Engine issue?

[lee]

I went for a ride tonight, did about 30 miles and everything was good. About half a mile away from home there was a sudden change in the engine. Very hard to describe but it sounded almost like the idle speed suddenly increased, but I don't think it did, and the engine sounded wrong somehow. As I said this happened all of a sudden right at the end of my ride. I think the exhaust started popping a tiny bit too. As I say it is hard to described but I definitely noticed something change.

I checked for an intake leak and I don't think there is one. I've also got a newly fitted ignition - could it be anything to do with that? I've done 120 miles or so since I installed the new ignition and it has been fine.

Could a drop in oil pressure cause something like this? How can you test for oil pressure if you don't have a gauge?

Any suggestions would be greatly appreciated - I'm a bit wary of riding the bike like this in case I cause damage.

Thanks gents
Lee

 

[slowrower]

Lee, I would get an Oil Pressure Gauge and mount it into the tappet screen plug as its very easy to get at and over time you know where the pressure should be if something changes.

A number of things could create your problem from a bad plug, plug wire, carb issues, dirty air filter.

Carb intake leak, or the crankcase vent hose from the front cylinder to the intake manifold could be causing a vacuum leak ( this could explain the increase in idle rpms).

When was the last time you lubed your throttle cables? the return cable could be binding not allowing it to go back to normal 1,000 rpm idle.

Change in ignition timing -- seeing how you just replaced it this could be a possibility.

As for riding, if your idiot light is working you have at least 7 or so PSI at the oil pump but again get a gauge, there cheap and easy to install. Oil pumps seem to be the last on the list of problems.

Let us know what you find ... also input from others! good luck.

 

[lee]

thanks Slow - I will get an oil pressure gauge
I have brand new NGK plugs but guess one could be bad - the air cleaner looks fine and I lubed my cables recently
the thing that bothers me as much as anything is that this change happened suddenly
thanks for all the suggestions - food for thought for sure

 

[BigDogBro1]

Even a NEW plug can be bad. Sorry, nothing else to add in addition to what has been advised. All good suggestions!

 

[KnotSo]

After doing those things, do a compression test.

 

[LamboV12]

Increase in idle + popping is an indication you're mixture went lean. Ignition/timing will do same. I would check the fuel mix adjuster on the carb if the spring has good tension and it don't not move on it's own. Then I would pull the carb in look for crap in the bowl or in the jets. A tiny piece of crap in the jet would allow less fuel, there by resulting in a leaner condition. BTW - did you go with a programable Crane ignition?

 

[lee]

thanks for all the suggestions everyone - Lambo, I put the IST ignition in (programs itself to your bike).

when I say the engine "sounded" a bit like the rpm's increased I'm not sure they actually did - the engine also sounded different, looser, if that makes any sense - more than just the rpm's increasing as though something went wrong with it somewhere indicating to me this goes deeper than just a sudden change in the mixture - I wonder if I lost a cylinder? perhaps a plug stopped firing or something? presumably the motor would still run on one cylinder? If I check for spark will the engine start just on the other cylinder? same question checking for compression? sorry about all the questions fellas

 

[LamboV12]

Yeah it will start on one cyl - but you can pull both plug wires and hold one up at a time to see if it arcs... I don't know - the fact that a ran OK then happend suddenly. If you fire it up now what happens? Does it idle OK?

 

[LamboV12]

^ Correct-a-mundo
Sul - did you hear it rattle or anything or just loose power?

 

[LamboV12]

Good catch and very rare...

So Lee - will she start and idle? What do the plugs look like?

 

[05chop]

Lee that IST has a code reader with flash codes.It talks about it here http://www.sscycle.com/modules/instruction/uploads/51-1156.pdf

 

[Vegas]

Like 5 monkeys fucking a football here....let's make sure there is a problem first. Fire it back up and ride it to see if there really is an issue. Your new ignition system may not be perfect. Maybe it was a little out of wack for a minute. I wouldn't go to any trouble until you verify the problem and get more symptoms.

 

[05chop]

Also if there is something loose like metallic object this can retard the spark from the knock sensor on the cylinder head. When in doubt go back to basic engine problems. Air,fuel,compression,spark.

 

[05chop]

Like 5 monkeys fucking a football here....let's make sure there is a problem first. Its all input vegas

 

[lee]

thanks for all the comments gents - I haven't tried starting the bike up again yet. I am going to print this off and take a look tonight and see what I can find - I really do appreciate all this. I'll let you know what I come up with. Just one quick dumb question, where are the compression releases??
Thanks again
Lee

 

[Vegas]

Like 5 monkeys fucking a football here....let's make sure there is a problem first. Its all input vegas

I understand that....but I don't see much to work from in his original post. Maybe he had one to many beers at the local bar.

 

[LamboV12]

thanks for all the comments gents - I haven't tried starting the bike up again yet. I am going to print this off and take a look tonight and see what I can find - I really do appreciate all this. I'll let you know what I come up with. Just one quick dumb question, where are the compression releases??
Thanks again
Lee

Middle of the cylinder on top. Covered with the rubber dome....

 

[lee]

not too many beers Vegas - just not easy to describe thats all.

thanks Lambo - how do I know if one has worked loose? Also, when checking for spark I'm not sure what to do with the plug I'm not checking - do I just leave it in the head and pull the lead off it?

 

[KnotSo]

Lee, make a video similar to the last one and we can compare how it sounds. SUL has a great ear for these things, as do some others I bet. I just wanna hear it run...

 

[lee]

good idea Knotso - I'll see what I can do :2thumbs: