Left cylinder not firing on 2 XS’s

[westonboege]

Sounds like youve isolated the left cylinder. Do what some have suggested, and perform a compression test. I suspect either compression loss... to o tight of a valve causing it to hang open possibly? I would think that if it was losing enough compression to not run at all, you should feel that cylinder to be much weaker when kicking the bike over. Even slowly kicking it, I would think it would be a noticeable difference from the stronger running right cylinder...

The other possibility is the carb is dumping too much fuel in. But you said you had ruled that out by swapping carbs?

 

[voelser]

Sounds like youve isolated the left cylinder. Do what some have suggested, and perform a compression test. I suspect either compression loss... to o tight of a valve causing it to hang open possibly? I would think that if it was losing enough compression to not run at all, you should feel that cylinder to be much weaker when kicking the bike over. Even slowly kicking it, I would think it would be a noticeable difference from the stronger running right cylinder...

The other possibility is the carb is dumping too much fuel in. But you said you had ruled that out by swapping carbs?

Swapping out the carbs yielded the same result indeed. However because it does not fire it tends to get very wet.

It certainly does not feel any weaker when kicking it over, but as above: a compression test is on the cards asap. Hopefully it's not that (ball ache) but possibly valve adjustement. The engine was freshly rebuild, but sat for about two years before I got it. Luckily indoors and warm, so I would not expect there to be a compression issue. But you never know.

 

[motorbikerx]

.........maybe not as long ago as me lol(1982 Oxford) back then we got generous Government grants in the UK I even received an additional 'Mature student' grant

If the engine was rebuilt by Howard it will be exceptionally good but I would still do the compression test and check your valve settings . Howard advocates looser settings for all models .His tests in the technical section are a 'must read' for anyone interested in improving xs650 engine performance
http://www.smedspeed.co.uk/tech.html

Interesting read the smedspeed, I note the 6 and 12 thou valve clearances and his reasoning behind it.
Might just open mine up now...
No moon to see...

 

[voelser]

Gentlemen, do I have a doozy for you today. Today I was planning on doing a compression test and checking the valves on the XS Chopper to see if there was a clue as to why the left cylinder is not firing. Before that there were a few small thing I wanted to tie up on the XS Cafe Racer. When I was done with those I wanted a make a quick spin on it and as I started it I noticed that the left cylinder was not firing. Yes, you read that right, this is not the chopper, but the other XS having the same issue now!

So I rode it a few weeks ago and did not notice any issues and I have been riding it for a couple of years before that on the old carbs. So the only change I made to this was addind the Mikuni TM34’s. And it did run on those a few weeks ago.

Anyway, check spark, fuel and air. It looks like it is not getting enough fuel. i can smell petrol on the plug, but its not wet, even after running it for a bit. The carb is getting fuel as the bowl is full. I opened it up and cleaned the jets (even though it is all brand new), that didn’t work. Swapped the carbs aound, same result. Put bigger pilot jet in, no go. Next I’ll try putting the old carbs back, but I ran out of time today.

I did do compression tests on bothe bikes. On the Cafe Racer I got about 125psi on either cylinder (carbs off, plugs removed, using the starter). I did try this with the kickstart, but as I am shit and kicking, it wouldn’t go higher than just under 100psi.

I performed the same on the chopper (carbs off, plugs removed), but this is kickstart only, so I struggled a bit. Bothe cylinders gave a reading of about 100psi. i realise that is low, but I reckon that is due to failure on my part rather than the bike! Besides, even if it is low, it still runs on the right and not on the left!

As both engines have Mikuni TM34’s now and on both engines it is the left cylinder that is refusing to fire I am thinking there is a correlation here. Could is be that because the bikes lean that way it gunks up the jets, floats, etc.? But then it should’ve worked when I cleaned the jets or swapped the carbs surely?

Running out of ideas really...

 

[peanut]

I would suggest that you start a separate thread for the cafe issue otherwise things are going to get damn confusing on this thread if they are not already.
There is no reason whatsoever to assume that a similar symptom on both bikes are due to the same cause.

I have tried to help you with some advice already and posted two long posts which took me some time and thought and you totally ignored my posts. You didn't respond or even acknowledge them so I'm afraid I am out..... good luck with your random troubleshooting approach you're going to need it

 

[voelser]

I would suggest that you start a separate thread for the cafe issue otherwise things are going to get damn confusing on this thread if they are not already.
There is no reason whatsoever to assume that a similar symptom on both bikes are due to the same cause.

I have tried to help you with some advice already and posted two long posts which took me some time and thought and you totally ignored my posts. You didn't respond or even acknowledge them so I'm afraid I am out..... good luck with your random troubleshooting approach you're going to need it

I’m sorry if I somehow offended you, I can assure you this was completely unintended. As for ignoring or not responding to your posts I can see that myself. I’ve looked back and have responded to virtually every post you made and took your advice on board and did some of the things you suggested. The ones I haven’t is because I have not had time to do them yet. But thanks for your time so far then.

 

[peanut]

http://www.xs650.com/threads/spark-...our-spark-plug-color.49040/page-4#post-538110

post Nos 68 and 70............... I deleted 2x lengthly detailed posts because you didn't respond to either of them

Without intending any offence I would respectfully suggest that you refer to a troubleshooting manual and follow a systematic and methodical testing procedure rather than the random stab in the dark approach you seem to be applying so far.

You need 3 things for your 4 stroke engine to run............. stoichiometric air & fuel mixture ,compression and a spark at the correct time.
Start with the simplest first .
do you have a strong consistant spark at both plugs ? Y/N I believe you said you do.
Do both plugs work ?
If yes then do you have compression and we know that you do
lastly do you have fuel and air to the cylinders Y/N it appears that you do not.

Check your fuel flow from the tank to the spark plug and find where the fuel is not getting through. Look particularly at the tank petcocks and filters .
Do a flow test by pulling the fuel hoses off the carbs and run the fuel into a jar.
Run the engine and squirt some easy start into the non running cylinder ....if it then runs normally it will confirm everything in just one quick easy test.

 

[voelser]

http://www.xs650.com/threads/spark-...our-spark-plug-color.49040/page-4#post-538110

post Nos 68 and 70............... I deleted 2x lengthly detailed posts because you didn't respond to either of them

Without intending any offence I would respectfully suggest that you refer to a troubleshooting manual and follow a systematic and methodical testing procedure rather than the random stab in the dark approach you seem to be applying so far.

You need 3 things for your 4 stroke engine to run............. stoichiometric air & fuel mixture ,compression and a spark at the correct time.Do both plugs work ?
Start with the simplest first .
do you have a strong consistant spark at both plugs ? Y/N I believe you said you do.
If yes then do you have compression and we know that you do
lastly do you have fuel and air to the cylinders Y/N it appears that you do not.

Check your fuel flow from the tank to the spark plug and find where the fuel is not getting through. Look particularly at the tank petcocks and filters .
Do a flow test by pulling the fuel hoses off the carbs and run the fuel into a jar.
Run the engine and squirt some easy start into the non running cylinder ....if it then runs normally it will confirm everything in just one quick easy test.

With all respect, are you in the right thread? This thread only has 47 posts, 48 including this one. And even so, I’ve been away on holiday, so may have missed them between you posting and removing them.

As for your advice, respectfully, I disagree with your observation my troubleshooting is random. I have systematically worked through each issue I could think off snd have described what I did, why I did it and what to result was each time.

More than once I stated that I’ve had spark and air on both bikes. It seems that on the chopper I may have too much fuel and on the caf too little. But sticking with the latter, I described what I did to remedy this (bar retesting the old carb): I did use some easy start (didnt list that as it is obvious), took the carb off, cleaned the jets and eventually swapped the carbs. I also stated that I had fuel in the floatbowl after opening the fuel tap, so this suggests that there is no blockage before the carb.

But I said all of this already. So maybe read the post first before replying in the manner that you have. Respectfully.

 

[jay760]

At the start of this thread you were on about the left plug getting oiled up now you are saying you think the jets are getting flunked up on the left side which would make it lean more likely the carb is letting fuel past and fouling up the left plug, Champion plugs are much more tolerant of this

 

[voelser]

At the start of this thread you were on about the left plug getting oiled up now you are saying you think the jets are getting flunked up on the left side which would make it lean more likely the carb is letting fuel past and fouling up the left plug, Champion plugs are much more tolerant of this

Possibly. It is my mistake for mixing two different bikes with a very similar issue, but different causes likely (as pointed out by Peanut). I will split this thread to avoid further confusion.

 

[peanut]

With all respect, are you in the right thread? This thread only has 47 posts, 48 including this one. And even so, I’ve been away on holiday, so may have missed them between you posting and removing them.

y.

I provided a link to the thread I was referring to at the beginning of my post .

perhaps you missed it .............

You managed to acknowledge a later post in the thread though from someone else and thanked them for their input. ,I deduced from that that you didn't see anything of merit in my posts so I deleted them.

Easy Start can also be a useful diagnostic tool which is why I suggested using it .. I assumed you would know how to use it for this purpose

 

[TwoManyXS1Bs]

What became of post #24?

 

[voelser]

I provided a link to the thread I was referring to at the beginning of my post .

perhaps you missed it .............

You managed to acknowledge a later post in the thread though from someone else and thanked them for their input. ,I deduced from that that you didn't see anything of merit in my posts so I deleted them.

Easy Start can also be a useful diagnostic tool which is why I suggested using it .. I assumed you would know how to use it for this purpose

Yes, I saw the thread you attached. I checked in case I’d forgotten, but it appears I do not have a single post in that thread, so again I have no idea what you are on about.

 

[voelser]

What became of post #24?

As I had to remove the exhaust for repair (of the chopper), I have not been able to try that yet. As for trying it on th3 cafe, I haven’t as it worked up until yesterday morning with the plugs I had and seemed to have plenty of spark when I checked.

Again, my mistake for mixing threads.

 

[TwoManyXS1Bs]

... seemed to have plenty of spark when I checked...

Yeah, just a long shot. Checking plug spark in dry, standard atmosphere is much different from the conditions in the cylinder with air/fuel mix at 100+ psi. Sometimes that additional stress feeds back into the coil. Closing the gap reduces that stress and can give you a diagnostic direction. Plus, it's easy, quick, cheep....

 

[voelser]

Yeah, just a long shot. Checking plug spark in dry, standard atmosphere is much different from the conditions in the cylinder with air/fuel mix at 100+ psi. Sometimes that additional stress feeds back into the coil. Closing the gap reduces that stress and can give you a diagnostic direction. Plus, it's easy, quick, cheep....

True...with the cafe it just didn’t cross my mind as it was working fine before. I just can’t shake the feeling it is too much of a coincidence that on both bikes the left cylinder has developed an issue...but maybe I’m just getting paranoid...lol

 

[TwoManyXS1Bs]

Is the drain water in your tub spinning in the other direction?

 

[voelser]

Is the drain water in your tub spinning in the other direction?

I have a shower? Lol