I recommissioned a climber 280 a few months back, and it starts and runs ok. I'm more into enduro and figure the climber would be fun for some lite enduro as i'm too old to start learning how to ride over cars etc

 

I'm concerned about snapping the kick start off, the compression is fierce, and the motor too. i'd be happy to tone it down a bit and i think people have done this in the past. My neighbour has suggested make a plate form 3mm copper to go in between the head and the barrel. the water channels and O'rings make this a bit of a challenge.

 

has anyone else done this, or know how it was done in the day ?

 

Yes they are a bit zippy

I think on watercooled bikes people sometimes use two base gaskets instead of one base gasket to reduce the compression ratio if needed. Yes it changes the port timing too but that is what I've heard.

3mm spacer under the head would be way too much anyway. I would think 0.5mm to 1mm would make a noticeable difference to compression ratio

Tipp for starting the bike.

Look up the top dead center then just a bit over and now you have enough engaging space for the momentum needed to start the engine.

When done a couple of times and you get used to it works quite well (at least to me).

I detuned a gas gas JT95 contact (327cc) by making a head gasket. Easy to do if you have a mill (with rotary table) and lathe.

Made mine out of aluminium.

Used the lathe to turn face and O ring grooves, then bored cylinder hole, and carefully parted off at 3mm. Note keep tip clear to get a good finish.

Next, on the rotary table and do the porting. This could be done with care on a drill press and file to make the slots, just more time needed.

 

The 3.5mm made the bike way more tractable when pulling from low revs, (much smoother, heaps more grip) and really didn't notice much drop in top end. Also I don't have to use 98+ octane anymore as it no longer knocks.

I ride in a grade that can see up to 1m high rocks,banks,logs fairly often, just to give a sense of previous statement.

I also used to have a 280 climber, great bike for tight trail rides, loved the power.