Determining Cylinder Bore?

[butcher bergs]

Nah, they are guys that do their own work and do two stroke top ends somewhat often.

Listen, just because they have tools doesn't make them mechanics.

If they have you filing down pistons and heads based on whether or not a fingernail catches the burr, well son, you should consider that.

The only proper is to diagnose the cause, repair that and replace damaged parts with new, previously-undamaged parts along with a proper build.

Then again, the flipside to that is, hack away my friend. Let us know how soon before it explodes again.

Ever ask these buddies of yours WHY they're doing top ends "somewhat often"?

["Dangerous" Dan K]

Listen, just because they have tools doesn't make them mechanics.

If they have you filing down pistons and heads based on whether or not a fingernail catches the burr, well son, you should consider that.

The only proper is to diagnose the cause, repair that and replace damaged parts with new, previously-undamaged parts along with a proper build.

Then again, the flipside to that is, hack away my friend. Let us know how soon before it explodes again.

Ever ask these buddies of yours WHY they're doing top ends "somewhat often"?

hey man, I agree. I'm not taking a file to the shit, i was just commenting on the difference between the shadetree mechanics and you guys. As far as saying they did their own top ends, it was merely in response to the statement they were the guys that sell a bike becaue it blew a top end. By no means am I saying it's the right way to go, or the way I'm gonna go. Anyway, I think most guys with small bore 2 stroke bikes that live in powerband to top ends somewhat often (although when you rebuild with bad stuff you'll be doing it even more often).

It seems like my options right now are

1) replace everything. cylinder, head, and top end kit.
2) send it out to a machine shop for a honing and re-nickeling, and still replace the cap
3) send it to one of the top end places that does the bore, head, etc.

I am going to price all three options. I have a feeling #1 will be the most expensive.

There's a place that did a big bore setup on one of 6 fingers bikes for like 450, including machining, plating, etc. of everything. Not sure if I want to go overbore or not. I don't have the link handy.

Someone also suggested this place to me. http://www.cmmachine.com/ Their prices seem reasonable, but I'd have to call them and see if they can even start with what I've got and get a price for what I need done.

A trusted resident mechanic here suggested a new cylinder, head, and top end kit all stock stuff. Gotta price that out too.

Be interesting to see what my local shop suggests & quotes as well.

[seth399]

I'm not sure how this managed to slip my mind for so long, but I just remembered this morning that this bike also had a serious cooling issue a while back. It was overheating something fierce after a little bit. I flushed the radiator and coolant hoses, pulled the side cover and impeller, gave everything a looking over and put it back together. It has not overheated since, but it has not had a real long hard ride since either. Anyway, I’m thinking that could have contributed to the damage.

I was going to ask if it had any coolant in it, the ports look like hell...I've never seen em look that black n gross. If anything, changing the impeller out for a new one should only be 50-100 bucks.

Also, a new cylinder/head/top end kit should run you 300-350ish so as long as your bottom end is ok you might not want to deal with those junked up parts and put new stuff on.

["Dangerous" Dan K]

It had coolant when I broke it apart. I'm not sure what the deal was before I flushed out the cooling system though. The impellor seemed ok, and I've seen my share of them from working on boat outboard motors.

If I coud replace everything for $300-$350 I would in a heartbeat. I'm thinking it's going to be substantially more, based on what I've been seeing looking around.

Seems like I'm looking @ 135 or so for the top end kit (wiseco, I can get a Namura kit for $95 but I've never even heard of them). The head is $110 or so, and I've been unable to find a new cylinder as of yet. It'll be interesting to hear what the shop says, hopefully I can get by there today.

Do you have anywhere in particular you suggest looking for parts?

[seth399]

well I was just looking into picking up a 2000 cr125 just for the hell of it to work on and it needs same parts. New Honda stuff, I can get the cylinder for 265, head for 65 and top end kit for 85 or so. As you mentioned the Kawi stuff might be/probably is more.

[seth399]

Ok ya, I just checked on chaplinkawasaki.com they have a microfiche part finder thing....head for your bike is 81 and cylinder is 335

so you'd be looking at $500 I guess for all new parts.

["Dangerous" Dan K]

Cool. Thanks for checking it out for me, and for the link. Now I just need to decide what to do

[seth399]

no prob. man, ya I would really side with new parts personally but its alot to spend on the bike as well so I know how you feel.

["Dangerous" Dan K]

no prob. man, ya I would really side with new parts personally but its alot to spend on the bike as well so I know how you feel.

Well, the thing is, if it's $500 (little more looks like) for new stuff, I'm within $100-150 of the Athena Big Bore kit, which is also all new parts, but includes larger water jackets for cooling and whatnot. Added hassle, especially down the road for rebuilds, but also added power, which is nice.

Then there's the option of just sending the stuff out to be honed and replated. Almost good as new there, but I'd need to figure out just how much it's going to cost.

I got some thinking to do, anyway. I appreciate your help.

[seth399]

ya let us know what you decide on...the bigbore kits are nice for a 125 to get some more grunt but I would do homework on how reliable the setup is as well as I know that varies alot between some kits/bikes.

["Dangerous" Dan K]

Will-do. I'm going to try to make it by the shop today, I'm hoping he can give me the word on the cylinder, if there is any warping, etc. There's no scarring. If he tells me I can reuse the cylinder I think I'll just order a head and top end kit. If the cylinder has got to go too I've got some decisions to make. I won't buy a big-bore without doing the research on how reliable they are. There is definitely an appeal to keeping the stock bore, especially if I can do it at a somewhat reasonable price.

["Dangerous" Dan K]

Then again, the flipside to that is, hack away my friend. Let us know how soon before it explodes again.

Well, I just got back from my local shop (lunch break). Looks like I'm going to take the "hack away" route. I'll let you know how soon before it blows up (although it wouldn't be "again", since it didn't blow up this time. I only tore it down because I knew it was overdue for a top end and I wanted it done before the season).

They inspected the cylinder and declared it fine. Actually “in surprisingly good shape for the age, nevermind the fact that there’s damage elsewhere in the motor”. They are going to clean up the head, order me a top end kit and call it a day. These guys have done countless top ends between my friends & I, they were the only shop around when I was a kid and none of us knew how to do our own work. Never had anything but good luck with them, so I've got faith in what he says. Time will tell - if it blows up this season I should have replaced it all. Still, just over $150 overall this time around so it won't be the end of the world. At least by then I'll be done buying my gear for the track and finishing my sailboat, so dropping the $500-$600 won't be as big a deal as it is right now.

Expect me to dig this thread back up for a laugh if it doesn't make it through the season. I'll be surprised though, all the work these guys have done for my friends and I in the past has turned out aces.

I probably would have replaced everything anyway if I wasn't so strapped for cash at the moment, but I've gotta buy the rest of my race gear and finish my sailboat for spring. If this gets me into mid-summer I'll be in a much better position to deal with the hit of replacing everything.

[Paul_E_D]

Sounds good. That's not hack. You had it measured, they're cleaning up the head and you're putting in new topend parts. I believe that's what was reccommended by many in this thread.

Measure and set the squish while you're setting it up and you'll have a nice, fresh bike.

["Dangerous" Dan K]

Cool, thanks. Looks like I could have this thing back together next weekend if all goes well. Of course, that implies I find time some night this week to do the carb, and it's looking like a busy week. We'll see. There's a foot of snow everywhere and I don't have studs/spikes anyway, so if it happens the following weekend it's not a big deal.

Appreciate all the help I got from everyone in this thread. Thanks!

[6 Fingered Man]

Cool, thanks. Looks like I could have this thing back together next weekend if all goes well. Of course, that implies I find time some night this week to do the carb, and it's looking like a busy week. We'll see. There's a foot of snow everywhere and I don't have studs/spikes anyway, so if it happens the following weekend it's not a big deal.

Appreciate all the help I got from everyone in this thread. Thanks!

Ill stud it for ya, as long as I get to take it out to remember what 6th gear feals like..... I love 125's its been to long

Then again, I do like giving the old clutch hand a break every now and then.

Good luck with the top end.

["Dangerous" Dan K]

Thanks for the offer. I'll keep it in consideration. I'm not sure if I'll get to it this week, and if I don't we're looking at the weekend of the 14th to even have the bike back together. We'll have to look at the weather after that and see if it even makes sense. Not really worth dedicating this set of tires to studs if I'm only going to get a ride or two before I need to buy another set for dirt and switch back. Then again, it is NH, which is in New England, so it might snow clear through June. Decisions, decisions.

Regardless, you know that you'll get to ride it as soon as I get it out there (and finish the break-in thing, I don't want you holding it WOT before it's broken in). My clutch hand can use a break every now and again too, and your 250 is just the ticket for it.

[SSearchVT]

A few tips for when you're putting it back together. Give the cylinder a good once over when you get it back. Blow out all the ports with compressed air - just in case a chip found it's way in there (stranger things have happened). Put a rag over the exposed part of the crank with the rod sticking out through to keep the gasket bits from falling in while you clean off the old base gasket (the case surface and cylinder surface can not be too clean). The rag also keeps the new circlip from falling into the crankcase when you drop it (not if - when...). Don't forget to take the rag out...

I used a very light film of regular motor oil on the cylinder when I did a top end and never had a problem. If the piston has a ring locating pin - make sure the ring is lined up when you go to slide the piton into the cylinder. It should slide nice and easy. I would hold down on the cylinder and cycle the kickstarter slowly to make sure everything was running smooth before putting any nuts on.

["Dangerous" Dan K]

A few tips for when you're putting it back together. Give the cylinder a good once over when you get it back. Blow out all the ports with compressed air - just in case a chip found it's way in there (stranger things have happened). Put a rag over the exposed part of the crank with the rod sticking out through to keep the gasket bits from falling in while you clean off the old base gasket (the case surface and cylinder surface can not be too clean). The rag also keeps the new circlip from falling into the crankcase when you drop it (not if - when...). Don't forget to take the rag out...

I used a very light film of regular motor oil on the cylinder when I did a top end and never had a problem. If the piston has a ring locating pin - make sure the ring is lined up when you go to slide the piton into the cylinder. It should slide nice and easy. I would hold down on the cylinder and cycle the kickstarter slowly to make sure everything was running smooth before putting any nuts on.

Cool, thanks for the tips. The bottom end is covered with a towel, and I'll leave it there for cleaning off the case surface for the gasket. The only surprising thing here is regular motor oil, I've been advised to use 2-stroke oil. I'd guess either will do the job, and it probably won't make a lot of difference either way. I'm pretty sure there's a half pint of 2 stroke oil right next to the bike.