Stiffer valve springs and Porting

[mitch_cats]

Hi everyone,
below are qeustions about the title^^
1. does anyone know if any of these springs would be any stiffer than the ones on my zonger140. AKUNAR MOTORCYCLE CAMSHAFTS , or any suggestions what spring and cam setup should i have to improve my bikes performance and where i can get this setup.
2. Do i even need a new camshaft if i do get stiffer springs?
3. What will i need to change the valve clearances to if i do get new springs?

(Porting)
4. Is there anywhere i can get my head ported in melbourne. i saw that they do it at AHP... too bad there american but its 95 bucks there so im hoping to get it done here for something under 150 (or something like that).
5. would someone be willing to do it on here (dont worry i'd pay good )

Thanks mitch.

 

[The_GDFP]

Yes, Akunar has some stiffer springs that will keep you out of float longer. DrATV in the States has a Z40 cam and springs that add good top end. Trail Bikes 300 is good, all around. Honda ATC125 inners with the stock outers will allow plenty of revs, if your dealer can get them. If you go with Akunar, grab a 28/24 valve set as well and have ports opened to suit. At least the intake valve. Does wonders up top on the BVH. Mark's $95 port job is more of a clean-up, but I'd bet there's an Aussie able to do a bang-up job.

 

[bulldog93]

These blocks have great aftermarket preformance parts:
- Classic Honda 50's Australia

You could port it yourself. All the info is in here:
- http://www.miniriders.com/motor-tutorials/6959-porting.html

Sean01 might be able to port it for you. Give him a PM:
- Mini Dirt Bikes & Pit Bikes Forum - View Profile: sean01

 

[sean01]

yep akunar springs are good, i use them all the time.

port work isnt a problem if you want to send me the head..

i can order and fit the new springs for you too. (and a cam if you want)

valve work isnt an issue either, a set of akunar valves and i can get all the machining done.
all depends on how far you want to go. but usually id recommend valve springs, port work and a 26mm oko carb kit (96mainjet and 36 pilot)

pics of a zonger140 i did a while back (pics are a bit shtty tho)

 

[mitch_cats]

YOU ARE A GOD SEAN!!
i'm really need that extra performance to keep up with my mates on there jap Jap 250's (even if theres are only farm bikes)
ill just have to see what weekends im going way riding over the next few weeks before i get anything finalised with you.
Do you reckon a new cam would be a worth while investment?
how much would you want for the job?
And dont worry about the carby ill do that myself as i dont think i'll be able to afford that aswell as the other stuff.

Thanks so much guys and sean
mitch

 

[sean01]

yeah cam would be good.. as for keeping up with ya mates jap 250's (mx'ers im guessing), well you'll still have trouble. but you wont need to ring its neck so much..

price wise depends on what actually gets done. but as a guide.. complete disassemble, port work, assemble with new parts or old parts you'd be looking at around $130-140 (plus parts)

pm Jamie from classichonda50's to see if he has the tb300 cam and springs to suit..
also ask if you need a new cam gear.. some are 2 bolt some are 3 bolt. do a tooth count on the cam gear too because these can change..
but if you feel its all too much for you i can order everything..

 

[mitch_cats]

Hi Sean,
pm'd Jamie and had all the parts you told me to ask for but he wasn't sure if it would suit a zonger 140. He also needed to now the installed spring height. Do you know? if not i'll find out.
And don't worry sean there only farm/fun bikes so hopefull now I definately wont have to slow them down to much anymore
Thanks Mitch

 

[sean01]

remove the cam cover from your engine (1 long 10mm bolt) and shoot jamie a pic of the cam, that should give him a good idea..

installed height would be the same as a yx engine.. i havent got a good enough sample here to measure..
maybe terry will jump on and let us know..

but if you want to measure it yourself you need to strip the head and reinstall just the valves and spring retainers then measure from under the retainer to where the bottom of the spring sits...

but lol im guessing this is all too much. i can work it out for you if you send it up..

 

[mitch_cats]

Thanks sean,
willl take photo and see if jamie knows the spring height of the yx's.

It probably would be easier for me to just send it to you but im trying to keep you from doing too much work and also the more i play round with engine the more i'll learn.

 

[ClassicHonda50]

Installed Spring Height

Hi Mitch

Have some YX heads laying around, will measure the spring heights in the morning.

Check cam size: Uses NTN bearings, 42mm large bearing, 28mm small bearing, Approx 70mm center to center.


Cheers

Jaimie

 

[The_GDFP]

All of the 27/23 type heads, Lifan, Zonger, YX that I've seen have very similar installed heights and use the same springs. Inners are the weak link, but they'll likely come as a set. Stock cam may look completely different, using the inner set of races on the head, but again, they're typically machined for either type cam. I set heads up differently than some, but shoot for about 27mm of stem tip to inner spring seat length. Then I use the adjusters to see that I'm 1.5mm or so from coil bind at the cam nose, shimming as needed to get there.


You'll almost certainly have to swap the small end bearing for the 32mm unit on the stock cam (seen just a few 28mm) and to swap to a 32t 2-hole sprocket. TBW9004 will be the correct part number for the package deal.

Stock cam should look like this, possibly a slightly different 3-bolt pattern:

My fingers are too fat, so I have my apprentice do most of the assembly.

Nice looking orifices, Sean I leave 'em a little rougher, but different tweaks for different freaks is my motto. There's lots of ways to skin a Wombat.

 

[mitch_cats]

thanks gdfp
but unforunately sean...
i just went broke. turns out i owed the oldes some money plus i was invited to the air show, and despirately need new boots before i do anything. So ill have to post pone the job.
but dont worry im going for a job interview tomorrow so... :grinning-smiley-003

 

[sean01]

no worries mate, just give me a pm when ya good to go..