Kx piston to Pe

[oldfart]

I have been asked what mods I had done to fit a KX 500 piston into my Pe 400

picture should say it all

[Grunter215]

Hey Oldfart, so hows the PE go with KX piston. Notice much difference. What carb setup ya running. I did same awhile ago,runs good but still sorting stuff out.

[maxvmx]

I would be interested in some tips about jetting as well, I'm using a RM 465 piston in a PE 400 motor and I'm still trying to get the jetting the way it should be.
John.

[oldfart]

Now that the top is sweet the bottom end needs a bit of attention ( new mains bearings )
With the jets   main = 310
                    pilot  = 50
                    clip down one from centre
Also it needs more fuel in the bowl ... so have set the level 1mm higher. Tip - also open vent the tank , as i have found it doesn't let enough air in when connected to pe handle bar thingy  ma bob

I run a paper thin head gasket - and std size base gasket       

[maxvmx]

I'm using a 320 main jet and although it runs reasonably well low to midrange, it pings its head off at full throttle! When I try to get that right by moving the needle clip down one, the midrange turns to mush again. I am using a KX fuel tap on it which has the bigger fuel line diametre, but I think it still starves itself out dry when youre giving it to it.

[oldfart]

Hence the reason why I have raised the fuel level in the bowl . STD should be at 10-2 to 11-2 measured at the jet body ( remove the jet ring ) to the the float  tang .....make sure that the spring loaded neddle is not compressed ( just touching is preffered ) measurements as per book with gasket removed

Best results are to secure the carb in a vice on it's side makeing sure the float pin is secure -

I have mine at 12-2 mm  ..... just dripping out of overflow when motor is not running with gasket on , so in effect I have mine set at 13-2 

Try the lozza tune method and it works .... run it at full throttle in top gear - pull the clutch in and hit the kill switch ....then check your plug

[maxvmx]

Thanks for the info, I'll definately check the float level, that's one I haven't thought about tinkering with. What I am wondering about is the exhaust port timing being altered by raising the barrel 5mm as is the case with a 465 piston. The conversion I have done on mine was highly recomended, but I don't know if it was as a performance improvement or just a way of getting use out of a worn out second oversize bore? Has anybody ever got one of these running crisp? What's involved in fitting a KX 500 piston anyway?

[oldfart]

As the pic indicates KX std piston is on RHS showing trim line  - PE piston is in centre - trimmed KX piston is on LHS

Trim the skirt on the KX piston so as to be the same as the PE .... ( view the pic and pay attention to pin and just above top ring hieght )

I have had a gig made up and had the Kx piston PIN  milled out to 20 mm the re groved to take the circlip.  Previous to that I had a crowed roller set up with Hardened steel washers as spacers between the piston and rod ( 1.5 mm either side x 19mm ) approx 2 seasons racing on this set up and no sign of wear on pin ( washers )

New set up uses PE pin and roller with thrust washers at the piston .
 
Yes I had contemplated the 465 piston set up ..... The kX gives me a lot more re bores 

[Mutch]

Just make sure its still going when I turn up

[Grunter215]

Thanks for info Oldfart.I need to get more compression so was going to use thinner head gasket aswell but was told it could blow out easier. I take it you havent had any trouble? Should i shave head+use std gasket. Any thoughts.

[Quicksilver]

Will this trick work in RM465 Stew?

[oldfart]

Bore on 465 is larger      ....much larger .    First you need top pin size  then bore size, check thru serco catalogue for a match or give  BB imports a buzz