timing/compression/fuel/air

[Jack455]

Ok, I'm a newb but picking things up. I've had my 650 on the road for one week, the start of which it was running fine but improved as I gave it a good day long ride. I then lubed the clutch cable because it was stiff and afterwards learnt that a kickstart works on the clutch.

Now the real problem.

Carried on riding fine, sort of, until the other morning on the way to work when it started to feel rough from starting, cut out after a miles riding at a set of lights. I kicked it and it started fine, ran another mile and it cut out again but this time took a good 10 minutes of kickstarting to get it going, in which time I saw a good puddle of oil (it was raining hard so it spread into a lovely rainbow puddle) which I have now located to coming from the starter but oil level looks fine still.

I got to work and now it is a pig to start, over 50 kicks varying techniques till I got it going. I noticed it didn't seem to be holding compression so engine just turned most of the time but no firing. When I got it going it was jerky at times, misfiring at low revs and cutting out any opportunity it got at a junction.

What are your thoughts?

 

[hotrdd]

We need a lot more information on your bike. Do you have pictures? What carbs and what ignition are you running? Battery or no battery? Custom wiring or vintage with the original fuse box? I would check for the usual AIR, FUEL, FIRE…

1) Are your filters clean?
2) Are you getting fuel? (Do you have fuel filters) Will it start if you spray a little starter fluid in the carbs?
3) Are both plugs sparking?
4) If this checks out start looking at your timing

 

[drewfunk]

Kicking and feeling no compression? Like the kickstarter just pushes down with no resistance? I had that problem too and it freaked me out, until i learned that the clutch not being adjusted correctly causes the kickstarter not to catch. Adjusted my clutch and the kickstart worked fine.

 

[retiredgentleman]

Before you chase around in circles, check your battery voltage (charging system). These bikes must have good voltage or they will not run well.

Engine at 3000 rpm.............battery must be 14.1 to 14.5 volts.

 

[hotrdd]

Does the voltage really need to be that high? I get a constant 13.5 – just below 14 but never as high as you are talking. Now you have me wondering if engine stumbling from 3500-5000 rpm is electrical and not carbs. hmmmm

 

[Inevitable]

Have you checked your plugs?

 

[5twins]

It should run fine putting out 13.5 volts, as long as it's keeping your battery charged. That's all mine put out for the 1st few years I had it. It does better now that I adjusted the voltage regulator.

 

[retiredgentleman]

Does the voltage really need to be that high? I get a constant 13.5 – just below 14 but never as high as you are talking. Now you have me wondering if engine stumbling from 3500-5000 rpm is electrical and not carbs. hmmmm

Yes, 14.1 volts is where your regulator should control voltage. If you run with less voltage, you may get by, but have occasional weak battery problems.

Quite often there are posts on the site, saying they use a "battery tender" on a regular basis to keep the battery charged. I always scratch my head and say, why do they need a battery tender, when the onboard charging system is designed to keep the battery fully charged at all times.

I drove yamaha bikes in the 70's and 80's, and never used any external chargers during riding season. The same applies now with my XS650. I have had it 6 seasons , and it has never had any external charger used during riding season. My onboard volt meter, always shows about 14.1 to 14.2 volts as I drive along the highway. Guess what, that voltage keeps my battery fully charged. I have had the same battery for those 6 seasons and I use the electric starter motor for every start up.

13.5 volts is not high enough to fully charge the battery. I'd recommend you find out why you are not getting 14.1 to 14.5 volts. What rectifier/regulator are you using, and how old are they.

 

[hotrdd]

I have the original equipment and I did adjust the regulator earlier this summer but, if I remember correctly, for some reason it wouldn't go above 13.5

Even at low RPM it's 13.5 and doesn't really change much as the RPMs go up.

 

[5twins]

That doesn't sound right. I get a little better than a 1 volt change between idle and revved. What exactly did you adjust on your regulator? Besides the adjustment screw, there are 2 air gaps that need to be checked/set.

 

[hotrdd]

I used the diagram that someone gave me off of this site and had to cleanup all of the connections and reset all of them. I'll need to go home and recheck this. BUT I've never had a problem with my battery dying.

 

[retiredgentleman]

I used the diagram that someone gave me off of this site and had to cleanup all of the connections and reset all of them. I'll need to go home and recheck this. BUT I've never had a problem with my battery dying.

Do you find the need to use an external charger during the riding season? If not, and the engine starts and runs well, no need to be concerned.

I'm just saying that 14.1 volts is what you should be getting at 3000 rpm. With engine idling at 1200 rpm, the alternator may only generate 13 to 13.4 volts. At idle you may draw current out of the battery, which is normal.

My everyday vehicle (Toyota Camry), also generates 14.1 volts at idle and at high rpms.

 

[scabber]

I would agree with retired. Replace the old regulator and go with the dual bridge rectifers and VR-115 regulator set that he has on his bike.

 

[Jack455]

Kicking and feeling no compression? Like the kickstarter just pushes down with no resistance? I had that problem too and it freaked me out, until i learned that the clutch not being adjusted correctly causes the kickstarter not to catch. Adjusted my clutch and the kickstart worked fine.

I've already encountered that, took me a couple of hours going back over work I'd done to work it out. But thanks

 

[Jack455]

Thanks all for your support, and apologies for not replying until now, I have been reading but had no new info to post. I've now had the carbs balanced and it's running a lot better but a few things I need to do.

What I know is
- Carbs / Air filters. Original Mikuni's (134's I think) with K&N copies will never work right without a jet kit which I cannot find so I'm looking at a full carb kit. Another problem this is causing is the sliders aren't closing with the increased air flow so the throttle's not shutting off. The carb kit will manually shut these off remedying this but my mechanic suggested taping up the filters some as a temporary measure.
- Charging. It's holding it's charge so it's either the alternator or the rec. I've just ordered another volt meter to diagnose that.
- Starter Motor. Sounds really tired even when I know there is juice in the battery. I'm going to strip it down and service it before I spend money there, I can sort that nasty oil leak from the starter gasket out while i'm at it.
- Plugs are good though not the projected tips they should be. Were sooted up from weak mixture
- Ignition system I think is good, has a retro fit Neutronics system

 

[Paulrxs650]

Hi

Check out the carb guide in the tech section and follow it -'it's excellent. Sounds like you have BS34's same as me. They are good carb. For jets in the UK try http://www.allensperformance.co.uk/ they are really helpful and have supplied me in the past!

Take your carbs off and clean them up methodically with lots of carb cleaner and airline. Pay particular attention to the diaphragms that there is not holes or tears.

Starters are a weak point and will fail. You can eliminate the starter and blank off the hole with a 47mm core plug gently ground down a 1/32.

Best regards

Paul

 

[XSLeo]

As far as jetting kits for these carbs, forget it, none out there. Just buy the jets, start out one up on the pilots and get 1 and 2 up on the mains. Put in one set, test, try another set test. It's all in the carb guide.
The starters are not a weak spot. Weak batteries, bad connections and weak springs and poor maintainance are. Give the starter system proper maintainance and it works fine.
Leo