Two Stroke Witchcraft. KX100

[davebike]

Back when I was mobile I would deal with crossers ! Bloody things I put mains and sealls in so often but the one that always got me were the bike I saw diagnosed mains failure and estimated a price "OH I not paying that !"
Next week same bike new owner " I not paying that "
Record was 5 times in 7 weeks same bike !! not counting the three visits to other Mechanics I heard about though the grape vine !!
Completion bikes look great but they need LOTS of maintenance to perform well if at all and unless you DIY it cost lots !
Friends who actually raced 2 strokes rebuilt the engines after most weekends !!

Dave

Dave

[aliengravy]

Bottoms..... It turns out there were two different barrel types between 1988 and 1990...one with large cooling channels and wide headbolt spacing.... And one with narrow channels, and narrow head bolt spacing.
The head i have is narrow, and the barrel that turned up was wide back to square one and the parts for these 1989 engines are like hens teeth......

[Black Sheep Radical]

My current theory's are:
1. Thrashing from cold
2. Wrong ring gapping (apparently sometimes you have to file the rings to the right tolerance?)
3. lean running

What do you guys reckon?

4. It's a 2-stroke

HTH

[aliengravy]

So far I've learnt that old MX'ers can be money pits if you cant get the bits for them...

But the most annoying thing is that there are NO bits for this! So even if it was a case of throwing money at it you cant.... No engines on eBay, no barrels... down to buying a complete bike and then you don't know what your going to get

[davebike]

Now you see why I no longer do full off road bikes
They need lots of parts and non are easy to source
They are built to last a couple of seasons that is all

Dave

[Harry Notts]

Go to default setting: Fit a CG125 engine.

[ll81]

Go to default setting: Fit a CG125 engine.

An old RM125 I used to rag about that needed continual attention to the aged electrics ended up in the hands of some young teenagers who promptly (and very badly) put a CG125 engine in it. It used to rock back and forth and the cylinder head pressed hard against the frame tube under power as it was the only thing stopping the engine from spinning round on it's single mounting bolt.

[Diesel Dave]

Blokey removed the pump 'cos he didn't understand how it worked.

Never rejetted for the added oil volume through the carb.

Used his fave oil inject 2t oil in the tank and it settled out into the bottom.

Then it seized.

Colour me unsurprised.

[aliengravy]

The early kx's weren't fitted with a pump as ll81 said earlier...

[Diesel Dave]

In that case I'm betting on cheap oil and not rejetting for ethanol in unleaded.

You need to upjet by 1 jet size and pay at least a tenner a litre for oil.

Someday I'll tell you about seizing a TZ because the rain dried up and the sun came out in mid race - they can be that sensitive.