1973 cr250m wont start

[jimg1au]

finished my cr but it wont start.new engine 4 mm longer rod kit with spacer under barrell 2 gaskets 1 each side.reed valve.reco ignition.38mm carby.have spark.timing at 1.5mm btdc.even sprayed areostart in plug hole still no starting.new plug new ignition coil.checked kill button (also new) its ok.nave good spark on plug.
any help would be great.
cheers
jimg

[cyclegod]

.even sprayed areostart in plug hole still no starting.

There's your problem! You should have used Wynn's "Start ya Bastard" 

I had a similar problem with my YZ465 (does yours backfire or phut at all?) which turned out to be the new plug (which showed a nice blue spark) but wouldn't run at all but for backfiring and phutting. It's going to be an annoyingly slow process of elimination but I'm sure it's going to be something simple and annoyingly obvious in the end. GOOD LUCK

[KB171]

The reed valve  one i got to have a quick blast on was a stubborn bugger to kick start too, I'd be out finding a decent hill, and roll starting it ,also it dont take much for the  kick start gears to break .i've done 3 sets,the last time they punched a hole in the back of the cases >And they love kickin back Good Luck ,

[jimg1au]

new plug old plug nothing no sound out of chamber at all.i can smell the aero start in the muffler of the chamber.
thanks
jim

[TM BILL]

I recently had simillar issues with an RM 125B  after a rebuild, had compression,spark, fuel . Wouldn,t even fire with a shot of dope. You start to question everything you've done , I still cant push start so John (Asasin) came over and doble checked everything before push starting it. It took a lot of pushing but once it went it was all good.

Starts first kick now  still dont know why it wouldn,t go.

Suggest you give the CR a good push or a tow , good luck.

[Rossvickicampbell]

as most will know I am far from a mechanics a.....e!  But having the same problems with my 250 at various times.  First one after a motor rebuild was the timing was out by 120 degrees (I think it was) - still had spark but at the wrong time.  Secondly (and this is a strange one) I couldn't get my bike to go at a meet one day and was about to put it back on the trailer - I undid the top of the carby for a last look, tried again and away it went - the only thing I could put that down to was a vapour lock?

Worth a try

Hope you get it going

Rossco

PS I had the GEM reed kit and didn't find it made it any harder to start - it either went or it didn't.

[Marc.com]

all sounds good, even timing issue would still result in somthing going snap crackle or pop. With all those gaskets and spacers hows the compression, might be a combination of things, lowered compression and the kicker on the 250M not spinning the motor over very fast.

My RM500 is a bit cranky if it sits a while and a real bummer to push start.

[caps 999]

try puttin a little bit of fuel in the plug hole it helps on the occasion

[KB171]

Gday ,just wonderin what size holes did you cut into the back of the piston ? I've got a gem block but know SFA    about what is needed to get the thing sorted. its got the middle petals trimmed back with a 2mm gap on the ends, dunno if that was a cure for hard starting or someone just experimenting 

[jimg1au]

my reed is a home made 1 from the 70s alloy manifold with a 1974 mx360 reed block.barrell has porting work done to it.piston has holes in exhurst side for bridge cooling and i hole in the cent of the inlet side.bike had all mods done before i got it.it was sitting against a fence in texas for 20 odd years befor i got it.

[Rossvickicampbell]

MarcFX - with my timing out I got nothing at all, zilch, bugger all, no cough, fart or splutter for 2 days before I took it back to where it was overhauled.  Then they found out it was put back together wrongly?

Rossco

[jimg1au]

it has good compression the spacer plate is to ofset the 4mm longer rod.
rossco what was the problem what did they do wrong when rebuilding the motor.mine has new crank pin,rod,piston,bearings and seals.new points ignition, new ht coil.i put it together myself after getting the rod put in the crank.

[jimg1au]

got it started today.problem was new h/t coil.put the old shity cr one back in and fired 2nd kick.put tank back on and kicked again and away she went.4t a little down low but revs clean only 1/8 throttle.getting coil replaced.whenit comes back put it back together and take it for a ride on the fire trail behind my house.i trail takes over 1 hour to walk.not bad back yard for sydney south.
cheers
jimg