Ihave an 1986 lt250r, Just rebuilt the top end after one of the rist pin washers broke and wiped out the piston. It ran fine up till then. Now put back together The only way to start it is by pulling it with another. It has great compression (drags rear tires while pulling it), when pulling it it sounds like the timming is retarded (bogging) until you drag it fast enough and then it takes off. As long as the rpm is up it runs great. Pulls hard etc. it wont idle you have to keep reving it to keep it running. And as long as you do that it is fine. But as soon as you try to let it idle it goes into retard mode. Ive rbuilt the carb and cleaned it. The spark is a sharp needle type orange and sometimes blue in color. I thought it was supposed to be a fat blue spark. Do I have week pusle coil, pick up coil, or what? The key on the mag is good Ive played with the stator ajustment and made no difference. Can anyone help?

 

hey welcome to the forum!

if you are absoloutley sure that the timing IS changing depending on rpm, then i'd say get a new CDI unit. they should be very cheap on ebay.

do you have a service manual? if so, it should give you what resistances to look for thru some of the coils and possibly even parts of the CDI.

oh and about the spark color, its *supposed* to be fat and blue, but i have an 86 aswell and its a thin orangey spark like yours, but ohhh boy it runs! so i wouldnt sweat that aspect...

good luck!

 

Hey thankyou for the info, yea thing thing has me stumped. I'm not 100% sure it is a timming thing, it just reminds me of retarding the timing in a vehicel. I get that that bogging very slow rev until it gets up in power band only when starting it. Once its running it is fine, just wont idle, And kick start aint happening, wont even think about it. Just can't get it to spin ast enough. And what really gets me is it never did that until I tore the cylinder off to replace the piston and rings.

 

well i guess the most cost-effective thing to do (before you start throwing new parts at it) would be to play with the pilot air mixture screw. just keep in mind; its an air bleed, not a fuel regulator. going IN RICHENS and going OUT LEANS the mixture at idle and up to around 1/4 throttle.

 

Okie Doke, but I think your on to something with the cdi ...........I did a little research and found that the cdi does control the spark intenseady for the amount of fuel your feeding it. Do you know how many LBS of compression is called for? in other words what is the min you can get away with? Thanks Dude

 

it should definatley run with any more than 80psi.

let me know how things work out.