Diffrent engine cases

[DustyFork]

Hey all I gotta get a new LHS engine case for me yx 160. Anyone know if there's differences in them? I read a post in hear a while back where someone got a new one and put the motor back together and had shifting problems. What I remember is it came down to a casing mismatch. Anyone shine some light one the subject or have a case up for grabs?

 

[my67xr]

sorry cant help.
i don't remember seeing that posted anywhere here.

as far as i know the only different case for the 160's was the r/h centre case, the early standard roller bearing, or the late needle bearing case

i haven't found any good used r/h centre cases yet either, i still need one too.

 

[DustyFork]

I thought I put it out there. What I remember that sean01 was in on the conversation and it all started with a shifting issue. This was back in 07 I think. I'll hunt it down tonight if I can find it. Looks like I'll just get one from small wheels and hope all goes right.

 

[zwebx]

usually when high quality engines are machined the final cut is done with the case halves together to ensure the shafts are running true.. (aka matched)

the shifting issue could be because he did not shim his new gearbox to the other case.. common may even happen when just splitting case to do eg crank bearings

 

[Phil67]

Yes, not shifting right in a new case is all about the shimming. Took me about 5 goes at it to get it right. Never put a shim on the left side of the gears if you can. Another issue is using the wrong amount of shims on the clutch basket, that can pull the shaft to far to the left and it will jam. My stock basket used 2 shims, but the TB one only needed one, when I had 2 in there the box would just jam up. You have to get it right or even simply laying your bike over to one side, the right side usually, it will go in gear by itself. I've run mismatched cases for about a year, and am about to put a different case on the right side and I'm sure it will be fun sorting out the gearbox!
I also don't think the left cases are different at all, only the rights have a few variants.
Do you know if you have a gen III engine? Roller bearing case?

 

[DustyFork]

Zwebx I recall that was mensioned in the discussion about the final cut done with cases together. What I thinkin too is these are china engines a tolorences can vary a lot. I don't know much about bottom ends but I'm having a play with it and see if I can get a new case and figure it out with me mate who build industrial machinery. I wish there was a video tutorial on how to rebuild a bottom end so if you guys out there wanna make one it would be appreciated by all. I fact there's not to many videos on youtube that I've found that go into detail into rebuilding these engines or more complex upgrades or repairs. It takes a lot of research and trial and error to get things spot on instead of wacking it together and she'll do.
I have a roller bearing RHS. I just got all new bearing except crank bearing but they seem fine. Any thing else I should do while I v got the bottom stripped down. Anyone know where I can read some more info about rebuilding the bottom end?
There a good clip on you tube but it's quite fast of a bloke who builds a yx from ground up and has a manual to work from. Only thing is its in a diffrent language, I think spanish

 

[Phil67]

I don't reckon it matters about this final cut stuff, like you said its China, I doubt they match cases at all, they would have bins and bins of left and right cases the builders just grab from when assembling. Some guys I know leave the centre case gasket out,this tightens up the clearances a bit. You can back cut the gears and weld the shift fork retaining pins in, but that's all wayyyyy too much if you ask me. Just make sure your gear sets and dogs aren't rounded and you may as well wack a new shift drum in whilst you have it apart. Check all the castings in the case, particularly the oil returns, they are often fully closed with casting flaws around the crank bearing in particular. Best method is however it came apart, that's how you put it back together. Don't swap shims around if you can help it. They really a very very simple engines and boxes.
I half thought about doing a video actually, but my super 8 camera isn't working anymore.

 

[DustyFork]

Ya right there only China's but having a little knowledge helps so ya can try to make these engines hold up a bit better. I've got a cracked case from chain comming off and smashing case but also got a shifting issue that does my head in. I'd have to free up the gears every time befor a ride, and it would be fine. Leave it a week and it would stop shifting. So I'm gunna change the shift drum everything else looks stright and good.
Pitty ya don't have a camera seems like ya got a bit of knowledge that is very handy. Thought about videoing off a phone?

 

[zwebx]

i have a ducar 70 apart, could do a simple little video after work tomorrow
remind me on the mr chat box..
you will see
Do you know whats on the clutch side of the case? that would make it easier

 

[DustyFork]

Mr chat box? What's that. I'm sure there ain't nothing on the clutch side not sure what you mean by this either

 

[my67xr]

the Miniriders chat box
home page near the bottom

 

[zwebx]

Mr chat box? What's that. I'm sure there ain't nothing on the clutch side not sure what you mean by this either

I meant have you seen inside the clutch side cover?
never mind i will try to include that on video too

 

[zwebx]

[video=youtube;AgE83NNxME8]http://www.youtube.com/watch?v=AgE83NNxME8&feature=youtu.be[/video]
ignore the audio

 

[DustyFork]

Went to the bike shop today and got mechanic to look at me bottom end. Seems like one for on my shift drum is worn. I'm just looking at it wondering why? Maybe I give the bike a ruff time and me being WOT and changing up and down gears all the time has worn me gears. They don't look to bad only a little wear. I thinking of getting a set of close ratio gears for the yx160 HO motor and new shift drum from DHZ do I need any thing else to make this work like new primary gear?

 

[DustyFork]

Cheers thanks for that. I know a bit on most of what ya went though I think it's more the Shims I don't understand but I'm getting there slowly but surely!

 

[zwebx]

It should be fine, the only difference is the gears on the shafts are different and closer sizes
plug and play the 160 and the 155 etc all have the same box's the only difference is when you get a front clutch engine

 

[zwebx]

Cheers thanks for that. I know a bit on most of what ya went though I think it's more the Shims I don't understand but I'm getting there slowly but surely!

Ahh okay, pretty much you cant have too much endplay on the trans shafts or the gears either move to the side and slip out of gear all the time (slip off the dogs) or not select because the shift drum can not move the gear over enough

eg it wont select 2nd so i take all the gears off and put a shim behind second so the shift drum does not have to move so far


all the shift drum is is a shaft with lines embeded on it like a cam almost forcing the shift drums when turned

 

[DustyFork]

Sort of with ya, if I get the new gear set it should be a matter of plug nd play hopefully. I want to try to make the box spot on though as when ya do a box it means more money and time off my bike

 

[zwebx]

Sort of with ya, if I get the new gear set it should be a matter of plug nd play hopefully. I want to try to make the box spot on though as when ya do a box it means more money and time off my bike

thats how it is when you split cases..
unless your on a honda or somthing where its more likley to be a perfect shift drum..
whereas with ****ter tolerances on shift forks, drum and everything sometimes shimming is what you have to do (and on high milage gearbox's)

 

[DustyFork]

When you say about having a front clutch my yx clutch is towards the front of the engine on RHS.