Honda CB250RS kickstarting difficulties

[Wilburtron]

Hello,

Sorry for my first post being a problem, but I'm having difficulties kickstarting a 1981 Honda CB250RS.

I finally got round to taking and passing my test a few months ago after, boh, over 8 years!! just pottering around on a 1973 C50. I bought a 2004 CBR125 2nd hand to do this, I kept that for a while but have now replaced it with the above. The 250's only done 17000 miles and is in excellent condition.

When I picked it up from the guy I checked first of all whether it was warm (and so potentially masking any starting cold problems) and then asked him to start it, he did this 2nd kick, no problems, though recommended that it needed a little throttle generally - although I thought the CB250RS had something to circumvent this need)

This was 22nd March. I brought it back home that evening and managed to start it after 6 or so kicks. However as this was late and right next to people's windows and the exhaust is custom and very loud I didn't keep it going for more than a minute.

Having finally got it taxed and insured and some time to go out on it, I just tried to start it this afternoon, but couldn't.

I turned the fuel valve on, ignition on, into neutral, engine stop switch to RUN, choke fully pulled out, hand on front brake, no throttle, straddling the bike I gently pushed kickstarter until I felt some resistance, then gave it a hard kick, but nothing. Tried a little throttle for a couple of times, nothing, very briefly did I get it started after about 30-40 attempts, but although I started revving it and was seeing around 5-6000rpm it died on me after about 10 seconds. Should I have really revved it to the redline at this point??? I then tried again, throttle off, throttle on, but couldn't start it again..

In case I flooded the engine, I turned the ignition off, fuel off, pushed choke down, open throttle fully, cranked the engine several times to clear it, then turned ignition no, fuel on, choke up etc...

I know the battery has nothing to do with it, although I think I should charge it anyway as the bike was SORN (it did come with a fresh day-old MOT) Surely the petrol can't be off? The seller started it fine, that's only

Am I maybe kicking too hard? I'm only used to the kickstart on a C50 so presumed this would need a hard kick.

Should I push gently until I feel resistance and then kick? Is it a good idea to try 2 kicks with the ignition off, choke down, and then ignition on, choke up?
If I get it starting, how hard should it need to be revved to stop it dying after 10 seconds? Surely it shouldn't need revving up to the redline to just keep it alive at this point?

Should I be twisting the throttle right at the end of the kick or does this just flood the engine for the next kick if that one fails?

One of the reasons I bought the RS was that I thought they were meant to be easy starters so it's most depressing to struggle like this.

Any pointers, help, even shaking of heads would be greatly appreciated.
Wilbur

[500 T C]

             Hello, I have owned a couple of RS 250s in the last 30 years ,never encountered any real starting problems like you have.
Firstly have you checked the spark plug? Is it loose in the hole?Have you checked spark,HT lead?Is the plug wet with fuel,if not ,the carb float needle could be stuck.  When you kick it over,you only need to give it a good through prod,if the kickstarter is hard to push down,then check the automatic de-compression cable ,does it have some free play ,check this with the manual probably the cause of your problems.
            Lastly dont rev the b##ks off it, on standstill,its like you getting out bed and told to do 100m at full sprint,the cam is only run in a casting,not bearings.Check the battery,charge it or change it,electronic ignition Im sure needs a good battery,Im sure some people will beg to differ,and have you given it fresh fuel? One other thing is the choke working correctly,
        Let me know how you get on,just a few things to consider.

[Dick Scratcher]

Hi, you could also check that the automatic valve lifter has a little 'slack' in the cable, if there isn't any the exhaust valve might be being held off the valve, there ought to be 2/3mm clearance at the 'head' end.

[Dick Scratcher]

Sorry, that should read 'seat' and not valve.

[SteveC#222]

Hi Wilbur, welcome to the thumper club.

Basically try what the others have said - start with the basics

Do you have a spark? if not try plug HT cap & lead Kill switch...also check if it has a cut out switch on the sidestand a lot of bikes do to stop you riding off with the stand down but they can get full of crap and stick.

Fuel - is it fresh? If it is, is flowing out of the tap? - take the pipe off at the tap and run some into a jam jar - if it has been standing you may have disturbed the muck in the bottom of the tank and the tap filter may be blocked. Check that the vent hole in the fuel cap is clear or it can vacuum lock. Is it getting to the plug - is the plug wet?

If it has been standing for some time with old fuel in the carb float bowl it can turn into a kind of varnish that will block up the slow running and starting jets so it might need the carb cleaning out - not a big job.

As for the revving - are the cables sticking? also are the cables routed correctly - on my XBR it would rev like mad with the bars turned right as the choke cable was routed wrongly and was being pulled on when you turned right.

Try that and see if it fixes it if not keep asking us, I'm sure we'll get it sussed!!

Oh and check the battery voltage - if the battery is a bit iffy the previous owner might have charged it up just before you bought it! also check the fuses including the main fuse.

And check the air filter is clean and that the airbox intake isn't obstucted....it wouldn't be the first time someone put a tool roll under his seat on top of the intake horn  ......

[Wilburtron]

Thanks guys that's some nice advice to start with,

I'm currently living in a bedsit and the bike's under a push-bike shelter so hoped I wouldn't need anything more than a few general spanners, pliers, screwdrivers etc for a while until I had time to collect some tools, but gotta ask my brother to send some pronto so they'll be a little delay, and also was why I couldn't check some things today. I did rebuild almost all of the C50 so I'm not utterly inept.

I'll check the colour of plug, for spark, check the decompression cable, choke, throttle, check the fuel line, carb, and switch the fuel around.

think I'll check the battery first, the neutral light was pretty weak, though it still felt weird the way it was revving the 2 times I did start it.

Cheers for the advice, I'll get back to you once some tools have arrived and I can get to work.

Wilbur

[SteveC#222]

The revving might just be the fact you are using full choke. On my XBR I use a quarter to half choke for starting. It doesn't like full choke and floods easily.

[johnr]

ok, essentially, what you are trying to do is to get the piston moving so fast that it will overcome the compression of the cylinder on the upstroke and do so fast enough to allow the spark to ignite the mix. what you want to do is gently push the kickstart down, till the piston is at top dead centre, the automatic valve lifter connected to the kickstart by cables should allow you to ease it over the top. once you have it at tdc, take your foot off the lever and let it come back to the top, now you know that you can give it a full kick and the piston will be able to build up enough velocity to fire it up. you dont want to kick it like youre taking a penalty, just stand on the lever and allow your weight to turn the engine over. starting a single on a kickstart is something that you will need to master, and once you have, you will wonder how you ever couldnt do it.