avenger kohler engine issue, help please

[Diverdave]

Hi All
My avenger 700 is playing up. Basically it is not starting well, with loads of back firing and rough running when it eventually starts, though eventually it will start and when running is ok, though down on power. The problem is intermittent, though happening most of the time. It appeared to happen after a bit of a bash whilst in the hills.
We have checked the exhaust, as we were told it can break down, but it is fine. We have checked the push rods, and they are straight. Carb and solenoid all appear fine.
Plugs are oily, but it has been starting and stopping on the choke so i think that is ok. So it sounds like it is an ignition module breaking down. I have a spark tester coming tomorrow and this will help confirm it is spark related. Does this sound like i am going in the right direction?
Firstly has anyone the part number for the modules, as ebay has loads, and they are way cheaper online than the UK dealers. Is it possible to change the ignition modules with the engine in? It looks like if i remove the radiator i should have reasonable access to remove, set and replace them. Is there anything else i need to check or consider? Fuel is new, carb has been cleaned out and was perfect anyway, filter is new, airfilter is clean, and after the bash it ran a little more rough all the way home and then the difficult starting started. It has been a superb starter, and even after the bash when it eventually started it ran for hours and pulled really well, it just had a perception of running slightly rougher.
Any help very much appreciated.
Dave

[ARGOJIM]

I'd start with new plugs.

[actionpaintball]

While you have the plugs out...do compression check; this will tell you the integrity of the valves and rings.

[Diverdave]

Thanks Guys
The plugs are new, probably 2-3 months old but we can change them again. I will do a compression check.
Does anyone know if the ignition modules can be replaced with the engine in and if so does anyone know the module part numbers I think i have found them but want to confirm.
cheers
Dave

[ARGOJIM]

Are you calling the modules the pick ups or the coils? Coils are easy, pickups are a bit more involving needing radiator removed.

[reichstall]

Another thing That fits a little more along the line of what you describe . I think you may have a valve starting to stick. This is caused by fuel problems heat or a couple of other things. The leak down gauge would help more than a compression gauge. If it comes and goes it is the start of it. it will not get better some cleaners claim to fix this. but for me it is just take it apart and do it right. Hope this helps.

[Diverdave]

Thanks All. I put the old plugs back in, and it helped a little. So i cleaned every electrical connection i could reach, inc the one on the coil packs. I started taking the radiator out and realised it was going to trash my bad back and decided it would be engine out to do this right, and i would pay for this. I re cleaned the carb, and replaced the plugs. It now runs well enough, though i think it is too rich, just a little but that is a job for another day. no obvious way to adjust the mixture on this carb, and the various manuals says it could be float or main jet. Main thing is it is starting and running well and that should keep me going next week.
cheers

[ARGOJIM]

Recently I had an issue with my 23 Command in the Buffalo, runs the same carb, my issue was the float needle had a build on it, just enough it would not slide freely so I wire brushed it clean and good to go. Do not use carb cleaner on rubber parts.

Unless you are convinced it electrical and or the carb has an accelerator pump, try to lube the linkage on the pump as I also had this issue on same carb.. This blasted gas is just one headache over another.

[racerone3]

Sounds like a valve adjustment issue to me.

[ARGOJIM]

Sounds like a valve adjustment issue to me.

Hydraulic lifters.