Misfire - Page 2

motomartin11 · 02-12-2022, 07:52 PM

Further update-fuel system cleaned again, carbs ultrasonically cleaned again, carbs full of silt (again), idle jet on rear cylinder carb blocked (again),pump contaminated shutting off pressure relief valve.
Carbs were put back on today-misfire returned on rear pot. Coils were swapped to no avail. Remote tank set up but misfire still persisted on one pot. Further checks threw up possible CDI black box issues. Luckily a set off a 600 were sourced on a loan basis and both boxes were swapped as I understand one faulty black box can result in the other being affected. Engine then ran reliably on BOTH pots. Had to order a pair of new CDI boxes off Fleabay Germany...Now awaiting delivery of fuel pump hit, manaul fuel tap, fuel filter and new CDI boxes..........

jerry · 03-12-2022, 10:50 AM

check ur plugs are correct I had problems with misfire on rear pot using Dpr9 after a rebuild which i had used on M750 for years put in a set of DPR 8 and problem dissapeared ???? but 2 of my 750 run ok on Dpr 9 ,,,

I had cleaned and rebuit carbs twice and changed ignighters coils and pickups so plug was last option its weird ,, that bike had run well on DPr9 for 11 years ???

utopia · 03-12-2022, 12:52 PM

You mention earlier that you are on your 4th fuel filter and second fuel pump rebuild in three or four years ... and then you report that your carbs are full of silt again and an idle jet is blocked.
Therefore I'm thinking that your tank must contain rather a lot of debris.
Have you ever drained and flushed it ?

For comparison, my 750 has done over 30,000 miles and is still on only its second fuel filter (original plus one change) and has never had its fuel pump rebuilt.

Sorry to hear that your's is giving you so much trouble.
Hope you get it sorted soon.
They are a lovely bike when they're running well.

motomartin11 · 03-12-2022, 05:07 PM

Thanks.
I did renew the plugs and caps when the first misfire occurred and this cured it for a few miles.
I must admit to buying another (resprayed )tank off Ebay as the original has begun to leak around the prop area and NOT (foolishly cleaning it out before fitting it to the bike). BE WARNED AND NOT LAZY like me.
Yes the tank has now been flushed out several times.
I'm told it runs really well now and is extremely mechanically quiet -well it did with the borrowed igniter boxes. Hopefully the German ones when they arrive will be fine.
https://www.ebay.co.uk/itm/173945178487

motomartin11 · 14-12-2022, 08:24 PM

German igniter boxes have been shipped apparently but guess which UK (not so Royal) mail outfit is tasked with delivering them...Yes they have gone into the black hole that was formerly known as Royal Mail .Been waiting for 2 weeks or so now for these items after waiting countless weeks for the clutch. Post Brexit, post pandemic but just no post any more! Such is life. Bike could be ready for the road come spring.

adie851 · 03-01-2023, 09:44 AM

I used to have an M900 and only used super unleaded fuel in it....found it runs better and the carbs didn't 'gum up' the same as if you use E10 fuel....The other thing is to turn off the fuel and run the carbs dry if its going to be left for any length of time between rides Carb jets do block up if left with fuel in them. I also use a fuel stabiliser when the bike is stored .Hope this helps.

Cheers , adie851

motomartin11 · 03-01-2023, 03:08 PM

Well this saga continues.........Ignition side was (we thought ) all sorted. Carbs were cleaned again. Road test proved to be OK but then misfire returned. The carbs and ignition were stripped again and there was a damaged woodruff key on the other ( inside) of the gear. Took my mate 4 hours to get the flywheel off as he had taken steps to lock it all up after the other damage to the crank end.
Anyway and I don't fully understand this as I haven't seen the bike since it went to my mate's in November. It appears the ignition timing was slightly out due to the damage to the gear so my mate removed the damage to the gear, made a new woodruff key and a spacer on his lathe to take up the play which the machining to the side of the gear had caused.
After more testing there was still a misfire so the carbs were ultra sonically cleaned again but more debris was found in the fuel filter. He's sent me a video of the tank being flushed through the filler with his hose and you can see the debris still coming out. The tank has now been dried with his airline and he's sent me a pic of it up against a radiator to complete the drying out process which will take several days.
He says if more debris appears in the fuel filter after this I will need to get the original tank repaired and try again!
Bike has always been run by me on super unleaded btw

motomartin11 · 03-01-2023, 09:03 PM

My mate has just phoned me to say he is unable to stop the debris from the tank blocking the fuel flow to the carbs so I'm going to have the old tank repaired as I am advised putting in a liner will be too risky .

900Rebuilder · 09-01-2023, 07:40 AM

Quote:

Originally Posted by motomartin11

My mate has just phoned me to say he is unable to stop the debris from the tank blocking the fuel flow to the carbs so I'm going to have the old tank repaired as I am advised putting in a liner will be too risky .

I assume that the debris you mention is rust? I've been having reasonable success with my Jeep tank and electrolysis.

Fill with water and some soda crystals then wire up to a battery charger (negative to tank) and pop in a piece of steel which will act as the sacrificial positive (make sure it doesnt touch the tank) and away you go. There are plenty of YouTube videos on the subject for the exact details of how to do it

motomartin11 · 09-01-2023, 08:47 AM

Quote:

Originally Posted by 900Rebuilder

I assume that the debris you mention is rust? I've been having reasonable success with my Jeep tank and electrolysis.

Fill with water and some soda crystals then wire up to a battery charger (negative to tank) and pop in a piece of steel which will act as the sacrificial positive (make sure it doesnt touch the tank) and away you go. There are plenty of YouTube videos on the subject for the exact details of how to do it

Thanks...I did consider this and it would certainly be worth a try but I'm so demoralised with this tank that at the moments I'm going to stick with the plan to repair the original tank which is internally (apart from the slight weep near the hinge) in much better condition than the second tank. Interestingly the second tank has already been repaired in this area.
As to the debris this is tiny paint / rust flakes and a fine sand like substance. If you put your finger on what has come out of the tank after flushing -after the water has evaporated away-you can feel the sand like substance on your fingers.
There has been a fair amount of speculation as to what has happened historically from attempts at sand blasting not being cleaned out thoroughly to corrosion both as a result of time and possibly from what occurred after the welding had been completed as it seems the tank may have been stored for a time after the welding has been carried out. It also seems likely poor preparation of the internal tank surfaces is an issue. There is also some evidence of other bodged repairs using resin type substances-hence the reluctance to continue using the second tank. There is a load of debris which can be seen in the new fuel filter and the small diameter fuel outlet in the tank doesn't help as this is becoming blocked and cutting off the fuel supply.

900Rebuilder · 09-01-2023, 01:23 PM

I dont understand where its all coming from then if you have cleaned it out once and you are starting each time from a clean tank. What ever is in there must not be fully coming out each time as I cant see a full petrol tank rusting quickly enough to cause your issues each time.

motomartin11 · 09-01-2023, 03:17 PM

Yes it's been cleaned out several times now and each time more residue appears. However the bike runs perfectly using a dummy tank.

350TSS · 10-01-2023, 09:24 AM

In your position I would give the tank one more concerted try with a hose/jet wash and some detergent and after about 4 thorough rinse outs I would dry the innards out with a hair drier in the filler opening (moving its position several times so you do not blister the paint). If the problem still persists then I would bin the tank.
Such issues can be very frustrating and demoralising - I wish you luck with whatever you decide

motomartin11 · 10-01-2023, 10:06 AM

Quote:

Originally Posted by 350TSS

In your position I would give the tank one more concerted try with a hose/jet wash and some detergent and after about 4 thorough rinse outs I would dry the innards out with a hair drier in the filler opening (moving its position several times so you do not blister the paint). If the problem still persists then I would bin the tank.
Such issues can be very frustrating and demoralising - I wish you luck with whatever you decide

Thank you.
Yes extremely frustrating and expensive due to the debris entering the carbs and quite possibly being indirectly responsible for the misfire which in turn led to the crank problems...
I have already been advised to bin the tank which I paid good money for-just goes to show how careful you have to be.
I think the only way this tank could be used is by the application of a liner but I know there are big problems with these now due to the composition of modern fuel.
The old tank has gone to a specialist for gas welding and will then need to be re-sprayed.

utopia · 10-01-2023, 01:48 PM

Sorry I'm a bit late with this advice but previous episodes reported on this forum have concluded that brazing is the best method for repairing the tank hinge area.
It may be something to do with the flow of the braze being better able to penetrate the joint fully .. I can't remember.
There will be an old thread on the subject if you do a search.
Big Oz was the main contributor.

03-12-2022, 10:50 AM	#17
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,816	check ur plugs are correct I had problems with misfire on rear pot using Dpr9 after a rebuild which i had used on M750 for years put in a set of DPR 8 and problem dissapeared ???? but 2 of my 750 run ok on Dpr 9 ,,, I had cleaned and rebuit carbs twice and changed ignighters coils and pickups so plug was last option its weird ,, that bike had run well on DPr9 for 11 years ??? __________________ MONSTERMAN

09-01-2023, 01:23 PM	#26
900Rebuilder Registered User Join Date: Sep 2022 Location: Beeston Bike: M900 Posts: 293	I dont understand where its all coming from then if you have cleaned it out once and you are starting each time from a clean tank. What ever is in there must not be fully coming out each time as I cant see a full petrol tank rusting quickly enough to cause your issues each time. __________________ Ducati Monster 900 - Yamaha tdr125 & dt200wr - Ford GPW

02-12-2022, 07:52 PM	#16
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Further update-fuel system cleaned again, carbs ultrasonically cleaned again, carbs full of silt (again), idle jet on rear cylinder carb blocked (again),pump contaminated shutting off pressure relief valve. Carbs were put back on today-misfire returned on rear pot. Coils were swapped to no avail. Remote tank set up but misfire still persisted on one pot. Further checks threw up possible CDI black box issues. Luckily a set off a 600 were sourced on a loan basis and both boxes were swapped as I understand one faulty black box can result in the other being affected. Engine then ran reliably on BOTH pots. Had to order a pair of new CDI boxes off Fleabay Germany...Now awaiting delivery of fuel pump hit, manaul fuel tap, fuel filter and new CDI boxes..........

03-12-2022, 12:52 PM	#18
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,545	You mention earlier that you are on your 4th fuel filter and second fuel pump rebuild in three or four years ... and then you report that your carbs are full of silt again and an idle jet is blocked. Therefore I'm thinking that your tank must contain rather a lot of debris. Have you ever drained and flushed it ? For comparison, my 750 has done over 30,000 miles and is still on only its second fuel filter (original plus one change) and has never had its fuel pump rebuilt. Sorry to hear that your's is giving you so much trouble. Hope you get it sorted soon. They are a lovely bike when they're running well.

03-12-2022, 05:07 PM	#19
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Thanks. I did renew the plugs and caps when the first misfire occurred and this cured it for a few miles. I must admit to buying another (resprayed )tank off Ebay as the original has begun to leak around the prop area and NOT (foolishly cleaning it out before fitting it to the bike). BE WARNED AND NOT LAZY like me. Yes the tank has now been flushed out several times. I'm told it runs really well now and is extremely mechanically quiet -well it did with the borrowed igniter boxes. Hopefully the German ones when they arrive will be fine. https://www.ebay.co.uk/itm/173945178487

14-12-2022, 08:24 PM	#20
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	German igniter boxes have been shipped apparently but guess which UK (not so Royal) mail outfit is tasked with delivering them...Yes they have gone into the black hole that was formerly known as Royal Mail .Been waiting for 2 weeks or so now for these items after waiting countless weeks for the clutch. Post Brexit, post pandemic but just no post any more! Such is life. Bike could be ready for the road come spring.

03-01-2023, 09:44 AM	#21
adie851 Member Join Date: Jan 2015 Bike: S4r Posts: 104	I used to have an M900 and only used super unleaded fuel in it....found it runs better and the carbs didn't 'gum up' the same as if you use E10 fuel....The other thing is to turn off the fuel and run the carbs dry if its going to be left for any length of time between rides Carb jets do block up if left with fuel in them. I also use a fuel stabiliser when the bike is stored .Hope this helps. Cheers , adie851

03-01-2023, 03:08 PM	#22
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Well this saga continues.........Ignition side was (we thought ) all sorted. Carbs were cleaned again. Road test proved to be OK but then misfire returned. The carbs and ignition were stripped again and there was a damaged woodruff key on the other ( inside) of the gear. Took my mate 4 hours to get the flywheel off as he had taken steps to lock it all up after the other damage to the crank end. Anyway and I don't fully understand this as I haven't seen the bike since it went to my mate's in November. It appears the ignition timing was slightly out due to the damage to the gear so my mate removed the damage to the gear, made a new woodruff key and a spacer on his lathe to take up the play which the machining to the side of the gear had caused. After more testing there was still a misfire so the carbs were ultra sonically cleaned again but more debris was found in the fuel filter. He's sent me a video of the tank being flushed through the filler with his hose and you can see the debris still coming out. The tank has now been dried with his airline and he's sent me a pic of it up against a radiator to complete the drying out process which will take several days. He says if more debris appears in the fuel filter after this I will need to get the original tank repaired and try again! Bike has always been run by me on super unleaded btw

03-01-2023, 09:03 PM	#23
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	My mate has just phoned me to say he is unable to stop the debris from the tank blocking the fuel flow to the carbs so I'm going to have the old tank repaired as I am advised putting in a liner will be too risky .

09-01-2023, 03:17 PM	#27
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Yes it's been cleaned out several times now and each time more residue appears. However the bike runs perfectly using a dummy tank.

10-01-2023, 09:24 AM	#28
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	In your position I would give the tank one more concerted try with a hose/jet wash and some detergent and after about 4 thorough rinse outs I would dry the innards out with a hair drier in the filler opening (moving its position several times so you do not blister the paint). If the problem still persists then I would bin the tank. Such issues can be very frustrating and demoralising - I wish you luck with whatever you decide

10-01-2023, 01:48 PM	#30
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,545	Sorry I'm a bit late with this advice but previous episodes reported on this forum have concluded that brazing is the best method for repairing the tank hinge area. It may be something to do with the flow of the braze being better able to penetrate the joint fully .. I can't remember. There will be an old thread on the subject if you do a search. Big Oz was the main contributor.