Top of Cylinder Chipped

So my yz has been down for a little bit because of this chipping in the cylinder.  Its only on the top but the rest of the cylinder looks good. Obviously its time for a new piston too.

I don't understand how the big bore kit that is in it (maxpowerrpms 285) is so loved, especially since when i called them about getting it repaired they guessed that it was chipped right there before i even told them.  The amount of material they leave until it hits the o-ring is scary.

Anyways, was hoping you guys could think of a better option to get the chips welded up for cheaper than the over $300 that maxpowerrpms wants, before even buying a new piston for it.

Let me know what you guys think!  

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Picture needed! 

51 minutes ago, Gunner132 said:

So my yz has been down for a little bit because of this chipping in the cylinder.  Its only on the top but the rest of the cylinder looks good. Obviously its time for a new piston too.

I don't understand how the big bore kit that is in it (maxpowerrpms 285) is so loved, especially since when i called them about getting it repaired they guessed that it was chipped right there before i even told them.  The amount of material they leave until it hits the o-ring is scary.

Anyways, was hoping you guys could think of a better option to get the chips welded up for cheaper than the over $300 that maxpowerrpms wants, before even buying a new piston for it.

Let me know what you guys think!  

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You have a bad case of lean burn and detonation. That cylinder is either going to need to be replaced or re-plated. You figure the cost because many just buy new, and others re-plate. 

Strip, Plate, Hone 189.00. Weld, machine 60.00 add shipping both ways.  

8 minutes ago, Smoking 2's said:

Picture needed! 

I see them.

Holy hell, must have been locked in space station still! Detonation I'm not familiar with, looks hot for sure! That cylinder is toast, wow was that a factory cylinder or already done before?

Maybe head gasket was leaking Abit, hot/cold scenario

51 minutes ago, 2 STOKE YZ DOC said:

You have a bad case of lean burn and detonation. That cylinder is either going to need to be replaced or re-plated. You figure the cost because many just buy new, and others re-plate. 

Strip, Plate, Hone 189.00. Weld, machine 60.00 add shipping both ways.  

Buying a new cylinder would probably be cheaper at this point, ebay units aren't terribly expensive but the big bore kit modded the power valve and the head too, so i think she has to stay a big bore, considering the other costs associated with getting the new cylinder.  And yeah the bike was running super hot and pinging a shit ton the last time i rode it...  which is why i tore it down in the first place to find this mess.

44 minutes ago, Smoking 2's said:

Holy hell, must have been locked in space station still! Detonation I'm not familiar with, looks hot for sure! That cylinder is toast, wow was that a factory cylinder or already done before?

A previous owner somewhere down the line got it done, when i bought the bike the seller told me it was stock bore!!  Its my first 2 stroke so ill chalk it up to a learning experience.  

41 minutes ago, Smoking 2's said:

Maybe head gasket was leaking Abit, hot/cold scenario

Yeah i think so too, when i disassembled the engine inner o ring that seals the head to the cylinder was half gone!

 

 

Alright so it sounds like my best course of action is to send it out and get it dialed, get the top welded up and the cylinder re-plated.  When i spoke with maxpowerrpms they told me to send my head and powervalve with the cylinder just so they could make sure it was all good. I might even see if i can get them to get my squish dialed in at this point. 

Im still confused why any of this happened in the first place, when i bought the bike the jetting seemed good and compression has always been really strong.  I even threw a lectron carb on it so i never had to mess with it again.  Oh well, starting fresh will be good!  Im pretty sure this is damage from a previous owner that i was unfortunate enough to inherit.

You can sometimes find a complete PV system for a stock head around 175 bucks, and a used damged OEM stock bore jug for 150 or less. That would give you the stock top end again, or a new jug is around 300.

If $300 includes welding and replating then I think that's your best bet. Did you price a piston from them?

You may also want to retard timing a little.

44 minutes ago, Blackwoodz said:

If $300 includes welding and replating then I think that's your best bet. Did you price a piston from them?

You may also want to retard timing a little.

My quotes are off the PowerSeal price sheet. 

Never price Millinuim, or others.

And we can't say, "Langcourt" in the USA any more since the company that used to do the work, dropped the franchise.

i think he quoted me $325 for welding and replating when i called maxpowerrpms.  Thought id give them first shot at it because it is their kit and I think they are the only ones with the 71mm piston that i need (that i can find). 

Millennium tech has a price listed on their website of $295, and are a much more known company so ill give them a call too.  

none of these prices are with a piston included, but i know maxpowerrpms offers 20% off any parts you order through them (including their 71mm wiseco piston), im not sure what millennium offers.

 

I still believe sending it to maxpower is your best option.....unless you just keep shopping eBay. You can find a used oem cylinder with pv.

Either way by the time all said and done you will have at least $500 into the topend. 

Talk to Eric gorr. He quoted me a very good price on welding boring porting a plating my 125 cylinder.

Does max power even do the replaying and the repair work themselves? Or do they just send it out to one of the cylinder repair shops like u.s. chrome or powerseal etc. 

I like powerseal work better than millennium.

8 minutes ago, SmokinJoe said:

Does max power even do the replaying and the repair work themselves? Or do they just send it out to one of the cylinder repair shops like u.s. chrome or powerseal etc. 

I like powerseal work better than millennium.

That's my new go to shop. 

10 minutes ago, nickmell said:

Talk to Eric gorr. He quoted me a very good price on welding boring porting a plating my 125 cylinder.

When Langcourt was on the menu, I would get 125's done for about 50 bucks less than 250's. Could be the size thing. PowerSeal has only done one 250 for me thus far and did a great job, but they don't have a CC price sheet, just straight forward. 

Solid reccommendation on powerseal!  They are cheapest so far and I just called them and they said the big bore was no problem. Just need to send them a piston so they can match it. 

My bike is sitting back home so I can't really get a good look at things to reference, but i think if I decide all I need is cylinder repair then they will be the ones getting my business. If the powervalve or head looks like it could use some work I'll send the whole thing off to maxpowerrpms for a refresh. All that will happen this weekend, I'll definitely take pictures if I have questions or need opinions.  

Not going to go into squish too much here because I know it's everywhere on these forums but I'll eventually measure that too when it's all put together, maybe machine my head down if needed on a lathe at school. 

just got off the phone with maxpowerrpms again, what happened to 2 strokes being cheap?!?! :lame:

maxpowerrpms:

$190 for a 71mm piston (exclusive to them, no way around it), maybe can get a discount if i use their service?

$225 for cylinder replate, $75 for welding.

- they told me again to send my head and powervalve to make sure its all good.

Total: $490 not including shipping or any other surprises

 

Powerseal:

(again $190 for a piston from maxpowerrpms)

$190 for cylinder replate, $60 for welding

- they told me all i need to send is a piston to match the bore to

Total: $440 not including shipping or other surprises

 

do you guys think its worth the extra ~$50 to send it out to the guys that did the kit originally?  My gut tells me they will go above and beyond to make their kit perfect again but every time ive talked to them it seems like they are reluctant to do me any favors.  I do like that they want to see the powervalve and head though, just so they can get a better picture on what went down.

 

 

Go back to 250cc stock bore to save $ on pistons.

Get the Wiseco piston number off the original box. 71mm sounds like early 80's size for the YZ250's, I just looked on flea-bay and they are listed as well as on the Wiseco site. 

Also check your exhaust pipe.  Make sure you have no cracks or leaks in it at the motor end.  If you do,  that will lean out the mixture and cause what you see here.

Send your cylinder us chrome.  www.usnicom.com.  They may be able to do a cylinder swap, or repair your cylinder. I would send them pictures first. They just re nickasil coated, polished and bored my head for like $200 plus shipping. I have a 1998 YZ 250. They did an amazing  job. There is also a coupon you can print off their website. 

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