YX 160 cam upgrade worth it?

[DvDRip]

I've been reading around a bit about cam options for a stock YX 160.....
It seems that the stock cam is already quite good and cam upgrades don't have much to offer.... is this true? all I found on ebay was the pitster decomp cam kit, and akunar I still need to email them to find out what this means:

YX150/160 (Smaller lift cam better in std Bore Engine than stock Cam)

CAMSHAFT 6.50mm Lift

I know a good cam works wonders on the yx140 but is it the same case for the yx 150/160? I mean like would a good cam from someone like akunar have a big impact on the stock 160 like it would to the milder engines...

links would be good

cheers guys

 

[sean01]

anything other than a stock cam is pretty much an improvement..

standard cams have a horrible profile... lobe centers are to far apart...

i would definitely email akunar... he will tell you the ins and outs regarding what is better or worse..

 

[wogtaz ryder]

Well the best cam for my old klx was the Yx cam ... its the biggest out there for the klx style heads... is what i have heard.

But yes.. bigger dont mean better

 

[no_crf50_here]

i'm not altogether sure if this cam fits the XY 160 but Akunar sent me this one for my GPX160 Right is stock cam, left is new one..

 

[DvDRip]

ok cool... seems I have been mis-informed
will see what akunar have to say

cheers guys

 

[sean01]

well if the chinga's are doin there job properly, as the engine size increases so should the duration and lift...
thats why you hear people say put a lifan 150 cam in a 125 or 140... the duration is bigger which raises the rev range...

also just by adding a couple more valve spring shims you can raise your rev limit which helps too..
valve float is terrible in china engines...

if cams were more available or if id get off my but and ring ivan tighe cams, i would do away with all stock cams. even if they were stock valve lift but the lobe centers closed up id be happy.

but i also see the sense in upgrading to a decomp cam, you get 2 for 1 deal(better profile and decomp).
altho i think there a little over priced considering how much you can get them direct...

 

[Cactus Jack]

Chinese horizontal motor valve springs are pretty weak compared to Honda XR75 springs ...

Pit bike "race" springs (left) compared to XR75 stock springs (right) :

Pit bike "race" springs (left) compared to XR75 Powroll race springs (right) :

Pit bike "race" springs (left) compared to XR75 S&W race springs (right) :

Pit bike "race" springs (left) compared to S&W XL70/SL70 Horizontal race springs (right) :

A guy from Planet Minis emailed me and told me the info in brackets below ...

[the tb crf head is junk! the seats sink in to the head, the intake valve is to soft,the seals get destroyed by the springs, and the ports are just wrong.it makes less power than my 28.1mm head.just a heads up.

the v2 is definately better but not as good as the tak.the dr.renamed the z40 for whatever reason i dont know.it comes in a generic brown box that has a "OEM motorcycle spare parts" sticker on it stating its for a crf70.the part# is"camshafts,performance".if you search throughout his website you can find the cam for as low as $39.95.(i think its on the home page).he has them on ebay for $50

also,the only v.springs i recommend are oem honda from the ct110/atc125m. the honda springs can handle 7mm lift no problem.the older dual springs from akunar were no good and i havent tried their new single spring setup(ranuka claims they are better).i also havent tried the tak springs due to cost and that the honda springs have handled everything ive thrown at them.the dratv springs do break.the worst springs are the ones from tb.

dave ]

 

[tormentandglory]

Ive got a TB #0304 cam on the way from t-bolt usa. When it arrives i'll measure it up and post the specs. Its been a 3 week wait so far, hope I haven't been burned.
I'm using takegawa +r springs in my yx head. They don't go in without a fight though. I had to reduce the diameter of the flange on the valve guide so they'd fit into the head, then I had to cut 1 1/2 coils off the bottom because they were to long and going solid. They're very closely wound at one end, so its quite safe to shorten them. The retainers need to be turned down to, and after machining they're down to 6grams from 8grams. Titanium retainers are on the way once holidays are over, no lathe at home! The tak inners are no good, I'm sticking with the stock yx inners.

 

[tormentandglory]

I might be getting a set of titanium valves out of an R1 soon, with a bit of work I'm pretty confident they'll go into a yx150. Tech bling!

 

[wogtaz ryder]

Should give Daimojay a msg , he said somewhere he put 450 springs in his V2 i got?

 

[no_crf50_here]

Ive got a TB #0304 cam on the way from t-bolt usa. When it arrives i'll measure it up and post the specs. Its been a 3 week wait so far, hope I haven't been burned.
I'm using takegawa +r springs in my yx head. They don't go in without a fight though. I had to reduce the diameter of the flange on the valve guide so they'd fit into the head, then I had to cut 1 1/2 coils off the bottom because they were to long and going solid. They're very closely wound at one end, so its quite safe to shorten them. The retainers need to be turned down to, and after machining they're down to 6grams from 8grams. Titanium retainers are on the way once holidays are over, no lathe at home! The tak inners are no good, I'm sticking with the stock yx inners.

Tbolt suck! payment too Posting 6 days then 12 more to get here. And their second order was slower!

 

[Cactus Jack]

Postage from the US has been painfully slow lately ... I buy from all over the place over there ... Certain areas are snowed-in ATM ... but most people are just still in Christmas holiday mode ...

 

[Cactus Jack]

Stock XR75 springs (left) ... S&W (Smith & Wesson) XR75 race springs (right) :

A few of the springs I've collected ...

Pit bike "race" springs (AKUNAR) are like piss weak toys which can be compressed in one hand whereas XR springs can barely be moved ... I'd say the chinese use weak springs due to their weak stock valve stems ... one piece stainless steel valves would be far better to use with decent springs ...

With Titanium valves you can't run strong springs and you need to run soft Beryllium-Copper or ductile iron valve seat inserts or they'll chop out pretty quickly ... Titanium is soft and is really a short lived race only material ... Drag cars with Titanium valves have their clearances checked and re-adjusted on every single run ...

The Ti valves used in MX bikes are coated with an extremely thin hard facing material to allow them live longer ... but once grit abrades the coating off they last 2 seconds ... Stainless steel and standard valve seats are far superior for everyday riding ...

CRF Heads

Del West Engineering - Valve Seat Inserts

Bundy Sales-Nickel and Ductile Iron Valve Seat Inserts

 

[tormentandglory]

My TB #0304 cam arrived today after a full month of waiting. It has about 0.5mm less lift than the dirtmax 150 cam that I wanted to replace, and at first glance, the TB cam appears to have less duration to. I'll stick a degree wheel on it and sus it all out, and post the timing figures for both cams.

What cams are other people running in their yx's? I know there are a lot of V2 setups out there. I've never seen a normal head yx with a hottie cam running before.

 

[Cactus Jack]

Sometimes smaller cc single cylinder engines perform better overall with a lower lift , shorter duration cam because they give a broader torque curve with better bottom end pull ... As you start going bigger in cams , you really need a bigger bore , stroke or more gears that are closer together to keep the engine revving in the cam's power range ...

 

[tormentandglory]

Well I should have checked the stock cam before buying a new one!! I loaded both cams into an engine tonight and measured them.

Tb #0304 cam

inlet
lift - 6.35mm
duration @ 0.020" lift - 245deg
duration @ 0.005" lift - 309deg

exhaust
lift - 6.47mm
duration @ 0.020" lift 248deg
duration @ 0.005" lift 340deg

lobe separation 123deg



Stock dirtmax yx150 cam

inlet
lift - 7.55mm
duration @ 0.020" lift - 263deg
duration @ 0.005" lift - 297deg

exhaust
lift - 7.55mm
duration @ 0.020" lift - 269deg
duration @ 0.005" lift - 332deg

lobe separation 117deg


I like the stock cam better, more lift, faster acceleration, smaller lobe centre angle. Spec isn't much different to the cams in the V2 heads.

 

[no_crf50_here]

That cam i posted the other day was fitted today in my TB V2 Head and it's NOT suited to it AT ALL, Valves touched when it was tuned over!! Exhaust valve needs to be 1/5-1 mm smaller

Back to std cam

Cams for roller rocker (V2) heads don't seem to work for STD heads and vice versa.

 

[tormentandglory]

Yes, thats right! They're not compatible at all. V2 heads have the rocker shafts located in different spots, and the rocker arms are a different ratio. You could run a stock type cam in a V2 head, it would run badly but not destroy anything (maybe) but a V2 cam in a stock head will trash everything!

 

[DvDRip]

now we're getting somewhere, cheers tormentandglory

Cams ain't cheap and it's hard to much info about the one's available, there's very few reviews and the people selling them give hardly any info on specs or what the cam is supposed to achieve.

 

[tormentandglory]

now we're getting somewhere, cheers tormentandglory

Cams ain't cheap and it's hard to much info about the one's available, there's very few reviews and the people selling them give hardly any info on specs or what the cam is supposed to achieve.

Yeah its hard alright. I've been looking for a while and all people say is that their cams are "full race" or "awesome" or some crap like that. I was told that the dirtmax engine I bought had a bigger cam than other yx's. I'd like to get my hands on a cam from another supplier of yx and measure that one to.