Pulling the TZ250 motor

[NYCSTRIPES]

I have decided to send out my TZ250 motor to MCE racing in CA for a full rebuild. Despite the mechanical downtime on the 250, it is still worth riding it. I have a full rebuild kit on order and when it arrives, I will pull the motor and send it out to Kevin Murray.
Upon its return it will have a new crank shaft, new pistons, new heads, bearings, seals and other related items. I expect that with a professional rebuild like this, I should have an easier time keeping it running properly. I just got frustrated with the unexpected items crapping out on my 1995 motor and going fresh with all new parts.
Should prove to be a good thing for the bike anyway. After this I should be able to keep up with scheduled maintenance a whole lot easier.
Ken

[Cakes206]

Cool stuff Ken. Lots of pics. Need any help let me know, be cool to check it out.

[NYCSTRIPES]

Be assured I will take plenty of pictures...it's the Japanese tourist gene I have... can't be helped. LOL

Ken

[carl_g]

Nice dude!

[High_Revs_17]

Is that typical? Seems like a huge labor of love. Either way you're doing it right for sure.

[NYCSTRIPES]

Not typical, but needed. Mine is a 1995 and I know it was never professionally serviced. I am still a 2 stroke newbie and my aim is to get this thing back into shape and make it reliable. Replacing all of the expendible parts at once and having qualified hands get a look inside at the same time will be something that will give me the confidence I need to run it for 2008.
It will also give me a solid timetable to run with leaving me near zero surprises. So, at 300 mile intervals I can change top ends and at 1200-1500 miles I can change out the crank. That should be the only things I need to worry about next season other than tires and fuel.

Ken

[carl_g]

just jet it fat and you should not blow it up!

[lets_racefast]

Ken,

There are a few things you need to know / do when you get your motor back.


power valve cable setup
Timing
Break-in Procedure...Oil ratio change, Heat Cycles and run time.
95' Carbs?...Well then you need to rebuild your carbs if you not already done so. The parts in the carbs wear and you would not believe how much difference it makes. Your motor will not work / run as hard and you gain HP.

[tommymac]

Is that typical? Seems like a huge labor of love. Either way you're doing it right for sure.

He owns a TL so hes used to it:lol:

Tom

[NYCSTRIPES]

Ken,

There are a few things you need to know / do when you get your motor back.


power valve cable setup
Timing
Break-in Procedure...Oil ratio change, Heat Cycles and run time.
95' Carbs?...Well then you need to rebuild your carbs if you not already done so. The parts in the carbs wear and you would not believe how much difference it makes. Your motor will not work / run as hard and you gain HP.


Thanks, I will keep that in mind. + Welcome aboard. Are you a member at www.tz250racing.com? Here are some pics from Summit Shenandoah over Labor Day.
Ken
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/TPMS8066.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/TPMS6615.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/IMG_3013.jpg

[NYCSTRIPES]

He owns a TL so hes used to it:lol:

Tom

Very True...LOL

[lets_racefast]

Thanks, I will keep that in mind. + Welcome aboard. Are you a member at www.tz250racing.com? Here are some pics from Summit Shenandoah over Labor Day.
Ken
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/TPMS8066.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/TPMS6615.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/IMG_3013.jpg

Nice bike!

Thanks for the welcome!...Yes, I'm a member of that site as well. I've been building and racing 250's for 15 years and they're AWESOME bikes to race on.

There a few little tricks you can do to gain more reliable power. Let me know if need some help.

I also make parts for Yamaha TZ 250's...pegs, fairing ears, brembo master cyl replacement washers and knobs, cush drive etc.

[NYCSTRIPES]

Nice bike!

Thanks for the welcome!...Yes, I'm a member of that site as well. I've been building and racing 250's for 15 years and they're AWESOME bikes to race on.

There a few little tricks you can do to gain more reliable power. Let me know if need some help.

I also make parts for Yamaha TZ 250's...pegs, fairing ears, brembo master cyl replacement washers and knobs, cush drive etc.


Sounds good, I will probably drop you a line when the motor comes back. I am just waiting for RSCYCLES to return before I can get my rebuild kit and new crank on the way.
I may have some gearing/jetting questions for you. I am trying to put together the gearing/jetting for different tracks so I can run the longer tracks as well as the smaller ones effectively.
I may be interested in getting some spare pegs..just in case.
Ken

[lets_racefast]

Sounds good, I will probably drop you a line when the motor comes back. I am just waiting for RSCYCLES to return before I can get my rebuild kit and new crank on the way.
I may have some gearing/jetting questions for you. I am trying to put together the gearing/jetting for different tracks so I can run the longer tracks as well as the smaller ones effectively.
I may be interested in getting some spare pegs..just in case.
Ken

Sure no problem...Glad to help out. I also sell DZUS 1/4 Fasteners if you need any.

[bondo]

just jet it fat and you should not blow it up!

Ken,
don't listen to Carl.
Jet it as lean as you want, especially in 40 degree weather and skip that stinky oil. Custom welded pistons are the HOT setup!


Seriously, glad to see th TZ getting some TLC. Looking forward to seeing it in the spring. :nod2:


This piston was the result of too little oil (spilled some in the wind mixing in the tank) and a little too lean at 1/4 throttle. Bigger main was not enough. It ran PERFECT, plug was nice and brown. Rolled off after a bonzi fireroad blast and she locked up tight.

[NYCSTRIPES]

Looks like a cylinder repair will be in the works. What bike is this?

[NYCSTRIPES]

Sure no problem...Glad to help out. I also sell DZUS 1/4 Fasteners if you need any.

Drop me a PM with prices for a set of pegs.
thanks
Ken

[carl_g]

Looks like a cylinder repair will be in the works. What bike is this?
2007 KTM 300 XCw.. I told him to go up one size on the pilot jet! :doh:

[lets_racefast]

2007 KTM 300 XCw.. I told him to go up one size on the pilot jet! :doh:

I could be wrong but it looks like there is a cracked port. If the port cracks then it will suck in air and seize on off throttle.

Millenium Technologies fixes cylinders really good.

[bondo]

2007 KTM 300 XCw.. I told him to go up one size on the pilot jet! :doh:

I don't really think it was the jetting... even the manual recommends a 35 pilot at 30 degrees F. I put a 42 in it in Sept.... I don't think raising the needle 1 click would have prevented melting my piston.

Also, the main is a 165, stock is a 162. My jetting is richer than the exact same motor I has running next to, but he runs more oil in the gas. I had 50:1 to start with and probably screwed up at the gas station, running it even leaner.

guess I was due for one :nopity:
I haven't blown up a bike since 1990 and even that was just experimenting with base gasket changes and squish rings.

[bondo]

I could be wrong but it looks like there is a cracked port. If the port cracks then it will suck in air and seize on off throttle.

Millenium Technologies fixes cylinders really good.


I think what you saw was casting flash. I'm going to clean that off before the I send out the cylinder.
I wish I could blame it on that... right now, I'm blaming myself :wtf: :lol:

[bondo]

Looks like a cylinder repair will be in the works. What bike is this?

Planning to send it to powerseal (http://powersealusa.com) as soon as my head and piston come back.

Ken,
Are you doing a "factory" rebuild or making any changes while it's opened up?
I hear the TZs are pretty hot as-is.

[NYCSTRIPES]

More than likely it will be kept to stock specs. I may opt to have some head work done on one of my older sets of heads. I have one NEW set of OEM heads going into the motor and I would like to have a spare set machined to match them as a backup. While the motor is there, I will more than likely be needing at least one of my cylinder sets to be replated before the start of next season.
Its gets expensive pretty quickly. I am quite happy with the power to weight ratio of the TZ250 as is. I can only expect it to run better just with the simple rebuild. I don't plan on doing much actual racing, so the extra engine mods are not going to be cost effective for me. If I were to race one, i would probably opt to purchase a newer version of the bike.

Ken

[NYCSTRIPES]

Motor is out, now I have to find a suitable shipping container.
Ken

[Kennedy]

Motor is out, now I have to find a suitable shipping container.
Ken

Ken how big is the motor? Find a plastic container barrel that they use to ship stuff in.

[Kennedy]

Something like this http://images.google.com/imgres?imgurl=http://machinograph.com/images/home4.gif&imgrefurl=http://www.machinograph.com/&h=230&w=261&sz=31&hl=en&start=8&um=1&tbnid=SfM0HjTOXJwUvM:&tbnh=99&tbnw=112&prev=/images%3Fq%3DPlastic%2BBarrel%2BShipping%2BContain ers%26svnum%3D10%26um%3D1%26hl%3Den%26safe%3Doff

[NYCSTRIPES]

The motor is pretty small. I was going to try Home Depot and grab a plastic storage bin and pad the motor inside of one of those if I can find one that will hold up to the trip in both directions.
I will probably use that foam insulating spray inside a plastic trash bag to make a custom fit pad to protect the motor. I ordered a replacement rim for my Explorer once and the new rim came sandwiched between two trash bags filled with foam insulation. The bags contained the foam, but the foam formed perectly around the part and once it hardened, it protected the new wheel. The same should work great with the motor.
My only concern is finding a container that will stand up to the round trip.
Ken

[NYCSTRIPES]

A square container would probably work better.
Ken

[carl_g]

A square container would probably work better.
Ken
Alot of people use a cooler.:ride:

[NYCSTRIPES]

Just got the TZ250 cylinders back from re-plating. Should be getting the motor back together in a week or so.
New heads too..should be good to go for my first track day in April.
Ken
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/006.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/005.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/007.jpg

[Kennedy]

They look pretty.

[carl_g]

Cool pics..you can see the cross hatches from the honing.. looks good man!

[IrocRob]

Nice Ken - Be certain that the port edges are not sharp.
They look like they are good to go but verify that just to be sure.
It's hard to tell from the pictures.

I made that mistake once and had a piston ring shatter
on the sharp edge of a transfer port after building up an
entire Kawasaki 100 from scavenged parts back when I
was about 12...I remember thinking:
"What the hell just happened? oh well, it's still running so it can't be that bad."
:doh::lol::doh:

[NYCSTRIPES]

Rob
it was the first thing I checked when the barrels came back. They did a good job of dressing the edges of the ports.
thanks
Ken
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/009.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/005.jpg

[FDNYDANO18]

Ay,
You start puttin her back together yet?:ride:

[NYCSTRIPES]

today it begins..

[NYCSTRIPES]

Got the motor completed today, just have to pressure test it. I put in a new clutch cover, new heads, replated cylinders, new pistons, bearings and some other stuff.
If I get the pressure testing done soon, I will fire it up and get it ready for the next track day.
Ken

[NYCSTRIPES]

Update.
I just got finished pressure testing the motor.
I have the left cylinder holding pressure at 6PSI. THe intake manifold was leaking air and it took a little while to find the leak. Now its A-OK.
The right one (forward cylinder) is leaking air into the cooling system. I pulled the head and re-sealed everything and checked the o-rings. Everything looked OK, but it still leaks. I have to pull the barrel now and check the base gasket to see that there is adequate sealant on the case/underside of the barrel.

I was also sent the wrong heads and I had to return them to RSCYCLES.com for an exchange. While I was at it, I ordered the replacements to be from a 2000 TZ125 and I am having Roland Cushway machine them for the TZ250. Looking forward to getting those installed on the motor at the next top end rebuild.

Tomorrow morning, I will be pulling the barrels again and re-checking the base gaskets and applying a little more Yamabond to everything. Sucks that I ran out of time today I have to head into work now. I am hoping that this takes care of the air leak. I would like to get the motor back into the bike this week so I can have my 250cc lawn mower back on the track soon.

Ken

[carl_g]

Update.
I just got finished pressure testing the motor.
I have the left cylinder holding pressure at 6PSI. THe intake manifold was leaking air and it took a little while to find the leak. Now its A-OK.
The right one (forward cylinder) is leaking air into the cooling system. I pulled the head and re-sealed everything and checked the o-rings. Everything looked OK, but it still leaks. I have to pull the barrel now and check the base gasket to see that there is adequate sealant on the case/underside of the barrel.

I was also sent the wrong heads and I had to return them to RSCYCLES.com for an exchange. While I was at it, I ordered the replacements to be from a 2000 TZ125 and I am having Roland Cushway machine them for the TZ250. Looking forward to getting those installed on the motor at the next top end rebuild.

Tomorrow morning, I will be pulling the barrels again and re-checking the base gaskets and applying a little more Yamabond to everything. Sucks that I ran out of time today I have to head into work now. I am hoping that this takes care of the air leak. I would like to get the motor back into the bike this week so I can have my 250cc lawn mower back on the track soon.

Ken
It will be all worth it in the end!
I am pulling mine apart tonight... new bottom end is needed I fear.

[NYCSTRIPES]

Turned out to be my front cylinder base gasket. Some high heat silicone and that was it.
All buttoned up and ready to re-install.
Ken

[FDNYDANO18]

Nice one Ken!

Ride it well and in good health!
ps: wish I was going this weekend :sun:

[Cakes206]

Nice work Ken, can't wait to see this thing in action :ride:

[NYCSTRIPES]

I got the motor re-installed. I have to clean the carbs and set the ignition timing in the morning. Looking to fire it up tomorrow.


Ken

[NYCSTRIPES]

Nice one Ken!

Ride it well and in good health!
ps: wish I was going this weekend :sun:

Thanks.
I am headed out with Jeff Quinn Saturday. Hitting the Boxing match in Jersey City on the way home. My brother is fighting in a charity bout there. Oh and clear out yout AOL mailbox ..emails have been getting kicked back for over a week.

Ken

[JimRBlue]

I must say this is quite the interesting post! Never owned a 2 stroke nor realized the amount of work that can be involved with them. Excellent thread!

[Cakes206]

Here ya go Ken...bring it up to Bogie!

http://www.youtube.com/watch?v=K2zcqr0cFs4

[carl_g]

I must say this is quite the interesting post! Never owned a 2 stroke nor realized the amount of work that can be involved with them. Excellent thread!
Any purpose built race bike requires tons of maintenance. It's not only a 2 stroke thing..look at the AMA LITES class.. All 250 4 strokes. Those bikes are so on the edge they require a full engine rebuild after just 4 hours of run time.:moocow:

I drool when I see pics of this bike and I am majorly jealous! Good luck with your first ride on it this season!

[NYCSTRIPES]

Its definitely been a learning curve. Jumping into a full on GP bike without having owned anything similar to this has been a bitter sweet experience. They were designed to be built for racing and as a track day machine, they can chalk up some expense. VP c12 (leaded) Racing Fuel is expensive, Castrol A747 two-stroke pre-mix oil is also costly. Combined, the fuel and oil comes out to about $15 per gallon. Top end rebuilds have to be performed at 300 mile intervals or every 3 track days. The good thing is that the top end is a simple task which can take about 60-90 minutes time.
Crankshafts about every 1200 miles..once a season.

I have had the bike on the track a couple of times and when I had it up and running, it was a serious blast. More fun to ride than any bike I have ever owned. I am still trying to get up to speed on having them up and running reliably. I have made some simple mistakes in tuning that has cost me two break downs so far. The good thing is that they were both common mistakes and they helped me to learn a lot about the internal workings of the bike.
There is a lot of support for them on the web which has been extremely helpful to me, being good with a wrench is a must though. Its not for the faint of heart. You MUST like to tinker to own a GP two stroke. It can be a great hobby riding and keeping one of these bikes in tune.
I have my fingers crossed for a good season, but either way, every time I have to tear it down, I wind up learning more about these amazing machines.

I just hope that they keep making parts for them.
Ken

[NYCSTRIPES]

Here ya go Ken...bring it up to Bogie!

http://www.youtube.com/watch?v=K2zcqr0cFs4

Joe
I will watch it when I get home tonight, no access to youtube or such websites through work.
Sadly I won't be making it to Canada this season. The road trips are expensive and with fuel costing this much, I will be trying to stay local this year. Summit will be the farthest I will want to go this season.
Ken

[NYCSTRIPES]

Any purpose built race bike requires tons of maintenance. It's not only a 2 stroke thing..look at the AMA LITES class.. All 250 4 strokes. Those bikes are so on the edge they require a full engine rebuild after just 4 hours of run time.:moocow:

I drool when I see pics of this bike and I am majorly jealous! Good luck with your first ride on it this season!
You know, I am skeptical about the new 450cc 4 stroke race bikes that Roland Sands has been pushing because of the maintenance. I guess we'll see how they hold up.
I will try to put up some more current pics of the TZ after my next track outing. Once I get the bike running the way I want, I will be repainting it...so stay tuned.
Ken

[NYCSTRIPES]

IT LIVES...

I managed to get everything set up and fired the old girl up today and buzzed the neighborhood with the TZ250.

Turned out to be quite a productive afternoon.
Ken

[carl_g]

Congrats dude! :clap:

[NYCSTRIPES]

I received a new set of heads for my bike yesterday, probably going to install them this weekend, weather permitting.
2 stroke tuner Roland Cushway machined these heads (2000 TZ125 heads) for my 1995 TZ250. The 2k TZ125cc head has a better combustion area shape and plenty of meat on the head for machining. Lends itself to be reshaped into a copy of the Kit-A leaded 1995 TZ250 heads. Should make for a nice overall improvement on power.
Ken
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/010.jpg
http://i20.photobucket.com/albums/b238/nycstripes/TZ250/014.jpg

[Respect_My_Authorita]

congrats :D

[carl_g]

I need to update my thread.. the crank is finally coming out this weekend and being sent off to get rebuilt!

[NYCSTRIPES]

cool beans.
Unfortunatlely TPM isn't carrying VP race fuel anymore and I will need to find a new local source for the C12 leaded race fuel I need. Just another hurdle.

Good luck with the crank rebuild.
Ken

[NYCSTRIPES]

After 2 disappointing appearances at Pocono this season, I think I finally have the TZ running properly. I spent the last two afternoons working on the bike trying to eliminate possible causes for the bike not revving past 6k RPM.

I pulled the carbs, heads, exhaust valves, plugs, installed new ignition coils, and still the bike wouldn't rev properly. The bike idled OK, but anything past 4K RPM was messy and it just choked out at 6k.

I also re-checked the ignition timing which was spot on. After scratching my head over this for 2 days with FDNYDANO who lent moral support and killed the local mosquitoes with his cigar, I swapped out the CDI Ignition and Magneto set for a spare I had in the garage.

Low and behold, the bike lives again...go figure. The ignition computer shit the bed without warning.

Glad I had a spare complete ignition set that I bought used last year, the new ones are $1500.00....:take_it:

So far this season I installed:
newly replated cylinders, new top end (pistons, rings, bearings, gaskets), new chain, new sprockets, new custom heads, new plugs, new tires, new ignition coils, rebuilt the carbs.


After getting the motor running again, I changed out the gearing to 15/40 for NJMSP for Friday, look out for the blue smoke. Hoping the gear selection will be good enough for that track since I am hearing about the wide open throttle sections.
Ken

[NYCSTRIPES]

Finally got a full day out of the TZ250
Riding at NJMSP Lightning was a thrill, definitely looking forward to riding there again now that I have a feel for the line on that track.
In the meantime I will be tinkering to get the TZ ready for Thunderbolt on Aug 4th.
Who's going?
Ken

[carl_g]

Nice dude so it's finally running well???

[NYCSTRIPES]

yes, now i have to get the jetting right. Its running a bit rich now. I ordered some more Mikuni jets to help with that. It was a blast on NJ Lightning.
Ken

[carl_g]

Cool! better a tad rich then too lean and go boom!!!!! :)