Breathers are not required for stock motors. It was probably added for aesthetic purposes. Fast50s recommends a breather kit for 88cc and up. The breather helps vent the increased "pumping" that comes with a big bore kit/high HP engine. Glad the vid helped!
One thing I've only seen mentioned once is the 2 dowel alignment pins that are used for the cylinder to case, and the two dowel pins for the head to cylinder are 2 different legnths. The shorter dowels are for the case to cylinder. The longer ones are for the head to cylinder. The base gasket is thinner than the head gasket which is why the shorter dowels are used on case to cylinder.
Your right. The problem is that there is not much room to swing the wrench. I try to compensate by leaving the it a bit loose and as you tighten the clearance falls where it should be. I think there is a special tool that has the screwdriver & nut driver in one, however, I don't do this everyday so it's not an issue.
Guys, dont forget to use assembly lube on the cylinder walls and on the piston before inserting the piston into the cylinder. I believe it's also recommended to put lube on the outside of the cylinder sleve.
Very good video. I would pack the crankcase with a rag when fitting the wrist pin circlip ( called a gudgeon pin in the UK) You never know where it could spring!
Believe me, there is a power gain :) I'll have the bike back in for some jetting, I'll post a vid on how it runs. The next step up would be to get a better head.
Does the adjustment for the cam remain the same 2000th intake and 3000th exhaust if you went with the larger cam that comes with the 88cc big bore stage 2 kit. Thanks for these videos btw!
good vids, only thing is you shouldn't use a ratchet when you adjust valves, it's better have a screwdriver on the adjuster holding it in the position you want then use a boxend wrench to tighten the lock nut it's way faster (especially when doing more than 2 valves)
hi, can someone please help me. I changed the piston rings on my 125cc pit bike and once i put it back together when i try to kick start it oil drips out of the bottom base gasket right were the oil pump is. I brought new gaskets and also tried gasket sealant but it still drips oil, can someone explain what the problem might be.
I know this prob an old video and I used to build these years ago when everyone had them but unfortunately after major head injury I'm pretty dumb now so thanks for making this video.. I havnt finished them all yet but what carb and jetting you recommend? And I want decent bottom end but lots of mid top range what sprockets you think? Like I said I've forgot everything I havnt touched one of these in over 12 years
Breathers are not required for stock motors. It was probably added for aesthetic purposes. Fast50s recommends a breather kit for 88cc and up. The breather helps vent the increased "pumping" that comes with a big bore kit/high HP engine. Glad the vid helped!
One thing I've only seen mentioned once is the 2 dowel alignment pins that are used for the cylinder to case, and the two dowel pins for the head to cylinder are 2 different legnths. The shorter dowels are for the case to cylinder. The longer ones are for the head to cylinder. The base gasket is thinner than the head gasket which is why the shorter dowels are used on case to cylinder.
Your right. The problem is that there is not much room to swing the wrench. I try to compensate by leaving the it a bit loose and as you tighten the clearance falls where it should be.
I think there is a special tool that has the screwdriver & nut driver in one, however, I don't do this everyday so it's not an issue.
Guys, dont forget to use assembly lube on the cylinder walls and on the piston before inserting the piston into the cylinder. I believe it's also recommended to put lube on the outside of the cylinder sleve.
its easier to use a regular wrench and a screw driver so you can hold the adjuster and it wont move
Very good video. I would pack the crankcase with a rag when fitting the wrist pin circlip ( called a gudgeon pin in the UK) You never know where it could spring!
Good tip
Believe me, there is a power gain :) I'll have the bike back in for some jetting, I'll post a vid on how it runs. The next step up would be to get a better head.
Does the adjustment for the cam remain the same 2000th intake and 3000th exhaust if you went with the larger cam that comes with the 88cc big bore stage 2 kit. Thanks for these videos btw!
good vids, only thing is you shouldn't use a ratchet when you adjust valves, it's better have a screwdriver on the adjuster holding it in the position you want then use a boxend wrench to tighten the lock nut
it's way faster (especially when doing more than 2 valves)
Thanks!
No prob.
Google "TRC CRANK 50/70". Seems like they use the same crank.
3 thou is .003"
If I buy a brand new 88 kit online will I have to adjust those valves like you did here in the beginning of the video?
Bro I just redid my whole front in for the first time thanks for the bid doggie
Vid
hi, can someone please help me. I changed the piston rings on my 125cc pit bike and once i put it back together when i try to kick start it oil drips out of the bottom base gasket right were the oil pump is. I brought new gaskets and also tried gasket sealant but it still drips oil, can someone explain what the problem might be.
valve adjustment on a raptor 80 will basically be the same, correct? maybe a different clearance, ill look for spec.. thanks!
I used motor oil. I may have left that out in the vid.
Do the 70 and the 50 have the same bottom end?
did the settings you used for the valve lash work out or did you need to re adjust from the previous 3000 exhaust 2000 intake?
I know this prob an old video and I used to build these years ago when everyone had them but unfortunately after major head injury I'm pretty dumb now so thanks for making this video.. I havnt finished them all yet but what carb and jetting you recommend? And I want decent bottom end but lots of mid top range what sprockets you think? Like I said I've forgot everything I havnt touched one of these in over 12 years
I don't recall jetting or gearing, sorry. Don't ever call yourself dumb, injury or not.
Besides the new gaskets and valve lash setting, all big bore kit is changing the piston?
Free vision New cylinder as well
At 8:50 you said the pins were in the piston and the gaps were 120 of each other, what do you mean by that?
The wrist pin is installed halfway in the piston. The piston ring gaps are spaced 120° apart from each other when viewed from top of piston.
Link to big bore kit plz
what web site did you order the 88 kit from? or what do you suggest?
no assembly lube??
hey Matt
will it also fit with a 70cc Chinese cylinderhead?
Not sure, contact tbolt usa, they should be able to answer that for you.
Try Tboltusa.com
The first part of the video with the gauging was jetting, right?
No, I was adjusting the valves.
My tremonolagy isn't good lol
Levi Omighty No worries. Did I answer your Q?
Yes'er thank you. Researched jetting lo
Is this for The stock head and cam?
***** I beleive both those were stock.
Did I miss the part where the engine was bored out to accept the bigger piston?
Kit comes with new cylinder.
was the valve tuning nessesary?
Setting valve lash? Yes!
Nice work:D
does it works for HONDA CD 70?
Engine looks very similiar. I'm sure you can find a big bore kit for it. Contact Tbolt USA.
2t or 4t???
4t
when he says thousandths he is saying .03 inch. thousanths of an inch not literally 3000
lol my bad thats what i meant