Why put a bigbore on a 155z/160ho over getting a 175cc engine?!

[rach88]

Okay, I always ask this question and no one gives me a good enough answer...

Why would you get a 155z/160ho engine and put a big bore on it to a 177cc or 184cc which needs rebuilds ever ten hours and isn't as reliable as a zonge 175cc? Wouldn't it be smarter to get a the 175cc in the first place so you have less issues and a more reliable bike?!

Plus watching the guys at the races the guys on the 175cc keep up fine with the guys on the 184cc and 177cc... Like Coolie kicks some arse on his 175cc over kids with 184cc... I just don't get it and I want answers!!! lol.

Cheers in advance

 

[sean01]

what makes you think the zonger 175 is more reliable.. there not..

to me the engine is an odd ball, no real thought went into it lol (as most chinese things haha)

iv seen and used the same bore kits as on the 175 but bigger and trust me there not reliable..
3 out of 3 worn the chrome off the bores within 20 hrs..

and not to mention they have pathetically low compression, about 5mm down the bore on the kits we used.. dont get me wrong they performed awesome but i thought theyd perform better..

and the zonger 175 isnt really a zonger 175, its not a factory zonger engine at all.. its just a 155 with a bore kit.

so really i think the question should be.."why the fook have the Chinese used a 63mm bore kit when they could of used a 64mm kit and made everything compatible"

im pretty sure people are getting well past 10hrs out of there TB kits too.. but even so its only a set of rings...

and you think about it, 10hrs is basically every second oil change. doesn't add up.
i bet tims engines have well over tht and probly running on the original build..

while im on the rings, where and who has replacement rings and gaskets for the 175 engine?
im sure cini does but who else lol.. DHZ sell the engines but no listing on top end spares..

another downfall is the 175 piston isnt straight up compatible with a V2 head so valve clearancing maybe be an issue for some people. and TB dont do a 63mm piston..

lets talk cams lol... i wonder what there running. cause the 160HO engine runs a decomp cam but im pretty sure the 175 doesnt.

adding the size of the engine ie: bore kit. actually makes the specs of the cam smaller so if your adding CC's then you should be adding valve lift and duration as well as closing the lobe centers up...(probly lost most ppl with this info but oh well)

i wouldnt mind if someone could post the part number of the cam up..

now believe it or not but a z155 with a v2 would smoke a 175 with stock head any day..

the rest of your post is all up to rider ability and has nothing to do with engine size apart from the power to weight..

oh and there not 175cc but whats 4cc (171cc)

theres no way that VVV piston is going to like a 30mm V2 inlet valve lol

YX/GPX 172CC ceramic cylinder kit YX172CC engine,YX172cc big bore kit,GPX172cc,172cc cylinder for YX160,YX160 big bore kits,YX160 172CC,GPX160 172cc [S2624] - US$120.00 : Alexwarehouse Industrial LTD

ill add more info as i come across it lol..

 

[DHZ_XR8cing]

my mate is getting a 175 engine for his X4r and I cant wait because my V2 160 is goin to smoke him..
Big bore bikes gain a bit of extra torque but lose a bit of top end.

 

[rach88]

Okay so why am I having no issues with my 175 as a noob and all the people around me having no issues with there 175s... yet all the people at the ride days with 155z and tb heads are constantly complaining there engine is screwed? Lol. Like why is it any different then, why don't I need to rebuild my motor as often as they do?

Just brought it up as after putting the BBK on my old rx I wasn't keen on doing it again to a different bike as any 150cc killed that bike and it was meant to be a 146cc, even when it had the oko.

But I have been told before its just a factory bbk on the 175s(171cc ), but yeah just feel like it keeps going and going! Oh and I guess my 40kgs to the 175cc probably is an advantage to a fatty on a 184cc for me lol.

 

[rach88]

Oh and I know you probably answered what I asked above in your first post... but like dumb it down for me... lol

 

[sean01]

a lot of things have to be taken into account with these other engines you talk about..

were they assembled properly, are they looked after service wise, are they tuned properly and lastly how clean was their assembly environment..

a rich or poor tuned carb will lower the engine/ring/bore life dramatically.

and rach the bore kits are not a factory bore kit... CHP or JJC or who ever the china factory is assemble them in there factory...

so really there is no difference apart from the bores quality and the build environment.

as for your 146cc, was everything checked when assembled? like compression, cam upgrade, did it have a big valve head.. blah blah blah..

oh and sorry but its pretty hard to dumb down lol

heres the kit from CHP site CHP TURNING 175cc BIGBORE Ceremic-cylinder Kits - Upgrade Parts

 

[rach88]

Yeah I just dunno the right wording, but like I understand it's still a bore kit put on the engine, just saying it comes outta china with it on. Rather then like someone here putting it on once they have the bike. Lol if that makes sense :S

But then other question why do the 184's "smoke" the 171? Plus is there much difference in a 177 to the 171?

 

[wogtaz ryder]

Probably because everyone that gets a 184 or 177 kit uses a V2 head , which kills the 171's stock head

 

[pbk]

i dont think there is much more to explain than what sean

but also alot of it is the rider most people cant ride there bikes to the full potential and decide to throw bbk's and performace heads on it not thinking there probably gonna ride slower than before because they dont know how to use it and then think they can compensate by putting a tall gearing on but instead you burn clutches

 

[sean01]

yeah i know what you mean about the factory bore kit now...

well are the 184's (177 on a 155 engine) assembled with a V2 head?

V2 head adds more performance than what a small bore kit does..

and also the 184/177 kits run a short piston so there is less friction in the bore (rev faster), but less engine life (maybe this is what they complain about but its not as bad as they are saying).

full skirted pistons and bores should be used for people that want a longer lasting engine..

also id like to ask how you find these 175's for valve bouncing? 155's are shocking..

 

[rach88]

Vavle bouncing... well I have no issue as I don't even use 4th gear... far too slow! ha ha. I will ask coolie or ando next time I see them.

But yes, my little brain is starting to understand now... like I am getting to understand the piston purpose, then there is the bore and the head yeah? so you could have one bore on but use a different head yeah? so possibly people don't always have the exact same set up?

 

[sean01]

yep your slowly getting it..

an engine builder will do a lot more as basically people just buy and fit lol..

 

[The_GDFP]

Sean nailed it, Builder vs Assembler. The 63mm kit has an $18 Alibaba-sourced piston. TB has gone back to a somewhat longer piston and skirted cylinder on the 64mm kits. I'm sure I wasn't the ONLY one griping about the short piston and thus life span. As soon as the skirt on a slipper piston shows ANY wear, it can rock, setting the rings away from flat on the wall and losing seal. They'll also either hit the head from rocking, or you put it together too far in the hole for good quench when new. A Swede buddy has the equipment to measure cams accurately, and found, as I did with the old degree wheel and dial indicator, that the roller heads aren't using their theoretical advantage of ramp speed.

63mm stock, and cut for V2 head, still a bit shallow, as valve float contact shows:

What I use for 66mm builds, when price is a factor. Smoothly radiused dome. Ignore 111cc markings. Engine is 104cc bigger than that...

Slipper/short skirt, long unsupported pin:

Cheapie vs "Legit" forged race piston:

Uses shorter, lighter, stronger pin:

Intermediate-length skirt, clears stroker cranks, provides plent of support:

 

[The_GDFP]

The reason most of the kits are 63-64mm or a cut skirt is because the case bore is too small for any bigger spigot. As-shipped... As long as the engine is being "built", the cases are likely to be split for trans and drum end-play setup (so they shift decent), you might as well punch the cases bigger. No?

Wimpy:

Hefty:

Crazy:

 

[pbk]

The reason most of the kits are 63-64mm or a cut skirt is because the case bore is too small for any bigger spigot. As-shipped... As long as the engine is being "built", the cases are likely to be split for trans and drum end-play setup (so they shift decent), you might as well punch the cases bigger. No?

um.....???

you reckon you could explain that for people who dont have huge mechanical knowledge like me lol

 

[sean01]

the TB 64mm kits run a short piston but the 63mm china kit runs a long piston, so this would be the only way that the 175's last longer apart from the reasons iv said above...

but i have no idea why TB didnt use a longer piston, the bore still has a spigot.. TB 184cc Big Bore Kit - GPX-YX160 - DHZ Mini Moto

im not a fan of the skirtless bores and pistons for this very reason..
i would always prefer to bore the cases and put the correct length slug in there..

i quickly measured up the pin offset on one of those china pistons (alibaba as FPM call it) the other day and it appears that the notch in the top of the dome is on the wrong side for a yx/zonger engine.

the notch is spose to face the spark plug when installed in its original engine but needs to be facing the opposite side in the yx/zonger..
this will cause some drama's to anyone not paying attention when building/rebuilding there 175.. (theres no other markings on the top of the piston)
the damage will result in a bore that will last less than a skirtless piston setup.

ill have to remember to remeasure it and confirm..

 

[The_GDFP]

um.....???

you reckon you could explain that for people who dont have huge mechanical knowledge like me lol

LOL. The hole's too small part? Or the fixing Chinese production tolerance variation part?

 

[The_GDFP]

the TB 64mm kits run a short piston but the 63mm china kit runs a long piston, so this would be the only way that the 175's last longer apart from the reasons iv said above...

but i have no idea why TB didnt use a longer piston, the bore still has a spigot.. TB 184cc Big Bore Kit - GPX-YX160 - DHZ Mini Moto

im not a fan of the skirtless bores and pistons for this very reason..
i would always prefer to bore the cases and put the correct length slug in there..

i quickly measured up the pin offset on one of those china pistons (alibaba as FPM call it) the other day and it appears that the notch in the top of the dome is on the wrong side for a yx/zonger engine.

the notch is spose to face the spark plug when installed in its original engine but needs to be facing the opposite side in the yx/zonger..
this will cause some drama's to anyone not paying attention when building/rebuilding there 175.. (theres no other markings on the top of the piston)
the damage will result in a bore that will last less than a skirtless piston setup.

ill have to remember to remeasure it and confirm..

TB discontinued the short skirt piston in my photo, and your link pic. It was pretty much a chopped version of their "old" and now "new" again unit. The chop-job was for KLX's and non-bored cases, spigot-less cylinder. Also discontinued. The current one looks very similar to the $175 Wiseco forged one shown. Mike hasn't updated the site photo, nor has DHZ, it seems.

Honda Trail Bikes
See June 28 updates.

Interesting aboot the pin offset. I'd assemble it with the plug notch correct and let it slap a little, if running one.

 

[Hillz]

Cheapie vs "Legit" forged race piston:

Uses shorter, lighter, stronger pin:

now thats what im talking about! forgie vs cast everyone who wants a big engine should be using the forgie

 

[sean01]

TB discontinued the short skirt piston in my photo, and your link pic. It was pretty much a chopped version of their "old" and now "new" again unit. The chop-job was for KLX's and non-bored cases, spigot-less cylinder. Also discontinued. The current one looks very similar to the $175 Wiseco forged one shown. Mike hasn't updated the site photo, nor has DHZ, it seems.

Honda Trail Bikes
See June 28 updates.

Interesting aboot the pin offset. I'd assemble it with the plug notch correct and let it slap a little, if running one.

we purchased and fitted a 64mm kit last week. (purchased from DHZ)
it definitely has a short piston and the spigot of the bore isnt as long as a genuine bore spigot but still could accommodate a longer piston.
theres still a good 20mm of the bore than doesnt get used..

actually heres a pic of one which is about 12months old. cactus due to bad assembly lol