Hi need help with 1200 Bandit

[Suzukisam77]

Hi my names Sam and I’ve been having engine problems with my 97 Bandit 1200 ever since I purchase it a few months ago. I’m wondering if someone here can help me as I don’t have a lot of experience in diagnosing engine problems.

 

When I first purchased the bike it ran good when seller ran it for me so I bought it. As soon as I got it home it ran horribly, hard to start and would barley stay running. I did a compression check on all four cylinders and cylinder 1 came up low at 130 psi while the others were 160 psi and head gasket leaked. When I added oil it shot up to 180psi so I though it must be rings. So I then took apart the engine and installed new rings and new had gaskets etc, also I honed the cylinders with a hone from harbor freight. Reassembled and it ran great and was 160psi across the board. The next time I fired it up it sounded horrible like a cylinder wasn’t firing or something, and would also backfire heavily. I take it apart again and find oil sitting on top of the cylinders. So this time I replace my valve seals as well as cleaning and lapping my valves. Put back together and wow it runs great. Again the second time I fire it up runs terrible again same as before. I look inside the cylinder with a bore scope and yep oil in there again? Anybody have any ideas on what went wrong or what I should do now? Thx

[wraith]

Is the oil in all 4 cylinders or just one? 

Did you replace the o rings that site between the head and cylinders or just replaced the head gasket? 

Are the valves guides worn and coursing the valves seals to not seal? Did you check this the second time you striped the engine down. 

Theses engines are usually good high mileage engines before you need to do the work you're doing, what's the mileage? 

[Suzukisam77]

@wraith

Well it’s only got 23000 miles on it so I wouldn’t expect this kind of engine wear either. The oil seems to be in cylinder 1-3, cylinder 4 seems to be dry. And yeah I did replace the 6 o-rings that go on the head gasket around the studs. I did not check the valve guides themselves but i did check how much the valves moved from side to side in them, and they didn’t move very much side to side.

[Suzukisam77]

Are the valve guides hard to remove and inspect?

[Gixer1460]

10 hours ago, Suzukisam77 said:

Are the valve guides hard to remove and inspect?

Yes! And if they are out, they get replaced not re-used!

[Swiss Toni]

Just a thought … you did fit the rings the right way up, didn’t you?

[Suzukisam77]

@Swiss Toni

Yeah I made pretty sure of the orientation of all the rings before I fitted the barrels. They had letters on them marking orientation. I maybe thinking now that the bores have gotten too wide as I checked them with a telescopic gauge and they were very close to the manuals service limit like .08mm away. I’m just finding it hard to believe they would get that way after 23000 miles? 

[imago]

17 hours ago, Suzukisam77 said:

Put back together and wow it runs great. Again the second time I fire it up runs terrible again same as before. I look inside the cylinder with a bore scope and yep oil in there again? Anybody have any ideas on what went wrong or what I should do now? Thx

 

If it's only doing this after sitting but runs fine before that, then it can only be oil running down past the seals and guides from the cam chest when the engine is standing. You'll get most oil in the cylinders which stop with the valves open.

To confirm this run it up to clear the bores as much as possible and get oil round the system. Stop it, take the cam cover off and the plugs out then leave it over night. Next day have a look in the bores, if there's a good bit of oil in the bores with the valves open then it's time for new guides, valves and seals or a head swap.

As for the mileage being 23,000, don't rely on that as accurate. It could be wrong, or a different engine to roiginal etc.

[Suzukisam77]

@imago

Ok I will try this and let you know how it goes. I thought the only way for oil to enter from the valve head would be through the valve stem seals which I replaced but the wear of the valve guide has an effect on this too?

[imago]

Just now, Suzukisam77 said:

@imago

Ok I will try this and let you know how it goes. I thought the only way for oil to enter from the valve head would be through the valve stem seals which I replaced but the wear of the valve guide has an effect on this too?

It can do, along with wear to the valve stem, it could also be a pinched or nicked seal.

The important pointer for me is that you say it doesn't do it when first run, but does the next time you start it up. So that means oil entering the cylinder when the engine isn't running, which can only be gravity, and the only point above the cylinders that oil sits is the cam chest. The only route from the cam chest to the cylinder is down the valve guide.

If the oil was coming past the rings the engine would smoke like a bastard whilst it burnt the oil but you wouldn't have oil sitting on the piston when the engine wasn't running as it would have to be sucked up past the rings to get there which can only happen on the induction stroke when it's running.

One other thought, when you fitted the stem seals did you press them home until the rib 'clicked' or snapped over the grove in the guide? They usually need a good shove with a socket on the outer to get them fully on and square. If they're not fully home then the oil can go around the stem seal. Lubrication equivalent of the Maginot Line 

[Suzukisam77]

@imago

Yeah I think your right. The valve stem seals I used were aftermarket from the Athena gasket kit not sure if they need to be Suzuki or not because the Athena ones looked different and they didn’t have the metal rings at the bottom, only on the top. Maybe they aren’t fully home because I just pressed them in with my fingers and I didn’t notice any click.

[wraith]

One other check, when you start it up and it's smoking as it's burning the oil off, dose it stop smoking as it gets hot or smokes all the time? 

1. If just at first, it's a head thing.

2. If smokes all the time, bores. or both 1 & 2

[imago]

13 minutes ago, Suzukisam77 said:

@imago

Yeah I think your right. The valve stem seals I used were aftermarket from the Athena gasket kit not sure if they need to be Suzuki or not because the Athena ones looked different and they didn’t have the metal rings at the bottom, only on the top. Maybe they aren’t fully home because I just pressed them in with my fingers and I didn’t notice any click.

I think from the last time I used Athena stuff that they have a more proud rubber ring moulded to the inside. They're a good bit stiffer to get home as the rubber has to squash between the outer face of the guide and the inner face of the metal collar/cup on the seal.

Did they look like this? If so they really need to be shoved home hard and square, but you can definitely feel when they're home.

[fatblokeonbandit]

21 hours ago, Suzukisam77 said:

Hi my names Sam and I’ve been having engine problems with my 97 Bandit 1200 ever since I purchase it a few months ago. I’m wondering if someone here can help me as I don’t have a lot of experience in diagnosing engine problems.

 

When I first purchased the bike it ran good when seller ran it for me so I bought it. As soon as I got it home it ran horribly, hard to start and would barley stay running. I did a compression check on all four cylinders and cylinder 1 came up low at 130 psi while the others were 160 psi and head gasket leaked. When I added oil it shot up to 180psi so I though it must be rings. So I then took apart the engine and installed new rings and new had gaskets etc, also I honed the cylinders with a hone from harbor freight. Reassembled and it ran great and was 160psi across the board. The next time I fired it up it sounded horrible like a cylinder wasn’t firing or something, and would also backfire heavily. I take it apart again and find oil sitting on top of the cylinders. So this time I replace my valve seals as well as cleaning and lapping my valves. Put back together and wow it runs great. Again the second time I fire it up runs terrible again same as before. I look inside the cylinder with a bore scope and yep oil in there again? Anybody have any ideas on what went wrong or what I should do now? Thx

That dosent sound like oil causing the backfiring???

could be fuel flooding the cylinder, washing all the carbon off the valves and head and would look like oil through a shufty scope..

defective float valve  or pilot jet fell out ..

Had the same when a bandit owner swore blind he had oil coming out of the exhaust headers join, it was neat fuel from a pilot jet that had fell out coming straight through the ebgine and dribbling out the exhaust join

can you get an IR thermometer and see which cylinders arent firing.. check carb from that cylinder before pulling the head again.. Might be nothing to do with it but easier than top end rebuild??

[TonyGee]

got to agree with fatblokeonbandit,  if the mileage is correct and it hasn't had a real hard life then I would say the engine is ok, (they are pretty tough) the first thing I would of looked at was the carbs.  they are getting on now and float valves are wearing out, ive seen this countless times, a new set of float valves usually fixes them. do a bench test on the carbs to rule them out before stripping the top end again. 

[Swiss Toni]

5 hours ago, Suzukisam77 said:

 I’m just finding it hard to believe they would get that way after 23000 miles? 

Not so unusual. I’ve got an engine with 18k on it, and the bores have only .0015” to go!

[Suzukisam77]

@wraith

interestingly I don’t see any smoke coming out of the exhaust which is now making me question if it is oil but actually gas mixed with carbon that just looks like oil like @fatblokeonbanditis saying. That thought did cross my mind as to why it wasn’t smoking if it looked like there was oil in there. Yeah I’ll try and get a thermometer and measure the exhaust temps. 

[Suzukisam77]

I think I’ll have another look at those carb floats and needles seats when I get the chance. maybe it ran great at first because there wasn’t enough gas in the bowl to flood it but then it started leaking fuel into the cylinder because fuel level got to high or the needle valve wasn’t stopping flow.

[fatblokeonbandit]

4 hours ago, Swiss Toni said:

Not so unusual. I’ve got an engine with 18k on it, and the bores have only .0015” to go!

I’ve had 25  B12’s or B12 powered bikes and never had a worn bore, except one I bought that I found out later had been left out side with no plugs, and another one that smoked when fired up that had half a ring missing….

Edited July 27, 2023 by fatblokeonbandit

[Suzukisam77]

Here’s a picture of the inside of a cylinder

[Suzukisam77]

1-3 are like this , 4 is dry

[wraith]

Ok, step by step,

1. Check that the fuel tap is working properly, IE only let's fuel out when you suck on the vacuum pipe or it's on prime. 

2. If the bike had been stud for some time with dry carbs the rubber o rings on the flot needles are probably f##ked. 

3. Check if carbs are flooding. 

4. Compression, is it content or does it go up or down after running good and bad.

5. How do the plugs look, black and wet or dry and sutty 

[Gixer1460]

Q. - do you generally use the side stand or main? If former, I'd say you've got a leaky fuel tap! Pistons are tooooooo clean!

[Suzukisam77]

Update

First off thanks for all your guys help so far I have tested my fuel tap and it’s working properly. It flows fuel when vacuum is present and doesn’t flow when there’s no vacuum. I think I’ve determined that it’s gasoline in my cylinder because I took a sample and it smelled like gas. So I’ve taken the carbs off and have been testing  the fuel needle and seat and they hold 6 psi pressure with a pressure gauge so I assume these are good. I replaced the needles and seats after I bought the bike with an all balls kit, they fit very loose and very wobbly is this normal? The fuel floats themselves don’t appear to be in very well even when I replaced the orings with oem. In addition there are no o-rings on the emulsion tubes, I’ve heard these emulsion tubes can get worn out and cause excessive rich condition. Any thoughts on this or what else I should check while I’m in the carbs?

@wraiththe spark plugs come up sooty and black even after 10 minutes

[TonyGee]

Do a bench test on the carbs. They'll probably show a leak.