My cylinder is damage ..Help !!

[aharoncross]

Hi
My YZ125 1999 was running well since I bought it 2 month ago.
It was time to rebuild my top end, so I took it apart and as I looked in my cylinder I saw it has large wear area,
It is the first time I rebuild the top end since I bought it .
After inspecting the cylinder surface carefully I understand that the guy who sold me the bike probably Broke ring or something, then he polished the cylinder surface (and obviously removing some coating), replace the piston and ring and sold me the bike ( ye I know I been screwed.....:mad: ).
I don’t know how but the bike run great (it’s not my first bike …) , and it’s look like the ring fit the cylinder surface and have good sealing except the area of the scratch/wear/polished ( whatever…) .
The damage area start at the top end of the exhaust port with 0.5” wide and it’s end just about 0.2” from the top of the cylinder with 0.1” wide, the dip is started from 0.02” to 0”at the top.
If any one interested I can send some photos of my cylinder.
My questions are:
1. Since I was riding for 2 month with no problem, can I just install new ring and ride as nothing wrong with this cylinder ( O.K. I will use more oil with the fuel)?
2. Can I replate the cylinder to the original size ?
3. Buying new cylinder is better then replating ? (I live in Israel, so shipping my cyl to USA and back will cost at lest 100$ shipping, new cyl will cost 308$ + 50$ shipping)

Thanks
:ugg:

 

[NO HAND]

It's a gamble here whether it's gonna blow up or hold together just fine for a while still. I've had a cylinder with a cracked plating at the bridge and I tried to keep it running because it was in the middle of the race season. It held up just fine until the end of the summer. It gave me the chance to finish the race season. Since it is on the exhaust side you have more chances that the plating will evacuate in the exhaust if it peels any further. But again, it's a chance you're taking. The plating chips may as well end up chewing up the con-rod bearing also and you will wish you choosed the safer option. It is possible to have the cylinder replated to the original bore if you choose so. Forward Motion does that.

 

[bscottr]

Another Solution....

I agree with No Hand regarding Forward Motion and re-plating. However, Forward Motion (Eric Gorr) also sell cylinders, pistons, rings, pins, circlips and gaskets as a complete kit. IMO you can't beat the price, especially if you need re-plating anyway. It is however a 150 kit and will most likely put a big smile on your face. In your case he has the package for $425 or you can send him your cylinder and receive the same kit for $350. But then you have shipping charges in both directions. He currently has your package in stock.

Check out this link: http://www.ericgorr.com/services/garage_sale.html

Another solution is to check the price for a cylinder from www.parkeryamaha.com. I think you’ll find that Eric has the better deal.

Good Luck,
Scott

 

[aharoncross]

New cylinder...

Thanks guys..
I am not sure about the prices Bscottr gave for replating ..,
new cylinder with new piston will cost around 365$ ,
so why replating if the prices are close to brand new cylinder?

Thanks

 

[NO HAND]

The plating that is used at Forward Motion is better than stock. A cylinder that has gone through them is better than a new one, and can be customized for the type of powerband you want.

 

[bscottr]

No Hand is Right,... Again!

That's one point I forgot to mention...the customized porting is included in the price. I made a mistake is my prior post. The kit for a YZ can be a 133,139 or144cc kit and may require case mods (also included for $375).

I highly recommend contacting Mr. Gorr to find out your best option. If you want to find out what others think about his work, do a search on his name in the Performance Forum.

The $365 for new cylinder and piston, does that include rings and gaskets?

Keep us posted,

Scott

WHAT’S INCLUDED WITH Forward Motion's CYLINDER REPLATING KITS

1)Your top end parts are carefully inspected to trace the cause of mechanical problems to save you money and recommend mechanical solutions.

2)The top end is disassembled and cleaned. A detailed work order is prepared noting mods needed to repair things like water leaks, faulty exhaust valves, broken bolts, casting flaws and cracks. Steel and aluminum parts are cleaned with different chemicals to prevent corrosion. Max Power charges you extra for each of these services and then hammers you with a hazardous waste charge of $15. I don’t charge extra and this work in included in the price of the package.

3)Next the metal machining process begins, including cylinder boring, porting, polishing, resurfacing of the top and bottom of the cylinder, cylinder head machining, and exhaust valve mods for the larger bore. You get to choose the powerband and type of fuel. This enables me to design the cylinder porting changes and head mods based on the fuel and if the bike is ridden at high altitude. RPM charges upwards of $300 and you don’t get a choice of powerbands. I only charge a maximum of $85 for more complete work. My specs are designed using recognized standards set by the Society of Automotive Engineers. I use TSR and Dynomation software to accomplish these design changes. For more information check out my Two-Stroke Technology page.

4)US Chrome handles all of my nickle-composite plating (NICOM) and diamond honing. USC has the best honing tooling in the business and an experienced German honing engineer that provides the roundest straightest cylinder bores for the best performance.

5)After the plating and honing is completed I chamfer all the ports and relieve the exhaust bridge using right angle porting tools and three grades of polishing media. Most of the competition relegates these tasks to the lowest paid laborers in their shops, yet it is one of the most important tasks because if its not done correctly it can lead to premature piston and ring wear.

6)The top surface of the cylinder is critical to head sealing. I machine an anti-detonation ring on the top of the cylinder, none of my competition does that! I also hand-lapp the top surface on a granite surface plate with polycrystalline media paper. Most of my competitors use things like sandpaper and glass, a hideous concept that is bone-chilling to real engineers and machinists!

7)Finally the top end is assembled with all the studs and exhaust valves and checked for proper operation. New COMETIC gaskets are included and the WISECO Pro-Lite piston kit is checked for fit and the ring gap is set.

8)Your top end is lubricated and sealed in a plastic bag ready for shipment.

9)Return shipping, I charge a flat fee of $15 for return shipping and when necessary I upgrade your package to UPS AIR to get it to you by Friday for no extra charge. My competitors use return shipping as a way to gouge you for things like insurance, packaging materials, and upgrades for air. Sometimes these additional “hidden” charges can total $75-$100 more that their advertised prices!

 

[bscottr]

Update

aharoncross,
What's the lastest? Which way did you decide to go?

Scott

 

[aharoncross]

Thanks you all..

I decided to ship my cylinder to Eric - Gorr.
After talking with him over the phone and send him my pictures,he recommand to replate or buy new cylinder .
the prices are much the same (I was mistaking regarding the shipping costs)
so I prefer Eric work over brand new cylinder , his replating is better then stock and one more.. My cylinder been ported so I don't wont to lose or change the power curve I hade.
Eric will receive my cylinder today and I will update you all as soon as I get my cylinder back.


Thanks

 

[bscottr]

aharoncross,
Thanks for the update. I believe you made a good decision. Mr. Gorr has my cyl/head now as well and I'm looking forward to riding soon.

Scott

 

[aharoncross]

Update..need your help

Hi
I just got my cylinder back from Eric and I am facing some problem.:mad:
1. I checked the cylinder piston fitting, pushed in the Wiseco piston and it is not moving smoothly, I hold the cylinder with its top end facing down, I hold the piston with its flat top facing down and insert it to the bottom of the cylinder and drop it, the piston stack with the skirts still out of the cylinder about 4mm above the bottom end of the cylinder. Using my hand I can push it down until it pops out from the top end of the cylinder, I tried my old Wiseco piston (same part number) and got almost same results.
Is that normal? :think :
I clean the piston and the cylinder carefully.but stiil the same.
I insert the ring to check the gap, it was ~0.01" with the Wiseco ring and 0.0157" with the genuine Yamaha ring (The user manual from Yamaha say gap=0.020"->0.028").

Please help guys...:ugg:
Thanks
Aharon

 

[aharoncross]

Last update !!

I talked to Eric and he asked me to send him back the cylinder and the piston.
He fixed the cylinder (hone it for 40 microns) and send it back to me the same day he receive it !! :) .
In addition he compensate me very generously, and now my YZ run grate!! :aj:
Thanks you all
And especially thanks to Eric!! :D

 

[bscottr]

Aharon,
Good to hear you have your bike running good now. Eric is something isn't he?!
I was just thinking of you this morning while watching the news from the middle east. Are you and your family OK? Hopefully the fighting isn't close by. Keep your head down.

Scott

 

[aharoncross]

Nice to have sombody thinking about you those days, :D Thanks, my family and me OK.
I lived in Hadera, which suffer some of terrorist booms and shooting action the last months, :think
Fighting is close by, the distance from the West Bank to the sea is only 10-20 miles, and Israel is between the West Bank and the sea....
But don't worry, thing hear are not as bad as they looks,
We go to work regularly, children go to school, people going on vacations,
I ride every weekend and planning my first race on 13/4/02 :aj: (races are rare here because stupid bureaucrats).

Thanks again

 

[bscottr]

Aharon,
Glad to hear everything is fairly normal. Hopefully it stays that way or even better, improves. Good luck on that first race!

Scott