Just Registered, have a couple of questions

Hello everyone, I've been reading this forum for quite some time while building my trike (my appologies for having 3 wheels :lol: ) and it has been very usefull, so first of all thanks!

My XJ650RJ engine is running hot, I've fitted an oil cooler and have replaced the exhausts with standard XJ650 system (with a 3ft extension welded in after the 4-2 collectors and balance pipe). Ive also replaced the airbox with K&N style filters, and the main jets are 118. The engine runs very well since fitting the exhausts but it splutters between 2500-3000 rpm.

I've checked the plugs and they look a nice brown colour, the oil is the right grade and only done 1000 miles.

Has anyone got any ideas why it should still be running hot? (by hot I mean, stuck in traffic you can't hold your hand on the clutch cover for more than a couple of seconds.......never had an XJ before so if they're all like that then thats my question answered! )

Thanks in advance of any help.
Lea

 

Welcome to the forum Lea, glad you joined us. My experience with my xj650 suggests that the motor should not be cool enough for you to touch it for more than a few seconds anyway. What experiences have you had with this motor to make you suspect it is too hot? Is this a recent issue? Running the K&N will lean out the mixture but your spark plugs will not show the lean out if you don't run the motor at high speed under load and then shut off the motor. That should tell you if your lean or not. You mention a sputtering at 3k RPM, this may well be a lean misfire. Check out the plugs and see if you can't obtain a Colourtune. Having extended the exhaust may also be a part of the issue. Best of luck to you.

 

Cheers Robert,

one of the reasons for suspecting it running too hot is, instead of having a breather pipe from crank case to air box (as standard ) I have a K&N 13mm filter on the breather exit (just behind the starter motor) after about 30 min riding I get steam coming out of it??? (I realise that with a standard air box on I wouldn't be aware of this).

As for the mixture, I will be colourtuning it this weekend to make sure all is well. Do you know what the idle jet size is on a standard XJ650, so I can check that the ones I have in are correct, my next job is to get a smooth tick over. It ticks over at 1000rpm ok then slowly it slows down until cut out after about 3 minutes? I am hoping that colour tuning will help rectify this.

Thanks for the reply, I'll let you know how I get on.
Lea

 

I wonder if you are really seeing steam? There should be no water in the crankcase and I suspect the engine would sieze long before the oil got hot enough to smoke.

Seems more likely you are seeing combustion gasses escaping past the rings. A certain amount of this blow-by is normal.

Question for the forum: On an automobile engine the crankcase is vented to the intake manifold to draw these gasses out and another vent goes to the air cleaner to allow clean, fresh air into the crankcase. This helps reduce oil contamination by combustion products and unburned fuel. Is there an equivalent system on our motorcycle engines?

 

Hi Lea,

According to my Haynes, your 650RJ with Hitachi HSC 32 carb should be main jet 110 / needle jet 3.2mm / jet needle Y-10 / pilot jet 40 / starter jet 40 / main air jet 50 / pilot air jet 195.

Hope that helps.

 

The pods are probably causing a lean situation. Lean can be dangerous if the engine is getting hot. If you are way too lean ... you could weld a hole right through the top of a piston.

Until you can ColorTune ... Tweak it.

Run the Pilot Screws OUT --- 3-1/2 turns from Bottomed-out. If the idle and performance is still poor ... bring them out another quarter turn.

UNTIL you can get the matter straightened-out -- RUN RICH!! Rich is going to be much better for you in the interim.

Tweak that engine ... don't push it until you do. Right now you have a simple mixture problem. Don't let it graduate to a complicated engine problem!

 

No. its just baffled but still in the airbox.

 

And hiya LincsTriker too...........

 

Actually most automotive engines have a PCV valve which pulls a vacuum on the crankcase, helping ring seal. Our motorcycles do not have the same setup...

 

Concerning LincsTriker's original question about running hot, it may not be running too hot, there's no way to tell without using a head temp or oil temp gauge. It's air cooled, remember, so it's going to always feel hot. The head normally runs at 300-350F and the crankcase 200F so it's going to be too hot to put your hands on. Installing an oil cooler is a good move and if the plugs are tan it's probably ok. The crankcase breather has nothing to do with engine temp. but if it gets clogged you will have oil squirting out around the gaskets so be careful.

 

Cheers Rick - that worked a treat. Engine now ticking over at just under 1000rpm (on rev counter, not a pro gadget!) lovely, ran it for 45 miles this afternoon and a bit of traffic light action on the way back and no cutting out.

Thanks again everyone for your help
Lea

 

Thanks Steve, after the run out today I think that it's running ok as regards the temp. I'm thinking of getting a temp gauge, I've seen them on e-bay that you replace the oil filler cap with the gauge, not sure if they're acurate or just a gimick :?:

Thanks for the advice though, much appreciated.
Lea

 

To clearify, MiCarl, our bikes do have a Positive Crankcase Vent, not to be confused with the cars Positive Crankcase Valve. Emissions requirements have mandated the use of this arrangement for the last three decades (early 70's when all this started). The XJ uses a baffle system to help knock down any oil vapor that may be floating in the blow-by vapor. As you mentioned, this system pulls blow-by into the airbox to be recycled, reducing the emissions of the machine. While not exactly the same in mechanics as a car, the principle is. Another benefit of the PCV is the vaccum placed in the crank case improves ring sealing and, by extension, improves combustion, thus lowering the blow-by contaminates. Nice little trick.
LincsTriker, I feel the vapor your referring to is in fact blow-by just as MiCarl suggested. Perfectly normal but it is a pollutant and should be controled in some manner. I've seen folks run the PVC output into one of their "socks" just to keep the system intact and to take advantage of the vaccum assisted sealing. This would necessitate the plumbing of each of the pod socks, but it shouldn't be to difficult, 1/4 inch pipes should work fine with a few "Y" connectors. Just a thought.