Planet Minis

daryl2cb · 08-26-2009, 06:06 PM

I have 4 minis a 77, and 86, 99 and a 2005. Now my question is this, I am currently restoring the 86, have the engine completely tore down. can I use the head from an xr?? I know there is an issue with the 77 but not sure about this one. Also if not, could I swap a whole crank from a xr 50 into that case to solve the valve issue if any???? I am pretty sure the cylinders are the same right?? please some one let me know. Also I am looking for a nice 80's tank if any one has one they are willing to get rid of, or if anyone knows of any hidden NOSers around. Thanks.

mexicanyella · 08-27-2009, 07:46 AM

You shouldn't need to swap the crank; they're both long-connecting-rod cranks. I think the piston is what you need to swap; I believe there were combustion chamber shape differences between '86 and '99/'05. Not sure if the differences are different enough to involve valve/piston contact or not, or if it's just in the interest of having the right compression ratio. I have an entire XR50 top end (I think) on a '86 bottom end, but I got the piston with it as the bottom end was just cases/guts with the connecting rod and camchain hanging out when I got it.

daryl2cb · 08-30-2009, 08:43 PM

so, are you saying to use a xr piston and head? Correct? Or are you saying use an 86 piston and xr head??

mexicanyella · 08-31-2009, 08:51 AM

I may be neglecting (or unaware of) some possibilities, but I believe you should use a XR/CRF piston with a XR/CRF head, or use a pre- '87 Z50R piston with an pre-'87 Z50R head.

Also be aware, if you're going to swap cranks, of the different flywheel tapers...Z50As and other US 6-volt bikes have one taper for three-speeds and another for four-speed manual clutch motors. Around the time of the switch to Z50Rs, '79 or '80, I think, the motors stayed 6-volt with points but got a new taper, before going to yet another taper for the 12V CDI ignition in I believe '88.

Someone straighten me out if I'm off on any of this; and I'm not trying to sound discouraging in any case, but it seems to me like you should figure out what head you want to run, know whether your bottom end is short-rod or long-rod ('86 Z50R is long-rod, and so are all later ones) and then check out the pistons in the performance section of the Dr. ATV site for an idea on what pistons are available to suit the various combinations. They're described there according to what rod length and combustion chamber dome they work with, and some allow some mixing and matching.

For instance, there's a 52mm piston for a 88cc bore kit that works with either a old 6V 50cc head's combustion chamber dome OR a later 12V 72cc head's dome, but I can't remember if it works on a short-rod or long-rod engine.

daryl2cb · 08-31-2009, 07:57 PM

thanks for the help, I do have a 2004 xr jug and piston laying around so I am just going to look for a new style head to match it up to. One remaining unknown is the rod length on the 86. the bike is an 86, and guessing the motor is original, hopefully. Any one know the actual length of the long and short rod??

mexicanyella · 08-31-2009, 09:15 PM

Hit up Firepower, Arlindsay, Dirtbkr188, Fatcaaat, or really just about anyone else but me about the head; could be you could run the Z50R head with the piston you have, and even if you need a different piston, that would be cheaper than a head if you've already got the '86 head. There's probably a combination that would work, but get more than my opinion before buying anything.

Then, take a look at this page for starters:

CONNECTING ROD KIT DIAMENSIONS

then goof around on the performance parts main page; there's lots of info regarding parts interchange between various eras of honda if you can get past the totally abysmal spelling and editing. The info itself is helpful.

Check your engine number (stamped on pad down by the shift shaft) against the engine/VIN decoder table here in the Z50 tech resources sticky in this forum. If your motor's an '86, it's a long-rod one. If it's '82 or later, in fact, it's a long rod one. I'm not sure about '79-'81, but others here would be. Somewhere in the '79-'82 range came the switch to long rod and final new crank/flywheel taper for 6V points ignitions...

mexicanyella · 08-31-2009, 10:54 PM

I might even take my own advice and refresh my own knowledge there once I'm awake tomorrow. I'll reread what combination you're talking about too.

My good New Jersey-dwellin buddy Tim Flacito traded me some stuff recently to help me with the Z50R I've been working on, plus he threw in a corn cob pipe, a plunger, some tall rubber boots with a hole in the toe (those have been really great) and one extra 50 piston. I can't remember if it was for a Z50R or a CRF, but as soon as I get off the computer here I'll go dig it out and look at it because I think he wrote what model it fits in Cyrillic. If it turns out to be the one you need and not a duplicate of what you already have, maybe I can hep you out.

More on this in the a.m.

dirtbkr188 · 09-01-2009, 06:45 AM

И белиеве тхат тхе пистон И сент ёу ис фор тхе ь82-ь87 модел еарс, Бен, бут тхе бест тхинг то до ис то пасте уп а пицтуре оф ит, анд И цан верифы тхат.

mexicanyella · 09-01-2009, 07:39 AM

И белиеве тхат тхе пистон И сент ёу ис фор тхе ь82-ь87 модел еарс, Бен, бут тхе бест тхинг то до ис то пасте уп а пицтуре оф ит, анд И цан верифы тхат.

See, there he is; he chimed in. I don't know what the hell he said or how to translate that back to something I can read, but I can guess it's probably something mundane that normal people would say, like "I tried to force the cat to assume a spherical shape" or "that toast would probably taste pretty good with some coffee grounds on it."

I looked at that extra piston he sent and it has '89 written on the crown. He must have written the cyrillic on one of the other items he sent. Maybe on the piston I put in my son's bike. You'd think I'd have remembered that, though...

Anyway, I'll have a look at the Dr. ATV info myself today but I have a spare '89 Z50 piston that looks like it could run as is if your cylinder is of stock bore and in reasonable condition. It's got rings on it too, and a piston pin, but no circlips because I jacked up one set trying to get them in on my son's bike.

EDIT: from looking at the Dr. ATV site it appears to me that if the head you're wanting to use is from an '86 motor, this '89 piston should work. But if you've got some other engine year in an '86 bike, you need to know that because I'm not sure an '89 piston will work with a post-'92 head, and I know it won't be right if your motor is older and has the short connecting rod. So look up your motor number on the ID table on this site and see what you've got.

mexicanyella · 09-01-2009, 02:55 PM

Okay, I tried to translate El Flaco's cyrillic outburst there and it was garbled but I think it basically said he thought the piston was '82-'87 and if I'd post up a photo of it he'd verify that. I'll hunt up a camera and do that later today...

dirtbkr188 · 09-01-2009, 05:45 PM

dirtbkr188 · 09-01-2009, 07:53 PM

I believe I sent you a piston from the '82-'87 model years, to go with the mid 80's cylinder head, for Morgan's bike. The piston on the crank was from a CT70(H?) or an ATC70, but not 100% positive. Here's a pic of the mid 80's piston.

mexicanyella · 09-02-2009, 07:11 AM

That looks to me like what I have, and as soon as the big computer isn't tied up here at home I'll be able to upload the photo I took for comparison. This "'89" marking MIGHT actually be "'84", with a smudged 4. Either way, it looks like the shallow conical dome of the one in the photo.

daryl2cb · 09-07-2009, 08:29 PM

ok, thanks for the help, as soon as I get back to it in a few days I should have some answers about the combo. went ahead and got a crf head for 35.00 shipped loaded with cam, if it works good if not cheap spare.

daryl2cb · 09-18-2009, 09:46 PM

well just got it together, it took forever. Wow amazing how work, wife and baby all seem to self destruct around me when I need z 50 time alone to put stuff together. A little back ground got the bike for 60 bucks and need everything had a bottom end the had water in it so I tore everything down sand blasted cleaned and replaced all it needed. my first case split and it went great considering it sat on the bench for almost 2 months. Anyway fired it up yesterday with a new top end and after a quick valve adjustment and timing chain torque, it is purring like a kitten

. so here it the combo 86 bottom end, which appears to have the exact same rod as the 84 parts motor I have with the stock piston and jug off of my 2004 crf, with a xr head from mx40racer and a tank from crawlerD Thanks guys. I used the mls cometic head gasket and this sucker feels like the crf as far as compression, and it should. So I just need a chain and rear tube and take her for a spin. So I am not sure if this was answered completely or not here is the conclusion

86 bottom and complete xr/crf top end and piston=== Works great

84 bottom and complete xr/crf top end and piston= should work and is my next project

In case anyone was wondering about the combo it does work and runs great so far but the street test will be the final verdict on whether it was worth doing and if there was any power gains. If nothing else the roller cam should be worth a few .00?? horsepower pics to follow soon.

08-26-2009, 06:06 PM	#1 (permalink)
daryl2cb PM Newbie Join Date: Aug 2006 Location: Greensburg, PA (go Steelers) Posts: 20 My Mood:	xr t0 zr questions I have 4 minis a 77, and 86, 99 and a 2005. Now my question is this, I am currently restoring the 86, have the engine completely tore down. can I use the head from an xr?? I know there is an issue with the 77 but not sure about this one. Also if not, could I swap a whole crank from a xr 50 into that case to solve the valve issue if any???? I am pretty sure the cylinders are the same right?? please some one let me know. Also I am looking for a nice 80's tank if any one has one they are willing to get rid of, or if anyone knows of any hidden NOSers around. Thanks.

08-27-2009, 07:46 AM	#2 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions You shouldn't need to swap the crank; they're both long-connecting-rod cranks. I think the piston is what you need to swap; I believe there were combustion chamber shape differences between '86 and '99/'05. Not sure if the differences are different enough to involve valve/piston contact or not, or if it's just in the interest of having the right compression ratio. I have an entire XR50 top end (I think) on a '86 bottom end, but I got the piston with it as the bottom end was just cases/guts with the connecting rod and camchain hanging out when I got it.

08-30-2009, 08:43 PM	#3 (permalink)
daryl2cb PM Newbie Join Date: Aug 2006 Location: Greensburg, PA (go Steelers) Posts: 20 My Mood:	Re: xr t0 zr questions so, are you saying to use a xr piston and head? Correct? Or are you saying use an 86 piston and xr head??

08-31-2009, 08:51 AM	#4 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions I may be neglecting (or unaware of) some possibilities, but I believe you should use a XR/CRF piston with a XR/CRF head, or use a pre- '87 Z50R piston with an pre-'87 Z50R head. Also be aware, if you're going to swap cranks, of the different flywheel tapers...Z50As and other US 6-volt bikes have one taper for three-speeds and another for four-speed manual clutch motors. Around the time of the switch to Z50Rs, '79 or '80, I think, the motors stayed 6-volt with points but got a new taper, before going to yet another taper for the 12V CDI ignition in I believe '88. Someone straighten me out if I'm off on any of this; and I'm not trying to sound discouraging in any case, but it seems to me like you should figure out what head you want to run, know whether your bottom end is short-rod or long-rod ('86 Z50R is long-rod, and so are all later ones) and then check out the pistons in the performance section of the Dr. ATV site for an idea on what pistons are available to suit the various combinations. They're described there according to what rod length and combustion chamber dome they work with, and some allow some mixing and matching. For instance, there's a 52mm piston for a 88cc bore kit that works with either a old 6V 50cc head's combustion chamber dome OR a later 12V 72cc head's dome, but I can't remember if it works on a short-rod or long-rod engine. Last edited by mexicanyella; 08-31-2009 at 08:54 AM.

08-31-2009, 07:57 PM	#5 (permalink)
daryl2cb PM Newbie Join Date: Aug 2006 Location: Greensburg, PA (go Steelers) Posts: 20 My Mood:	Re: xr t0 zr questions thanks for the help, I do have a 2004 xr jug and piston laying around so I am just going to look for a new style head to match it up to. One remaining unknown is the rod length on the 86. the bike is an 86, and guessing the motor is original, hopefully. Any one know the actual length of the long and short rod??

08-31-2009, 09:15 PM	#6 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions Hit up Firepower, Arlindsay, Dirtbkr188, Fatcaaat, or really just about anyone else but me about the head; could be you could run the Z50R head with the piston you have, and even if you need a different piston, that would be cheaper than a head if you've already got the '86 head. There's probably a combination that would work, but get more than my opinion before buying anything. Then, take a look at this page for starters: CONNECTING ROD KIT DIAMENSIONS then goof around on the performance parts main page; there's lots of info regarding parts interchange between various eras of honda if you can get past the totally abysmal spelling and editing. The info itself is helpful. Check your engine number (stamped on pad down by the shift shaft) against the engine/VIN decoder table here in the Z50 tech resources sticky in this forum. If your motor's an '86, it's a long-rod one. If it's '82 or later, in fact, it's a long rod one. I'm not sure about '79-'81, but others here would be. Somewhere in the '79-'82 range came the switch to long rod and final new crank/flywheel taper for 6V points ignitions... Last edited by mexicanyella; 08-31-2009 at 09:18 PM.

08-31-2009, 10:54 PM	#7 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions I might even take my own advice and refresh my own knowledge there once I'm awake tomorrow. I'll reread what combination you're talking about too. My good New Jersey-dwellin buddy Tim Flacito traded me some stuff recently to help me with the Z50R I've been working on, plus he threw in a corn cob pipe, a plunger, some tall rubber boots with a hole in the toe (those have been really great) and one extra 50 piston. I can't remember if it was for a Z50R or a CRF, but as soon as I get off the computer here I'll go dig it out and look at it because I think he wrote what model it fits in Cyrillic. If it turns out to be the one you need and not a duplicate of what you already have, maybe I can hep you out. More on this in the a.m.

09-01-2009, 06:45 AM	#8 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,972	Re: xr t0 zr questions И белиеве тхат тхе пистон И сент ёу ис фор тхе ь82-ь87 модел еарс, Бен, бут тхе бест тхинг то до ис то пасте уп а пицтуре оф ит, анд И цан верифы тхат.

09-01-2009, 07:39 AM	#9 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions И белиеве тхат тхе пистон И сент ёу ис фор тхе ь82-ь87 модел еарс, Бен, бут тхе бест тхинг то до ис то пасте уп а пицтуре оф ит, анд И цан верифы тхат. See, there he is; he chimed in. I don't know what the hell he said or how to translate that back to something I can read, but I can guess it's probably something mundane that normal people would say, like "I tried to force the cat to assume a spherical shape" or "that toast would probably taste pretty good with some coffee grounds on it." I looked at that extra piston he sent and it has '89 written on the crown. He must have written the cyrillic on one of the other items he sent. Maybe on the piston I put in my son's bike. You'd think I'd have remembered that, though... Anyway, I'll have a look at the Dr. ATV info myself today but I have a spare '89 Z50 piston that looks like it could run as is if your cylinder is of stock bore and in reasonable condition. It's got rings on it too, and a piston pin, but no circlips because I jacked up one set trying to get them in on my son's bike. EDIT: from looking at the Dr. ATV site it appears to me that if the head you're wanting to use is from an '86 motor, this '89 piston should work. But if you've got some other engine year in an '86 bike, you need to know that because I'm not sure an '89 piston will work with a post-'92 head, and I know it won't be right if your motor is older and has the short connecting rod. So look up your motor number on the ID table on this site and see what you've got. Last edited by mexicanyella; 09-01-2009 at 07:49 AM.

09-01-2009, 02:55 PM	#10 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions Okay, I tried to translate El Flaco's cyrillic outburst there and it was garbled but I think it basically said he thought the piston was '82-'87 and if I'd post up a photo of it he'd verify that. I'll hunt up a camera and do that later today...

09-01-2009, 05:45 PM	#11 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,972	Re: xr t0 zr questions

09-01-2009, 07:53 PM	#12 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,972	Re: xr t0 zr questions I believe I sent you a piston from the '82-'87 model years, to go with the mid 80's cylinder head, for Morgan's bike. The piston on the crank was from a CT70(H?) or an ATC70, but not 100% positive. Here's a pic of the mid 80's piston.

09-02-2009, 07:11 AM	#13 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 984	Re: xr t0 zr questions That looks to me like what I have, and as soon as the big computer isn't tied up here at home I'll be able to upload the photo I took for comparison. This "'89" marking MIGHT actually be "'84", with a smudged 4. Either way, it looks like the shallow conical dome of the one in the photo.

09-07-2009, 08:29 PM	#14 (permalink)
daryl2cb PM Newbie Join Date: Aug 2006 Location: Greensburg, PA (go Steelers) Posts: 20 My Mood:	Re: xr t0 zr questions ok, thanks for the help, as soon as I get back to it in a few days I should have some answers about the combo. went ahead and got a crf head for 35.00 shipped loaded with cam, if it works good if not cheap spare.

09-18-2009, 09:46 PM	#15 (permalink)
daryl2cb PM Newbie Join Date: Aug 2006 Location: Greensburg, PA (go Steelers) Posts: 20 My Mood:	Re: xr t0 zr questions well just got it together, it took forever. Wow amazing how work, wife and baby all seem to self destruct around me when I need z 50 time alone to put stuff together. A little back ground got the bike for 60 bucks and need everything had a bottom end the had water in it so I tore everything down sand blasted cleaned and replaced all it needed. my first case split and it went great considering it sat on the bench for almost 2 months. Anyway fired it up yesterday with a new top end and after a quick valve adjustment and timing chain torque, it is purring like a kitten. so here it the combo 86 bottom end, which appears to have the exact same rod as the 84 parts motor I have with the stock piston and jug off of my 2004 crf, with a xr head from mx40racer and a tank from crawlerD Thanks guys. I used the mls cometic head gasket and this sucker feels like the crf as far as compression, and it should. So I just need a chain and rear tube and take her for a spin. So I am not sure if this was answered completely or not here is the conclusion 86 bottom and complete xr/crf top end and piston=== Works great 84 bottom and complete xr/crf top end and piston= should work and is my next project In case anyone was wondering about the combo it does work and runs great so far but the street test will be the final verdict on whether it was worth doing and if there was any power gains. If nothing else the roller cam should be worth a few .00?? horsepower pics to follow soon.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)