Any room for improvement in this setup? E50 Magnum XK

Andrew B /

andrewbk

Jun 04, 2019 01:02PM

As per the title, here's what I'm looking at.

Magnum XK

15mm bing (2nd richest needle, 2.17 atomizer or whatever it comes with, and 78 jet)

MLM 15mm intake

Metal mesh filter

3 shoe OEM clutch with "ESO" springs turned 2.5 turns in from flush (no fish scale)

Estoril pipe (modded to fit)

15x40 gearing

Stock 2hp hi comp head and cylinder (no head gasket)

Performance wise the bike runs well. Turns over easily, no air leaks, idles fine, etc. Clutch slips until around 3800-4000rpm and the butt dyno tells me it slips until around 15mph or so. Low end is still pretty meh unless i pedal a bit. Midrange is good and the ped tops out at around 35ish on the flats. I weigh around 180lbs.

I have a feeling the bike may be a bit lean in the lower rpms and rich up top. At speed, if I go full throttle it starts to bog and will die / foul the plug if i keep it pinned. Runs fine at 90% throttle.

I'm wondering if I'm missing something and there are a few mph left to squeeze out of it or if I should leave it alone and

be happy?

not interested in any kits at the moment. Thanks ya'll

Andrew (edited)

Re: Any room for improvement in this setup? E50 Magnum XK

Totally normal JBOT /

capturedbyrobots

Jun 04, 2019 01:15PM

Duh your main jet is too big.

Drop jetting until you can wot all day

Re: Any room for improvement in this setup? E50 Magnum XK

Probably Fred /

roffman

Jun 04, 2019 03:19PM

Main jet sounds good for 78 is about par for the 217 atomizer (you could try a 77 jet and or or different needle clip selections) but you need to dremel open intake hole on cylinder to around 16mm,

notch piston skirt for full open intake @ tdc, sand or mill the head head ring and tabs flat, base space cylinder at least 1.5 mm bevel piston sides a bit more for full open transfers @ bottom dead center, 18 degree timing

Do this and your carb settings will probably match better and you will hit about 40mph

With the mods I just said but with stock 12mm carb and stock pipe with just a 5/16 hole added to inside and end cap I get 35-40 mph with my 200 lb

Re: Any room for improvement in this setup? E50 Magnum XK

Andrew B /

andrewbk OP

Jun 04, 2019 05:30PM

> Ken Roff Wrote:

> -------------------------------------------------------

> Main jet sounds good for 78 is about par for the 217 atomizer (you

> could try a 77 jet and or or different needle clip selections) but you

> need to dremel open intake hole on cylinder to around 16mm,

>

> notch piston skirt for full open intake @ tdc, sand or mill the head

> head ring and tabs flat, base space cylinder at least 1.5 mm bevel

> piston sides a bit more for full open transfers @ bottom dead center, 18

> degree timing

>

> Do this and your carb settings will probably match better and you will

> hit about 40mph

>

> With the mods I just said but with stock 12mm carb and stock pipe with

> just a 5/16 hole added to inside and end cap I get 35-40 mph with my 200

> lb

>

Im liable to screw something up when it comes to the porting and machining you mentioned. Also dont have the tools for it and have never done it before. What's your going rate for this magic mystery science?

Re: Any room for improvement in this setup? E50 Magnum XK

Probably Fred /

roffman

Jun 04, 2019 05:46PM

I use use a belt sander 100 grit and then I finish sanding with 800 to 1000 grit paper for the head!

I are use a old Dremel single speed with carbide bit that I got in 1992 to open intake and remove some of metal on the piston skirts and sides of dome,

I use a electric drill to drill a hole in the stock exhaust, I buy a thick base gasket or double them up,

I buy the cheapest timing light at Harbor freight,

I tune the clutch with treats thick kickstart springs

this is all so easy its not funny

On my other magnum xk I run a two speed za50 engine with 74cc gila kit, 24tm carb and estroil pipe, this was not very hard either and was built 10 years ago and still runs great keeps up with traffic on 55 mph roads :

Re: Any room for improvement in this setup? E50 Magnum XK

* * /

countryboy1

Jun 05, 2019 01:34PM

> Ken Roff Wrote:

> -------------------------------------------------------

> I use use a belt sander 100 grit and then I finish sanding with 800 to

> 1000 grit paper for the head!

>

> I are use a old Dremel single speed with carbide bit that I got in 1992

> to open intake and remove some of metal on the piston skirts and sides

> of dome,

>

> I use a electric drill to drill a hole in the stock exhaust, I buy a

> a thick base gasket or double them up,

>

> I buy the cheapest timing light at Harbor freight,

>

> I tune the clutch with treats thick kickstart springs

>

> this is all so easy its not funny

>

> On my other magnum xk I run a two speed za50 engine with 74cc gila kit,

> 24tm carb and estroil pipe, this was not very hard either and was built

> 10 years ago and still runs great keeps up with traffic on 55 mph roads

> :

>

That seems pretty slow for that set up.

Re: Any room for improvement in this setup? E50 Magnum XK

Andrew B /

andrewbk OP

Jun 05, 2019 02:08PM

Seems like a lot of effort for a small improvement in MPH for me. especially since I'm hovering around 35mph+ atm and dont have a belt sander / time for all of it

Re: Any room for improvement in this setup? E50 Magnum XK

Probably Fred /

roffman

Jun 05, 2019 03:03PM

> Andrew B Wrote:

> -------------------------------------------------------

> Seems like a lot of effort for a small improvement in MPH for me.

> especially since I'm hovering around 35mph+ atm and dont have a belt

> sander / time for all of it

5mph plus 2x the take off and hill climbing power is like 1 or more hp

You’re gonna have to live with the set up you got if you don’t want to go any farther but You can buy a 50cc hi comp head at treats, it will give you some more boost but it’s a smaller maxi head not magnum,

You need near 40mph with takeoff as fast as a normal takeoff in a car to be safe on a 35Mph road, barely 35mph with slow take off just don’t work with hurried distracted drivers nowadays

Re: Any room for improvement in this setup? E50 Magnum XK

Graham Motzing /

Go to branch

grahammotzing

Jun 05, 2019 04:47PM

wait what? why not just jet it properly and see what it does. go from there.

Re: Any room for improvement in this setup? E50 Magnum XK

Probably Fred /

roffman

Jun 05, 2019 06:16PM

> Graham Motzing Wrote:

> -------------------------------------------------------

> wait what? why not just jet it properly and see what it does. go from

> there.

That will do nothing to get to the 40 mph! with take off as fast as a normal car takes off That is needed for safe riding !

Mangum cylinders on Magnum xk or any magnum is worth about four or five HP with correct tuning but if you’re off jetting by one jet or timing or tuning of a degree or so you will have a dog!

MOPED ARMY

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