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My drz125 to 143 or so bore up

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OK, whoot and any of the rest of you that did it yourself. How tight was your piston in the newly bored cylinder?

I put my piston with rings in and it seemed mighty tight. I guess I'm going to file the rings since there was very little gap. Maybe that's it. Only other thing I can think of is the machinist didn't bore it out enough.

What you think?

Also...where the heck is the T on the flywheel? I have yet to find it.

Thanks.

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Did you measure the bore after the machine work? It may be worth double checking with a caliper.

The bore should be somewhat tight. I had to compress the ring all the way into the groove to get into the jug. The piston should take a little effort to move up and down, and you should get a bit of a sucking noise from the plug hole as it moves up and down with the head on. I don't have the gap meausrements as I had my machinist prep the rings to the bore.

If you can't get the rings in the bore, check the orientation of the top ring. Its crosssection should have a keystone shape to it. If you put it in upside down it won't slide all the way into the groove and will make you think the end gap is wrong.

I'd also insert the piston into the bore with the bore on the workbench, then connect the piston to the rod.

1st. insert one circlip into the hole for the wrist pin.

2nd. slide the wrist pin into the piston just far enough to be able to slide it home when you get it lined up in a few steps.

3rd. put the piston into the bore on the workbench, making sure the rings are oriented properly.

4th. install the base gasket on the motor then take the piston/jug over to the motor (Mine was in my bike) and line up the piston and the wrist pin.

5th. slide the wrist pin home and install the second circlip

6th. slide the bore down into the case, don't forget to put the base gasket on!

To set the cam timing:

1st. pull the sight plug or remove the left side engine cover (Clutch side)

2nd. turn the motor over by hand with the kick start lever until the white line accross the clutch basket lines up with the arrrow stamped in the case (about the 11o clock position right near a bolt hole)

3rd. holding the motor at TDC, slip the cam into place with the two - - marks on the cam paralell with the head casing (not the ground) and the hole in the cam gear up. install the valve cover gently.

hope this helps.

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Thanks Whoot for the great advice! Great tip on putting the piston in the cylinder first, then attacting to the conrod. Was afraid I got the cam gear a tooth off at first but the bike started on the third kick and spun up like a charm.

Seems to have more power across the band. Definitley higher top speed. Seems to get there faster too.

We raced today and came in fourth. Could have done better but got blocked by the same rider both motos. We'll see how we do next race.

I guess my worries about the piston tightness were unfounded. It was good though that I checked the ring gap clearance. That would be my advice to the next guy boring his drz125. I always thought the rings came pre gapped to the right size. Guess not.

All and all, a pretty basic weekend job. As always, once you do it, only then do you really get it. Before that, it's the details that had me worried. I wasn't sure which was the first and second ring. Whoot helped me out there confirming that the bronze colored one was number one and the dark grey was second.

Biggest pain in the neck was making sure the cam chain was on the crank gear right. I don't know who could remove the head and jug and replace yet still have the chain on the little bottom gear. And once you get the jug and head back on, that little gear is way down there. I had to have four sets of hands to get it done. One to hold the crank on tdc, another to hold the chain tight (once I managed to flip the chain on that little gear), one to hold the flashlight that allowed me to see down there, and mine to reset the cam and install the gear.

Oh, here's a point I didn't hear mentioned before. What about the "positioning pin" on the cam? The stock one had, but the hot cam didn't. Wasn't sure what to do so I just used the bolts to hold the gear on. Where was I supposed to find a positioning pin at 10pm sat night before raceday? &%$#@!?

OK, that's it for now. Thanks again, whoot!

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w00ht and hawncase. That's all great info. I'll be doing the same thing in October/November. I don't trust my "skilz" or rather .. lack there of.. so I want to wait until the race season is over here.

I think I get about 90% of it. That cam chain part sounds tedious. But I'll have 3 months or so to get it right. Thanks for taking the time to post.

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What about the "positioning pin" on the cam? The stock one had, but the hot cam didn't. Wasn't sure what to do so I just used the bolts to hold the gear on. Where was I supposed to find a positioning pin at 10pm sat night before raceday? &%$#@!?

You just pull the pin out of the stock cam and use it with the new one.

They usually pull out pretty easy with a pair of pliers.

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w00ht and hawncase. That's all great info. I'll be doing the same thing in October/November. I don't trust my "skilz" or rather .. lack there of.. so I want to wait until the race season is over here.

I think I get about 90% of it. That cam chain part sounds tedious. But I'll have 3 months or so to get it right. Thanks for taking the time to post.

The whole cam chain thing is much easier it you use a plastic rod or something laying through the chain to keep from falling into the lower end. Then you can slip it on the lower gear with two hands. You can also use some magic fingers to extract the chain if you drop it.

Hawn, you should have mentioned the pin! I totally forgot to mention it. Glad it is running well.

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Damn, I tried my best to get the pin out of the stock cam but it just wasn't coming so I though I was supposed to have picked up a new one from somewhere. I suppose I gotta go back in and put one in, huh? I don't know...my 50/88 did fine with two bolts only on the cam. What do y'all think?

The other thing other thing that was a bit of a pain at first was the cam gear bolts. I didn't have a cam gear holder or "universal holding tool" for that so it took me a while to figure out that I could hold back up on one bolt, while turning the other. Then on the second bolt (the one that didn't break loose), I put the box end wrench on the bolt that broke loose, then used a wratchet/socket to break the tight one. Of courese the loose bolt turned but only until the wrench came into contact with the socket/wratchet which wouldn't let it turn any further. Only then did the second bolt break loose. The above will probably only make sense to me...sorry. But just know that there is a way to get the cam bolts off without the gear holder if you can't find one...

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If the pin is stuck I believe you can use a small drift to tap it out from

the back side. I think you should get a pin in the new cam. Otherwise

every time you think hear a strange sound from the motor you will be

wondering 'is that the cam sprocket finally working loose?'

Installing the pin is pretty easy. You can slide it in from the outside of

the cam sprocket without removing the sprocket from the cam. Just

be careful not to drop it down the cam chain run!

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Finally got around to putting that little pin in the cam/gear. Would you believe the stock cam has gone missing (might have actually been stolen by a dude who wandered into my garage) and I had to order a pin from suzuki???

Thanks Jeff for the tip on going through the gear and into the cam. Slid in aweful easy. Only had to give the slightest tap to get it in fully. Was so easy I got scared and put some lock tight on it just in case.

FYI the cam hadn't loosened a bit. Hell, I think I'm gonna be worrying more about the pin coming out than the gear coming loose without the pin.

New issue though...both the old piston and head had lots of crusty but hard stuck on carbon build up. What's up with that? The plug came out a very light grey color which I would think is ok, if maybe a bit lean. But if lean, why so much carbon buildup? I wonder if I'm gonna get more since the bore up?

I had re-jetted to 110 back when I got an aftermarket pipe (big gun). I just went to 112.

So am I going the right direction? I mean the plug seems to say lean, but the carbon buildup seems like it must be rich? Yes? No? I'm so confused.

I'm thinking of getting the keihn 24 but would like to get the stock carb dialed in. Any suggestins

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Thanks Jeff for the tip on going through the gear and into the cam. Slid in aweful easy. Only had to give the slightest tap to get it in fully. Was so easy I got scared and put some lock tight on it just in case.

There is a 'bend tab' style lock plate that keeps the cam bolts from

being able to back out. That lock plate will hold the pin in it's hole.

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Ahahahahaha! Dang it! I have that tab deal 180 degrees off???

Guess I'm going back in! Third times the charm!

Thanks, Jeff!

P.S. I had spoke with you long time ago over the net about lightening the flywheel for this bike. I don't know if that's going to help that much. What has been your experience? Worth the effort?

Thanks.

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A guy I race with had his flywheel lightened. He said it revs a lot quicker but it also stalls easier. No real problems though. He likes it. He also had a 143cc bore, and I think a cam and carb done.

I've also been thinking of doing this myslef... but after looking through the posts... I am SO sure I will screw it up... :thumbsup:

Well done though.. hope the changes make it tear up the track.

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I had spoke with you long time ago over the net about lightening the flywheel for this bike. I don't know if that's going to help that much. What has been your experience? Worth the effort?

The DRZ125 is so detuned that just about any performance mod will make a

usable improvement. The DRZ won't benefit as much from lightening as a

TTR125 will. Don't worry about it being too easy to stall. The DRZ has a huge

heavy crankshaft to do the job of keeping the motor turning.

My dyno test mule DRZ has the PVL inner rotor ignition ($450!) which is more

than 2 lbs lighter than the stock flywheel. It is not really that prone to stalling.

_

_

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Hey Jeff,

I was checking out your website and noticed the larger valves for the drz125. I don't remember those from about a year ago when I was there. I'm wondering...do you also do the valve job for them? Like, could I send you my head and you send it back with the new valves in?

I'm pretty interested. And for anyone else, here's his website.

http://www.procycle.us/bikepages/drz125.htm

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Yes, those valves are a new item along with a few other things (and more to come)

I would recommend taking the big valve install job to a shop that specializes in

porting work. The ports have to be opened up quite a bit to take advantage of

the bigger valves. We don't do porting work on a regular basis so when we do

it takes 3 times as long as a guy who works ports every day.

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Thanks for the tip, but check their response to my inquiry.

Sir,

At this time we do not deal with the lightening of flywheels.

Thanks for your inquiry,

Trail Tech

Sure seemed like that did from their website. Too bad. Trail Tech sucks!

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