now that all the carbon is out!
There is a lot of carbon build up on cylinders 2 and 3 way more than on #1 and 4 , #2 and #3 were the two cylinders low on compression.
I'm supposing the carbon buildup is on the heads/valves? Make sure there isn't any carbon on the -backside- of those valves! It's quite possible that carbon buildup there was causing a valve not to seat fully, resulting in a loss of compression. Severe carbon buildup can do that.
As for what causes carbon buildup? Usually an incorrect mixture adjustment, probally -way- rich, or the engine being run for a long time with poor spark plugs that resulted in an unclean burn. Lugging the motor and not getting her into the powerband can do it too. Some people are afraid of Revs, but on engines that are built for them, low revs can actually be worse (carbon buildup).
As a plus, at least you are getting all the carbon cleaned out! If a chunk had broken off on the highway and fallen into the combustion chamber, you'd could be in bad shape.
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The carbon build up is most noticable on the pistons themselves. I can actually see the contours of the tops of the piston on 1 and 4 but 2 and 3 are heavily built up. The build up on the heads and valve area doesn't look too bad. I plan on readjusting the valves once its back together.
Maniac what specifically should I check with the tensionser.
I'm almost positive the mixture isn't too rich. It ran fine after I bought it other than it had sit for a winter. I am definately not afraid to rev it either. The problems started after I changed the oil for my first time using the wrong plug to drain the pan.
Thanks Again
Shawn
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Maniac what specifically should I check with the tensionser.
I'm almost positive the mixture isn't too rich. It ran fine after I bought it other than it had sit for a winter. I am definately not afraid to rev it either.
Not saying you are, but this is probally the first time someone's had that head off. Sometime in it's life the mixture was either off, or something happened to cause bad carbon buildup. I suppose if the head gasket had been blown for a while, that could do it too...
Basically just check the tensioner for operation, make sure the spring is still good and it's not worn out. Chance are it's fine since you haven't mentioned any rattling, but since you've got her apart it can't hurt to check.
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I don't know much about engines, but could the blown head gasket let air into 2 and 3 and cause them to run lean? Or vice-versa, 1 and 4 and the carbs were set up so that 1 and 4 ran correctly, but with them pulling air in through the gasket and 2 and 3 not, then 2 and 3 would run rich.
Or, did all that carbon on the 2 and 3 piston cause the pressure to go UP in those cylinders until the head gasket blew?
OR, was there so much oil pressure that the oil was pushed past the rings and that is where the carbon came from? Then, cylinder pressure increases and it blows the gasket?
Like I said, I don't know much about engines. Maybe there is no way to tell and you just fix the symptoms. (not a very satisfying answer for my analytical head). :shock:
Ron
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Any of those three are a valid scenario.
Did the head gasket blow because the compression ratio was raised by the carbon? Depends on how much carbon and how high the compression ratio went. This is realtivly unlikely, though, since it'd probally take a lot of carbon to do it.
Did the carbon form do to the engine sucking in air through the blown head gasket? Possible! This is actually probally the most likely scenario, in my opinion.
The carbon -could- have come from oil being pushed passed the rings, but from my understanding he didn't drive it a lot with the overfilled condition. For a lot of carbon to build up, it'd take a while. However if enough oil made it's way into the combustion chamber, it's wholly possible that it was what caused the head gasket to blow.
Determining the exact cause may be really difficult, the important thing at this point is that he's cleaing the combustion chambers and installing a new gasket. It'd be a little easier to diagnose if we knew -when- the gasket had blown. The bike will probally run a lot better afterwards.
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The scenario I thought most of was the oil pushing past the rings after over filling. But why would it be just the two cylinders that have so much carbon, I figured all of them would be like that. Oh well gonna make up a parts list and go to the shop to order them up. Another week of waiting now.
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Did the carbon form do to the engine sucking in air through the blown head gasket? Possible! This is actually probally the most likely scenario, in my opinion.
I disagree!
If you were sucking AIR you'd be running lean and carbon wouldn't build up. You might burn a hole in the head of a piston, but you wouldn't get carbon buildup.
Now, if you were sucking MIXTURE between the two cylinders, maybe, but the vacuum of both of those cylinders would be weak, so they wouldn't draw a normal mixture.
Does the B4 have oil passages between the block and head that would be sealed by the head gasket? If so, and the gasket blew near one of these passages, oil could be sucked into cylinders and cause carbon buildup at minor stages.
More likely though, either #2 & 3 are richer than #1 & 4 or there is an oil consumption problem from valves, guides, rings or scored cylinder walls - or a combination of these.
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I disagree!
You know, now that I think of it, your right. Sucking air would have leaned the mixture and burned the valves/pistons. Since we're not seeing that, then there must be another cause for the carbon.
I don't -believe- the engine block has oil passages in it, since there are external oil lines visible. However those may be feeder lines with the oil running back down through the block to the crankcase, I'm not sure.
Best advice I can give is to clean everything up, inspect it for wear, and if it's OK put it back together. Was the bike using oil? It was never mentioned, so I'm going to guess it probally wasn't really using enough to be noticable. Either way, once it's back together I forsee a carb tune and balance in it's future.
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Well in the short time I owned it before it went south I didn't notice any oil consumption. I put roughly 3000 miles on it after I bought it before anything went wrong. I talked to the previous owner to get some maintenance history, all he can come up with for sure is that the carbs have been played with a few times.
There was no apparent scoring on the cylinder walls they look very smooth.
OK some tech questions, once I measure piston cylinder clearance and make sure it's in spec should I hone the cylinder walls before replacing the rings, and putting it back together.
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OK some tech questions, once I measure piston cylinder clearance and make sure it's in spec should I hone the cylinder walls before replacing the rings, and putting it back together.
YES!
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Well red you seem pretty damn sure so I'll go wit ya on that one.
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A lot of people will say, "No, not if they look OK", but it's still a pretty darned good idea. Besides, you have the bike apart already, might as well hump that cylinder block over to a machinist!
I'd really recommend taking a good hard look at the heads too, check the combustion chambers and valves for signs of carbon buildup and burning.
Just out of curiousity, where was the head gasket blown? Looking at the pics in my manual, it doesn't look like there are oil passages in the block other than the valve chain passage.
If you got the dough, you should see if GSXRRacer has anymore of those GSXR400 cams that bolt right on. :grin:
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He did say:
There was no apparent scoring on the cylinder walls they look very smooth.
If you're putting in fresh rings and the existing bore is "very smooth" then you need to at least run a hone thru and get some good 45* cross-hatching on them so the new rings will have something to seat to. You don't need to take it to a machine shop, you can usually rent a bore hone from a parts or rental store, but if you're not comfortable with doing it yourself, then by all means, take it to a pro.
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It's hard saying if the head gasket was blown. It definately didn't look like it was in too good of shape. There is some black gunk, I don't know if it was a sealant or if its burnt oil all over it right around the cylinder walls. I'll try and get some pictures up soon so ya'll can see what I'm dealing with.
Hopefully I can get it running pretty quick I still want to ride before winter. Might even ride from wear I'm at near the Spokane, WA area to meet up with some other northwest riders if it would be possible.
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always deglaze your cylinder same goes with rotors when you change brake pads ! truely check your head as you might have bad valve seals or a worn valve guide! Mind you all you can get is stock rings not the next size over as they are dis continued so if your bore is out of round you are F-ed ! cheers bro
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Hope I'm not f'd but if worse comes to worse and it's still goin I may jump in on the group buy for the 442 kit, but as of this moment I dont have the cash to throw down on it.
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Hope I'm not f'd but if worse comes to worse and it's still goin I may jump in on the group buy for the 442 kit, but as of this moment I dont have the cash to throw down on it.
do what you can, some auto parts stores will lend you the tools free you just pay/deposit and then return them for a full refund; I think you can get them for 30days. you should try to take the head to a shop that will look at it just to be sure its really ok. I wouldn't pay for any machine work yet. you seem pretty capable/confident. I'd save the machine shop labor bills for the group buy kit.
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Well there are only 9000 original miles on the bike. I can't imagine there being too much machine work involved. I may sound confident but this is my first real adventure into the inner workings of an engine. I've talked to mechanics here and there, I'm going to clean up the head and turn it upside down so I can fill the chambers with solvent to check for leaky valves. Hopefully all it needs is the rings, gaskets and a valve adjust, along with all other maintenance that should be done with this mileage anyways. I think I've read the service manual about 5 times by now. Thats probably where the confidence is coming from.
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I think I've read the service manual about 5 times by now. Thats probably where the confidence is coming from.
It scares me that I've memorized the torque values for most of the bike, but can't remember easy things like birthdays and anniversaries....
9000 miles with proper maintenance shouldn't involve too much work. I've got twice that may miles with only doing regular maintenance and the engine is still strong.