dt 125lc cdi compatibility

[lizzie40f]

I have a dt 125lc 1985 and have just put another engine that i got off ebay in it but i cannot get it to run i have a spark and fuel but it just about runs and backfires and dies if you turn off the choke or try to rev it.I have tried a different carb and reeds but it makes no difference so i am wondering if its a timing thing or my cdi is not compatible with my engine,does anyone know a way of checking or are all the cdi"s the same.I was told by the seller that the engine came out of an 89 dt and mine is a 1985

[Vez]

Can't answer for certain, but i think they will be different as the LC became the R in 88 so you may need a CDI from a later model.

Vez.

[Cynic]

I have a dt 125lc 1985 and have just put another engine that i got off ebay in it but i cannot get it to run i have a spark and fuel but it just about runs and backfires and dies if you turn off the choke or try to rev it.I have tried a different carb and reeds but it makes no difference so i am wondering if its a timing thing or my cdi is not compatible with my engine,does anyone know a way of checking or are all the cdi"s the same.I was told by the seller that the engine came out of an 89 dt and mine is a 1985

Have you tried swaping the stator plates across, so the 89 engine has the stator and flywheel from the earlier engine. They will in all likelyhood swap straight over.

Secondly, the carb you tried, was it an 89 carb or an 85, you should check the differences they can be quite remarkable. As an example a 79DT175 has a 130 main. The following year it increaced to 160 just on the strength of a different air filter design that was less restrictive.

[lizzie40f]

Have you tried swaping the stator plates across, so the 89 engine has the stator and flywheel from the earlier engine. They will in all likelyhood swap straight over.

Secondly, the carb you tried, was it an 89 carb or an 85, you should check the differences they can be quite remarkable. As an example a 79DT175 has a 130 main. The following year it increaced to 160 just on the strength of a different air filter design that was less restrictive.

no i have not tried swopping stator plates yet but i did phone my local yam dealer and he checked the part numbers for an 85 against an 89 and the stator is the same and the cdi is different number that superseeds over to the same as the 89 so unless my cdi packed up when the engine died and lost compression then i have no ideas.The carb i tried was one i got second hand that i fitted to old engine and it worked the bike was flying so i presumed it was the same as the old carb

I took the head off the old engine and the rings have broken up and scored the barrel,should there be any left and right play in the conrod as mine slides left and right a bit and you can wobble it a bit so i think bearings have gone aswell.

the bike just about starts and the most i can get to idle at is about 1200 rpm with the choke on and the idle screw right in,if you try to rev it it just coughs and dies,sometimes when its a bit warmer you can put the choke in and a couple of times slowly increased the revs up to about 5000rpm but it just coughs backfires and dies

any ideas

[Cynic]

no i have not tried swopping stator plates yet but i did phone my local yam dealer and he checked the part numbers for an 85 against an 89 and the stator is the same and the cdi is different number that superseeds over to the same as the 89 so unless my cdi packed up when the engine died and lost compression then i have no ideas.The carb i tried was one i got second hand that i fitted to old engine and it worked the bike was flying so i presumed it was the same as the old carb

I took the head off the old engine and the rings have broken up and scored the barrel,should there be any left and right play in the conrod as mine slides left and right a bit and you can wobble it a bit so i think bearings have gone aswell.

the bike just about starts and the most i can get to idle at is about 1200 rpm with the choke on and the idle screw right in,if you try to rev it it just coughs and dies,sometimes when its a bit warmer you can put the choke in and a couple of times slowly increased the revs up to about 5000rpm but it just coughs backfires and dies

any ideas

I have to be honest that sounds more like some kind of air leak to me or mixture problem. Is the engine good?

As to the conrod, a little side to side play or 'wiggle' as you put it is normal. Its VERTICAL movement you do not want in any amount.

[lizzie40f]

I have to be honest that sounds more like some kind of air leak to me or mixture problem. Is the engine good?

As to the conrod, a little side to side play or 'wiggle' as you put it is normal. Its VERTICAL movement you do not want in any amount.

I got the engine off ebay and it beginning to look like i got ripped off as the engine was sold as a rebuilt engine but i think its only had a top end on it and like you said it sounds like something internal

my old engine either needs a top end rebuild or its blown the crankcase oil seals is there anyway of checking the oil seals without a strip down because if the seals are ok then i can get the top done and put old engine back in

[Cynic]

my old engine either needs a top end rebuild or its blown the crankcase oil seals is there anyway of checking the oil seals without a strip down because if the seals are ok then i can get the top done and put old engine back in

Opps, cart before the horse i'm afraid, the only effective way of checking them needs the engine running and even then its not absoloutely accurate.

I havent done them on one of the lc engines but you can apparently change them without spliting the cases. For the work envolved will the top end of the new engine not fit the bottom of the old and see what happens?

[lizzie40f]

thats interesting i thought the case had to be split to do the crank oil seals it would be well handy as i dont really want to split engine just yet,does anyone 100% know if this is possible to do or is it a case split job.

i think i will end up doing a head swop when i know for certain about the oil seals as the bike lost compression and there are a couple of deep scores in the barrel and piston so hopefully my crank seals are ok and a head swop will fix problem

thanks for all the help guys

[Vez]

thats interesting i thought the case had to be split to do the crank oil seals it would be well handy as i dont really want to split engine just yet,does anyone 100% know if this is possible to do or is it a case split job.

i think i will end up doing a head swop when i know for certain about the oil seals as the bike lost compression and there are a couple of deep scores in the barrel and piston so hopefully my crank seals are ok and a head swop will fix problem

thanks for all the help guys

The DTR crank seals can be removed without splitting the case, i have done it, you have to destroy them to get them out though, which can be a PITA but usually easier than splitting cases. I presume the DT lc is the same as the DTR.

Hope this helps.

Vez.