I bought a mark1 lc about 18 months ago, it was in pretty bad shape cosmetically seemed to run ok albiet topend was poor and start first time on the kick. When I open her up it loses power to the point of being in top gear and dropping it to 3rd just to get it moving again. Thought it could be a exhaust problem as it was welded leaking and all the rest of it so went and bought a new big one exhaust, changed air filter box for k&n style filter and I'm still having problems from 3rd gear up with power loss anybody help

Hi Chris, It's usual to do an INTRO in the new members section BEFORE you do a "how do I fix my bike" question, just so we can get to know you, it's a bit like meeting new folks in the pub and jumping in to their conversation without saying Hi first. Glad you found us and hope you stick around so please be kind enough to nip over to the Intro section and you will get more results if folks don't think your a 1 hit wonder. Welcome to the YOC mate always nice to have new folks join in.

Thanks for the warm reception and the point in the right direction

Hi Chris , did you rejet the carb and do a plug chop ? Also , check for air leaks between airbox / carb / inlet stub and make sure the inlet stub is not perished or cracked . Best of luck .

do a compression test chris, the motor could be worn out fella, if you're lucky just new rings will sort it but start with a comp test

Thanks for the replys everyone Haven't done rejet on carb yet as had the problem before upgrade exhaust although if i remember correctly my plug was pitted with black carbon deposit so might need rejet do i go up or down? no noticeable leaks but will have a better luck tomorrow or over weekend , compression seems to be ok only done thumb over spark plug test and if its rings won't it smoke badly out the exhaust ? The rings have been in the back of my mind as i dont think they've ever been changed Should mention that I premix my two stoke, two caps to a full jerry can. Too much or too little thanks again for the help everyone

And could someone explain plug chop as I've never heard the term thanks

.................and if its rings won't it smoke badly out the exhaust ? ............

Its a 2 stroke, if it were a 4 stroke that might be the case

Its a 2 stroke, if it were a 4 stroke that might be the case

Any noise I should be listening out for and how will rings appear if there worn ?

the easiest way to test the rings is a compression test in the first instance, if compression is down you would strip down the top end and examine the wear of the rings/bore/piston etc

You need to be systematic with these things. A shotgun approach (tinkering with everything in the hope you get it right) rarely works.

First things first. Clean the carb. Check the jet sizes and float height. Reset all to standard settings and jets. Get 2 new spark plugs of the right specification.

Adding a big one exhaust and a different air filter will affect the bike and normally I would say you need to jet up (bigger pilot/main jets) but until you have a proper place to start you won't know.

As Airhead says, can you do a compression test or not? Does the use water? Why are you pre-mixing oil?

You need to be systematic with these things. A shotgun approach (tinkering with everything in the hope you get it right) rarely works.

First things first. Clean the carb. Check the jet sizes and float height. Reset all to standard settings and jets. Get 2 new spark plugs of the right specification.

Adding a big one exhaust and a different air filter will affect the bike and normally I would say you need to jet up (bigger pilot/main jets) but until you have a proper place to start you won't know.

As Airhead says, can you do a compression test or not? Does the use water? Why are you pre-mixing oil?

You need to be systematic with these things. A shotgun approach (tinkering with everything in the hope you get it right) rarely works.

First things first. Clean the carb. Check the jet sizes and float height. Reset all to standard settings and jets. Get 2 new spark plugs of the right specification.

Adding a big one exhaust and a different air filter will affect the bike and normally I would say you need to jet up (bigger pilot/main jets) but until you have a proper place to start you won't know.

As Airhead says, can you do a compression test or not? Does the use water? Why are you pre-mixing oil?

I understand I need to be systematic in my approach to finding the problem. Cleaned the carb out its set at standard on all fronts, I had the problem before I changed exhaust and air filter they were both changed due to them being in extremely bad state,(cracked, holed, split). And understand that I will have to rejet it due to this even though the problem hasn't got any worse

No 2 stroke tank so have to premix, yes it uses water and will be doing a compression test when I can get my hands on one or the money to buy one

If it's using the water then perhaps it needs a new head gasket and the head will need to be checked for warpage